Animal Cognition最新文献

Detection dogs are trained using limited samples and then expected to generalize this ability to recognize wild samples while maintaining specificity to a target category. Such specificity is critical because dogs are often used to locate targets that are difficult to visually identify. Little is known about how to regain target specificity when false alerts become frequent or established. This case study assessed the training of two conservation dogs that alerted to off-target caracal (Caracal caracal) and leopard (Panthera pardus) scat samples during training to detect cheetah (Acinonyx jubatus) scat. The dogs were trained using an extinction-based differential reinforcement protocol consisting of the non delivery of reinforcement to reduce false alerts to caracal and leopard scats while maintaining sensitivity to cheetah scats. All training was conducted in situ in Samburu County, Kenya, by local handlers under the guidance of trainers. Sessions were filmed and coded for false alerts, true alerts, and where possible, misses and correct dismissals. Within four training sessions, both dogs exhibited an extinction burst demonstrated by an increase and then decrease in both the number and duration of false alerts. They continued to make fewer false alerts for the remainder of the training program. These results demonstrate the ability to reduce false alerts in operational detection dogs via extinction coupled with systematic reinforcement of desired behaviors. This case study highlights the importance of record-keeping and handling protocols for training samples. To our knowledge, this study represents the first publication on an extinction protocol to reduce false alerts in detection dogs.

Cooperative turn-taking, a fundamental characteristic of human social interaction, has been postulated as a crucial mechanism for language emergence and is observed across the primate lineage. However, relatively little is known about the influence of demographic and social factors on turn-taking. As according to the sociolinguistic Communication Accommodation Theory, individuals adapt their communication according to their recipient characteristics, which may shape turn-taking. Thus, we aimed to gain insights into the factors (age, relatedness, dominance rank, and social bonds) in relation to the turn-taking infrastructure of one of our closest living relatives, the chimpanzee (Pan troglodytes schweinfurthii) of the Ngogo population in Kibale National Park, Uganda. We specifically focused on a cooperative context, grooming, including gestures and actions, and collected data over nine months (September 2021 to June 2022) involving 42 male chimpanzees. We analysed 311 grooming interactions among 157 dyads concerning the role of demographic and social factors in turn transition infrastructure, turn transition types, and temporal relationships. Our findings demonstrated that turn transitions and types were influenced by age and dominance rank, whereas social bonds and relatedness did not exhibit effects. Specifically, the probability of turn transitions was higher for older initiators and lower-ranking or younger recipients. These effects varied across turn transition types, where initiator’s dominance rank and relatedness showed no effects on any type. In addition, no effect was found for the temporal relationships. Although the social dynamics of turn-taking remain largely unexplored across both human and non-human studies, our findings suggest that turn-taking can occur selectively between certain individuals, in line with the Communication Accommodation Theory, underscoring the need for greater focus on investigating how demographic and social factors shape turn-taking.

Urbanization has drastically altered natural habitats, forcing non-human primates (NHPs) to adapt to human-modified environments. This study examines one such adaptation undertaken by free-ranging Hanuman langurs residing in Dakshineswar, a temple area and a tourist hub in West Bengal. Our observations reveal that they have come up with solicitation behaviors resembling human begging wherein they ask for food from nearby humans using various gestures. Notably, we identified seven distinct ‘begging’ gestures, with those involving embracing human legs and pulling their clothes having strong correlation with successful outcome. Moreover, adult female langurs predominantly initiate such gestures, with successful solicitation events peaking during evening sessions. The findings underscore langurs' adaptive capacity to exploit anthropogenic resources, where they have started to associate human beings as their food source. This study sheds light on primate behavior in urban landscapes, adding further evidence to the complex dynamics of human-monkey interactions.

When animals observe human signals, they may learn from them. Such learning from humans has been reported for intentional communication between humans with animals, but animals might also learn socially by observing unintentional information transfer when eavesdropping on humans-human encounters. In this study, 12 of 17 horses significantly changed their preference for a feeding location after observing approval in a human-human interaction there, and horses kept in social housing adapted in a higher percentage of trials to human-human demonstrations than those in individual housing. This indicates, for the first time, that some animals change their feeding strategies after eavesdropping on human-human demonstrations and that this adaptation may be dependent on social experience. As horses maintained the observed preference for a feeding location when the demonstrators were absent, we suggest that they learned by applying individual and social learning mechanisms. The horses social rank, age and sex did not affect their learning performance. However, particular demonstrators tended to have a stronger impact on the horses’ performance. Future research should further investigate the durability of this preference change in the absence of repeated demonstrations, and establish whether long-term social learning sets in. This would have important implications for unintentional long-term impacts of human interactions on interspecies communication.

When quantifying animal cognition, memory represents one of the most tested domains and is key to understanding cognitive evolution. Memory tests thus play an important role in comparative cognitive research, yet slight variations in the experimental settings can substantially change the outcome, questioning whether different memory tests tap into different memory systems or whether they test memory at all. Here, we first assessed memory performance of 16 common marmosets (Callithrix jacchus) in two distinct paradigms varying in their format and delay. First, we examined marmoset memory in a 24-h delay memory test (24 h-DMT) in which they could freely explore an environment with three novel objects of which one contained food. We examined their retention the day after, and the procedure was iterated cumulatively with previous objects remaining in the enclosure until the marmosets had to choose the correct out of 30 objects. Second, we administered a classical delayed response test (DRT) in the same animals with three objects and a maximum delay of 30 s. In the DRT, marmoset performance was poor and not better than chance after 15 s already. However, individuals excelled in the 24 h-DMT, performing above chance level after 24 h even with tenfold the number of objects to choose from compared to the DRT. Moreover, individual performances in the two tests were not correlated, and typical age effects on memory could not be detected in both experiments. Together, these results suggest that the two tests explore different domains, and that the 24 h-DMT examines long-term memory. The outcome of the DRT is more difficult to assign to memory since individuals performed only moderately even in the 0-s delay condition. This puts into question whether this task design indeed tests memory or other cognitive processes.

