text:
The Experimental Analysis of Behavior
By B. F. Skinner
The 1957 American Scientist article, reproduced in full
The 1957 American Scientist article, reproduced in full
Not so long ago the expression "a science of behavior" would have been regarded as a contradiction in terms. Living organisms were distinguished by the fact that they were spontaneous and unpredictable. If you saw something move without being obviously pushed or pulled, you could be pretty sure it was alive.
This was so much the case that mechanical imitations of living things—singing birds which flapped their wings, figures on a clock tolling a bell—had an awful fascination which, in the age of electronic brains and automation, we cannot recapture or fully understand. One hundred and fifty years of science and invention have robbed living creatures of this high distinction.
Science has not done this by creating truly spontaneous or capricious systems. It has simply discovered and used subtle forces which, acting upon a mechanism, give it the direction and apparent spontaneity which make it seem alive. Similar forces were meanwhile being discovered in the case of the living organism itself. By the middle of the seventeenth century it was known that muscle, excised from a living organism and out of reach of any "will," would contract if pinched or pricked or otherwise stimulated, and during the nineteenth century larger segments of the organism were submitted to a similar analysis. The discovery of the reflex, apart from its neurological implications, was essentially the discovery of stimuli—of forces acting upon an organism which accounted for part of its behavior.
For a long time the analysis of behavior took the form of the discovery and collection of reflex mechanisms. Early in the present century, the Dutch physiologist Rudolph Magnus [1], after an exhaustive study of the reflexes involved in the maintenance of posture, put the matter this way: when a cat hears a mouse, turns toward the source of the sound, sees the mouse, runs toward it, and pounces, its posture at every stage, even to the selection of the foot which is to take the first step, is determined by reflexes which can be demonstrated one by one under experimental conditions. All the cat has to do is to decide whether or not to pursue the mouse; everything else is prepared for it by its postural and locomotor reflexes.
To pursue or not to pursue is a question, however, which has never been fully answered on the model of the reflex, even with the help of Pavlov's principle of conditioning. Reflexes—conditioned or otherwise—are primarily concerned with the internal economy of the organism and with maintaining various sorts of equilibrium. The behavior through which the individual deals with the surrounding environment and gets from it the things it needs for its existence and for the propagation of the species cannot be forced into the simple all-or-nothing formula of stimulus and response. Some well-defined patterns of behavior, especially in birds, fish, and invertebrates are controlled by "releasers" which suggest reflex stimuli [2], but even here the probability of occurrence of such behavior varies over a much wider range, and the conditions of which that probability is a function are much more complex and subtle. And when we come to that vast repertoire of "operant" behavior which is shaped up by the environment in the lifetime of the individual, the reflex pattern will not suffice at all.
In studying such behavior we must make certain preliminary decisions. We begin by choosing an organism—one which we hope will be representative but which is first merely convenient. We must also choose a bit of behavior—not for any intrinsic or dramatic interest it may have, but because it is easily observed, affects the environment in such a way that it can be easily recorded, and for reasons to be noted subsequently, may be repeated many times without fatigue. Thirdly, we must select or construct an experimental space which can be well controlled.
These requirements are satisfied by the situation shown in Figure 1. A partially sound-shielded aluminum box is divided into two compartments. In the near compartment a pigeon, standing on a screen floor, is seen in the act of pecking a translucent plastic plate behind a circular opening in the partition. The plate is part of a delicate electric key; when it is pecked, a circuit is closed to operate recording and controlling equipment. Colored lights can be projected on the back of the disk as stimuli. The box is ventilated, and illuminated by a dim ceiling light.
We are interested in the probability that in such a controlled space the organism we select will engage in the behavior we thus record. At first blush, such an interest may seem trivial. We shall see, however, that the conditions which alter the probability, and the processes which unfold as that probability changes, are quite complex. Moreover, they have an immediate, important bearing on the behavior of other organisms under other circumstances, including the organism called man in the everyday world of human affairs.
Probability of responding is a difficult datum. We may avoid controversial issues by turning at once to a practical measure, the frequency with which a response is emitted. The experimental situation shown in Figure 1 was designed to permit this frequency to vary over a wide range. In the experiments to be described here, stable rates are recorded which differ by a factor of about 600. In other experiments, rates have differed by as much as 2000:1. Rate of responding is most conveniently recorded in a cumulative curve. A pen moves across a paper tape, stepping a short uniform distance with each response. Appropriate paper speeds and unit steps are chosen so that the rates to be studied give convenient slopes.
Among the conditions which alter rate of responding are some of the consequences of behavior. Operant behavior usually affects the environment and generates stimuli which "feed back" to the organism. Some feedback may have the effects identified by the layman as reward and punishment. Any consequence of behavior which is rewarding or, more technically, reinforcing, increases the probability of further responding. Unfortunately, a consequence which is punishing has a much more complex result [3]. Pecking the key in our experimental space has certain natural consequences. It stimulates the bird tactually and auditorily, and such stimulation may be slightly reinforcing. We study the effect more expediently, however, by arranging an arbitrary consequence which is clearly so. For example, food is reinforcing to a hungry pigeon (for our present purposes we need not inquire why this is so), and we therefore arrange to present food with a special magazine. When a solenoid is energized, a tray containing a mixture of grains is brought into position in the square opening below the key in Figure 1, where the pigeon has access to the grain for, say, four seconds.
We can demonstrate the effect of operant reinforcement simply by connecting the key which the pigeon pecks to the solenoid which operates the food tray. A single presentation of food, following immediately upon a response, increases the rate with which responses to the key are subsequently emitted so long as the pigeon remains hungry. By reinforcing several responses, we may create a high probability of responding. If the magazine is now disconnected, the rate declines to, and may even go below, its original level. These changes are the processes of operant conditioning and extinction, respectively. More interesting phenomena are generated when responses are merely intermittently reinforced. It is characteristic of everyday life that few of the things we do always "pay off." The dynamic characteristics of our behavior depend upon the actual schedules of reinforcement.
The effects of intermittent reinforcement have been extensively studied in the laboratory [3] [4]. A common sort of intermittency is based on time. Reinforced responses can be spaced, say, ten minutes apart. When one reinforcement is received, a timer is started which opens the reinforcing circuit for ten minutes; the first response after the circuit is closed is reinforced. When an organism is exposed to this schedule of reinforcement for many hours, it develops a characteristic performance which is related in a rather complex way to the schedule. A short sample of such a performance is shown in Figure 2, obtained with a cumulative recorder. The scales and a few representative speeds are shown in the lower right-hand corner. The experimental session begins at a. The first reinforcement will not occur until ten minutes later, and the bird begins at a very low rate of responding. As the 10-minute interval passes, the rate increases, accelerating fairly smoothly to a terminal rate at reinforcement at b. The rate then drops to zero. Except for a slight abortive start at c, it again accelerates to a high terminal value by the end of the second 10-minute interval. A third fairly smooth acceleration is shown at d. (At e the pen instantly resets to the starting position on the paper.) The over-all pattern of performance on a "fixed interval" schedule is a fairly smoothly accelerating scallop in each interval, the acceleration being more rapid the longer the initial pause. Local effects due to separate reinforcements are evident, however, which cannot be discussed here for lack of space [4]. If the intervals between reinforcements are not fixed, the performance shown in Figure 2 cannot develop.
If the length of interval is varied essentially at random, responding occurs at a single rate represented by a constant slope in the cumulative record. Two examples are shown in Figure 3. In the upper curve, a hungry pigeon is reinforced with grain on a variable-interval schedule, where the mean interval between reinforcements is 3 minutes. Reinforcements occur where marked by pips. In the lower curve a hungry chimpanzee, operating a toggle switch, is reinforced on the same schedule with laboratory food. The over-all rate under variable-interval reinforcement is a function of the mean interval, of the level of food-deprivation, and of many other variables. It tends to increase slowly under prolonged exposure to any one set of conditions. The constant rate itself eventually becomes an important condition of the experiment and resists any change to other values. For this reason the straight lines of Figure 3 are not as suitable for baselines as might be supposed.
Reinforcements may be scheduled with a counter instead of a timer. For example, we may maintain a fixed ratio between responses and reinforcements. In industry this schedule is referred to as piecework or piece-rate pay. Anyone who has seen workers paid on such a schedule is familiar with some features of the performance generated: a high rate is sustained for long periods of time. For this reason, the schedule is attractive to employers, but it is generally recognized that the level of activity generated is potentially dangerous and justified only in seasonal or other periodic employment.
Performances of a pigeon under fixed-ratio reinforcement are shown in Figure 4. In the left-hand record reinforcements occur every 210 responses (at a, b, c, and elsewhere). The over-all rate is high. Most of the pauses occur immediately after reinforcement. At the right is the performance generated when the pigeon pecks the key 900 times for each reinforcement. This unusually high ratio was reached in some experiments in the Harvard Psychological Laboratories by W. H. Morse and R. J. Herrnstein. A short pause after reinforcement is the rule.
A variable-ratio schedule programmed by a counter corresponds to the variable-interval schedule programmed by a timer. Reinforcement is contingent on a given average number of responses but the numbers are allowed to vary roughly at random. We are all familiar with this schedule because it is the heart of all gambling devices and systems. The confirmed or pathological gambler exemplifies the result: a very high rate of activity is generated by a relatively slight net reinforcement. Where the "cost" of a response can be estimated (in terms, say, of the food required to supply the energy needed, or of the money required to play the gambling device), it may be demonstrated that organisms will operate at a net loss.
When the food magazine is disconnected after intermittent reinforcement, many more responses continue to occur than after continuous reinforcement. After certain schedules, the rate may decline in a smoothly accelerated extinction curve. After other schedules, when the rate itself enters prominently into the experimental conditions, it may oscillate widely. The potential responding built up by reinforcement may last a long time. The writer has obtained extinction curves six years after prolonged reinforcement on a variable-ratio schedule [5]. Ratio schedules characteristically produce large numbers of responses in extinction. After prolonged exposure to a ratio of 900:1 (Figure 4) the bird was put in the apparatus with the magazine disconnected. During the first 4-1/2 hours, it emitted 73,000 responses.
