We investigated the interaction between supervision and category structure in visual categorization across two species that we assumed to have different abilities to selectively attend. Specifically, we compared humans and pigeons in a category learning task, in which the category structure (dense vs. sparse) and the level of supervision by corrective feedback (low vs. high) were manipulated. Results showed a benefit of supervision across species, which was particularly strong in learning the sparse categories. Moreover, both species benefited from category structures that had multiple category-relevant dimensions (i.e., dense categories). In addition, humans, who have a more advanced ability to attend selectively, showed faster learning and better generalization overall. Finally, attention was optimized to the category-relevant dimension in the sparse category only in humans. Subsequent computational simulation of the data indicated that these patterns were well explained by a parameter that controls the organism's ability to flexibly switch attention to category-relevant dimensions. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

The serial multiple choice task is a cross-species model of serial pattern learning that recruits multiple cognitive mechanisms concurrently. The task requires subjects to learn a complex sequence of responses that follow a specific pattern, which is further organized by the placement of distinct cues throughout the sequence. These cues, termed phrasing cues, denote locations in the pattern where response strategy shifts. Although research suggests that phrasing cues facilitate pattern learning, there is a lack of information on how subjects encode these phrasing cues during the pattern learning process. Thus, the current study investigated this further. In this study, rats and humans completed a computerized version of the serial multiple choice task, in which subjects learned a complex serial pattern with either a temporal or spatial phrasing cue. Following acquisition of the pattern, the phrasing cues were then switched between groups to assess if pattern performance could generalize across different phrasing cue modalities. Although both phrasing cues similarly facilitated pattern acquisition, the subsequent cue switch produced performance impairments for both species. These results indicate limits in the cognitive flexibility available during serial pattern learning, as neither humans nor rats appeared to readily abstract the function of the phrasing cue independent of its stimulus characteristics. Instead, subjects encoded the specific stimulus characteristics of the phrasing cue within the pattern as it was learned, somewhat limiting the generalizability of their learned behavior to novel contexts. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Animal perceptual systems can shape the evolution of communication signals that help individuals negotiate social interactions. Here, we study this concept by exploring how conserved object recognition systems in anuran amphibians relate to evolutionary innovations in visual signaling behavior. We focus specifically on Bornean rock frogs (Staurois parvus), given that males of this species wave at each other with their hindlimbs (foot flag) to compete for access to mates. Past work shows that males who see this signal freeze as though they saw a predator; thus, we test whether perceptual systems that help frogs and toads detect and respond to looming threats are intertwined with mechanisms that govern sexual competition. We find that this is likely the case, as visual activation of cognitive systems for predator detection trigger the output of behavior that typically mediates sexual competition, as well as hints of antipredator behavior (freezing and avoidance). When we visually activate these same cognitive systems for predator detection in anuran species that do not foot flag, we find no evidence of aggression-rather, these individuals simply produce canonical antipredator reactions. Altogether, these findings suggest that the perceptual systems for threat detection in foot flagging S. parvus are likely intertwined with the cognitive systems that underlie sexual competition. These results illuminate the way perceptual systems might drive signal innovations, potentially giving rise to bizarre displays that are otherwise difficult to explain. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

