Extended Data Fig. 2: Summary statistics for the knapsack task and monkeys’ performance.

a) Histogram shows the distribution of the sum of optimal solutions in the knapsack task. b) Histogram shows the distribution of the number of items included in the optimal solutions. c) Box plots show the probability monkey G (orange) and monkey B (brown) selected combinations whose sums exceeded the limit. n = 36 and n = 26 sessions for monkeys G and B respectively. d) Line plot shows the instance-averaged performance as a function of the number of repetitions the animals experienced. For each instance, both monkey G (orange) and monkey B (brown) experienced around 15 repetitions across a month for a single stimulus set. The repetitions for an instance were sorted according to the order the animals experienced them and binned into 4 bins. Diamonds are data from stimulus set 1 and circles are data from data set 2. Error bars are SEM across n = 462 instances.