Sarah Boysen

• The Ohio State University

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 better understand the evolution of object use, this study explored how objects are used in social interactions in semi-wild chimpanzees (Pan troglodytes). We used an observa...

Joint attention (JA) is an early manifestation of social cognition, commonly described as interactions in which an infant looks or gestures to an adult female to share attention about an object, within a positive emotional atmosphere. We label this description the JA phenotype. We argue that characterizing JA in this way reflects unexamined assumpt...

A converging literature has revealed the existence of a set of largely consistent, hierarchically organized personality traits, that is broader traits are able to be differentiated into more fine-grained traits, in both humans and chimpanzees. Despite recent work suggesting a neural basis to personality in chimpanzees, little is known with regard t...

Human trafficking has been identified as a global human rights violation. This study aimed to investigate the predictors of prosocial behaviors toward sex-trafficked persons. Participants were 223 undergraduates randomly assigned to read a vignette and answer follow-up questions along with measures of empathy, just world belief, attitudes toward pr...

Emotional Engagement Enhanced and Predicts Joint Attention and Cooperation in Young Chimpanzees

Social cognition in infancy is evident in coordinated triadic engagements, that is, infants attending jointly with social partners and objects. Current evolutionary theories of primate social cognition tend to highlight species differences in cognition based on human-unique cooperative motives. We consider a developmental model in which engagement...

Displaced reference is the ability to refer to an itemthat has beenmoved (displaced) in space and/or time, and has been called one of the true hallmarks of referential communication. Several studies suggest that nonhuman primates have this capability, but a recent experiment concluded that in a specific situation (absent entities), human infants di...

Researchers investigating the evolutionary roots of human culture have turned to comparing behaviours across nonhuman primate communities, with tool-based foraging in particular receiving much attention. This study examined whether natural extractive foraging behaviours other than tool selection differed across nonhuman primate colonies that had th...

The relationship between adaptive behavior and cardiac indices of orienting, habituation, and associative learning were evaluated in a heterogeneous population of developmentally disabled infants and young children. Cardiac reactivity and habituation were examined through responses to simple nonsignal stimuli, and associative learning was evaluated...

The burgeoning literature on numerical skills, counting and quantity judgements by animals over the past two decades attests that the long shadow of Clever Hans has finally dissipated. Not only have the types of tasks expanded, but the number of species, particularly those outside the mammalian order, is beginning to become more diverse. The primat...

Studies of causal understanding of tool relationships in captive chimpanzees have yielded disparate findings, particularly those reported by Povinelli & colleagues (2000) for tool tasks by laboratory chimpanzees. The present set of experiments tested nine enculturated chimpanzees on three versions of a support task, as described by Povinelli (2000)...

Three capuchin monkeys (Cebus apella) were tested on a 2-choice discrimination task designed to examine their knowledge of support, modeled after Hauser, Kralik, and Botto-Mahan's (1999) experiments with tamarins. This task involved a choice between 2 pieces of cloth, including 1 with a food reward placed on its surface, and a second cloth with the...

Nine chimpanzees (Pan troglodytes) were tested for their ability to assemble or disassemble the appropriate tool to obtain a food reward from two different apparatus. In its deconstructed form, the tool functioned as a probe for one apparatus. In its constructed form, the tool functioned as a hook, appropriate for a second apparatus. Each subject c...

Primates rely on visual attention to gather knowledge about their environment. The ability to recognize such knowledge-acquisition activity in another may demonstrate one aspect of Theory of Mind. Using a series of experiments in which chimpanzees were presented with a choice between an experimenter whose visual attention was available and another...

Recent evidence for different tool kits, proposed to be based upon culture-like transmission, have been observed across different chimpanzee communities across Western Africa. In light of these findings, the reported failures by seven captive juvenile chimpanzees tested with 27 tool use tasks (Povinelli 2000) seem enigmatic. Here we report successf...

This chapter examines the role of symbol training in facilitating the cognitive performance of enculturated chimpanzees. It argues that immersion in symbol-laden human culture and long-term social relationships with human beings dramatically increases the attentional resources of chimpanzees. It analyses how numerals modulate the evaluative disposi...

The study of how animals learn, behave, and think, often from a comparative perspective, is the crux of animal cognition research. Recent topics explored in this field include understanding of abstract concepts, spatial learning and memory, imitation, representation of social relations, and examining the similarities between nonhuman primates and h...

