Free recall of emotionally positive, neutral, and negative adjectives was used as an indirect assessment of the effects of reward on expectations about intrinsic interest. Reward for performing later activities described as interesting (a "bonus" orientation) produced recall of a greater number of emotionally positive adjectives, whereas reward for the same activities described as boring (a "bribe" orientation) produced recall of a larger number of negative adjectives. A cued-expectancy analysis suggests that reward serves to polarize initial attitude about forthcoming tasks; these polarized attitudes, like moods, influence the nature of words retrieved from memory.
American Psychological Association
Boggiano, A.K., & Hertel, P.T. (1983). Bonuses and bribes: Mood effects in memory. Social Cognition, 2(1), 49-61.