<P> This experiment tested the hypothesis that if an individual is intrinsically motivated to perform an activity, introduction of an extrinsic reward decreases the degree of intrinsic motivation to perform the task . </P> <P> Twenty - four undergraduate psychology students participated in the first laboratory experiment and were assigned to experimental (n = 12) and control group (n = 12). Each group participated in three sessions conducted on three different days . During the sessions, participants were engaged in working on a Soma cube puzzle--which the experimenters assumed was an activity college students would be intrinsically motivated to do . The puzzle could be put together to form numerous different configurations . In each session, the participants were shown four different configurations drawn on a piece of paper and were asked to use the puzzle to reproduce the configurations while they were being timed . </P> <P> The first and third session of the experimental condition were identical to control, but in the second session the participants in the experimental condition were given a dollar for completing each puzzle within time . During the middle of each session, the experimenter left the room for eight minutes and the participants were told that they were free to do whatever they wanted during that time, while the experimenter observed during that period . The amount of time spent working on the puzzle during the free choice period was used to measure motivation . </P> <P> As Deci expected, when external reward was introduced during session two, the participants spent more time working on the puzzles during the free choice period in comparison to session 1 and when the external reward was removed in the third session, the time spent working on the puzzle dropped lower than the first session . All subjects reported finding the task interesting and enjoyable at the end of each session, providing evidence for the experimenter's assumption that the task was intrinsically motivating for the college students . The study showed some support of the experimenter's hypothesis and a trend towards decrease in intrinsic motivation was seen after money was provided to the participants as external reward . </P>

Humanistic theories of motivation emphasize the idea that