Figure 4: Motivation Incentive Integration Effects by Age Group.

Figure 4a illustrates reward rate by monetary reward level and liquid type for both age groups. Younger adults performed significantly better with juice compared to neutral solution feedback, as well as with neutral solution compared to saltwater feedback, and these liquid effects interacts with monetary reward level (see text for statistics). Older adult task performance was not modulated by liquid. Figure 4b illustrates reward rate effects by incentive block and liquid type. Younger adult task performance did not differ by liquid type in block 1, but these liquid effects were significant in the third block. In contrast, older adults show the opposite pattern - with marginally significant liquid effects in the first, but not the last, incentive block. All error bars in all plots indicate standard error of the mean.