Journal of Comparative Psychology最新文献

Emotional expressions play an important part in social communication of dogs and humans, but comparative studies between dogs and humans are rare. In addition, little is known about how emotions are perceived across species and how attention is divided among different parts of faces. Here, we compared the gazing behavior of dogs and adult humans toward emotional dog and human facial expressions. Dogs mostly gazed at the eye and nose areas, whereas the humans' focus also included the mouth area. The gazing behavior of both species was affected by the facial expressions and species presented, and they gazed at emotional more than neutral stimuli. Dogs and humans demonstrated attentional bias toward angry and happy eyes of their own species, which highlights the ecological salience of the species and the importance of eyes in reading conspecifics' emotional expressions. For both species, mouths of aggressive dogs were gazed at more than those of angry humans, whereas mouths of happy humans were gazed at more than happy dog mouths. Thus, the mouth area provides important emotional cues for recognizing emotions across species, suggesting the ecological salience of facial expressions connecting to the subcortical visual pathway across mammalian species. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Many species forage collectively, and this will shape how they search for prey. However, theories of visual attention and search image formation have not considered social foraging, and studies of collective foraging rarely consider cognitive constraints. Here, we connected these ideas and present an agent-based model of collective foraging on cryptic prey in agents that either can or cannot form search images. Agents focused on one prey type reduce its local density, biasing other agents to form search images for other prey types. This effect, attentional character displacement, may reduce competition, as foragers occupy separate regions of "attention-space." We found that the ability to modulate attention increases distance in attention-space and reduces competition, improving success rates. Agents that cannot modulate their attention benefit from foraging with those that can. We also found that some top-down control of search is critical to taking advantage of this effect. This cognitive-ecological approach to modeling collective foraging suggests that competition is a critical driver of the evolution of search images. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Probabilistic reasoning-the ability to predict outcomes based on the likelihood of different possibilities-is a key component of numerical cognition and is critical for navigating uncertain environments. However, it is unclear whether this capacity is shared with our closest relatives, the great apes, or with even more distantly related species such as the small apes. Here, we presented two gibbons (Nomascus leucogenys), two siamangs (Symphalangus syndactylus), and three chimpanzees (Pan troglodytes) with a proportional probability task requiring them to reason from the distribution of items in a population to the likely contents of a sample. In contrast to previous research, we ensured that participants could not rely on two salient heuristics-the absolute quantity of the preferred item or majority sampling-to solve the task. We found that individuals of all species were able to distinguish between 0% versus 50% and 50% versus 100%, and that two individuals (one chimpanzee and one siamang) were able to convincingly distinguish between 33% versus 67%. These results suggest that an antecedent to probabilistic reasoning was shared by a common ancestor of humans, great apes, and small apes. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Perceptual categorization is grouping objects based on similar physical features. Otters may use categorization to classify predators, prey, and conspecifics. This study was the first to examine whether North American river otters (Lontra canadensis) are capable of perceptual categorization. Previously, otters at the Seneca Park Zoo were trained to discriminate between a circle and an equilateral triangle in a two-alternative forced-choice task. In the present study, these otters were presented with novel geometric shapes (e.g., an oval and a right triangle) in Experiment 1 and novel drawings of real-world objects (e.g., a tomato and a tent) in Experiment 2 that could be classified into the circle or triangle category. Two otters performed significantly better than chance during Experiment 1 on subsets of the novel test stimuli. In Experiment 2, one otter was able to categorize drawings of real-world objects into two shape categories of circles and triangles, but only when the triangle-like stimuli were composed of straight lines, not when stimuli were composed of curved lines. The results from both experiments suggest that line type (straight vs. curved) and symmetry may have been salient features for the otters. It appears that otters have the ability to perceptually categorize two-dimensional shapes and line drawings, though further research with additional subjects and different stimuli is needed. Better understanding this ability in otters can expand our knowledge of categorization behavior in a variety of nonhuman animals. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Humans are capable of recognizing the temporal organization of a rhythm by perceiving its metrical structure even when it is evoked only by temporal alterations. There is also plenty of data suggesting that several animal species can track different rhythmic cues. However, there is no clear evidence that nonhuman animals can extract metrical information from an auditory rhythm. To explore this issue, we familiarized rats (Rattus norvegicus) to auditory rhythmic sequences. We then tested them with novel sequences that presented temporal variations at the metrical, grouping, or tone duration level. We observed that the animals responded differently to the familiar versus the novel sequences, suggesting that temporal alterations are sufficient for the animals to discriminate between auditory rhythmic sequences. Likewise, the use of temporal accents could be relevant to provide metrical information, although it is still an open issue the extent to which the animals are able to induce meter from rhythmic sequences. