Figure 1.
Percentage of total refusals (to return the token and to accept the food reward combined) by male and female chimpanzees in each condition. ETLV: equity test, low value; ETHV: equity test, high value; IT: inequity test; FC: food control; DT: delay test; GR: gift reward; DETLV: differential exchange test, low value; DETHV: differential exchange test, high value (see Table 1 for details of each condition). Significant differences (P < 0.05) between sexes within each condition are indicated with an asterisk below the X axis. Significant differences (P < 0.05) between conditions for males (solid line) and females (dashed line) are indicated by a bold hatch.