Individual Variation, Social Access and Device Solvability During Cognitive Enrichment in Captive Spider Monkeys (Ateles geoffroyi)

Cognitive enrichment can provide zoo-housed primates with opportunities for exploration, problem solving and control, but outcomes may depend on individual engagement, social access, personality and device design. We studied 11 captive Geoffroy’s spider monkeys (Ateles geoffroyi) using five food-rewarded puzzle devices (D1–D5). Five individuals were singly housed and six lived in two social groups of three; each individual or group was presented with each device in five trials. During group trials, three units of D1 were presented simultaneously, whereas D2–D5 were presented as single shared devices. We recorded contact latency, manipulation duration, frequency of use, reward acquisition, resolution time, agonistic displays and device monopolization. Because testing context was not experimentally assigned and the two contexts comprised different individuals, comparisons between contexts were interpreted descriptively. Singly housed individuals showed greater manipulation duration, higher frequency of use and shorter contact latency than group-tested individuals. The only personality association that remained significant after FDR correction, which we consider preliminary, was a negative relationship between neophilia and contact latency during group presentation of the shared devices D2–D5. Devices D1–D4 were solved in 76–88% of solitary trials and 40–90% of group presentations, whereas D5 was never solved in either context; the required functional action was not observed in any trial. Nevertheless, D5 showed the highest combined frequency of agonistic displays and monopolization. These findings suggest that cognitive enrichment should be evaluated across three complementary dimensions: individual engagement, equitable social access and functional solvability.