Interval and ratio schedules have different effects for several reasons. When a reinforcement is scheduled by a timer, the probability of reinforcement increases during any pause, and first responses after pauses are especially likely to be reinforced. On ratio schedules responses which are part of short runs are likely to be reinforced. Moreover, when a given schedule of reinforcement has had a first effect, the performance which develops becomes itself an important part of the experimental situation. This performance, in combination with the schedule, arranges certain probable conditions at the moment of reinforcement. Sometimes a schedule produces a performance which maintains just those conditions which perpetuate the performance. Some schedules generate a progressive change. Under still other schedules the combination of schedule and performance yields conditions at reinforcement which generate a different performance, which in turn produces conditions at reinforcement which restore the earlier performance.
Charles B. Ferster and the writer have checked this explanation of the effect of schedules by controlling conditions more precisely at the moment of reinforcement [4]. For example, we guaranteed that all reinforced responses would be preceded by pauses instead of making this condition merely probable under an interval schedule. In a variable interval performance, such as that shown in Figure 3, it is not difficult to find responses which are preceded by, say, 3-second pauses. We can arrange that only such responses will be reinforced without greatly disturbing our schedule. When this is done, the slope of the record immediately drops. On the other hand, we may choose to reinforce responses which occur during short rapid bursts of responding, and we then note an immediate increase in rate.
If we insist upon a very long pause, we may be able to reinforce every response satisfying these conditions and still maintain a very low rate. The differential reinforcement of low rates was first studied by Douglas Anger in the Harvard Laboratories. Wilson and Keller at Columbia have reported an independent investigation [6]. Recently W. H. Morse and the writer have studied the effect of relatively long enforced pauses. Figure 5 shows the performance obtained in one such experiment. Any response which followed a pause at least 3 minutes in duration was reinforced. Whenever a response was made before 3 minutes had elapsed, the timer was reset and another 3-minute pause required. Under these conditions a very low stable rate of responding obtains. The figure shows a continuous performance (cut into segments for easier reproduction) in a single experimental session of 143 hours, during which time the pigeon received approximately 250 reinforcements. At no time did it pause for more than 15 minutes, and it seldom paused for more than 5 minutes.
The situation under this schedule is inherently unstable. Rate of responding increases with the severity of food deprivation and decreases as the bird becomes satiated. Let us assume that at some time during the experiment, say, at a in Figure 5, reinforcements are occurring too infrequently to maintain the bird's body weight. The bird is operating, so to speak, at a loss. The increasing deprivation then increases the rate of responding and makes it even less likely that the pigeon will wait 3 minutes in order to respond successfully for reinforcement. Nothing but starvation lies ahead in that direction. If, on the other hand, the bird is receiving slightly more reinforcements than necessary to maintain body weight, the level of deprivation will be decreased. This will produce a lower rate of responding, which in turn means that the 3-minute pause is more frequently satisfied and reinforcements still more frequently received. In such a case the result is a fully satiated bird, and the experiment must be brought to a close. This actually happened at b in Figure 5 where reinforcements had become so frequent that the bird was rapidly gaining weight. This inherent instability can be corrected by changing the required pause in terms of the organism's performance. If the over-all rate of reinforcement begins to drift in either direction, the required pause may be appropriately changed. Thus the experiment in Figure 5 could have been continued if at point c, say, the required interval had been increased to 4 minutes. By an appropriate adjustment of the interval, we have been able to keep a pigeon responding continuously for 1500 hours—that is, 24 hours a day, 7 days a week, for approximately 2 months. Pigeon breeders have said that pigeons never sleep (roosting is merely a precautionary device against blind flying), and the statement seems to be confirmed by experiments of the present sort.
By differentially reinforcing high rates of responding, pigeons have been made to respond as rapidly as 10 or 15 responses per second. Here technical problems become crucial. It is not difficult to construct a key which will follow rapid responding, but the topography of the behavior itself changes. The excursions of head and beak become very small, and it is doubtful whether any single "response" can be properly compared with a response at a lower rate.
In their study of different kinds of schedules of reinforcement, Ferster and the writer found that it was possible to set up several performances in a single pigeon by bringing each one of them under stimulus control. Several different colored lights were projected on the translucent key and responses were reinforced on several corresponding schedules. Figure 6 shows a typical performance under such a multiple schedule of reinforcement. When the key was red, the pigeon was reinforced on a 6-minute fixed-interval schedule. The usual interval scallops are seen, as at a and b. When the key was green, the pigeon was reinforced upon completing 60 responses (a fixed ratio of 60:1). The usual ratio high rate is shown as at c and d. When the key was yellow, reinforcements followed a variable-interval schedule where a pause of 6 seconds was required. The resulting low steady performance is shown at e, f, and elsewhere. In one experiment we were able to show nine different performances under the control of nine different patterns on the key.
The experiment may be complicated still further by introducing more than one key and by reinforcing on two or more schedules concurrently. An example of the resulting performances is shown in Figure 7, from some research by Ferster, at the Yerkes Laboratories for Primate Biology at Orange Park, Florida. In Ferster's experiment, a chimpanzee operates two toggle switches, one with each hand. Responses with the right hand are reinforced on a fixed ratio of approximately 210:1, and the performance recorded from the right toggle switch is shown in the upper part of Figure 7. As usual in many ratio performances, pauses occur after reinforcements. Responses with the left hand are at the same time being reinforced on a variable-interval schedule with a mean interval of 5 minutes, and the performance is shown in the lower part of the figure. There is some interaction between the performances, for reinforcements in the variable-interval record usually correspond to slight pauses in the ratio performance. In general, however, the experiment shows a remarkable independence of two response systems in a single organism.
In speaking about colors projected on the key or the fact that a key is on the right or left, we are, of course, talking about stimuli. Moreover, they are stimuli which act prior to the appearance of a response and thus occur in the temporal order characteristic of the reflex. But they are not eliciting stimuli; they merely modify the probability that a response will occur, and they do this over a very wide range. The general rule seems to be that the stimuli present at the moment of reinforcement produce a maximal probability that the response will be repeated. Any change in the stimulating situation reduces the probability. This relationship is beautifully illustrated in some experiments by Norman Guttman [7] and his colleagues at Duke University on the so called stimulus generalization gradient. Guttman makes use of the fact that, after a brief exposure to a variable-interval schedule, a large number of responses will be emitted by the organism without further reinforcement (the usual extinction curve) and that, while these are being emitted, it is possible to manipulate the stimuli present and to determine their relative control over the response without confusing the issue by further reinforcement. In a typical experiment, for example, a monochromatic light with a wave length of 550 millimicrons was projected on the key during variable-interval reinforcement. During extinction, monochromatic lights from other parts of the visible spectrum were projected on the key for short periods of time, each wavelength appearing many times and each being present for the same total time. Simply by counting the number of responses made in the presence of each wavelength, Guttman and his colleagues have obtained stimulus generalization gradients similar to those shown in Figure 8. The two curves represent separate experiments. Each is an average of measurements made on six pigeons. It will be seen that during extinction responding was most rapid at the original wavelength of 550 millimicrons. A color differing by only 10 millimicrons controls a considerably lower rate of responding. The curves are not symmetrical. Colors toward the red end of the spectrum control higher rates than those equally distant the violet end. With this technique Guttman and his colleagues have studied gradients resulting from reinforcement at two points in the spectrum, gradients surviving after a discrimination has been set up by reinforcing one wavelength and extinguishing another, and so on.
The control of behavior achieved with methods based upon rate of responding has given rise to a new psychophysics of lower organisms. It appears to be possible to learn as much about the sensory processes of the pigeon as from the older "introspective" methods with human subjects. An important new technique of this sort is due to D. S. Blough [8]. His ingenious procedure utilizes the apparatus shown in Figure 9. A pigeon, behaving most of the time in total darkness, thrusts its head through an opening in a partition at a, which provides useful tactual orientation. Through the small opening b, the pigeon can sometimes see a faint patch of light indicated by the word Stimulus. (How this appears to the pigeon is shown at the right.) The pigeon can reach and peck two keys just below the opening b, and it is sometimes reinforced by a food magazine which rises within reach at c. Through suitable reinforcing contingencies Blough conditions the pigeon to peck Key B whenever it can see the light and Key A whenever it cannot. The pigeon is occasionally reinforced for pecking Key A by the presentation of food (in darkness). Blough guarantees that the pigeon cannot see the spot of light at the time this response is made because no light at all is then on the key. By a well established principle of "chaining," the pigeon is reinforced for pecking Key B by the disappearance of the spot of light. This suffices to keep responses to both keys in strength.
A further fact about the apparatus is that Key B automatically reduces the intensity of the spot of light, while Key A increases it. Suppose, now, that a pigeon is placed in a brightly lighted space for a given interval of time and then put immediately into the apparatus. The spot of light is at an intensity in the neighborhood of the bright adapted threshold. If the pigeon can see the spot, it pecks Key B until it disappears. If it cannot see the spot, it pecks Key A until it appears. In each case it then shifts to the other key. During an experimental session of one hour or more, it holds the spot of light very close to its threshold value, occasionally being reinforced with food. The intensity of the light is recorded automatically. The result is the "dark-adaptation curve" for the pigeon's eye. Typical curves show a break as the dark adaptation process shifts from the cone elements in the retina to the rods.
By repeating the experiment with a series of monochromatic lights, Blough has been able to construct spectral sensitivity curves for the pigeon which are as precise as those obtained with the best human observers. An example is shown in Figure 10, where data for the pigeon are compared with data for an aphakic human [9]—one who has had a crystalline lens removed for medical reasons. Such a person sees violet light more sensitively than normal subjects because the light is not absorbed by the lens. Even with this advantage the human observer is no more sensitive to light at the violet end of the spectrum than the pigeon. The discontinuities in the photopic curves (the lower set of open circles) of the pigeon appear to be real. The surprising correspondence in the scotopic curves (after dark adaptation, and presumably mediated by the rods) is remarkable when we recall that the avian and mammalian eye parted company in the evolutionary scale of things many millions of years ago.