It is well known that children's activities are full of pretending and imagination, but it is less appreciated that animals can also show similar activities. Originally published in 2002, this book focuses on comparing and contrasting children's and animals' pretenses and imaginative activities. In the text, overviews of research present conflictin...

Primate Origins of Human Cognition and Behavior. T. Matsuzawa, Ed. Springer, Tokyo, 2001. 599 pp. $129, €119, ¥9,500. ISBN 4-431-70290-3. In a volume that highlights Japanese contributions to primatology, Matsuzawa and his colleagues explore a broad range of topics from the fields of behavioral ecology, psychology, and cognitive science.

In the present study, the contributions of spatial and object features to chimpanzees' comprehension of scale models were examined. Seven chimpanzees that previously demonstrated the ability to use a scale model as an information source for the location of a hidden item were tested under conditions manipulating the feature correspondence and spatia...

The results from these preliminary studies show that chimpanzees are capable of understanding the relationship between a scale model or photographs of the corresponding real space. The results replicate and extend the innovative studies of similar skills in children (e.g., DeLoache, 1987, 1991) to a nonverbal species with whom previous attempts to...

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 retest...

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 serched an enclosure for a hidden item after watching an experimenter hide a miniature item in the analogous location in a scale model were reteste...

The authors previously reported that chimpanzees (Pan troglodytes) showed a striking bias to select the larger of 2 candy arrays, despite a reversed reward contingency in which the animals received the smaller, nonselected array as a reward, except when Arabic numerals were used as stimuli. A perceptual or incentive-based interference occurred that...

The authors previously reported that chimpanzees (Pan troglodytes) showed a striking bias to select the larger of 2 candy arrays, despite a reversed reward contingency in which the animals received the smaller, nonselected array as a reward, except when Arabic numerals were used as stimuli. A perceptual or incentive-based interference occurred that...

Six chimpanzees (Pan troglodytes) were presented with pairs of color photographic images of 5 different categories of animals (cat, chimp, gorilla, tiger, fish). The subjects responded to each pair using symbols for "same" and "different." Both within- and between-category discriminations were tested, and all chimpanzees classified the image pairs...

The current study examines the modality preference and its change in the course of development. Based on findings from previous research (Balaban & Waxman, 1997; Roberts, 1995; Sloutsky & Lo, 1999), it was expected that the auditory modality would be privileged at a very young age. In the experiment, participants after being trained to select a tar...

Six chimpanzees (Pan troglodytes) were presented with pairs of color photographic images of 5 different categories of animals (cat, chimp, gorilla, tiger, fish). The subjects responded to each pair using symbols for “same” and “different.” Both within- and between-category discriminations were tested, and all chimpanzees classified the image pairs...

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 severa...

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 greet interest to severa...

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 t...

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 t...

Examined tool use in 15 captive lowland gorillas. Throughout the 17 hrs of observation, 283 sessions at the site of tool placement were evaluated. Ss were observed displaying the capacity for tool modification and innovating techniques for food retrieval using stick tools. The findings indicate that gorillas have the requisite cognitive capacities...

We previously reported that chimpanzees were unable to optimally select the smaller of two candy arrays in order to receive a larger reward. When Arabic numerals were substituted for the candy arrays, animals who had had prior training with numerical symbols showed an immediate and significant improvement in performance and were able to select reli...

Comparative cognition is an emerging interdisciplinary field with contributions from comparative psychology, cognitive/experimental and developmental psychology, animal learning, and ethology, and is poised to move toward greater understanding of animal and human information-processing, reasoning, memory, and the phylogenetic emergence of mind. Thi...

Three chimpanzees with a history of conditional and numeric token training spontaneously matched relations between relations under conditions of nondifferential reinforcement. Heretofore, this conceptual ability was demonstrated only in language-trained chimpanzees. The performance levels of the language-naive animals in this study, however, were e...

Three chimpanzees with a history of conditional and numeric token training spontaneously matched relations between relations under conditions of nondifferential reinforcement. Heretofore, this conceptual ability was demonstrated only in language-trained chimpanzees. The performance levels of the language-naive animals in this study, however, were e...

Five chimpanzees with training in counting and numerical skills selected between 2 arrays of different amounts of candy or 2 Arabic numerals. A reversed reinforcement contingency was in effect, in which the selected array was removed and the subject received the nonselected candies (or the number of candies represented by the nonselected Arabic num...

