Conspecific recognition in the chimpanzee (Pan troglodytes): cardiac responses to significant others

The ability of a chimpanzee (Pan troglodytes) to recognize photographs of conspecifics was evaluated with heart-rate measures. Heart rate was recorded before, during, and after viewing photographs of an aggressive chimpanzee, a friendly companion animal, and an unfamiliar chimpanzee. The subject displayed a differential pattern of heart-rate response to the stimulus animals, without prior experience with the photographs. Responses to the aggressive animal were acceleratory, which suggests a defensive response. Respiratory sinus arrhythmia suggested that this response was associated with sympathetic activation. In contrast, responses to the familiar animal were minimal, whereas cardiac deceleration was observed in response to the strange chimp, which likely reflects an orienting response. Results suggest the chimpanzee is able to recognize photographs of individual conspecifics and that heart-rate change can reflect the nature of established social relationships between chimpanzees.     

Scale-model comprehension by chimpanzees (Pan troglodytes)

The ability of chimpanzees (Pan troglodytes) to recognize the correspondence between a scale model and its real-world referent was examined. In Experiments 1 and 2, an adult female and a young adult male watched as an experimenter hid a miniature model food in 1 of 4 sites in a scale model. Then, the chimpanzees were given the opportunity to find the real food item that had been hidden in the analogous location in the real room. The female performed significantly above chance, whereas the male performed at chance level. Experiments 3 and 4 tested 5 adult and 2 adolescent chimpanzees in a similar paradigm, using a scale model of the chimpanzees' outdoor area. Results indicate that some adult chimpanzees were able to reliably demonstrate an understanding of the relationship between a scale model and the larger space it represented, whereas other subjects were constrained by inefficient and unsuccessful search patterns.     

Biased Assimilation and Attitude Polarization in Response to Learning About Biological Explanations of Homosexuality

According to attribution theory stigmatized behaviors with biological explanations will be perceived more positively than those with psychological explanations, but informing people of the biological explanations of homosexuality has produced mixed results on attitudes. To examine if biased processing could explain previous findings we tested whether biased assimilation (initial attitudes’ effect on perceived persuasiveness) and attitude polarization (initial attitudes’ effect on reported attitude change) affected learning about biological explanations of homosexuality among 210 U.S. undergraduates. General Linear Model analyses showed that (1) individuals with positive attitudes toward homosexuality saw biological explanations as a more persuasive reason to accept homosexuality than those with negative attitudes, and (2) initial attitudes generally led to a strengthening of those attitudes after learning about biological explanations.     

Inferences about guessing and knowing by chimpanzees (Pan troglodytes)

The visual perspective-taking ability of 4 chimpanzees (Pan troglodytes) was investigated. The subjects chose between information about the location of hidden food provided by 2 experimenters who randomly alternated between two roles (the guesser and the knower). The knower baited 1 of 4 obscured cups so that the subjects could watch the process but could not see which of the cups contained the reward. The guesser waited outside the room until the food was hidden. Finally, the knower pointed to the correct cup while the guesser pointed to an incorrect one. The chimpanzees quickly learned to respond to the knower. They also showed transfer to a novel variation of the task, in which the guesser remained inside the room and covered his head while the knower stood next to him and watched a third experimenter bait the cups. The results are consistent with the hypothesis that chimpanzees are capable of modeling the visual perspectives of others.     

The effect of response contingencies on scale model task performance by chimpanzees (Pan troglodytes)

The effects of modified procedures on chimpanzees' (Pan troglodytes) performance in a scale model comprehension task were examined. Seven chimpanzees that previously participated in a task in which they searched an enclosure for a hidden item after watching an experimenter hide a miniature item in the analogous location in a scale model were retested under procedures incorporating response costs. In Experiment 1, chimpanzees were trained under procedures that rewarded only item retrievals occurring on the 1st search attempt. During test trials, 6 chimpanzees performed above chance, including 4 that were previously unsuccessful under the original procedures (V. A. Kuhlmeier, S. T. Boysen, & K. L. Mukobi, 1999). Experiment 2 compared performance under the new and original procedures. Results indicated that for some chimpanzees, performance depended on procedures that decreased the use of competing search strategies and encouraged strategies based on information from the scale model.     

Evidence for blatant dehumanization of mental illness and its relation to stigma

ABSTRACT

People with mental illness face stigma, and due to their low social status, they may also face blatant dehumanization that denies their status as fully evolved human beings. In the current research, three studies documented the existence of blatant dehumanization of mental illness. Study 1 (N = 112) showed that participants rated people with mental illness in general as being significantly less human than other dehumanized social groups such as Mexican immigrants and Muslims. Study 2 (N = 158) showed that dehumanization occurs for specific mental disorders but that the level of dehumanization varies widely among disorders. Study 3 (N = 223) documented significant correlations between dehumanization of mental illness and standard measures of stigma such as fear, pity, and social distance. Overall, the results establish the relevance of blatant dehumanization to mental illness stigma and suggest new directions for understanding stigma.     

Object use in communication of semi-wild chimpanzees

Animal Cognition - Object interactions play an important role in human communication but the extent to which nonhuman primates incorporate objects in their social interactions remains unknown. To...     

Primate Numerical Competence: Contributions Toward Understanding Nonhuman Cognition

Nonhuman primates represent the most significant extant species for comparative studies of cognition, including such complex phenomena as numerical competence, among others. Studies of numerical skills in monkeys and apes have a long, though somewhat sparse history, although questions for current empirical studies remain of great interest to several fields, including comparative, developmental, and cognitive psychology; anthropology; ethology; and philosophy, to name a few. In addition to demonstrated similarities in complex information processing, empirical studies of a variety of potential cognitive limitations or constraints have provided insights into similarities and differences across the primate order, and continue to offer theoretical and pragmatic directions for future research. An historical overview of primate numerical studies is presented, as well as a summary of the 17‐year research history, including recent findings, of the Comparative Cognition Project at The Ohio State University Chimpanzee Center. Overall, the archival literature on number‐related skills and counting in nonhuman primates offers important implications for revising our thinking about comparative neuroanatomy, cross‐species (human/ape) cognitive similarities and differences, and the evolution of cognition represented by the primate continuum.