options to choose at different task difficulties. The person is free to choose among several possible options of task difficulty. The motivational intensity theory offers a logical and consistent framework for research. Researchers can predict a person's actions by assuming effort refers to the energy investment. The motivational intensity theory is used to show how changes in goal attractiveness and energy investment correlate. Mood Mood, like emotion, is an affective state. However, an emotion tends to have a clear focus (i.e., its cause is self-evident), while mood tends to be more unfocused and diffuse. Mood, according to Batson, Shaw and Oleson (1992), involves tone and intensity and a structured set of beliefs about general expectations of a future experience of pleasure or pain, or of positive or negative affect in the future. Unlike instant reactions that produce affect or emotion, and that change with expectations of future pleasure or pain, moods, being diffuse and unfocused and thus harder to cope with, can last for days, weeks, months or even years (Schucman, 1975). Moods are hypothetical constructs depicting an individual's emotional state. Researchers typically infer the existence of moods from a variety of behavioral referents (Blechman, 1990). Habitual negative affect and negative mood is characteristic of high neuroticism. Positive affect and negative affect (PANAS) represent independent domains of emotion in the general population, and positive affect is strongly linked to social interaction. Positive and negative daily events show independent relationships to subjective well-being, and positive affect is strongly linked to social activity. Recent research suggests that high functional support is related to higher levels of positive affect. In his work on negative affect arousal and white noise, Seidner found support for the existence of a negative affect arousal mechanism regarding the devaluation of speakers from other ethnic origins. The exact process through which social support is linked to positive affect remains unclear. The process could derive from predictable, regularized social interaction, from leisure activities where the focus is on relaxation and positive mood, or from the enjoyment of shared activities. The techniques used to shift a negative mood to a positive one are called mood repair strategies. Social interaction Affect display is a critical facet of interpersonal communication. Evolutionary psychologists have advanced the hypothesis that hominids have evolved with sophisticated capability of reading affect displays. Emotions are portrayed as dynamic processes that mediate the individual's relation to a continually changing social