So far our data have been taken from the pleasanter side of life—from behavior which produces positive consequences. There are important consequences of another sort. Much of what we do during the day is done not because of the positive reinforcements we receive but because of aversive consequences we avoid. The whole field of escape, avoidance, and punishment is an extensive one, but order is slowly being brought into it. An important contribution has been the research of Murray Sidman [10] on avoidance behavior. In the Sidman technique, a rat is placed in a box the floor of which is an electric grid through which the rat can be shocked. The pattern of polarity of the bars of the grid is changed several times per second so that the rat cannot find bars of the same sign to avoid the shock. In a typical experiment a shock occurs every 20 seconds unless the rat presses the lever, but such a response postpones the shock for a full 20 seconds. These circumstances induce a rat to respond steadily to the lever, the only reinforcement being the postponement of shock. The rat must occasionally receive a shock—that is, it must allow 20 seconds to pass without a response—if the behavior is to remain in strength. By varying the intervals between shocks, the time of postponement, and various kinds of warning stimuli, Sidman has revealed some of the important properties of this all-too-common form of behavior.
A sample of behavior which W. H. Morse and the writer obtained with the Sidman procedure is shown in Figure 11. Here both the interval between shocks and the postponement time were 8 seconds. (White space has been cut out of the record and the separate segments brought together to facilitate reproduction.) The records report a 7-hour experimental session during which about 14,000 responses were emitted. Occasional shocks are indicated by the downward movements of the pen (not to be confused with the fragments of the reset line). A significant feature of the performance is the warm-up at a. When first put into the apparatus the rat "takes" a number of shocks before entering upon the typical avoidance pattern. This occurs whenever a new session is begun. It may indicate that an emotional condition is required for successful avoidance behavior. The condition disappears between sessions and must be reinstated. The figure shows considerable variation in over-all rate and many local irregularities. At times small groups of shocks are taken, suggesting a return to the warm-up condition.
The consequences of behavior, whether positive or negative, and the control acquired by various stimuli related to them do not exhaust the variables of which behavior is a function. Others lie in the field commonly called motivation. Food is a reinforcement only to a hungry organism. In practice this means an organism whose body weight has been reduced substantially below its value under free feeding. Reinforcing stimuli are found in other motivational areas. Responding to a key can be reinforced with water when the organism is deprived of water, with sexual contact when the organism has been sexually deprived, etc. The level of deprivation is in each case an important condition to be investigated. How does food deprivation increase the rate of eating or of engaging in behavior reinforced with food? How does satiation have the opposite effect? The first step toward answering such questions is an empirical study of rate of responding as a function of deprivation. An analysis of the internal mechanisms responsible for the relations thus discovered may require techniques more appropriately employed in other scientific disciplines.
An example of how the present method may be applied to a problem in motivation is an experiment by Anliker and Mayer [11] on the familiar and important problem of obesity. Obese animals eat more than normal, but just how is their ingestive behavior disrupted? Anliker and Mayer have studied several types of normal and obese mice. There are strains of mice in which the abnormality is hereditary: some members of a litter simply grow fat. A normal mouse may be made obese by poisoning it with goldthioglucose or by damaging the hypothalamus. The food getting behavior of all these types of obese mice can be observed in the apparatus shown in Figure 12. A fat mouse is shown depressing a horizontal lever which projects from the partition in the box. On a fixed-ratio schedule, every 25th response produces a small pellet of food, delivered by the dispenser seen behind the partition. A supply of water is available in a bottle.
Each mouse was studied continuously for several days. The resulting cumulative curves (Figure 13) show striking differences among the patterns of ingestion. Curve C shows normal cyclic changes in rate. The nonobese mouse eats a substantial part of its daily ration in a single period (as at a and 6), and for the rest of each day responds only at a low over-all rate. The result is a wave-like cumulative curve with 24 hour cycles. A mouse of the same strain made obese by goldthioglucose poisoning does not show this daily rhythm but continues to respond at a fairly steady rate (Curve A). The slope is no higher than parts of Curve C, but the mechanism which turns off ingestive behavior in a normal mouse appears to be inoperative. Curve B is a fairly similar record produced by a mouse of the same strain made obese by a hypothalamic lesion. Curves D and E are for litter mates from a strain containing a hereditary-obese factor. E is the performance of the normal member. Curve D, showing the performance of the obese member, differs markedly from Curves A and B. The hereditary obese mouse eats at a very high rate for brief periods, which are separated by pauses of the order of one or two hours. A different kind of disturbance in the physiological mechanism seems to be indicated.
Williams and Teitelbaum [12] have recently produced a fourth kind of obese animal, with an apparatus in which a rat must eat a small amount of liquid food to avoid a shock. The avoidance contingencies specified by Sidman and illustrated in Figure 11 are used to induce the rat to ingest unusually large amounts of even unpalatable food. A condition which may be called "behavioral obesity" quickly develops.
Other powerful variables which affect operant behavior are found in the field of pharmacology. Some drugs which affect behavior—alcohol, caffeine, nicotine, and so on—were discovered by accident and have had a long history. Others have been produced explicitly to yield such effects. The field is an active one (partly because of the importance of pharmacotherapy in mental illness) and available compounds are multiplying rapidly. Most of the behavioral drugs now available have effects which would be classified in the fields of motivation and emotion. There is no reason, however, why the effects of various contingencies of reinforcement could not be simulated by direct chemical action—why "intelligence" could not be facilitated or confusion or mental fatigue reduced. In any case, the behavior generated by various contingencies of reinforcement (including the control of that behavior via stimuli) are the base lines against which motivational and emotional effects are felt. The present technique for the study of operant behavior offers a quantitative, continuous record of the behavior of an individual organ ism, which is already being widely used—in industry as well as the research laboratory—in screening psychopharmacological compounds and investigating the nature of pharmacological effects.
An example is some research by Peter B. Dews [13], of the Department of Pharmacology of the Harvard Medical School. Dews has studied the effect of certain sedatives on the pigeon's performance under a multiple fixed-interval fixed-ratio schedule. A standard base line obtained in a short daily experimental session is shown in the upper half of Figure 14. The pigeon is reinforced on a fixed-interval schedule when the key is red and on a fixed-ratio schedule when the key is green, the two schedules being presented in the order: one interval, one ratio, two intervals, ten ratios, two intervals, four ratios. In addition to the usual characteristics of the multiple performance, this brief program shows local effects which add to its usefulness as a base line. For example, the period of slow responding after reinforcement is greater when the preceding reinforcement has been on a ratio schedule—that is, the scallops at a and b are shallower than those at c and d. The effect of moderate doses of barbiturates, bromides, and other sedatives under a multiple fixed-interval fixed-ratio schedule is to destroy the interval performance while leaving the ratio performance essentially untouched. The lower half of Figure 14 was recorded on the day following the upper half. Three milligrams of chlorpromazine had been injected 2.5 hours prior to the experiment. The tranquilizing effect of chlorpromazine develops only with repeated doses; what is shown here is the immediate effect of a dose of this magnitude, which is similar to that of a sedative.. It will be seen that the ratios survive (at e, /, and g) but that the interval performances are greatly disturbed. There is responding where none is expected, as at A, but not enough where a rapid rate usually obtains. This fact provides a useful screening test, but it also throws important light on the actual nature of sedation. The difference between intervals and ratios may explain some instances in which sedatives appear to have inconsistent effects on human subjects.
The interval performance is also damaged by chlorpromazine in a different type of compound schedule. Ferster and the writer have studied the effect of concurrent schedules in which two or more control ling circuits set up reinforcements independently. In one experiment a rat was reinforced with food at fixed intervals of 10 minutes and also by the avoidance of shock, where a shock occurred every 20 seconds unless postponed for 20 seconds by a response to a lever. The normal result of this concurrent schedule is shown in the upper part of Figure 15. When the rat is "working for food and to avoid a shock," its performance suggests the usual interval scallop tilted upward so that instead of pausing after reinforcement, the rat responds at a rate sufficient to avoid most shocks. A one-milligram dose of chlorpromazine immediately before the experiment has the effect shown in the lower part of the figure. The interval performance is eliminated, leaving the slow steady responding characteristic of avoidance conditioning.
Drugs which alter emotional conditions may be studied by examining the effect of the emotional variable upon operant behavior. An example is the condition usually called "anxiety." Many years ago Estes and the writer [14] showed that the normal performance under fixed-interval reinforcement was suppressed by a stimulus which characteristically preceded a shock. In our experiment, a rat was reinforced on a fixed interval schedule until a stable base line developed. A stimulus was then introduced for 3 minutes and followed by a shock to the feet of the rat. In later presentations the stimulus began to depress the rate of responding—an effect comparable to the way in which "anxiety" interferes with the daily behavior of a man. Hunt and Brady [is] have shown that some of the "treatments" for human anxiety (for example, electroconvulsive shock) temporarily eliminate the conditioned suppression in such experiments. Brady has recently applied this technique to the study of tranquilizing drugs. In his experiment, a rat is reinforced on a variable interval schedule until responding stabilizes at a constant intermediate rate. Stimuli are then presented every 10 minutes. Each stimulus lasts for 3 minutes and is followed by a shock. Conditioned suppression soon appears. In Figure 16 each simple arrow shows the onset of the stimulus. In order to isolate the performance in the presence of the stimulus, the record is displaced downward. In the saline control, shortly after the onset of the stimulus, the rate falls to zero, as shown by the horizontal portions of the displaced segments. As soon as the shock is received (at the broken arrows, where the pen returns to its normal position), responding begins almost immediately at the normal rate. The base line between stimuli is not smooth because a certain amount of chronic anxiety develops under these circumstances. A suitable dose of a stimulant such as amphetamine has the effect of increasing the over-all rate, as seen in the middle part of Figure 16. The sup pressing stimulus is, if anything, more effective. A course of treatment with reserpine, another tranquilizer, has the effect of slightly depressing the over-all rate but restoring responding during the formerly suppressing stimulus. Thus, in the lower part of Figure 16, the slopes of the displaced segments of the record are of the same order as the over-all record itself. The reserpine has eliminated an effect which, from a similarity of inciting causes, we may perhaps call anxiety.
