Self- and partner-choice to cooperate. Top, percentage of pushes for which fixations on the partner occurred within 1,000 ms of choice in each session. Pair 1, P = 1.91 x 10 - 4 ; pair 2, P = 2.44 x 10 - 4 ; Wilcoxon signed-rank test. Bottom, percentage of pushes for which fixations on the partner and/or reward system occurred within 1,000 ms of choice in each session. Pair 1, P = 0.0004, r = 0.7 and P = 0.03, r = 0.5; pair 2, P = 0.002, r = 0.7 and P = 0.2, r = 0.3; self and partner-choice, respectively; linear regression and Pearson correlation.
