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

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.     

Factors Influencing Clinical Follow-Up for Individuals with a Personal History of Breast and/or Ovarian Cancer and Previous Uninformative <Emphasis Type="Italic">BRCA1</Emphasis> and <Emphasis Type="Italic">BRCA2</Emphasis> Testing

Genetic testing for inherited cancer risk has recently improved through the advent of multi-gene panels and the addition of deletion and duplication analysis of the BRCA genes. The primary aim of this study was to determine which factors influence the intent of individuals with a personal history of breast and/or ovarian cancer and negative or uncertain BRCA1 and BRCA2 testing to return to a hereditary cancer program for additional genetic risk assessment, counseling, and testing. Surveys were sent to 1197 individuals and 257 were returned. Of those participants who were planning to return to clinic, most cited having family members who could benefit from the test result as the primary motivation to return. Many participants who were not planning to return to clinic cited the cost of testing as a barrier to return. Cost of testing and concerns about insurance coverage were the most commonly cited barriers for the group of participants who were undecided about returning to clinic. Results from this study may be used to guide re-contact efforts by clinicians to increase patient uptake to return to clinic for up-to-date genetic risk assessment, counseling, and testing.     

Observational learning of tool use in children: Investigating cultural spread through diffusion chains and learning mechanisms through ghost displays

In the first of two experiments, we demonstrate the spread of a novel form of tool use across 20 “cultural generations” of child-to-child transmission. An experimentally seeded technique spread with 100% fidelity along twice as many “generations” as has been investigated in recent exploratory “diffusion” experiments of this type. This contrasted with only a single child discovering the technique spontaneously in a comparable group tested individually without any model. This study accordingly documents children’s social learning of tool use on a new, population-level scale that characterizes real-world cultural phenomena. In a second experiment, underlying social learning processes were investigated with a focus on the contrast between imitation (defined as copying actions) and emulation (defined as learning from the results of actions only). In two different “ghost” conditions, children were presented with the task used in the first experiment but now operated without sight of an agent performing the task, thereby presenting only the information used in emulation. Children in ghost conditions were less successful than those who had watched a model in action and showed variable matching to what they had seen. These findings suggest the importance of observational learning of complex tool use through imitation rather than only through emulation. Results of the two experiments are compared with those of similar experiments conducted previously with chimpanzees and are discussed in relation to the wider perspective of human culture and the influence of task complexity on social learning.