Another field in which important variables affecting behavior are studied is neurology. Performances under various schedules of reinforcement supply base lines which are as useful here as in the field of psychopharmacology. The classical pattern of research is to establish a performance containing features of interest, then to remove or damage part of the nervous system, and later to have another look at the behavior. The damaged performance shows the effect of the lesion and helps in inferring the contribution of the area to normal behavior.
The procedure is, of course, negative. Another possibility is that neurological conditions may be arranged which will have a positive effect. A step in this direction has been taken by James Olds [17] with his discovery that weak electrical stimulation of certain parts of the brain, through permanently implanted electrodes, has an effect similar to that of positive reinforcement. In one of Olds' experiments, a rat presses a lever to give itself mild electrical stimulation in the anterior hypothalamus. When every response is so "reinforced," behavior is sustained in strength for long periods of time. One of Olds' results is shown in Figure 17. The electrical "reinforcement" was begun shortly after noon. The rat responded at approximately 2000 responses per hour throughout the day and night until the following noon. There are only three or four brief pauses during this period. When the experiment was continued the following day, however, the rat fell asleep and slept for 20 hours. Then it awoke and began again at approximately the same rate. Although there remain some puzzling differences between behavior so reinforced and behavior reinforced with food, Olds' discovery is an important step toward our understanding of the physiological mechanisms involved in the operation of the environmental variable. A similar reinforcing effect of brain stimulation has been found in cats by Sidman, Brady, Boren, and Conrad [18] and in monkeys by Lilly, of the National Institutes of Health, and Brady, in the laboratories of the Walter Reed Army Institute of Research.
What about man? Is rate of responding still an orderly and meaningful datum here, or is human behavior the exception in which spontaneity and caprice still reign? In watching experiments of the sort described above, most people feel that they could "figure out" a schedule of reinforcement and adjust to it more efficiently than the experimental organism. In saying this, they are probably overlooking the clocks and calendars, the counters and the behavior of counting, with which man has solved the problem of intermittency in his environment. But if a pigeon is given a clock or a counter, it works more efficiently [19], and without these aids man shows little if any superiority.
Parallels have already been suggested between human and infrahuman behavior in noting the similarity of fixed-ratio schedules to piece-rate pay and of variable ratios to the schedules in gambling devices. These are more than mere analogies. Comparable effects of schedules of reinforcement in man and the other animals are gradually being established by direct experimentation. An example is some work by James Holland [20] at the Naval Research Laboratories on the behavior of observing. We often forget that looking at a visual pattern or listening to a sound is itself behavior, because we are likely to be impressed by the more important behavior which the pattern or sound controls. But any act which brings an organism into contact with a discriminative stimulus, or clarifies or intensifies its effect, is reinforced by this result and must be explained in such terms. Unfortunately mere "attending" (as in reading a book or listening to a concert) has dimensions which are difficult to study. But behavior with comparable effects is sometimes accessible, such as turning the eyes toward a page, tilting a page to bring it into better light, or turning up the volume of a phonograph. Moreover, under experimental conditions, a specific response can be reinforced by the production or clarification of a stimulus which controls other behavior. The matter is of considerable practical importance. How, for example, can a radar operator or other "lookout" be kept alert? The answer is: by reinforcing his looking behavior.
Holland has studied such reinforcement in the following way. His human subject is seated in a small room before a dial. The pointer on the dial occasionally deviates from zero, and the subject's task is to restore it by pressing a button. The room is dark, and the subject can see the dial only by pressing another button which flashes a light for a fraction of a second. Pressing the second button is, then, an act which presents to the subject a stimulus which is important because it controls the behavior of restoring the pointer to zero.
Holland has only to schedule the deviations of the pointer to produce changes in the rate of flashing the light comparable to the performances of lower organisms under comparable schedules. In Figure 18, for example, the upper curve shows a pigeon's performance on a fairly short fixed-interval. Each interval shows a rather irregular curvature as the rate passes from a low value after reinforcement to a high, fairly constant, terminal rate. In the lower part of the figure is one of Holland's curves obtained when the pointer deflected from zero every three minutes. After a few hours of exposure to these conditions, the subject flashed the light ("looked at the pointer") only infrequently just after a deflection, but as the interval passed, his rate accelerated, sometimes smoothly, sometimes abruptly, to a fairly constant terminal rate. (An interesting feature of this curve is the tendency to "run through" the reinforcement and to continue at a high rate for a few seconds after reinforcement before dropping to the low rate from which the terminal rate then emerges. Examples of this are seen at a, b, and c. Examples in the case of the pigeon are also seen at d and e. In their study of schedules, Ferster and the writer had investigated this effect in detail long before the human curves were obtained.)
Other experiments on human subjects have been conducted in the field of psychotic behavior. In a project at the Behavior Research Laboratories of the Metropolitan State Hospital, in Waltham, Massachusetts, a psychotic subject spends one or more hours each day in a small room containing a chair and an instrument panel as seen in Figure 19. At the right of the instrument board is a small compartment (a) into which reinforcers (candy, cigarettes, coins) are dropped by an appropriate magazine. The board contains a plunger (b), similar to that of a vending machine. The controlling equipment behind a series of such rooms is shown in Figure 20. Along the wall at the left, as at a, are seen four magazines, which can be loaded with various objects. Also seen are periscopes (as at b) through which the rooms can be observed through one-way lenses. At the right are cumulative recorders (as at c) and behind them panels bearing the controlling equipment which arranges schedules.
It has been found that even deteriorated psychotics of long standing can, through proper reinforcement, be induced to pull a plunger for a variety of reinforcers during substantial daily experimental sessions and for long periods of time. Schedules of reinforcement have the expected effects, but the fact that these organisms are sick is also apparent. In Figure 21, for example, the record at A shows a "normal" human performance on a variable-interval schedule where the subject (a hospital attendant) is reinforced with nickels on an average of once per minute. A straight line, similar to the records of the pigeon and chimpanzee in Figure 3, is obtained. Records B, C, and D are the performances of three psychotics on the same schedule working for the same reinforcers. Behavior is sustained during the session (as it is during many sessions for long periods of time), but there are marked deviations from straight lines. Periods of exceptionally rapid responding alternate with pauses or periods at a very low rate.
That a schedule is nevertheless effective in producing a characteristic performance is shown by Figure 22. A fixed-ratio performance given by a pigeon under conditions in which there is substantial pausing after reinforcement is shown at A. In spite of the pauses, the general rule holds: as soon as responding begins, the whole ratio is quickly run off. Fixed-ratio curves for two psychotic subjects, both severely ill, are shown at B and C. Only small ratios can be sustained (40 and 20, respectively), and pauses follow all reinforcements. Nevertheless, the performance is clearly the result of a ratio schedule: once responding begins, the complete ratio is run off.
It is unfortunate that a presentation of this sort must be confined to mere examples. Little more can be done than to suggest the range of application of the method and the uniformity of results over a fairly wide range of species. The extent to which we are moving toward a unified formulation of this difficult material cannot be properly set forth. Perhaps enough has been said, however, to make one point—that in turning to probability of response or, more immediately, to frequency of responding we find a datum which behaves in an orderly fashion under a great variety of conditions. Such a datum yields the kind of rigorous analysis which deserves a place in the natural sciences. Several features should not be overlooked. Most of the records reproduced here report the behavior of single individuals; they are not the statistical product of an "average organism." Changes in behavior are followed continuously during substantial experimental sessions. They often reveal changes occurring within a few seconds which would be missed by any procedure which merely samples behavior from time to time. The properties of the changes seen in the cumulative curves cannot be fully appreciated in the non-instrumental observation of behavior. The reproducibility from species to species is a product of the method. In choosing stimuli, responses, and reinforcers appropriate to the species being studied, we eliminate the sources of many species differences. What emerges are dynamic properties of behavior, often associated with the central nervous system.
Have we been guilty of an undue simplification of conditions in order to obtain this level of rigor? Have we really "proved" that there is comparable order outside the laboratory? It is difficult to be sure of the answers to such questions. Suppose we are observing the rate at which a man sips his breakfast coffee. We have a switch concealed in our hand, which operates a cumulative recorder in another room. Each time our subject sips, we close the switch. It is unlikely that we shall record a smooth curve. At first the coffee is too hot and sipping is followed by aversive consequences. As it cools, positive reinforcers emerge, but satiation sets in. Other events at the breakfast table intervene. Sipping eventually ceases not because the cup is empty but because the last few drops are cold.
But although our behavioral curve will not be pretty, neither will the cooling curve for the coffee in the cup. In extrapolating our results to the world at large, we can do no more than the physical and biological sciences in general. Because of experiments performed under laboratory conditions, no one doubts that the cooling of the coffee in the cup is an orderly process, even though the actual curve would be very difficult to explain. Similarly, when we have investigated behavior under the advantageous conditions of the laboratory, we can accept its basic orderliness in the world at large even though we cannot there wholly demonstrate law.
In turning from an analysis of this sort many familiar aspects of human affairs take on new significance [21]. Moreover, as we might expect, scientific analysis gives birth to technology. The insight into human behavior gained from research of this sort has already proved effective in many areas. The application to personnel problems in industry, to psychotherapy, to "human relations" in general, is clear. The most exciting technological extension at the moment appears to be in the field of education. The principles emerging from this analysis, and from a study of verbal behavior based upon it, are already being applied in the design of mechanical devices to facilitate instruction in reading, spelling, and arithmetic in young children, and in routine teaching at the college level.
In the long run one may envisage a fundamental change in government itself, taking that term in the broadest possible sense. For a long time men of good will have tried to improve the cultural patterns in which they live. It is possible that a scientific analysis of behavior will provide us at last with the techniques we need for this task—with the wisdom we need to build a better world and through it better men.
Click "American Scientist" to access home page