The peak-end effect, in which evaluations of experiences are disproportionately influenced by their most intense, most recent, or final moments, is seen consistently in humans but inconsistently in nonhuman primates. Understanding in what species and contexts these biases appear can help us better understand the evolution of these decision-making biases. Previous evidence in monkeys is contradictory, likely due to differences in experimental procedures. Thus, to assess whether capuchin monkeys (Sapajus [Cebus] apella) exhibit such biases, we tested 14 individuals in a manual two-item food sequence task. Across conditions, monkeys consistently preferred to consume the higher value item first, showing a start bias rather than the end bias characteristic of human decision-making and seen in some other primate studies. This preference was strongest among low- and middle-ranking individuals. However, replacing the low-value item with a delay did not affect choices, suggesting that it was discounted or ignored when monkeys were making their decisions. We consider several explanations for why our monkeys show a start bias rather than an end bias, including possible methodological influences on their choices, and how this affects our understanding of the evolution of these biases. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Emotional crying refers to the uniquely human characteristic of producing visible tears in response to emotionally salient experiences. Originating in infancy as a biologically prepared distress signal, emotional crying persists across the lifespan with relatively stable social effects across cultures, appearing to function to recruit the attention and support of others. Although particular to humans, comparative research suggests crying visible emotional tears can be situated in a broader evolutionary pattern. Across a range of other social species, adults strategically redeploy juvenile-typical behaviors that can influence the responses of conspecifics. Recent primatological work has termed this paedomorphic signaling. We suggest this provides a valuable conceptual anchor for understanding the evolutionary origins of emotional tears in humans. We propose that paedomorphic signaling by adults is effective in eliciting care from conspecifics because, in humans and others species that invest in the care of dependent young, adults have evolved predispositions to attend to and respond to juvenile-like signals. Understanding emotional tears as a form of paedomorphic signaling provides a coherent evolutionary account of their potency, context-sensitivity, and developmental persistence and generates novel predictions that may guide future research. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Comments on an article by K. Ighalo & N. Miller (see record 2027-04636-001). In the context of numerous foragers in an environment, the story becomes more complicated. Now, many foragers searching for one cryptic prey type means less of those prey and a greater relative prevalence of other prey that may then be easier to identify by other foragers. As this process plays out and some foragers focus attention on some prey types because those are the ones they first encounter, other foragers then focus on other prey types because they are more prevalent as a result. This can lead to a reduction in competition among the foragers. The article by Ighalo and Miller is about exactly that kind of situation in which individual foragers engage in "attentional character displacement." Ighalo and Miller's model was based on a simplified version of Guided Visual Search, which proposes that individuals engage visual scenes by first processing basic features (such as color and size) across the entire field in parallel. These features are combined with the individual's goals to create a priority map that guides attention toward likely target locations. Ighalo and Miller predicted that attentional character displacement would reduce competition and improve success rates in their group of simulated foragers, and that each individual forager would experience this effect whether those foragers were able to modulate attention or not. They also predicted that this outcome would be modulated by other effects such as group size, the number of prey types available, and how cryptic the prey were. When the simulation included only two types of prey, Ighalo and Miller found that smaller groups foraged more successfully than larger groups, but it also was true that a higher proportion of attention-modulating foragers led to higher success rates across group sizes. What can be concluded is that a cognitive-ecological modeling approach such as that used by Ighalo and Miller shows that competition likely leads to the evolution of search images. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Gibbons (family Hylobatidae) are small apes comprising lar gibbons (Hylobates spp.), crested gibbons (Nomascus spp.), siamangs (Symphalangus syndactus), and hoolocks (Hoolock spp.). These four genera are closely related to one another and to orangutans (Pongo spp.). Gibbon phylogeny and socioecology make them uniquely suited to improve our understanding of the origins of personality factors. Personality trait ratings of lar gibbons, crested gibbons, and siamangs-sufficient data on hoolocks were not available-were analyzed using exploratory factor analyses. All three genera possessed factors labeled Dominance, Extraversion, and Agreeableness. In addition, lar gibbons and siamangs possessed factors labeled Neuroticism and Conscientiousness, lar gibbons possessed a factor labeled Individualism, and crested gibbons possessed factors labeled Dyscontrol and Avoidance. Exploratory factor analysis of the combined data, which included hoolocks, revealed a Conscientiousness factor and four factors-Extraversion, Dominance, Agreeableness, and Neuroticism-that resembled four of the five orangutan personality factors. Genus- and family-level analyses revealed that better subjective well-being and health-both measured using informant ratings-were associated with higher sociability, emotional stability, and conscientiousness. Based on these results, we concluded that social group size and/or arboreality are related to factor structure, Conscientiousness evolved in hominoids 16-20 million years ago (much earlier than previous estimates), and that relationships in humans between personality and psychological and physical well-being have very early origins. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

