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Abstract Characterizing individual differences in cognition is crucial for understanding the evolution of cognition as well as to test the biological consequences of different cognitive traits. Here, we harnessed the strengths of a uniquely large, naturally‐living primate population at the Cayo Santiago Biological Field Station to characterized individual differences in rhesus monkey performance across two social cognitive tasks. A total ofn = 204 semi‐free‐ranging adult rhesus monkeys participated in a data collection procedure, where we aimed to test individuals on both tasks at two time‐points that were one year apart. In thesocioemotional responses task,we assessed monkeys' attention to conspecific photographs with neutral versus negative emotional expressions. We found that monkeys showed overall declines in interest in conspecific photographs with age, but relative increases in attention to threat stimuli specifically, and further that these responses exhibited long‐term stability across repeated testing. In thegaze following taskwe assessed monkeys' propensity to co‐orient with an experimenter. Here, we found no evidence for age‐related change in responses, and responses showed only limited repeatability over time. Finally, we found some evidence for common individual variation for performance across the tasks: monkeys that showed greater interest in conspecific photographs were more likely to follow a human's gaze. These results show how studies of comparative cognitive development and aging can provide insights into the evolution of cognition, and identify core primate social cognitive traits that may be related across and within individuals.
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This content will become publicly available on February 1, 2026
Familiarity, Active Memory And Pressure During A Delayed Matching-To-Sample Task In Tufted Capuchin Monkeys (Sapajus [Cebus] Apella)
Delayed matching-to-sample (DMTS) tasks are commonly used in the field of comparative cognition to study memory, including working memory. However, specific task demands vary across studies and species, and as such, DMTS tasks may engage different memory systems when features such as the available stimulus pool differ. Further, individual or species-wide differences in response to pressure to perform may increase variation within a species. We explored how task features, memory systems, and pressure interact in tufted capuchin monkeys (Sapajus [Cebus] apella) to influence performance on a DTMS task by varying the size of the possible stimulus pool across testing blocks. We also varied the amount of pressure within a testing block by training monkeys to associate a background color change with a more difficult, but more highly rewarded, trial, as we had done in previous work. In accordance with previous literature (Basile & Hampton, 2013), we found that performance greatly decreased when the possible stimulus pool was limited as compared to a large possible stimulus pool, likely because monkeys could not rely on passive familiarity memory to complete the task. However, we found no overall species tendency to fail under pressure in either the limited- or large-set conditions; instead, we found a surprising tendency to thrive under higher pressure. Taken together, our results further highlight the importance of considering DMTS task features when studying specific memory systems in non-human species and suggest that the DTMS task might not be the best paradigm for testing pressure effects without consideration of individual differences.
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- PAR ID:
- 10631617
- Publisher / Repository:
- Animal Behavior and Cognition
- Date Published:
- Journal Name:
- Animal Behavior and Cognition
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2372-4323
- Page Range / eLocation ID:
- 32 to 44
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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