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Maybe you're not the most accurate when it comes to snapping photos. Maybe you're always just a little too late, or a little too early. Congratulation on being a human like the rest of us. Window's Research new camera application—BLINK—can give you a hand with that (the picture-taking) on Windows Phone 8. How? The shotgun approach.
Much like Nokia's Smart Group Shot, BLINK controls for lack of quality with an excess of quantity. Unlike Nokia's solution, you can get it on any Windows Phone. As soon as you go to take a "shot" with BLINK, it'll go ahead and capture nearly a dozen, after which you can scroll through the results and pick out your favorite. Once you've done that, you can get rid of all the trash, or hang onto it in case you change you mind later, or want to print a flip-book or something.
Once installed, BLINK will show up as a lens on WP8 Phone, and if it seems up your alley, you can download it right now, from the Windows Phone 8 store for free.

subset: commoncrawl


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I'm interested in this problem: Given an undirected graph $G(E, V)$, Is there a partition of $G$ into graphs $G_1(E_1, V_1)$ and $G_2(E_2, V_2)$ such that $G_1$ and $G_2$ are isomorphic? Here $E$ is partitioned into two disjoint sets $E_1$ and $E_2$. Sets $V_1$ and $V_2$ are not necessarily disjoint. $E1∪E2=E$ and $V1∪V2=V$.
This problem is at least as hard as Graph Isomorphism Problem. I guess it is harder than Graph Isomorphism but not NP-hard.
Is this partition problem $NP$-hard?
I posted it on CS theory without any answer.


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The energy policy of the future should be sung to the tune of "Here Comes the Sun."
Events out of Japan persist in an irradiated gloom. The disaster unfolding in Fukushima Daiichi represents a level of calamity for which adjectives have yet to be invented. It's quite possible that in the end, in a replay of the Chernobyl disaster, areas around the plant may not be suitable again for human habitation.
You would think such a wretched outcome might give a prudent observer pause, but among energy policy wonks and boosters of bipartisanship in the United States the refrain remains the same: Nuclear energy, our long-time power pinch-hitter, still waits on deck.
Yes, renewable energy sources sure would be nice, these guys will assure you, but, shucks, for the foreseeable future, America has no choice but to power its industrial output and middle-class lifestyle via reliable fossil fuels: natural gas, coal, oil—and the dangerous atom.
Let's put aside for a moment that this self-serving position is supported in Washington with cash from traditional energy corporations. Let's ignore the fact that these energy sources look economically efficient compared to renewable energy only if you completely discount the industry's many subsidies and neglect to include in the price its diseconomies: degradation of land, water, and air; poisoning of cattle and people; climate change; the potential for 20,000 years or so of nuclear contamination; etc.
What if renewable energy were already cost-competitive with the national grid's traditional sources of power? Wouldn't it make the most sense, observing the precautionary principle, to maintain a preferential option for renewable energy?
One leftie, Birkenstock-sporting news source, Bloomberg Business News, reports that solar energy's time may have already arrived. Turns out part of the reason solar power has never compared well to fossil-fuel generated energy has been a fundamental misassumption about how to price the power. The costs of solar are often overstated because they include prices paid by consumers and small businesses who install roof-top power systems instead of the rates utilities charge each other to produce power. This is like comparing a utility plant's apples to your Aunt Betty's oranges.
According to Bloomberg solar production is already viable against fossil fuels in the world's sunny regions. A solar infrastructure boom has begun and industry executives, perhaps with too sunny a perspective, are predicting solar capacity to double by 2013 after quadrupling since 2008.
General Electric, noted hippie energy naturalists, are constructing the nation's largest photovoltaic panel factory with a goal to build enough panels to produce 400 megawatts of power each year. Government initiatives, like California's commitment to producing a third of its energy via renewables by 2020, will help drive down solar's overall costs even further.
As a big fan of good stewardship, the church has already found practical ways to endorse a light switch to renewable power, installing solar panels at the Vatican and committing the Curia to carbon neutrality. Pope Benedict XVI has frequently added personal insight on what could be called the spirituality of sustainability.
In 2008 he warned: "The brutal consumption of creation begins where God is not, where matter is henceforth only material for us, where we ourselves are the ultimate demand, where the whole is merely our property and we consume it for ourselves alone."
Here in the United States, the Catholic Climate Covenant (catholicclimatecovenant.org) offers training for "climate ambassadors" to take its message of good energy stewardship to U.S. parishes.
No energy source is without its problems, but we may be able to dispense with the biggest obstacle to solar power, a rhetorical barrier that proposes it is prohibitively expensive. So when we look for paths ahead to modernize our energy grid and get the fossil fuels out of our economy, our politics, and our foreign policy, let's just say no to atomic energy's planned second coming, and let's start building a sustainable grid that's a true investment in the future.
This article appeared in the June 2011 issue of U.S. Catholic (Vol. 76, No. 6, page 39).
Image: Tom Wright


