Reward and number of choices in children's probability learning: An attempt to reconcile conflicting findings

Five event schedules (75:0, 75:25, 75:0:0, 72:25:0, 75:12.5:12.5) were examined in a size discrimination task with penny rewards and plastic token markers. The subjects were 100 fourth graders (mean age = 9.4 years) and 100 undergraduates of both sexes. Whether or not the event probabilities summed to unity proved to be a more important determiner of terminal performance than the number of response alternatives in the task (p < .01). Females maximized more than males (p < .001) and college students more than fourth graders (p < .001). Greater maximization was exhibited by fourth graders in the reward condition (p < .01). These reward effects appeared to be more consistent with a detrimental-effects-of-reward interpretation than either utility or expectancy interpretations.