Journal of Comparative Psychology最新文献

In recent decades, there has been a growing interest in exploring the cognition of domestic dogs. However, the role of olfaction and vision in dogs' perception of everyday situations has been underexplored. To investigate this topic, we used a simple food-searching paradigm. A treat was hidden in one of three locations, either (a) visible from the starting point (vision condition), (b) invisible from the starting point (smell condition), or (c) invisible with an additional decoy treat presented as a distraction (fake condition). About 87 dogs of various breeds were categorized into either the olfactory-focused or the vision-focused group based on their sniffing behavior in a pretest. It was hypothesized that olfactory-focused dogs would preferentially use their sense of smell for task solving, whereas vision-focused dogs would rely more on visual information. Thus, it was expected that dogs of each group would have an advantage in the corresponding condition. However, there was no difference between groups in the duration to find the food in the three conditions. In general, food was approached faster in the vision condition, and dogs in all groups were distracted by the presence of the fake food. Thus, for all dogs, the visual sense was more dominant than the olfactory sense, and they could easily switch between using the two senses. The results are discussed in light of breed differences and general perception skills of domestic dogs. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

A study of wild chimpanzees using a brief questionnaire identified four factors that only weakly resembled those identified in zoo- and laboratory-housed samples. To test whether the failure to recover these factors was attributable to the small number of questionnaire items sampled in that study, the present study obtained ratings on 40 chimpanzees in Budongo Park, Uganda on the 54-item Hominoid Personality Questionnaire. Exploratory factor analysis using a matrix-free likelihood method for extracting factors obtained four personality factors-Dominance, Disagreeableness, Openness, and Extraversion-from 46 items that passed reliability screening. These factors resembled, but were not identical to, personality factors found in earlier samples of chimpanzees in human care. These findings are consistent with the notion that a universal structure of chimpanzee personality exists and that there may be some variation across habitats and populations. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Philosophers of science and mind have paid increasing attention to the field of comparative psychology. Two recurring points of discussion in the literature are the methodological value of Morgan's Canon and the distinction between associative and cognitive processes. Although the existing literature regularly makes claims about the beliefs and attitudes of comparative psychologists, there are few empirical studies verifying these claims. This article fills this gap by presenting and analyzing the views of over 200 comparative psychologists on Morgan's Canon and the associative-cognitive distinction. We found that while there is some agreement between the claims in the existing literature and the views of the practitioners surveyed here (e.g., that Morgan's Canon is a parsimony principle), there are also surprising points of divergence (e.g., practitioners do not view the associative-cognitive distinction as a version of Morgan's Canon). We intend for this study to inform existing philosophical and theoretical work on perennial questions regarding how to study animal minds and behavior. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

The Producer-Scrounger game proposes that individuals in social foraging situations tend to choose one of two strategies: (a) actively invest effort in searching for resources (producing) or (b) exploit resources discovered by others (scrounging). Models have typically given scroungers an advantage. In Vickery et al.'s (1991) model, remaining food in a patch is equally shared among scroungers regardless of their position or visual range. Similarly, agent-based models assume scroungers have a comprehensive view of the habitat, enabling them to detect all opportunities to exploit resources, while producers move randomly. This study examined the effect of visual range on producer-scrounger dynamics using a computerized behavioral task where four human participants interacted in real time within a virtual habitat. Two groups, differing in food probability (λ80 and λ20), were exposed to four experimental conditions that varied visual range by manipulating the top-down camera angle (45° or 75°) and camera distance (240 or 80 px). Results showed that the producer index was higher when the probability of finding resources increased, and highest in the 75°-240 px condition, where participants had limited depth of view but could better perceive their immediate surroundings. A modified agent-based model that included visual range parameters revealed a similar pattern. These findings highlight the importance of visual range, often underestimated in theoretical models, for producer strategies. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Cotton-top tamarins (n = 14, aged 7-24 years) were tested over a 10-year period on tasks conventionally differentiating aging from dementia in humans. Three tasks were developed on iPads to collect response accuracies in tests of attention (visual search [VS]), working memory (delayed matching-to-sample), and executive processing (rule-shifting). A fourth task utilized a spontaneous object recognition paradigm to test familiarity memory in the subjects' home cages. Linear regression analyses revealed cognitive decline with increasing age in particular components of these tasks. Specifically, accuracy to direct attention in a VS to targets with overlapping features decreased with age. All older monkeys showed accuracy to remember sample items through 1- and 10-s delays in a recognition test, but their ability to remember through these delays was compromised with more extreme aging. Rule-shifting involving attending to a dimension previously irrelevant to the game was particularly problematic with increased age. Cognitive maintenance with aging occurred with simpler VS targets, rule-shifting within the same dimension or feature, and familiarity memory. Tamarins' initiation of cognitive decline mapped closely to the age found in published work of the accumulation of Aβ (beta amyloid species and plaques) in tamarins. The failures in cognition in aging tamarins corresponded with common failures in elderly humans. Moreover, eight of the 14 tamarins showed more severe cognitive deterioration that might signal a kind of dementia. Further study is needed to measure cognitive maintenance and loss across a variety of species of primates with different lifespans and backgrounds. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Like other domesticated species, most notably dogs, horses have been reported to follow human gestures and successfully use them to gain rewards in an object choice task. Empirical support for the hypothesis that a domain-general mechanism may underlie this ability comes from studies in which horses have successfully solved the task by using not just a human pointing gesture but also an arbitrary physical cue, namely a wooden marker. Here, we replicated the two conditions in which these two cues were used by Proops et al. (2010) with two critical changes: first, we positioned the marker out of the horses' sight, and second, we positioned the marker such that it was in the same position where the gesture would be when the experimenter showed the pointing gesture. Horses successfully solved the task using both the pointing gesture and the marker, and their performance did not differ statistically significantly between these two conditions. The robustness of this result was corroborated by complementary model comparisons, which further showed that the horses' performance was not significantly influenced by their age or sex. Our findings thus support the consistency of previously reported findings in these specific testing conditions and suggest that at least part of the horses' ability to solve the object choice task with different types of cues is based on a domain-general mechanism. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