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text: Showtunes Guest Spot for Flute Showtunes Guest Spot for Flute Showtunes Guest Spot for Flute Showtunes Guest Spot for Flute (5 ratings) £6.99 Quantity: at £6.99 each Add To Basket At Oggies Music we specialise in second-hand, refurbished and ex shop display items that we sell at internet prices. Only personal items are sold as new such as reeds and lubrication.Please note that we judge the condition of this product to be: Used Good"Ten big stage hits in melody line arrangements by Simon Lesley with specially recorded backing tracks"--Cover. No words.We aim to ship items within 1 working day, orders placed after 9.00 am will be shipped the next working day. For international orders please use Ebay and Ebay Global Shipping. We have a shop in Dulverton, Somerset and always encourage you to come and look at the items before you buy. If it is an instrument you are welcome to try it before buying, just get in contact. Payment options are, Paypal, cash on collection, or when collecting any major card, we also accept bank transfers just ask for details.


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Use the tools below to refine your search by only displaying reviews with a certain number of star ratings or to only show reviews from a certain time period. Eg click on '1 star' to just display the reviews we have which received a 1 star rating click or 'Within the last month' to display just reviews posted over the last month.
As rated by our community of reviewers
" Excellent.Camera " Read More
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Recent Posts
Monday, 8 August 2011
Adele - Set Fire to the Rain Lyrics
Posted by Reem Adeeb
The weather has been chronically bad here; storms with thunder so loud it makes you burrow your way into your mattress when it hits in the wee hours of the morning.... rain drops the size of golf balls and just as destructive,my awning has been folded in like origami by the sheer weight of the water...and the mosquito's? There are mozzy raids at dawn and dusk...it is all very "Apocalypse Now".
So what happened to summer? Who knows but I'll just " Set Fire to the Rain"....


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taking in consideration this simple query:
- Code: Select all Expand viewCollapse view
select distinct "Colors" from "Items"
"Colors" may have 1 or several lines with colors into, exmple:
- Code: Select all Expand viewCollapse view
I just need to obtain all distinct color entries but with the detail that "Colors" may have a color for each line. Char(10) as line change.
So i want to query and obtain all results that are distinct but with that kind of read each line on "colors".
By the moment i have no idea how can i do that from SQL....


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kitchen closed
Wine open.
The cook is off duty.
Also available printed onto oatmeal linen
100% natural white linen
screenprinted with eco-friendly ink in black
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text: As a record label, you're bound to get music sent to you from aspiring musicians, hoping that their creative efforts find fertile ground and we welcome these submissions. Obviously, the more well known the label, the more music you get and from further afield. Sadly, the quantity far outstrips the quality by a thousand-fold and the process of sifting through all of this, um, creativity requires the persistence and patience of a '49er panning for precious metals in a streambed. The Beautiful New Born Children are one of those bands that make such a labor of love worthwhile. Yes, Virginia, there is a Santa Claus and, occasionally, bands do get signed off unsolicited demos. The music came on a non-descript CD-R (with no contact info, mind you) that belied the contents within: feverish blasts of raw rock 'n' roll that stomps and swaggers all over the garage. Imagine The Sonics recording Slanted And Enchanted in 1966 for In The Red Records and you're in the neighborhood. Have we oversold? Perhaps. But what the hell, careers have been built on worse hyperbole. Much remains a mystery still. It took weeks to track 'em down through a six-degrees-of-separation game that only the internet age could possibly facilitate. And once contact was made, details were slow in coming. Sure, we've corresponded, even spoken once or twice. The lead singer plays guitar both here and with a bevy of other projects on the docket including, surprisingly, Schneider TM. The other guitarist is usually a bassist who happens to make a living designing lace patterns for women's lingerie. The drummer is usually a guitarist who picked up the sticks for the first time for The BNBC and was in a band before with the bassist, who's married to the lead singer. And, yes, they're all parents to beautiful children, though only one of them is new born.


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A bridal shower tea party is a great theme to consider when planning this pre-wedding party bash. Why? For a number of reasons: it's absolutely girly, can be great for a low budget and smaller guest list (as you can avoid serving a full meal), and can be held anywhere, from someone's home or backyard or even a tea house, if you can find one in your area.
Our tea party favors will be the perfect gift to commemorate an Alice in Wonderland-inspired event. Popular choices of favors for a tea party include our personalized tea bags or tea infusers that are often paired with personalized apothecary jars filled with the bride's favorite blend of loose tea.


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LSU Men's Golf Facilities
November 30, 2018, 02:04 PM (CT)
LSUsports.net (@LSUsports)
LSU Sports Interactive
LSU Sports Interactive
Members of the LSU men's golf team have access to some of the finest facilities in the nation in which to improve their level of competition on and off the golf course.
The University Club, which serves as the team's home course, was recently named the 13th best home for college golf in the country by Golf Digest, while the LSU Golf House opened in 2002 as one of the leading practice facilities in the nation with the latest state-of-the-art equipment and technology.
Team members also have the tools needed to succeed in the classroom by using the Cox Communications Academic Center for Student-Athletes, a $15 million facility that opened to rave reviews in the fall of 2002
University Club
Bilyeu Golf Practice Facility
Academic Center for Student-Athletes


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What's Gone Wrong With HP?
In 2010, Hewlett-Packard Co.'s then-chief executive Mark Hurd boasted the company was "the largest IT company in the world" and said "we are still not to our full potential."
Two years and two CEOs later, HP is stumbling. Over that time, the Palo Alto, Calif., company's market capitalization has fallen to less than $30 billion from more than $100 billion. On Friday, HP's shares hit a new 10-year low.