In animals, high fission-fusion dynamics (FFD) characterize groups in which individuals frequently split into subgroups of different size and composition. Through evolution, this might have led to an increase in specific cognitive skills that allowed individuals to better cope with the challenges they usually experience under such social conditions. This hypothesis has rarely been tested empirically, and therefore we compared 2 species of zebras to assess potential differences in their cognitive skills. The Chapman's zebras (Equus burchelli chapmanni) typically show lower levels of FFD associated with stable multilevel social groups, whereas Grevy's zebras (Equus grevyi) show higher levels of FFD and therefore live in less cohesive groups. We tested 8 Grevy's zebras and 5 Chapman's zebras in experimental tasks assessing their object permanence, short-term memory, inference, and quantity discrimination skills. Our results showed that Grevy's zebras, typically showing higher FFD, performed better than Chapman's zebras, which live in more cohesive groups, in tasks requiring complex inference skills and marginally in quantity discrimination skills. These findings provide preliminary support to the hypothesis that high FFD may be linked to the enhancement of specific cognitive skills also in taxa other than primates. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

This study examined whether saline acts as an aversive stimulus for planarians and how it influences learning and memory. Using saline as an unconditioned stimulus, we first tested conditioned place avoidance. Saline did not support conditioned place avoidance acquisition; instead, it disrupted habituation to initially preferred tactile and visual stimuli. Further experiments assessed the establishment of conditioned place preference using food as the reinforcer with visual cues. Following training, exposure to saline impaired the expression of conditioned place preference for both light and dark contexts, indicating that the disruptive effect of exposure to saline extends beyond habituation. These findings suggest that saline interferes with the expression of learned behaviors through state-dependent retrieval failure caused by physiological changes induced by saline exposure. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

The conjunction fallacy, a well-known cognitive bias, occurs when individuals erroneously judge the conjunction of 2 events as more probable than either event occurring independently (Tversky & Kahneman, 1983). Although this fallacy has been extensively studied in humans, recent research from our lab shows that nonhuman animals, such as rats, also demonstrate this bias (González, Sadeghi, et al., 2023). In González et al.'s study, rats were trained in a feature-positive/feature-negative go/no-go discrimination (A-/AX+; B+/BY-, where A and B were auditory cues and X and Y were visual cues, and + and-indicate that lever pressing was reinforced or not). At test, cues A and B were presented on probe trials with cues X and Y either unoccluded and off or occluded by a metal shield. Responding was low to A and high to B when the light was visible (and off). When the light was occluded, however, this pattern reversed, with high responding to A and low responding to B. This indicated a bias toward expecting the occluded light to be present rather than absent, consistent with a conjunction fallacy. In a go/no-go procedure, however, some trial types are rewarded, whereas others are unrewarded. This reward asymmetry may bias attention to the different cue conditions. Thus, the current study replicated this conjunction bias using a 2-alternative choice procedure where reinforcement was available on all trial types, removing this potential bias. Our demonstration of a strong conjunction fallacy replicated our prior results, setting the stage for parallel studies in rats and humans. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

The case of Rakus, an orangutan observed treating a wound with medicinal leaves, exemplifies clear, observable animal self-medication and highlights a bias toward studying physically visible behaviors. In contrast, psychoactive self-medication-using substances to regulate internal states such as stress or fear-is harder to detect and interpret. Drawing on Torres et al. (2025), this paper evaluates evidence from anecdotal field observations and controlled laboratory studies. While animals are known to consume psychoactive substances, and experiments show stress-related increases in intake, results remain ambiguous and context-dependent. Criteria for identifying such behavior emphasize prior negative states, relevant pharmacology, and measurable behavioral change. Overall, psychoactive self-medication is plausible but unproven, requiring integrative approaches that combine ecological validity with experimental control. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

