Journal of Comparative Psychology最新文献

Comments on an article by Limor Raviv et al. (see record 2023-07345-001). Raviv et al. argue that the conflicting findings from human language and from studies of communication in nonhuman animals boil down to different levels of analysis used by researchers studying non-humans compared with those studying humans. Researchers studying nonhuman animal communication typically focus on the size of signal repertoires or the structural variation within and among signals within a repertoire. Researchers studying human language, conversely, largely focus on the question of grammatical rules that govern the way units (words and phrases) are put together in speech streams. Rules of composition that govern the way units are put together are considered more complex in nonhuman signaling systems, but simpler in human language systems. The discrepancy here, according to Raviv et al., stems from two sources. According to the commenting authors, the take home message of Raviv et al. is one that will be helpful to future studies of the evolution of communication systems. Raviv et al. recommend that we work harder to avoid terms such as "complex" and "simple" with regard to communication and instead focus on the specifics of what we are analyzing. Phrases such as "larger repertoire size" or "stronger compositional structure" represent cleaner and more neutral phrases for discussions of communication and would better allow findings from non-humans and from humans to be compared. Finally, Raviv et al. advocate for greater collaborative work across nonhuman and human communication systems, and interdisciplinary work has a long history of fundamental discoveries. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Associating with kin provides individual benefits but requires that these relationships be detectable. In humans, facial phenotype matching might help assess paternity; however, evidence for it is mixed. In chimpanzees, concealing visual cues of paternity may be beneficial due to their promiscuous mating system and the considerable risk of infanticide by males. On the other hand, detecting kin can also aid chimpanzees in avoiding inbreeding and in forming alliances that improve kin-mediated fitness. Although previous studies assessing relatedness based on facial resemblance in chimpanzees exist, they used images of captive populations in whom selection pressures and reproductive opportunities are controlled and only assessed maternity or paternity of adult offspring. In natural populations, the chances of infanticide are highest during early infancy, suggesting that young infants would benefit most from paternity concealment, whereas adults and subadults would benefit from the detection of all types of kin, including half-siblings. In our experiment, we conducted an online study with human participants, in which they had to assess the relatedness of chimpanzees based on facial similarity. To address previous methodological constraints, we used chimpanzee images across all ages, as well as maternal and paternal half-siblings. We found that kin status was detected above chance across all relatedness categories, with easier kin detection of father-offspring pairs, females, and older chimpanzees. Together, these findings support the existence of paternity confusion in infant chimpanzees and provide a possible mechanism for incest avoidance and kin-based social alliances in older individuals. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Visual illusions are of particular interest to cognitive researchers because they reflect the active role of the brain in processing the world around us. Yousif and Scholl (2019) recently described a new visual experience, the one-is-more illusion, in which adult humans perceived continuous objects as longer than sets of discrete objects of equal length. In the current study, we investigated this phenomenon in human children (Homo sapiens) and rhesus macaques (Macaca mulatta). Children were presented with a computerized 2-choice discrimination task and successfully selected the longer of 2 images for control trials. On trials in which 2 versions of the same image were presented (identical in length), and one was of a continuous form and the other consisted of 2 or more distinct units, children showed a bias for the continuous object. Monkeys were given the same computerized task and learned to choose the longer of 2 otherwise identical stimuli. However, monkeys did not show a bias to choose the continuous probe images as longer than the discrete images in the critical test trials with equal-length stimuli. These results are discussed in light of developmental and comparative research on related illusory experiences and perceptual mechanisms. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

One of the hallmarks of complex motor planning in humans involves grasping objects in preparation for future actions, termed second-order motor planning. This ability has an extended developmental trajectory in humans and is also shared with nonhuman primates. Here, we presented seven cotton-top tamarins with a dowel task that has prompted variable grasping behaviors for some primate species. Tamarins could use either an efficient grasp to bring food stuck onto the end of a dowel to their mouth (radial grasp) or an inefficient grasp that required repositioning (ulnar grasp). The tamarins were very consistent in their use of radial grasps. These data support the morphological constraint theory suggesting that species with limited dexterity (inability to perform precision grasps) may demonstrate more consistent second-order motor planning due to the increased cost of inefficient grasping postures. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

