Fig. 4

Class data for Exercise 3 generated using Avida-ED. The number of updates to the first appearance of NOT is plotted for each student’s pair of trials, first when no reward is present for being able to perform NOT (light blue bars) and then when there is a reward present for being able to perform NOT (dark red bars). In some instances, NOT appeared more quickly when there was a reward and, in other instances, NOT appeared more quickly when there wasn’t a reward for it. Statistical analysis using a t test on the class data showed no difference in the time to first appearance of NOT in the presence or absence of reward