Figure 4.

Progressive ratio task detects the effects of age on motivation. (A) Graph depicting the number of rewards obtained by the adult and aged baboons during each day of the progressive ratio task. (B) Quantitative analysis of rewards obtained during progressive task. Adult baboons obtained significantly more rewards compared to the aged group (*** p<0.001). (C) Graph depicting the number of responses made by the baboons during progressive ratio task. (D) Quantitative analysis of stimulus responses on the progressive task. Aged baboons made significantly fewer response touches compared to adult baboons (*** p<0.001).