Biology subjects

Kano, F.

Publications and source records attributed to Kano, F..

11 recordsLinked to original sources

bioRxiv2025

Individual bounded rationality destabilizes cooperative dynamics in human-AI groups

Cooperative dynamics arise from interactions among individuals, including humans and artificial agents, yet it remains unclear how individual-level cognition and motion shape collective dynamics in such human-AI groups. We combined a dynamic cooperative task, in which one attacker was controlled by a human and two by heuristic artificial agents facing a deep reinforcement learning defender, with counterfactual simulations of artificial groups. Across nine task conditions, groups including a human consistently underperformed relative to groups composed solely of artificial agents. Humans exhibited restricted movement options and probabilistic rather than deterministic action choices, which shifted coordination dynamics towards less symmetric, less organized patterns and reduced performance for both individuals and groups. Embedding these boundedly rational movement and decision parameters into artificial agents reproduced human-like behavior and performance declines. These results demonstrate how limitations of a single individual can destabilize cooperative dynamics and provide insights into the design of robust human-AI systems.

animal behavior and cognition↗

bioRxiv2025

Rapid Social Transmission of Predator Location via Gaze Following in Pigeons

Social information transmission is a key advantage of group living, particularly in uncertain or high-stakes contexts. During collective predator vigilance, individuals often initiate evasive action based on social cues--such as the escape behaviour of others--before detecting threats themselves. Yet these cues can be ambiguous or misleading, leading to costly false alarms. Gaze following, a key socio-cognitive skill widespread across species, may reduce this ambiguity by allowing individuals to localize threats with minimal effort and avoid unnecessary escapes. Although this vigilance function has long been hypothesized, direct evidence is lacking. Here we show that pigeons foraging in flocks detect a predator and socially transmit its location rapidly via gaze following, before any escape behaviour occurs. In experiments simulating predator attacks, we reconstructed predator-oriented gaze using high-resolution posture tracking and modelled social transmission with dynamic multi-network Bayesian models. Comparing models based on distinct social cues, we found that pigeons responded selectively to conspecific gaze toward the predator, rather than locomotion, head-up vigilance, or gaze elsewhere. Analyses of network structure further revealed that this transmission occurs through visually connected networks, particularly via peripheral rather than foveal vision. While individuals occasionally followed gaze to non-threatening locations, flocks reliably converged on the actual threat. These findings uncover a previously undocumented, cognition-based mechanism of collective detection. To our knowledge, this is the first evidence that gaze following serves an adaptive function in survival contexts, illustrating how individual-level cognition and group-level dynamics interact to the adaptive value of group living.

animal behavior and cognition↗

bioRxiv2025

Holding a Steady Look at the Human Eye: Rebuttal to Critiques of the Gaze-Signalling and Cooperative Eye Hypotheses

The Cooperative Eye Hypothesis (CEH) and the Gaze-Signalling Hypothesis (GSH) propose that the human eye--distinguished by pronounced scleral exposure and a uniformly white sclera-- evolved as a unique trait among primates to enhance eye-gaze visibility and facilitate cooperative communication. A recent review by Perea-Garcia and colleagues (2025) questioned four central premises of these hypotheses: (1) that human eye morphology is unique among primates, (2) that it is expressed consistently across individuals and populations, (3) that it improves gaze-following, and (4) that it is linked to the evolution of social cognition. Here, we revisit each claim through reevaluation of evidence and reanalysis of published data. First, we show that although some primates exhibit scleral depigmentation, humans uniquely combine this with high scleral exposure, resulting in markedly greater gaze visibility. Second, despite variation in scleral brightness, cross-species comparisons of sclera-iris-skin contrast confirm that human eyes remain distinct from those of other closely related apes. Third, experimental studies demonstrate that the white sclera confers a clear communicative advantage under ecologically relevant conditions, and that only humans consistently exploit these cues. Finally, developmental, cross-cultural, and neurocognitive evidence indicates that humans possess dedicated perceptual mechanisms for eye-gaze, consistent with its evolutionary embedding in social cognition. We conclude that while claims of human uniqueness should be moderated, the CEH and GSH remain the most plausible explanations for the evolution of human eye morphology. We also highlight key directions for future behavioral, anatomical, and genetic research.

evolutionary biology↗

bioRxiv2024

Gaze Following in Pigeons Increases with the Number of Demonstrators

Gaze following, orienting ones gaze in the same direction as another individual, is widespread across species and well-studied in terms of cognitive mechanisms. However, the role of collective context on this behavior is less understood. This study tested whether the number of conspecifics looking in a particular direction facilitates gaze following in pigeons (Columba livia). We presented attention-getting stimuli to subsets of pigeons (demonstrators), while other pigeons (observers) could not see the stimuli directly. We used a motion-capture system to track fine-scale movements of head and body orientations. Observer pigeons followed the gaze of demonstrators, specifically toward the target object rather than a perceptually similar distractor. Critically, the likelihood and frequency of gaze following increased with the number of demonstrators looking at the target. We observed no nonlinear effects, such as saturation or quorum thresholds, in this increasing trend, at least under our experimental conditions. In group-living species like pigeons, multiple individuals looking in the same direction may serve as a more reliable social signal. To our knowledge, this is the first study to demonstrate that the number of demonstrators influences gaze following in non- human animals, highlighting the critical role of collective context in animal social cognition.