Five chimpanzees (Pan troglodytes) were tested to assess their understanding of causality in a tool task. The task consisted of a transparent tube with a trap-hole drilled in its middle. A reward was randomly placed on either side of the hole. Depending on which side the chimpanzee inserted the stick into, the candy was either pushed out of the tub...

A chimpanzee (Pan troglodytes) experienced in counting arrays of 0-7 items and trained for comprehension of number symbols, spontaneously displayed a variety of indicating acts (e.g., pointing, touching, and rearranging items) during counting. Twenty-five sessions were videotaped, and all trials were evaluated for the relations among number of item...

Two chimpanzees were trained to select among 2 different amounts of candy (1-6 items). The task was designed so that selection of either array by the active (selector) chimpanzee resulted in that array being given to the passive (observer) animal, with the remaining (nonselected) array going to the selector. Neither animal was able to select consis...

Two chimpanzees were trained to select among 2 different amounts of candy (1–6 items). The task was designed so that selection of either array by the active (selector) chimpanzee resulted in that array being given to the passive (observer) animal, with the remaining (nonselected) array going to the selector. Neither animal was able to select consis...

Self-Awareness in Animals and Humans, a collection of original articles on self-awareness in monkeys, apes, humans, and other species, focuses on controversies about how to measure self-awareness, which species are capable of self-awareness and which are not, and why. Several chapters focus on the controversial question of whether gorillas, like ot...

The principle of evaluative bivalence asserts that behavioral processes often organize along the evaluative dimension, due to a fundamental pattern of bivalent neurobehavioral organization extending throughout the neuraxis. This principle offers a powerful approach to the explication of complex behavioral relationships and the integration of divers...

We describe the first brain event-related potential (ERP) study of cognitive processes in the chimpanzee. In an extension of our studies on the ontogeny of vocal perception, ERP measures were obtained during the presentation of simple nonsignal stimuli as well as conspecific and human vocalizations. We initially confirmed findings from humans and m...

Three chimpanzees (Pan troglodytes) were trained to discriminate among pairs of boxes in an ABCDE-ordered series. The 2nd member of each pair was reinforced, until all 4 training pairs were learned. During novel tests the nonadjacent BD pair was presented, and all 3 animals reliably selected D. In Experiment 2, numerals 1-5 served as stimuli. One c...

Three chimpanzees ( Pan troglodytes) were trained to discriminate among pairs of boxes in an ABCDE-ordered series. The 2nd member of each pair was reinforced, until all 4 training pairs were learned. During novel tests the nonadjacent BD pair was presented, and all 3 animals reliably selected D. In Exp 2, numerals 1–5 served as stimuli. One chimpan...

Four chimpanzees, Pan troglodytes, were individually trained to cooperate with a human partner on a task that allowed both participants to obtain food rewards. In each chimpanzee-human dyad, one of the participants (the informant) could see which pair of food trays on a four-choice apparatus was baited, but had no means of obtaining it. The other p...

provides a vivid account of the day-to-day concerns in socializing and teaching her [the author] animals [chimpanzees] / offers unique insights into the development of bonding and the establishment of relationship ground rules / focuses on the animal's cognitive abilities (PsycINFO Database Record (c) 2012 APA, all rights reserved)

A rational strategy for the automated detection of artifacts in heart period data is outlined and evaluated. The specific implementation of this approach for heart period data is based on the distribution characteristics of successive heart period differences. Because beat-to-beat differences generated by artifacts are large, relative to normal hea...

This is the first collection of articles completely and explicitly devoted to the new field of 'comparative developmental evolutionary psychology' - that is, to studies of primate abilities based on frameworks drawn from developmental psychology and evolutionary biology. These frameworks include Piagetian and neo-Piagetian models as well as psychol...

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 bu...

Presents an overview of an approach to cognitive evaluation which capitalizes on intrinsic physiological responses that do not depend on the somatic repertoire, verbal skills, or active cooperation of the S. This approach is conducive to the study of the ontogeny of cognitive processes and to investigations of the phylogenetic and comparative aspec...

The present study examined cardiac and behavioral reactions of infant chimpanzees to white noise and to conspecific screams and laughter. Chimpanzee screams evoked typical deceleratory cardiac orienting responses. Analysis of stimulus-evoked changes in respiratory sinus arrhythmia suggested that this cardiac deceleration arose from an increase in p...

