Asymmetries in the production of self-directed behavior by chimpanzees and gorillas during a computerized cognitive test

Abstract

Self-directed behaviors (SDBs) are a commonly used behavioral indicator of arousal in nonhuman primates. Experimental manipulations, designed to increase arousal and uncertainty, have been used to elicit SDB production in primates. Beyond measuring rates of SDB production, researchers have also recorded their lateralized production by primates, thought to reflect laterality of hemispheric brain control and response to emotion. Although a handful of such studies exist, all have been conducted with chimpanzees. Expanding on this line of inquiry, we tested both chimpanzees (N = 3) and gorillas (N = 3) in a serial learning task presented on a touchscreen interface that incorporated both EASY (two-item list) and HARD (four-item list) versions of the task. Although SDB production by the apes did not differ across the two levels of task complexity, both species produced higher rates of SDB when they made an error, regardless of task difficulty. Furthermore, the apes made more SDB with the left hand-directed to the right side of their body (contralateral SDB) and left side of their body (ipsilateral SDB)-when they made an incorrect response. There was no difference in the rate of SDB produced with the right hand across correct compared to incorrect trials. The apes' responses reflect previous reports that show humans are quicker at selecting negative emotional stimuli when using their left, compared to their right, hand (the reverse is true for positive stimuli). However, previous work has shown that chimpanzees are more likely to produce (contralateral) SDB with their right hand when aroused and so we discuss our results in relation to these findings and consider how they relate to the 'right hemisphere' and 'valence' models of emotional processing in apes.

Social Models Enhance Apes’ Memory for Novel Events

“…The chimpanzees lived together in a social group of six. All subjects had previous experience viewing stimuli on a touch-screen monitor38.…”

Serial Cognition and Personality in Macaques

“…The SimChain paradigm has been used in several species (Terrace, 1993; Wagner, Hopper, & Ross, 2015), with immature and adult individuals (Inoue & Matsuzawa, 2009); the task is repeatable and informative. Distinct cognitive tasks are likely to tap into general or domain specific intelligences to varying degrees, and since it is not known how many factors are best for modeling macaque intelligence, it remains an open question which domains SimChain performance draws on.…”

An assessment of touchscreens for testing primate food preferences and valuations

“…The subject for this evaluation was a 12year-old male gorilla (Gorilla gorilla gorilla) who lived in an all-male group comprising four gorillas (average age: 10.8 years) at the Lincoln Park Zoo, Chicago, USA. As with many of the apes at the Lincoln Park Zoo, prior to this study the subject had had several years of experience using touchscreen computers, specifically with serial-learning tasks (e.g., Wagner, Hopper, & Ross, 2016), but had never before been shown photographs of real-life objects on the touchscreen, nor had he participated in preference testing using the touchscreen. Previous preference testing, in which the subject was manually offered two foods simultaneously in a forced choice paradigm (sensu Hopper et al, 2015), had revealed that this gorilla preferred grapes over pieces of carrot, but no other food preferences had been formally tested.…”