Cerebral lateralisation, the differential cognitive processing in the two brain hemispheres, is variable among individuals in most vertebrates. Part of this variance has been attributed to plasticity in response to environmental stressors experienced by individuals and might be therefore mediated by the action of glucocorticoids (GCs). Accordingly, we tested the hypothesis that the GC pathway related to stress, which involved its cognate receptor GR, affects individuals’ lateralisation. First, we characterised the behavioural lateralisation phenotype of outbred wild-type zebrafish using three different tests: a motor test, a test involving a visual social stimulus (subject’s mirror image), and a test with a visual stimulus of negative valence (predator). Subsequently, we quantified the expression of the gr gene in the brain of the subjects, specifically in the telencephalon and mesencephalon of each hemisphere. Our zebrafish population exhibited individual variation but no population-level bias in behavioural lateralisation and gr expression across the two hemispheres. When we correlated the lateralisation patterns in the behavioural tests with gr expression, we observed that individuals with higher mesencephalic expression of gr in the right hemisphere were more inclined to process their mirror image using the right hemisphere. Additionally, individuals with higher gr expression in the telencephalon, showed reduced lateralisation in processing the predator stimulus. This study supports the hypothesis that GCs might affect some aspects of lateralisation, in particular those related to visual stimuli, thought the GC-Gr pathway and suggests that intraspecific variance in lateralisation could result from individual differences in gr expression.

Individual recognition requires animals to compare available cues with stored information. For goats, living in stable social groups and forming social hierarchy, it is reasonable to assume they can discriminate between familiar and unfamiliar conspecifics. This study focuses on the cognitive mechanisms underlying goats’ perception of conspecific photographs, particularly whether they demonstrate image equivalence. Two groups of goats were trained to discriminate between portrait photographs of familiar and unfamiliar conspecifics. The goats in group A (n = 12) were trained to select familiar individuals, whereas the goats in group B (n = 12) were trained to select unfamiliar individuals. Subsequent transfer test was conducted to assess their ability to generalise learned preferences to novel photographs of previously unseen goats. During the first training tasks (Tr1 and Tr2), no differences in learning performance between the two groups were observed. However, in the later tasks (Tr3 and Tr4), the goats in Group A exhibited better learning performance than did those in Group B. In the transfer test, five goats in Group A, but only one goat in Group B, demonstrated preferences for novel familiar or unfamiliar conspecifics. The superior performance of Group A goats in Tr3 and Tr4 and the number of goats that successfully transferred the familiarity concept to novel individuals provide compelling evidence for the formation of true image equivalence. While goats can establish image equivalence through familiarity, the abstraction of unfamiliar concepts is a more challenging cognitive task.

In this study, we assessed the interspecific “social buffering effect” of humans on horses, exploring how human presence influences stress responses in horses in an unfamiliar environment using the “isolation paradigm.” We examined nine Haflinger horses under two counterbalanced conditions: with a passive human stranger (social condition) or alone (isolation condition). Stress responses were assessed through cortisol measurements, heart rate monitoring, and behavioral observations. While cortisol levels significantly increased in both conditions, with no notable differences before and after the tests, heart rate data revealed a different pattern. Results indicated that stress generally decreased in both scenarios, impacting heart rate. Initially, during the first five minutes, heart rate was significantly higher in the social condition compared to isolation, but this trend reversed in the following intervals, with heart rate significantly decreasing as interaction with the stranger increased. Positive interaction between time and stranger-directed behaviors suggested the stranger’s influence on heart rate strengthened over time. Overall, these finding suggest that while cortisol data did not reflect a social buffering effect, other metrics indicated that human presence effectively reduced stress in horses after a brief adjustment period, supporting the hypothesis that horses can benefit from human presence during stress, after a short adaptation time. This study highlights the complex nature of stress responses in horses and the potential role of humans as social buffers in interspecific contexts.

When foraging, individuals often need to assess potential risk from competitors. Within many food-caching (food-storing) species, individuals can modify their caching behavior depending on whether other individuals are present during the caching event. During caching, individuals may interact with not only conspecifics but also heterospecifics. However, the extent to which individual cachers can discriminate between conspecifics and heterospecifics that present a pilfering threat or not, has received little attention. During this study, we examined this issue with food-storing birds, highly social pinyon jays and less social Clark’s nutcrackers. Cachers were given a choice to store their seeds in one of two visually distinct trays. Subsequently, one of the trays was given to an individual (either a conspecific or a heterospecific) who pilfered the caches, whereas the other tray was given to an individual (either a conspecific or a heterospecific) who did not pilfer the caches. When the two trays were returned to the cachers, they recached the seeds from the tray given to the pilfering observer individual more so than the tray given to the non-pilfering observer, but only when the pilferer was a conspecific. Our results suggest that the pinyon jays and nutcrackers could distinguish between conspecifics based on their pilfering behavior, but not between heterospecifics. Together, our results reconsider the ability of corvids to discriminate between individuals based on their pilfering risk and the importance of doing so while caching.