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Identifying and Treating ADHD
We have all had one of these experiences at one time or another. Perhaps it was at the grocery store, watching frustrated parents call their children's names repeatedly and implore them to "put that down." Maybe it was a situation at school with a child who could not seem to sit still and was always in motion. Maybe we noticed a child who appears always to be daydreaming in class-the student who will not focus on an activity long enough to finish it. Possibly the child is bored with a task, seemingly as soon as it has begun, and wants to move on to something else. We all puzzle over these challenging behaviors.
Attention Deficit Hyperactivity Disorder (ADHD) has many faces and remains one of the most talked-about and controversial subjects in education. Hanging in the balance of heated debates over medication, diagnostic methods, and treatment options are children, adolescents, and adults who must manage the condition and lead productive lives on a daily basis.
What is ADHD?
Attention Deficit Hyperactivity Disorder (ADHD) is a neurological condition that involves problems with inattention and hyperactivity-impulsivity that are developmentally inconsistent with the age of the child. We are now learning that ADHD is not a disorder of attention, as had long been assumed. Rather, it is a function of developmental failure in the brain circuitry that monitors inhibition and self-control. This loss of self-regulation impairs other important brain functions crucial for maintaining attention, including the ability to defer immediate rewards for later gain (Barkley, 1998a). Behavior of children with ADHD can also include excessive motor activity. The high energy level and subsequent behavior are often misperceived as purposeful noncompliance when, in fact, they may be a manifestation of the disorder and require specific interventions. Children with ADHD exhibit a range of symptoms and levels of severity. In addition, many children with ADHD often are of at least average intelligence and have a range of personality characteristics and individual strengths.
Children with ADHD typically exhibit behavior that is classified into two main categories: poor sustained attention and hyperactivity-impulsiveness. As a result, three subtypes of the disorder have been proposed by the American Psychiatric Association in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV): predominantly inattentive, predominantly hyperactive-impulsive, and combined types (Barkley, 1997). A child expressing hyperactivity commonly will appear fidgety, have difficulty staying seated or playing quietly, and act as if driven by a motor. Children displaying impulsivity often have difficulty participating in tasks that require taking turns. Other common behaviors may include blurting out answers to questions instead of waiting to be called and flitting from one task to another without finishing. The inattention component of ADHD affects the educational experience of these children because ADHD causes them to have difficulty in attending to detail in directions, sustaining attention for the duration of the task, and misplacing needed items. These children often fail to give close attention to details, make careless mistakes, and avoid or dislike tasks requiring sustained mental effort.
Although these behaviors are not in themselves a learning disability, almost one-third of all children with ADHD have learning disabilities (National Institute of Mental Health [NIMH], 1999). Children with ADHD may also experience difficulty in reading, math, and written communication (Anderson, Williams, McGee, & Silva, 1987; Cantwell & Baker, 1991; Dykman, Akerman, & Raney, 1994; Zentall, 1993). Furthermore, ADHD commonly occurs with other conditions. Current literature indicates that approximately 40-60 percent of children with ADHD have at least one coexisting disability (Barkley, 1990a; Jensen, Hinshaw, Kraemer, et al., 2001; Jensen, Martin, & Cantwell, 1997). Although any disability can coexist with ADHD, certain disabilities seem to be more common than others. These include disruptive behavior disorders, mood disorders, anxiety disorders, tics and Tourette's Syndrome, and learning disabilities (Jensen, et al., 2001). In addition, ADHD affects children differently at different ages. In some cases, children initially identified as having hyperactive-impulsive subtype are subsequently identified as having the combined subtype as their attention problems surface.
These characteristics affect not only the academic lives of students with ADHD, they may affect their social lives as well. Children with ADHD of the predominantly hyperactive-impulsive type may show aggressive behaviors, while children of the predominantly inattentive type may be more withdrawn. Also, because they are less disruptive than children with ADHD who are hyperactive or impulsive, many children who have the inattentive type of ADHD go unrecognized and unassisted. Both types of children with ADHD may be less cooperative with others and less willing to wait their turn or play by the rules (NIMH, 1999; Swanson, 1992; Waslick & Greenhill, 1997). Their inability to control their own behavior may lead to social isolation. Consequently, the children's self-esteem may suffer (Barkley, 1990a).
In the United States, an estimated 1.46 to 2.46 million children (3 percent to 5 percent of the student population) have ADHD (American Psychiatric Association, 1994; Anderson, et al., 1987; Bird, et al., 1988; Esser, Schmidt, & Woemer, 1990; Pastor & Reuben, 2002; Pelham, Gnagy, Greenslade, & Milich, 1992; Shaffer, et al., 1996; Wolraich, Hannah, Pinock, Baumgaertel, & Brown, 1996). Boys are four to nine times more likely to be diagnosed, and the disorder is found in all cultures, although prevalence figures differ (Ross & Ross, 1982).
What Causes ADHD?
ADHD has traditionally been viewed as a problem related to attention, stemming from an inability of the brain to filter competing sensory inputs such as sight and sound. Recent research, however, has shown that children with ADHD do not have difficulty in that area. Instead, researchers now believe that children with ADHD are unable to inhibit their impulsive motor responses to such input (Barkley, 1997; 1998a).
It is still unclear what the direct and immediate causes of ADHD are, although scientific and technological advances in the field of neurological imaging techniques and genetics promise to clarify this issue in the near future. Most researchers suspect that the cause of ADHD is genetic or biological, although they acknowledge that the child's environment helps determine specific behaviors.
Imaging studies conducted during the past decade have indicated which brain regions may malfunction in patients with ADHD, and thus account for symptoms of the condition (Barkley, 1998a). A 1996 study conducted at the National Institutes for Mental Health (NIMH) found that the right prefrontal cortex (part of the cerebellum) and at least two of the clusters of nerve cells known collectively as the basal ganglia are significantly smaller in children with ADHD (as cited in Barkley, 1998a). It appears that these areas of the brain relate to the regulation of attention. Why these areas of the brain are smaller for some children is yet unknown, but researchers have suggested mutations in several genes that are active in the prefrontal cortex and basal ganglia may play a significant role (Barkley, 1998a). In addition, some nongenetic factors have been linked to ADHD including premature birth, maternal alcohol and tobacco use, high levels of exposure to lead, and prenatal neurological damage. Although some people claim that food additives, sugar, yeast, or poor child rearing methods lead to ADHD, there is no conclusive evidence to support these beliefs (Barkley, 1998a; Neuwirth, 1994; NIMH, 1999).
How Do We Identify ADHD?
Although toddlers and preschoolers, on occasion, may show characteristics of ADHD, some of these behaviors may be normal for their age or developmental stage. These behaviors must be exhibited to an abnormal degree to warrant identification as ADHD. Even with older children, other factors (including environmental influences) can produce behaviors resembling ADHD.
The criteria set forth by the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) are used as the standardized clinical definition to determine the presence of ADHD (see DSM-IV Criteria for ADHD). A person must exhibit several characteristics to be clinically diagnosed as having ADHD:
|The behavior in question must occur more frequently in the child than in other children at the same developmental stage.
|Early onset.
|At least some of the symptoms must have been present prior to age 7.
The symptoms must also have been present for at least 6 months prior to the evaluation.
The symptoms must have a negative impact on the child's academic or social life.
The symptoms must be present in multiple settings.
The specific DSM-IV criteria are set forth in the following chart.
|DSM-IV Criteria for Attention Deficit/Hyperactivity Disorder
|American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Washington, DC, American Psychiatric Association, 1994.
Legal Requirements for Identification of and Educational Services for Children With ADHD
Two important federal mandates protect the rights of eligible children with ADHD-the Individuals with Disabilities Education Act (IDEA) and Section 504 of the Rehabilitation Act of 1973 (Section 504). The regulations implementing these laws are 34 CFR sections 300 and 104, respectively, which require school districts to provide a "free appropriate public education" to students who meet their eligibility criteria. Although a child with ADHD may not be eligible for services under IDEA, he or she may meet the requirements of Section 504.
The requirements and qualifications for IDEA are more stringent than those of Section 504. IDEA provides funds to state education agencies for the purpose of providing special education and related services to children evaluated in accordance with IDEA and found to have at least one of the 13 specific categories of disabilities, and who thus need special education and related services. Attention Deficit Hyperactivity Disorder may be considered under the specific category of "Other Health Impairment" (OHI), if the disability results in limited strength, vitality, or alertness, including a heightened alertness to environmental stimuli that results in limited alertness with respect to the educational environment and that is due to chronic or acute health problems.
Under IDEA, each public agency-that is, each school district-shall ensure that a full and individual evaluation is conducted for each child being considered for special education and related services. The child's individualized education program (IEP) team uses the results of the evaluation to determine the educational needs of the child. The results of a medical doctor's, psychologist's, or other qualified professional's assessment indicating a diagnosis of ADHD may be an important evaluation result, but the diagnosis does not automatically mean that a child is eligible for special education and related services. A group of qualified professionals and the parent of the child determine whether the child is an eligible child with a disability according to IDEA. Children with ADHD also may be eligible for services under the "Specific Learning Disability," "Emotional Disturbance," or other relevant disability categories of IDEA if they have those disabilities in addition to ADHD.
After it has been determined that a child is eligible for special education and related services under IDEA, an IEP is developed that includes a statement of measurable annual goals, including benchmarks or short-term objectives that reflect the student's needs. The IEP goals are determined with input from the parents and cannot be changed without the parents' knowledge. Although children who are eligible under IDEA must have an IEP, students eligible under Section 504 are not required to have an IEP but must be provided regular or special education and related aids or services that are designed to meet their individual educational needs as adequately as the needs of nondisabled students are met.
Section 504 was established to ensure a free appropriate education for all children who have an impairment-physical or mental-that substantially limits one or more major life activities. If it can be demonstrated that a child's ADHD adversely affects his or her learning-a major life activity in the life of a child-the student may qualify for services under Section 504. To be considered eligible for Section 504, a student must be evaluated to ensure that the disability requires special education or related services or supplementary aids and services. Therefore, a child whose ADHD does not interfere with his or her learning process may not be eligible for special education and related services under IDEA or supplementary aids and services under Section 504.
IDEA and Section 504 require schools to provide special education or to make modifications or adaptations for students whose ADHD adversely affects their educational performance. Such adaptations may include curriculum adjustments, alternative classroom organization and management, specialized teaching techniques and study skills, use of behavior management, and increased parent/ teacher collaboration. Eligible children with ADHD must be placed in regular education classrooms, to the maximum extent appropriate to their educational needs, with the use of supplementary aids and services if necessary. Of course, the needs of some children with ADHD cannot be met solely within the confines of a regular education classroom, and they may need special education or related aids or services provided in other settings.
Components of a Comprehensive Evaluation
A diagnosis of ADHD is multifaceted and includes behavioral, medical, and educational data gathering. One component of the diagnosis includes an examination of the child's history through comprehensive interviews with parents, teachers, and health care professionals. Interviewing these individuals determines the child's specific behavior characteristics, when the behavior began, duration of symptoms, whether the child displays the behavior in various settings, and coexisting conditions. The American Academy of Pediatrics (AAP) stresses that since a variety of psychological and developmental disorders frequently coexist in children who are being evaluated for ADHD, a thorough examination for any such coexisting condition should be an integral part of any evaluation (AAP, 2000).
Behavioral Evaluation
Specific questionnaires and rating scales are used to review and quantify the behavioral characteristics of ADHD. The AAP has developed clinical practice guidelines for the diagnosis and evaluation of children with ADHD, and finds that such behavioral rating scales accurately distinguish between children with and without ADHD (AAP, 2000). Conversely, AAP recommends not using broadband rating scales or teacher global questionnaires in the diagnosis of children with ADHD. They suggest using ADHD-Specific rating scales including:
CPRS-R:L-ADHD Index
(Conners Parent Rating Scale-1997
Revised Version: Long Form, ADHD Index Scale)
CTRS-R:L-ADHD Index
(Conners Teacher Rating Scale-1997
Revised Version: Long Form, ADHD Index Scale)
CPRS-R:L-DSM-IV Symptoms
(Conners Parent Rating Scale-1997
Revised Version: Long Form, DSM-IV Symptoms Scale)
CTRS-R:L-DSM-IV Symptoms
(Conners Teacher Rating Scale-1997
Revised Version: Long Form, DSM-IV Symptoms Scale)
(Barkley's School Situations Questionnaire-Original Version, Number of Problem Settings Scale)
(Barkley's School Situations Questionnaire-Original Version, Mean Severity Scale)
(Taken from Green, Wong, Atkins, et al. (1999). Diagnosis of Attention Deficit/Hyperactivity Disorder. Technical Review 3. Rockville, MD: U.S. Department of Health and Human Services, Agency for Health Care Policy and Research, as cited in AAP, 2000).
As with all psychological tests, child-rating scales have a range of measurement error. Appropriate scales have satisfactory norms for the child's chronological age and ability levels.
Collecting information about the child's ADHD symptoms from several different sources helps ensure that the information is accurate. Appropriate sources of information include the child's parents, teachers, other diagnosticians such as psychologists, occupational therapists, speech therapists, social workers, and physicians. It is also important to review both the child's previous medical history as well as his or her school records.