We studied mother-infant relationships and infant independence in wild Geoffroy's spider monkeys (Ateles geoffroyi) during the first 3 years of infant life. We used 15-min focal sampling to collect data on mother-infant interactions and infant behavior in 12 mother-infant dyads in the Yucatan peninsula, Mexico. Data were analyzed using generalized linear mixed models. Newborns spent almost all their time in proximity and in contact with their mothers. The time infants spent within one-arm reach from the mother decreased with age, and the infant was primarily responsible for maintaining proximity. The time infants spent farther than 8 m from the mother, in independent locomotion, exploration, and proximity with group members other than the mother increased with age. We identified two developmental periods associated with critical milestones of infant independence: the first at 8 to 10 months when independent locomotion and exploration began, and the proportion of time in proximity with group members other than the mother increased and the second at 19 to 21 months when the mother's rejection started, maternal carrying ended and mother's help, in the form of bridging canopy gaps, peaked. Compared with other primate species of similar size, Ateles geoffroyi have an extended dependence period, which could be related to the cognitive and developmental challenges imposed by their socioecological characteristics. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Unlike nonhuman primates, individual differences between humans in dominance do not appear as broad personality factors. This may be attributable to differences between the questionnaires used to study human and nonhuman primate personality. Alternatively, this may reflect differences in the organization of personality in humans and nonhuman primates. To determine which of these possibilities was most likely, 1,147 participants were recruited and asked to rate their personality and/or that of somebody else on the Hominoid Personality Questionnaire (HPQ), which has been used to study nonhuman primate personality. A large subset of these participants (~80%) also completed self- and/or rater reports of one of three questionnaires used to measure human personality. Exploratory factor analyses of HPQ rater report data yielded five factors. These factors correlated mostly in expected ways with scales from questionnaires used to study human personality. Exploratory factor analyses of HPQ self-report data yielded no clear number of factors and no consistent evidence with respect to the presence of a dominance factor. Subsequent analyses compared HPQ scales that represented dominance factors in chimpanzees, bonobos, mountain gorillas, and orangutans to scales derived from the Revised NEO Personality Inventory, including Fearless Dominance, which combined Neuroticism, Agreeableness, Conscientiousness, and Extraversion facets, Emotional Stability (the inverse of Neuroticism), and Extraversion's Assertiveness facet. Fearless Dominance and Assertiveness were most like the great ape dominance factors. The absence of human dominance factors, therefore, appears to reflect present or past social conditions of our species. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

On the surface, the fields of animal communication and human linguistics have arrived at conflicting theories and conclusions with respect to the effect of social complexity on communicative complexity. For example, an increase in group size is argued to have opposite consequences on human versus animal communication systems: although an increase in human community size leads to some types of language simplification, an increase in animal group size leads to an increase in signal complexity. But do human and animal communication systems really show such a fundamental discrepancy? Our key message is that the tension between these two adjacent fields is the result of (a) a focus on different levels of analysis (namely, signal variation or grammar-like rules) and (b) an inconsistent use of terminology (namely, the terms "simple" and "complex"). By disentangling and clarifying these terms with respect to different measures of communicative complexity, we show that although animal and human communication systems indeed show some contradictory effects with respect to signal variability, they actually display essentially the same patterns with respect to grammar-like structure. This is despite the fact that the definitions of complexity and simplicity are actually aligned for signal variability, but diverge for grammatical structure. We conclude by advocating for the use of more objective and descriptive terms instead of terms such as "complexity," which can be applied uniformly for human and animal communication systems-leading to comparable descriptions of findings across species and promoting a more productive dialogue between fields. (PsycInfo Database Record (c) 2022 APA, all rights reserved).