English speakers respond more quickly to small numbers with a leftward response and large numbers with a rightward response, a phenomenon known as the spatial-numerical association of response codes (SNARC) effect. Two prevailing theories to explain the SNARC effect make contrasting predictions about individual variability. If the SNARC effect stems from stable long-term memory representations, participants in a culturally homogeneous population (e.g., college students in a Western, English-speaking country) should exhibit a culturally consistent left-to-right SNARC with low variability between individuals within a magnitude domain and within individuals across domains. Alternatively, if the effect arises from an online working memory strategy, participants may be expected to show greater variability both between and within individuals, across and within domains. We present the results of three within-subject experiments in which participants engaged in multiple SNARC tasks across eight magnitude domains. Across the three experiments and 17 task presentations, we consistently found substantial variation in the orientation of the relationship between magnitude and space, both within a magnitude domain and across domains, in a culturally homogeneous Western sample. These findings are more consistent with accounts positing a flexible, context-dependent strategy than with those proposing a stable mental number line as an explanation of the SNARC effect. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

The world is full of uncertainty, often requiring decisions that involve unknown outcomes. Responses to uncertainty, or risk, have been widely studied, revealing both species-level and individual differences. Risk studies have focused on a few key species, so to increase taxon diversity, we investigated the risk sensitivity of four female beluga whales (Delphinapterus leucas) living under human care. We presented them with two options that had identical mean value but differed in their respective variability. The safe option provided four fish every time it was selected, and the risky option provided either zero or eight fish with equal probability. Belugas' preferences varied, with two whales preferring the safe option and two whales preferring the risky option. Testing across morning and afternoon sessions revealed that satiation, assumed to be higher in the afternoon due to feeding schedules, exacerbated existing tendencies toward the safe option in two whales, but did not change any of the belugas' overall preferences. In addition, whales maintained their preferences irrespective of what they had received on the previous trial. Therefore, within individuals, neither short (previous trial) nor longer (time of day) term contexts influenced individuals' preferences, suggesting that these differences were stable. Our results emphasize the importance of considering individual differences in animal decision-making. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

Comparative cognition can make itself more relevant to those who care largely (or entirely) about humans by making itself less WEIRD and less focused on humans. That feels nonintuitive, I know, but psychology has long wanted to find itself at the table with the so-called "hard" sciences, and those sciences have already addressed their WEIRDness largely because they have not wanted humans to be the main character in their story. This cannot be the goal for psychological science to take humans out of it entirely, or should it be. However, there is a fertile middle ground between humans always being the central character and instead sometimes being a "supporting" character in proper comparative perspective or perhaps in some cases not being a character at all (e.g., for some evolutionary questions in which humans are too distantly related to be relevant to the study of certain phylogenetic or mechanistic questions of closely related species). This approach can facilitate greater appreciation for the need to study cognition across cultures and across species (as well as other potential sentient entities such as those emerging in artificial intelligence). (PsycInfo Database Record (c) 2026 APA, all rights reserved).

In this study of mutual gaze (MG) and emotion, using multiple groups of chimpanzee infants to compare with multiple groups of human infants, we provide a methodology to assess two deeply rooted assumptions: (1) Psychological outcomes in chimpanzees are uninfluenced by socioecological conditions, and (2) samples from humans living in Western, middle-class family settings are adequate representatives of humankind. Even though MG is widely viewed as foundational for social cognition, and gaze becomes coordinated with emotion around 1 year of age, these topics have rarely been studied in 1-year-old chimpanzees. We studied four diverse chimpanzee groups-that is, 1-year-old infants living at Chester Zoo (n = 4), in Gombe National Park (n = 12), at the Primate Research Institute (n = 3), and in a human home (n = 2)-and compared them with three diverse groups of human 1-year-olds: urban-UK (n = 8), subsistence farming-Nso (n = 12), and foraging-Aka (n = 10). MG occurred 22% of the time and did not differ across groups or species. We found no species differences in any infant Emotion or in any MG-Emotion co-occurrence pattern. In three of five types of MG-Emotion co-occurrence, the Primate Research Institute chimpanzee infants differed from at least one of the other chimpanzee groups (we reject Assumption 1), and the UK infants differed from at least one of the other human groups (we reject Assumption 2). We conclude there are meaningful influences of socioecology on the functions of some social cognition outcomes, and, thus, it is necessary to sample multiple diverse groups to detect true species differences. (PsycInfo Database Record (c) 2026 APA, all rights reserved).