text:
Hurricane Sandy ravaged large parts of New York City and New Jersey, flooding streets and homes, washing away piers, cutting down trees and power lines, forcing people to flee their homes, scrounge for food, line up for gas and search for power to charge their cell phones.
While metro New York residents are looking forward to a return to normalcy, some national security analysts are warning that what Americans in the Northeast experienced temporarily could be the merest foretaste of what all Americans can expect if action is not taken to prevent a full-blown assault on vital U.S. infrastructures.
Indeed, while surveys show most Americans thought this week's U.S. presidential election was all about the economy, these voices are saying the threat from countries like Iran or North Korea may restore foreign and defense policy to voters' top concerns.
At issue is the danger of an electromagnetic pulse (EMP) attack, a plausible nuclear threat that has gotten no attention in the recent campaign.
Whereas military planners used to focus on nuclear weapons deployed against a major U.S. population center, which would take a fair amount of sophistication to target precisely, the new worry concerns a nuclear explosion detonated at high altitude.
A rogue band of terrorists or nuclear rogue state like Iran may be in a position to launch a single nuclear payload into the atmosphere above the United States, and thereby incapacitate every electric system in the U.S. Hospitals would be without power, banks could not transfer funds electronically, people could not use credit cards or cell phones.
The Obama Administration is currently developing an executive order on the issue of cybersecurity.
Concern over an EMP attack prompted the U.S. to set up in 2001 a commission to study the nature of the threat, the vulnerabilities of U.S. military and civilian systems and the capacity of the U.S. to recover from an attack.
Its 2008 official report warned: "An EMP attack potentially could disrupt or collapse the food infrastructure over a large region encompassing many cities for a protracted period of weeks, months or even longer. Widespread damage of the infrastructures would impede the ability of undamaged fringe areas to aid in recovery. Therefore, it is highly possible that the recovery time would be very slow and the amount of human suffering great, including loss of life."
The commission's 2004 official report stated that "…some potential sources of EMP threats are difficult to deter—they can be terrorist groups that have no state identity, have only one or a few weapons, and are motivated to attack the U.S. without regard for their own safety. Rogue states, such as North Korea and Iran, may also be developing the capability to pose an EMP threat to the United States, and may also be unpredictable and difficult to deter."
Indeed, Iran recently announced its intention to project its naval power off the U.S. coastline in the next few years, making vivid the possibility of ship-based EMP assault. A fresh Congressional Research Service report issued last month by a naval analyst warns of a lower-level worry – that the Chinese military is working on electromagnetic systems to disrupt U.S. warfighting capabilities. The purpose of these "low-yield EMP warheads" would be to disable U.S. aircraft carriers in a future conflict over Taiwan.
But the bigger danger that has EMP activists concerned, is of a single, crude nuclear device with a primitive missile device of the kind Iran or Iranian-sponsored terrorists could deliver.
A bipartisan, nonprofit organization dedicated to forestalling the danger of the EMP threat called EMPACT America has organized around this issue.
Also, Congress is considering the Shield Act (H.R. 668), which would empower the Federal Energy Regulatory Commission to protect the national electric grid by ensuring there are enough extra-high-voltage transformers to survive and recover from an EMP attack. That bill was referred to a subcommittee last year and has yet to receive a full hearing.


text:
A collection of scholarly works about individual liberty and free markets. A project of Liberty Fund, Inc.
Plutarch's Lives. The Translation called Dryden's. Corrected from the Greek and Revised by A.H. Clough, in 5 volumes (Boston: Little Brown and Co., 1906). https://oll.libertyfund.org/titles/1770,
A five volume translation by Dryden.
The text is in the public domain.
This material is put online to further the educational goals of Liberty Fund, Inc. Unless otherwise stated in the Copyright Information section above, this material may be used freely for educational and academic purposes. It may not be used in any way for profit.


text:
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Books in the News
James A. Garfield Collection - Unboxed Collection
Unboxed Collection
Donation of Duane L. Ross (on shelf, not boxed):
Folio scrapbook covering the assassination and death of President James A. Garfield, and the trial and execution
of Charles Guiteau. [Compiled by the Toledo Commandery, No. 7, Knights Templar?] From the library
of H.M. Ross.
Framed Garfield Items (including those hanging in archival reading room):
Garfield, James A. Autograph letter, signed, to Wallace Ford regarding the election of 1874 and personal financial
matters, 10/19/1874. Framed with an engraved portrait of Garfield by H.B. Hill's Sons, NY.
Garfield, James A. Letter penned by secretary and signed by Garfield regarding district politics and defending the
courage of his convictions, 1/17/1870. Framed with an engraved portrait of Garfield.
Garfield, James A. Autograph letter, signed, to Wallace Ford regarding his resignation from the Western Reserve
Eclectic Institute and the need to equip himself for his army commission, 8/17/1861. Framed with
photograph of Garfield by Sarony.
Color lithograph of Garfield family. Framed. No publication data.
Engraved card announcing memorial service for James A. Garfield, February 27, 1882 in the House of
Representatives. Framed with engraved portrait of Garfield. Bureau of Engraving and Printing, [1882].
Matching photographs of James A. and Lucretia Rudolph Garfield in original frames. n.d.
Photograph of James A. Garfield in original frame. n.d.
Photograph of Eliza Ballou Garfield, given to Mrs. F.H. Pierce and Mrs. B.B. Franklin shortly after Garfield's
death in 1881. [Original frame?] Gift of Carolyne Weasner, 1/1989.
Poster for Hiram College Theatre production "A Shooting Star: the life and achievements of James A. Garfield," by
John Shaw, 2/1981. Framed.
Pastel portrait on cloth of James A. Garfield by C. Lehman, originally hung in Ohio State Capitol (1880-1936).
Framed. Gift of James A. Jones.
"The Inauguration of James A. Garfield," lithograph by A.B. Frost for Harper's Weekly, March, 1881. Framed.
Gift of Thorn Pendleton.
Color lithograph of Garfield family c. 1880. Framed.
"National Memorial Services Upon James A. Garfield…from the Congressional Record," February 28, 1882.
Photolithograph by D.A. Partridge. Framed. Gift of Thorn Pendleton.
"Funeral of the Marty-President at Cleveland, Ohio," lithograph by E.B. Nock for Frank Leslie's Illustrated
Newspaper, 10/15/1881. Framed. Purchase, John S. Kenyon Endowment.
Lithograph of James A. Garfield and Family by Kurz and Allison, Chicago, 1882 in original frame.
Lithograph of James A. Garfield and Family by J.H. Bufford's Sons, 1882. Purchase, John S. Kenyon Endowment.
"From the Cradle to the Grave, Scenes and Incidents in the Life of Gen. James A. Garfield," lithograph by Mayer,
Merkell & Ottman, c. 1882. Framed.
"The Garfield Memorial in Lake View Cemetery," chromolithograph by Diana Weber Gardner, [c. 1990-91]. Gift
of Russell D. Sibert. Framed.
Garfield Bronze Bust and Plaster Cast:
"President James A. Garfield," bronze bust and plaster cast by Preston Powers, 1883.
American Flag from Garfield Funeral Car, 9/19/1881:
No provenance.
Labels for Items Exhibited in Garfield Memorial Exhibit at Hiram College, 1981
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