Animal Cognition最新文献

In coral reef ecosystems, anthropogenic change is rapidly altering habitat structure, but the consequences for fish cognition remain poorly understood. We tested whether structural habitat complexity influences spatial learning and strategy use in the humbug damselfish (Dascyllus aruanus). Juveniles were reared in aquaria containing either high- or low-complexity coral structures and trained in a T-maze task, requiring the use of egocentric (turn-based) and/or allocentric (landmark-based) strategies to locate a reward. Performance was assessed using the number of trials to reach a learning criterion and latency to make correct decisions. Probe trials with conflicting cues assessed navigation strategies. Turn direction was the strongest predictor of performance. Fish trained to turn left reached criterion in fewer trials and consistently relied on egocentric strategies, indicative of a lateralisation bias. In contrast, right-turning fish increasingly relied on landmark cues during probe trials and made faster decisions when doing so, suggesting that allocentric strategies reduced the cost of acting against intrinsic turn biases. Contrary to our expectation, environmental complexity did not affect the number of trials required to reach criterion. However, high-complexity fish located the reward faster during early training and showed longer decision latencies during probe trials, suggesting greater sensitivity to landmark information when cues conflicted. Our results suggest that spatial task performance may be shaped more by turn biases and strategy use than by environmental complexity alone, highlighting the importance of considering intrinsic behavioural constraints when interpreting spatial cognition.

Facial displays are an important channel of communication for primates, yet it remains unclear based on which criteria monkeys evaluate facial expressions. We trained two rhesus macaques to categorize videos of four facial expression types (neutral, lip-smacking, silent bared-teeth (SBT) and open-mouth threat displays) and then tested generalization to novel individuals and avatars while measuring pupillary responses. The animals were able to categorize facial expressions and generalized their classifications to novel, untrained videos, although performance was not perfect. Misclassifications were not driven solely by visual similarity between expression categories, as demonstrated by a novel automated approach integrating deep learning-based motion tracking with the Macaque Facial Action Coding System to enable objective quantification of facial action units. Instead, open-mouth threats were readily categorized correctly and distinguished from lip-smacking, while also eliciting the strongest arousal responses. By contrast, categorization of SBT displays varied substantially across stimulus identities, influenced by body weight, gaze direction, and coordinated movements of eyebrows and ears. Morphed avatar expressions were categorized according to expression component intensity, demonstrating graded perception. Avatar manipulations revealed that categorization was robust against lack of coherent motion and lack of facial realism beyond a basic level of texture. However, human facial expressions elicited no systematic categorizations or differential arousal. Our findings indicate that conspecific facial expressions were perceived as functionally meaningful, context-dependent social signals shaped by all components of facial behavior and signaler characteristics, rather than fixed, mouth movement-defined categories.

Goal-directed intentionality is the ability to communicate with the intention of eliciting reactions from recipients. Long considered uniquely human, today it has been reported in the signalling of several species, most notably in the large, flexible gestural repertoires of non-human apes. Semi-captive elephants have also shown goal-directed intentionality when gesturing to humans. However, whether wild elephants gesture intentionally to conspecifics has not been systematically explored. Elephants frequently engage in agonistic interactions, in which goal-directed intentional communication may help resolve conflict and prevent escalation. Here, we systematically investigated intentional gesturing in wild African savannah elephants by examining agonistic interactions in the Addo and Marakele populations in South Africa. Elephants used 41 gesture types (derived from 32 gesture actions) to communicate two main goals: “Move away” and “Stop behaviour”. The gesture types used by the populations largely overlapped, suggesting a shared context-specific repertoire for agonistic interactions. However, the populations differed in the gesture types they used most frequently and in the resources they competed over (water in Addo, reeds in Marakele). Our study supports the convergent evolution of extensive and flexible intentional gestural communication in elephants, providing insights into the drivers of elephant agonistic behaviour and highlighting potential conservation implications.

Since 2020, Iberian orcas have repeatedly interacted with sailing vessels, often targeting rudders. These well-documented interactions have been discussed primarily as play, exploration, maladaptation, or a product of cultural transmission. Here, I argue for a complementary interpretation. This phenomenon also exposes a broader explanatory issue in animal cognition: complex animal behavior in the wild is often described without an explicit theory of action. Drawing on cognitive action–effect approaches, I suggest that rudder-directed interactions may also be understood as actions organized around anticipated environmental consequences. The orca case thus highlights the need for action models that can travel across species, ecological contexts, and disciplinary boundaries.