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 respon...

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 respon...

Used heart rate measures to examine the functional response of young chimpanzees and orangutans to acoustic stimuli, including white noise and chimpanzee vocalizations (threat, stress, and alarm). The initial response of the Ss to all stimuli was characterized by a cardiac (CAR) deceleration and an increase in heart period variability. The decelera...

A chimpanzee (Pan troglodytes), trained to count foods and objects by using Arabic numbers, demonstrated the ability to sum arrays of 0-4 food items placed in 2 of 3 possible sites. To address representational use of numbers, we next baited sites with Arabic numbers as stimuli. In both cases performance was significantly above chance from the first...

Cardiac responses to non-signal stimuli and to signal stimuli in a vigilance task were examined in children born with congenital heart defects (CHD), and in normal and attention deficit disordered (ADD) subjects. Overall task performance was lower in subjects with heart defects and in the ADD group. Cardiac measures revealed that normal children di...

Three chimpanzees (Pan troglodytes) were provided with 18 different stimulus pages for drawing. The resulting 618 drawings were coded for drawn marks, and results were compared with early reports on ape drawing (Morris, 1962; Schiller, 1951) and with more recent systematic studies (Smith, 1973). The findings of the present study confirm Smith's obs...

Evaluated tonic and phasic measures of heart rate (HR) during vigilance performance in a chimpanzee. Patterns of cardiac activity were correlated with critical dimensions of performance and were comparable to those of humans. Baseline HR decreased within sessions and increased over sessions, corresponding with trends in reaction time (RT). Faster R...

The ability of a chimpanzee to recognize individuals depicted in photographs was evaluated through the use of heart rate measures. Heart rate was recorded before and during photographic projections of human caregivers, familiar individuals, strangers, and blank control slides. In the absence of explicit training or reinforcement, the chimpanzee dis...

The ability of a chimpanzee to recognize individuals depicted in photographs was evaluated through the use of heart rate measures. Heart rate was recorded before and during photographic projections of human caregivers, familiar individuals, strangers, and blank control slides. In the absence of explicit training or reinforcement, the chimpanzee dis...

Visual evoked potentials (VEPs) in response to flash stimuli were recorded from occipital and central-scalp electrodes in the chimpanzee and gorilla. The most notable occipital component of the VEP was a surface-positive wave (P90), the latency of which decreased with development. Central scalp responses, apparent only in older animals, included a...

Visual evoked potentials (VEPs) in response to flash stimuli were recorded from occipital and central-scalp electrodes in the chimpanzee and gorilla. The most notable occipital component of the VEP was a surface-positive wave (P90), the latency of which decreased with development. Central scalp responses, apparent only in older animals, included a...

The relationship between adaptive behavioral function and cardiac reactivity to auditory, somatosensory, and visual stimuli was evaluated using a heterogeneous population of developmentally disabled infants and young children. Stimuli of all sensory modalities resulted predominantly in a cardiac deceleration, and the magnitude of these responses va...

Cardiac patterns of startle and orienting in response to auditory and vibrotactile stimuli were investigated in the infant chimpanzee and gorilla. Results revealed a notable cardiac acceleration in response to the initial presentations of stimuli of either modality. This acceleratory response appeared to reflect the cardiac correlate of startle and...

The authors review the evidence of symbolic representation capacity in apes and state that every language program starts from the same assumption: signs, lexigrams, and plastic tokens are indeed real vocabulary elements whenever apes are able to perform the right behaviour label in the presence of the respective fact or object. They consider as cru...

Through use of learned symbols, two chimpanzees accurately specified 11 foods by name to one another when the food item's identity was known by only one. They could not do this when denied use of the symbols. The chimpanzees then spontaneously requested specific foods of one another by name. Requests resulted in cooperative and reciprocal symbolica...

Three approaches have been used to teach language skills to apes, each employing a different communication system and training philosophy. The performances of apes in a large number of studies are reviewed. Although all researchers have used similar training techniques, differences in modality, criteria, and social setting are described, and the si...

Explore the question of developmental differences in shadow self-recognition in the authors' 2 youngest chimpanzees. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

[discusses how] studies of numerical competence in the chimpanzee continue to provide new insights into the range and capacity for quantitatively based information processing in this species / suggests that this area remains a rich and fruitful source of contributions to our understanding of animal cognition and behavior motor tagging during coun...

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