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Comparative psychology has its share of historical ironies. A particularly delightful one comes from Lloyd Morgan himself. In Animal Behavior, which was published after An Introduction to Comparative Psychology (which contains Morgan's Canon), he marvels at a digger wasp that picks up a small pebble in her mandibles and uses it as a hammer to pound and tamp the earth sealing her burrow. what does the Canon mean to the scientists who use it today? A recent article in this issue by Voudouris et al. (2025) gives us a first empirical insight. Using systematic surveys, they shed light on what comparative cognition researchers actually think about Morgan's Canon, the associative-cognitive distinction, and the role of parsimony in interpreting animal behavior. Morgan's Canon began as a plea for rigor. Over time, it became a slogan, sometimes a straitjacket, occasionally a scapegoat. But it remains also a guardrail, a guide, and a goad: it guards against overreach, guides control design and interpretation, and goads us to spell out mechanisms. The new survey shows that researchers still value the Canon but use it with more flexibility and less dogmatism than in the past. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Uncovering the cognitive bases of egg rejection behavior in avian hosts of brood parasites carries significant comparative implications not only for our understanding of host-parasite coevolution but also for cross-species research aimed at assessing decision-making. In this study, we focused on the American robin (Turdus migratorius), a species that lays large, elongated, and immaculate blue eggs and is well studied for its robust rejection of smaller, rounder, white, and maculated eggs laid by the brood parasitic brown-headed cowbird (Molothrus ater). Employing a randomized multiple simultaneous parasitism paradigm, we experimentally investigated how model egg color, dimensions, and maculation influenced the rejection rates of eight distinct egg types across 28 different pairings of two eggs at a time. First, we assessed whether egg rejection decisions depended on model egg features. Then, for a subset of trials (36%) where one egg was accepted and the other was rejected, we utilized a conjoint design analysis, a methodology borrowed from economics and marketing. Using the conjoint analysis, we showed that white model eggs were 50% more likely to be rejected relative to blue eggs, small-round eggs were 39% more likely to be rejected compared to large-elongated model eggs, and maculated eggs were 19% more likely to be rejected compared to immaculate eggs. These findings reaffirmed the roles of egg color, dimension, and maculation as key visual cues influencing egg rejection behavior in American robins. These findings also offer methodological advancements to study egg rejection behavior and lend themselves to future comparisons of human and nonhuman decision-making processes. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Recent research has shown that personality similarity between pair-bonded individuals can lead to better compatibility and well-being in humans. In our study, we explored the personality of 27 pairs of captive coppery titi monkeys (Plecturocebus cupreus), using a Hominoid Personality Questionnaire of 54 personality items. We also examined the effect of pair duration, pair affiliation, and the presence of offspring on the personality of these pairs. We built a model with five components to describe titi monkey personality structure in our colony and labeled these components as aggressive, cool, cautious, innovative, and helpful. Helpful, which we relate to "agreeableness," was significantly higher in males than in females. Aggressive and helpful were correlated within couples. Helpful was also negatively related to the time spent since pairing. Innovative was higher for pairs with higher affiliation. Additionally, we compared personality similarity between a group of pairs that were created based on initial compatibility (determined via a "speed-dating" experiment), and a group of tenure-matched pairs that were determined quasirandomly. Pairs determined from speed dating were more helpful than pairs from the colony comparison group, which suggests that high levels of initial attraction may facilitate an increase in prosocial personality traits. Our findings, including the negative correlation of "helpful" with time since pairing and the heightened "innovative" trait in pairs with stronger affiliation, may suggest subtle dynamics within titi monkey personalities. These insights contribute to a broader understanding of nonhuman primate personalities. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Social negotiation is crucial in human interactions and often involves clear communication, strong socialization skills, adept problem-solving abilities, and strategic planning. Chimpanzees exhibit evidence of social negotiation through manual gesturing to achieve imperative goals. Chimpanzee social negotiations are influenced by demographic factors like age, sex, social rank, and identity, as well as communicative properties such as gesture type, gesture modality, gesture position, and context. In our study, we build on prior research by analyzing how chimpanzees use facial signals during social negotiations. We used machine learning models and sequential pattern analysis to analyze the combined effects of facial signals and manual gesturing properties, along with demographic factors. Our analyses revealed that facial signals and manual gesturing are important for predicting the success of chimpanzee social negotiations. We also found that clear communication (using distinct facial signals and manual gestures in each context) is important for navigating social negotiations, much like is true for humans. Our research showcases the immense value of machine learning techniques in exploring the evolution of social behavior in primates. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Domestic dogs have been shown to respond to their auditory environment, with different genres of music triggering different behavioral and physiological responses. It is still unknown, however, whether the auditory environment can influence canine affect. This study therefore explored the influence of auditory stimulation on the short-term mood of dogs. Forty-five pet dogs were randomly assigned to one of the three conditions of auditory stimulation (a control of silence, classical music, or audiobook). While being exposed to the auditory stimulus relevant to their condition, each subject animal participated in a commonly employed cognitive bias test, during which their latency to approach a bowl placed in one of the three ambiguous positions was recorded. All dogs were successfully trained, with intact animals taking fewer sessions to reach criterion than neutered subjects. As expected, dogs became increasingly slower to reach the bowl the further it was positioned from the positive location. The animals' latency to reach the bowl placed in the ambiguous positions did not differ significantly between auditory conditions. The study suggests that canine affect is not influenced by the auditory environment, at least in the short term. Methodological issues, both in relation to the protocol adopted in the present investigation and the cognitive bias test more generally, are considered. (PsycInfo Database Record (c) 2025 APA, all rights reserved).