The matching law, which posits that animals allocate their responses in proportion to the rate of reinforcement, has been supported across diverse animal taxa. Although originally formulated in the context of operant choice, matching also applies to time allocation in foraging and to Pavlovian responses, indicating its generality across behavioral domains. However, empirical evidence has thus far been largely limited to vertebrates and arthropods. Addressing the broader applicability of this principle requires extending investigations beyond these taxonomic groups, across a wider phylogenetic spectrum. Here, we examined phototactic behavior in the acoel flatworm Praesagittifera naikaiensis, a species that acquires nutrients through photosynthesis by symbiotic algae and exhibits positive phototaxis. Using a custom-built T-maze in which the number of illuminated LEDs varied across arms, we found that the animals distributed themselves in proportion to relative brightness, consistent with matching behavior. Moreover, prior exposure to light for 24 hr attenuated this pattern. This manipulation was intended to induce a state of nutritional sufficiency, and the resulting decline in phototactic responses suggests that internal physiological states can modulate even seemingly reflexive locomotor behaviors. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

The use of plants with medicinal properties by nonhuman animals has been extensively documented. However, little emphasis has been placed on evidence suggesting that animals also appear to use/consume substances with psychoactive properties. This psychological self-medication (PsycSM) hypothesis posits that the voluntary use of substances that alter emotional/mental states is guided by the substance's ability to reduce negative states or promote positive states. The objective of this narrative review is to provide a rigorous interpretation and critique of findings, point out contributions and limitations of available research, and provide a synthesis useful to design further studies aimed at testing the PsycSM hypothesis. Criteria derived from this hypothesis are used to establish behaviors as PsycSM examples. Areas for potentially useful interactions between field and laboratory research are specified. Anecdotal evidence from field observations suggests that animals voluntarily consume substances that affect their emotional state. Although laboratory research reviewed herein suggests that nonhuman animals intentionally consume substances that can affect their emotional/mental state, the underlying mechanisms are still poorly understood. One such mechanism is hypothesized to involve a reinforcement process produced by a change in the internal state contingent on substance consumption, whether to reduce negative emotions or to enhance positive emotions. The criteria for PsycSM developed in this review may guide further research into these effects. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Grey parrots have been shown to reason via inference by exclusion in various experiments, but so far only one bird has been shown to succeed on a four-cup task originally tested on young children, a purportedly stronger test of inference than experiments involving two cups. In the procedure with four cups (two pairs: AB, CD), a reward is hidden in one cup of each pair-for example, B, C; then one cup-for example, A-is shown to be empty. Successful subjects should conclude that the reward is 100% likely in B, only 50% likely in C or D, and accordingly choose B, thereby demonstrating modal and logical concepts in addition to epistemic ones. Here we replicate the task with three other Grey parrots to demonstrate that the ability is not restricted to one individual with extensive experimental experience. Thus, several subjects are now available for further testing necessary to examine the extent to which Grey parrots understand inference by exclusion. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Sharing food with immature individuals is costly and should therefore only occur when the benefits outweigh the costs. Accordingly, sharing typically decreases when immature individuals get older and become more proficient independent foragers. Providers would gain more if they could adjust food sharing not only to immature age but also to their skill level. Such sensitivity to others' skill deficits is expected to be rare, but may be found in species with high prosociality and other-regarding preferences, such as cooperative breeders. Here, we compared the food-sharing patterns of cooperatively breeding common marmosets (Callithrix jacchus) and closely related but independently breeding squirrel monkeys (Saimiri boliviensis) under two conditions. In the baseline condition, food was easily accessible whereas in the experimental condition, individuals had to solve a puzzle to access the food. We found that the cooperatively breeding marmosets, but not the independently breeding squirrel monkeys, shared more when immatures lacked the skill to obtain the food from the apparatuses. Skill sensitivity might be associated with the presence of other-regarding preferences and a strong proclivity to proactively share food during baseline conditions. This proclivity has evolved in marmosets, but not squirrel monkeys, in the context of cooperative breeding and may facilitate the emergence of skill recognition, information donation, and teaching. (PsycInfo Database Record (c) 2025 APA, all rights reserved).