animal behavior and cognition↗

bioRxiv2024

YOLO-Behaviour: A simple, flexible framework to automatically quantify animal behaviours from videos

Manually coding behaviours from videos is essential to study animal behaviour but it is labour-intensive and susceptible to inter-rater bias and reliability issues. Recent developments of computer vision tools enable the automatic quantification of behaviours, supplementing or even replacing manual annotations. However, widespread adoption of these methods is still limited, due to the lack of annotated training datasets and domain-specific knowledge required to optimize these models for animal research. Here, we present YOLO-Behaviour, a flexible framework for identifying visually distinct behaviours from video recordings. The framework is robust, easy to implement, and requires minimal manual annotations as training data. We demonstrate the flexibility of the framework with case studies for event-wise detection in house sparrow nestling provisioning, Siberian jay feeding, human eating behaviours, and frame-wise detections of various behaviours in pigeons, zebras, and giraffes. Our results show that the framework reliably detects behaviours accurately, and retrieve comparable accuracy metrics to manual annotation. However, metrics extracted for event-wise detection were less correlated with manual annotation, and potential reasons for the discrepancy between manual annotation and automatic detection are discussed. To mitigate this problem, the framework can be used as a hybrid approach of first detecting events using the pipeline and then manually confirming the detections, saving annotation time. We provide detailed documentation and guidelines on how to implement the YOLO-Behaviour framework, for researchers to readily train and deploy new models on their own study systems. We anticipate the framework can be another step towards lowering the barrier of entry for applying computer vision methods in animal behaviour.

animal behavior and cognition↗

bioRxiv2024

Peering into the world of wild passerines with 3D-SOCS: synchronized video capture and posture estimation

O_LICollection of large behavioural data-sets on wild animals in natural habitats is vital in ecology and evolution studies. Recent progress in machine learning and computer vision, combined with inexpensive microcomputers, have unlocked a new frontier of fine-scale markerless measurements. C_LIO_LIHere, we leverage these advancements to develop a 3D Synchronized Outdoor Camera System (3D-SOCS): an inexpensive, mobile and automated method for collecting behavioural data on wild animals using synchronized video frames from Raspberry Pi controlled cameras. Accuracy tests demonstrate 3D-SOCS markerless tracking can estimate postures with a 3mm tolerance. C_LIO_LITo illustrate its research potential, we place 3D-SOCS in the field and conduct a stimulus presentation experiment. We estimate 3D postures and trajectories for multiple individuals of different bird species, and use this data to characterize the visual field configuration of wild great tits (Parus major), a model species in behavioural ecology. We find their optic axes at approximately {+/-}60{degrees} azimuth and -5{degrees} elevation. Furthermore, birds exhibit functional lateralization in their use of the right eye with conspecific stimulus, and show individual differences in lateralization. We also show that birds convex hulls predicts body weight, highlighting 3D-SOCS potential for non-invasive population monitoring. C_LIO_LI3D-SOCS is a first-of-its-kind camera system for wild research, presenting exciting potential to measure fine-scaled behaviour and morphology in wild birds. C_LI

animal behavior and cognition↗

bioRxiv2024

Fine-scale tracking reveals visual field use for predator detection and escape in collective foraging of pigeon flocks

During collective vigilance, it is commonly assumed that individual animals compromise their feeding time to be vigilant against predators, benefiting the entire group. One notable issue with this assumption concerns the unclear nature of predator "detection", particularly in terms of vision. It remains uncertain how a vigilant individual utilizes its high-acuity vision (such as the fovea) to detect a predator cue and subsequently guide individual and collective escape responses. Using fine-scale motion capture technologies, we tracked the head and body orientations of pigeons (hence reconstructed their visual fields and foveal projections) foraging in a flock during simulated predator attacks. Pigeons used their fovea to inspect predator cues. Earlier foveation on a predator cue was linked to preceding behaviors related to vigilance and feeding, such as head-up or down positions, head-scanning, and food-pecking. Moreover, earlier foveation predicted earlier evasion flights at both the individual and collective levels. However, we also found that relatively long delay between their foveation and escape responses in individuals obscured the relationship between these two responses. While our results largely support the existing assumptions about vigilance, they also underscore the importance of considering vision and addressing the disparity between detection and escape responses in future research.

animal behavior and cognition↗

bioRxiv2023

Gaze tracking of large-billed crows (Corvus macrorhynchos) in a motion-capture system