Behavioural contagion occurs when the behaviour of one individual elicits the same behaviour in another individual observing the event, and it is considered one of the fundamental mechanisms promoting group coordination and cohesion in social species, including humans. Empirical research on behavioural contagion has focused primarily on yawning and has shown evidence of it in several animal species. Here, we studied behavioural contagion in 2 groups of captive wolves (N = 20) and 3 groups of captive dog-admixed wolves (N = 13). We conducted behavioural observations of naturally occurring yawning events and monitored the yawning behaviour of the other group members in the two minutes following each event. Our results showed that, in both admixed and non-admixed wolves, individuals who had the opportunity to observe the initial yawn were significantly more likely to yawn within the subsequent two minutes than those who had not observed the event. Crucially, this effect was stronger in non-admixed than in admixed wolves. Furthermore, individuals that were more socially integrated were more likely to elicit behavioural contagion in both admixed and non-admixed wolves. In contrast, neither individual rank nor dyadic relationship quality between the yawner and the observer mediated the probability of contagion. By revealing variation in behavioural contagion patterns between admixed and non-admixed wolves, this study provides insights into how introgressive hybridization with domestic species may influence mechanisms underlying social coordination and pack cohesion in wolves.

Behavioural innovations can be crucial for animals to adjust to changing environments and to exploit novel resources. While ecological and evolutionary implications of innovativeness have been investigated intensely, the proximate mechanisms underlying this behaviour are less well understood. Intrinsic individual differences arising from differences in competitive abilities have been hypothesised to drive differences in innovation propensity (bad-competitor hypothesis). We here investigated the relationship between early-life competition among siblings as well as effects of several physiological and personality traits on innovation propensity in young wild cavies (Cavia aperea). Our study aimed to test whether competitive situations in early life, such as being a small sibling or being born in larger litters, enhanced innovation propensity. Furthermore, we tested if intrinsic physiological or behavioural characteristics differed between solvers and non-solvers. We found that neither size rank nor litter size influenced innovation propensity in young cavies at independence. Likewise, physiological traits such as cortisol level, heart rate, and resting metabolic rate did not differ systematically between solvers and non-solvers, although heart rate and resting metabolic rate were repeatable. However, individuals that interacted more with novel objects and innovation tasks were more likely to solve them. Our results suggest that innovation propensity is not shaped by early-life competition or physiological differences but may rather develop consistent individual differences later in life, potentially by competition for mating opportunities.

Experiences of social isolation alter the developing social behavior of animals. Association preference is an important behavioral tendency for amphibian larvae (tadpoles) that exhibit social aggregation as a means of predator avoidance. For tadpoles that exhibit social aggregation, the learning period during exposure to conspecifics could be crucial. This study investigated how water quality and social experience influence association preferences to unfamiliar conspecifics in Bufo formosus (Eastern-Japanese common toad) tadpoles. Using a 2 × 2 factorial design, subject tadpoles were reared either in tap or pond water and under group or solitary conditions. Binary-choice tests were then conducted to examine whether the tadpoles preferred siblings, non-siblings, or neither (neutral zone). No significant kin-biased association was detected in any treatment. However, social experience significantly affected the proportion of time spent in neutral zone. Solitary-raised tadpoles spent the most time in the neutral zone, whereas group-raised tadpoles spent more time on the effective-stimulus sides irrespective of water quality. It suggests that social isolation in early developmental stage reduces responsiveness to conspecifics. These findings indicate that social aggregation in B. formosus is shaped by social experience rather than kinship and aquatic environment.

Crossmodal correspondences, spontaneous links between sensory modalities, are well documented in humans and other animals. The Bouba–Kiki effect, where sharp sounds typically map onto angular shapes and soft sounds onto rounded ones, possibly constitute a peculiar case of such correspondences, as it was documented in preverbal infants and non-human species. Here we test whether a spontaneous association between “Bouba” and “Kiki” sounds, and round and spiky shapes respectively, also appears in a reptile, the Testudo marginata. In a free-exploration task, 10 tortoises were exposed to repeated “Bouba” or “Kiki” sounds while presented with a round and a spiky 3D object. Strikingly, tortoises showed a reversed mapping compared to humans and birds: they spent longer exploring the round object during “Kiki” playbacks and the spiky object during “Bouba”. This unexpected inversion raises key questions about the origins of crossmodal cognition. We argue that the reversed pattern may reflect the interaction between an underlying sound-shape correspondence and the structure of the free-exploration task. Under this interpretation, auditory stimuli may generate expectations regarding visual shapes, whereas exploratory behaviour may promote investigation of unexpected sound-shape combinations. Alternatively, tortoises may rely on fundamentally different principles of perceptual organisation, revealing that crossmodal associations are not universally aligned across species.