extrinsic rewards on decreasing intrinsic motivation. Participants were randomly assigned to two groups. A chess-problem task was used in this study. Data was collected in two sessions. Session I Participants were asked to complete a background questionnaire that included questions on the amount of time the participant played chess during the week, the number of years that the participant has been playing chess for, amount of enjoyment the participant gets from playing the game, etc. The participants in both groups were then told that the experimenter needed to enter the information in the computer and for the next 10 minutes the participant were free to do whatever they liked. The experimenter left the room for 10 minutes. The room had similar chess-problem tasks on the table, some magazines as well as coffee was made available for the participants if they chose to have it. The time spent on the chess-problem task was observed through a one way mirror by the experimenter during the 10 minute break and was used as a measure of intrinsic motivation. After the experimenter returned, the experimental group was told that there was a monetary reward for the participant who could work on the most chess problems in the given time and that the reward is for this session only and would not be offered during the next session. The control group was not offered a monetary reward. Session II The second session was the same for the two groups: After a filler task, the experimenter left the room for 10 minutes and the time participants spent on the chess-problem task was observed. The experimental group was reminded that there was no reward for the task this time. After both sessions the participants were required to respond to questionnaires evaluating the task, i.e. to what degree did they find the task interesting. Both groups reported that they found the task interesting. The results of the study showed that the experimental group showed a significant decrease in time spent on the chess-problem task during the 10-minute free time from session 1 to session 2 in comparison to the group that was not paid, thus confirming the hypothesis presented by Deci that contingent monetary reward for an activity decreases the intrinsic motivation to perform that activity. Other studies were conducted around this time focusing on other types of rewards as well as other external factors that play a