Adult age differences in learning from positive and negative probabilistic feedback.

Abstract

Past research has investigated age differences in frontal-based decision making, but few studies have focused on the behavioral effects of striatal-based changes in healthy aging. Feedback learning has been found to vary with dopamine levels; increases in dopamine facilitate learning from positive feedback, whereas decreases facilitate learning from negative feedback. Given previous evidence of striatal dopamine depletion in healthy aging, we investigated behavioral differences between college-aged and healthy older adults using a feedback learning task that is sensitive to both frontal and striatal processes. Seventeen college-aged (M = 18.9 years) and 24 healthy, older adults (M = 70.3 years) completed the Probabilistic Selection task, in which participants are trained on probabilistic stimulus-outcome information and then tested to determine whether they learned more from positive or negative feedback. As a group, the older adults learned equally well from positive and negative feedback, whereas the college-aged group learned more from positive than negative feedback, F(1, 39) = 4.10, p < .05, r(effect) = .3. However, these group differences were not due to older individuals being more balanced learners. Most individuals of both ages were balanced learners, but while all of the remaining young learners had a positive bias, the remaining older learners were split between those with positive and negative learning biases (chi(2)(2) = 6.12, p < .047). These behavioral results are consistent with the dopamine theory of striatal aging, and suggest there might be adult age differences in the kinds of information people use when faced with a current choice.