The visually guided behaviors of corvids (Corvidae) are often examined in previous studies because they provide important clues about their perception, attention, and cognition. However, the details regarding how they orient their heads toward the visual targets (or how they use their visual fields when attending to the visual targets) remain largely unclear. This study used a newly established motion capture system to examine the visual field use of large-billed crows (Corvus macrorhynchos). Study 1 employed an established ophthalmoscopic reflex technique to identify the visual field configuration, including the binocular width and optic axes, as well as the degree of eye movement. Study 2 used the motion capture system to track the head movements of freely moving crows and examined how they oriented their reconstructed visual fields toward attention-getting objects. When visual targets were moving, the crows used their binocular visual fields, particularly around the projection of the beak-tip. When the visual targets stopped moving, crows frequently used non-binocular visual fields, particularly around the regions where their optic axes were found in Study 1 (close to their visual axes). On such occasions, the crows slightly preferred the right eye. Overall, the visual field use of crows is clearly predictable. Thus, while the untracked eye movements could introduce some level of uncertainty (typically within 15 degrees), we demonstrated the feasibility of inferring a crows attentional focus by 3D tracking of their heads. Our system represents a promising initial step towards establishing gaze tracking methods for studying corvid behavior and cognition.

animal behavior and cognition↗

bioRxiv2021

Oxytocin promotes social grooming in bonobos: testing the biobehavioural feedback loop hypothesis

Oxytocin has attracted research attention due to its role in promoting social bonding. In bonobos and chimpanzees, the two Pan species closely related to humans, urinary oxytocin is known to correlate with key behaviours related to social bonding, such as social grooming in chimpanzees and female-female sexual behaviour in bonobos. However, no study has demonstrated that the administration of oxytocin promotes real-life social interactions in Pan, leaving it unclear whether oxytocin is merely correlated with social behaviors or does affect them in these species. To test this, we administered nebulized oxytocin or saline placebo to a group of female bonobos and subsequently observed the change in their gross behavior during free interaction. We found an overall effect of more frequent grooming in the oxytocin condition. However, on the individual level this effect remained significant for only one participant in our follow-up models, suggesting future work should explore inter-individual variation. Our results provide some experimental support for the biobehavioural feedback loop hypothesis, which posits that some functions of the oxytocin system support the formation and maintenance of social bonds through a positive feedback loop; however, further tests with a larger number of individuals are required. Our results, at a minimum, demonstrated that oxytocin affects spontaneous, naturalistic social interactions of at least some female bonobos, adding to accumulating evidence that oxytocin modulates complex social behaviors of Pan.

animal behavior and cognition↗

bioRxiv2021

What is unique about the human eye? Comparative image analysis on the external eye morphology of human and nonhuman great apes

The gaze-signaling hypothesis and the related cooperative-eye hypothesis posit that humans have evolved special external eye morphology, including exposed white sclera (the white of the eye), to enhance the visibility of eye-gaze direction and thereby facilitate conspecific communication through joint-attentional interaction and ostensive communication. However, recent quantitative studies questioned these hypotheses based on new findings that humans are not necessarily unique in certain eye features compared to other great ape species. Therefore, there is currently a heated debate on whether external eye features of humans are distinguished from those of other apes and how such distinguished features contribute to the visibility of eye-gaze direction. This study leveraged updated image analysis techniques to test the uniqueness of human eye features in facial images of great apes. Although many eye features were similar between humans and other species, a key difference was that humans have uniformly white sclera which creates clear visibility of both eye outline and iris -the two essential features contributing to the visibility of eye-gaze direction. We then tested the robustness of the visibility of these features against visual noises such as darkening and distancing and found that both eye features remain detectable in the human eye, while eye outline becomes barely detectable in other species under these visually challenging conditions. Overall, we identified that humans have distinguished external eye morphology among other great apes, which ensures robustness of eye-gaze signal against various visual conditions. Our results support and also critically update the central premises of the gaze-signaling hypothesis.

animal behavior and cognition↗

bioRxiv2021

Experimental evidence for the gaze-signaling hypothesis: White sclera enhances the visibility of eye gaze direction in humans and chimpanzees

Hallmark social activities of humans, such as cooperation and cultural learning, involve eye-gaze signaling through joint attentional interaction and ostensive communication. The gaze-signaling and related cooperative-eye hypotheses posit that humans evolved unique external eye morphology, including exposed white sclera (the white of the eye), to enhance the visibility of eye-gaze for conspecifics. However, experimental evidence is still lacking. This study tested the ability of human and chimpanzee participants to detect the eye-gaze directions of human and chimpanzee images in computerized tasks. We varied the level of brightness and size in the stimulus images to examine the robustness of the eye-gaze directional signal against visually challenging conditions. We found that both humans and chimpanzees detected gaze directions of the human eye better than that of the chimpanzee eye, particularly when eye stimuli were darker and smaller. Also, participants of both species detected gaze direction of the chimpanzee eye better when its color was inverted compared to when its color was normal; namely, when the chimpanzee eye has artificial white sclera. White sclera thus enhances the visibility of eye-gaze direction even across species, particularly in visually challenging conditions. Our findings supported but also critically updated the central premises of the gaze-signaling hypothesis.

animal behavior and cognition↗