Animal Cognition最新文献

Exaggerated prosody directed toward dogs has multiple functions, including attention getting and maintaining as well as expressing positive emotions toward the canine partner. However, the role of prosody in owner-dog familiarity remains unclear. To address this gap, we examined the effect of familiarity on the acoustic and visual prosodic features of dog-directed speech. To this end, we analyzed the prosodic features of female speakers when interacting with their own dogs vs. an unfamiliar dog of the same breed during three different situations: Attention-getting, Task-solving, and Nursery rhymes. Interestingly, only the mean pitch was affected by familiarity as speakers used a higher pitch when interacting with the unfamiliar dog compared to their own dog. Meanwhile, pitch range and the intensity of ‘happy’ facial expressions were affected by the dog’s size: speakers used a wider pitch range and more intense ‘happy’ expressions when interacting with smaller dogs. The Nursery rhymes situation evoked the most intense visual prosody, perhaps due to the use of nursery rhymes when interacting with infants. Our results suggest that a heightened overall pitch may serve as a way to appear friendly toward an unfamiliar being, acting as a universal engaging mechanism in human-dog communication. In contrast, the ‘happy’ facial expression and pitch range seem to be less sensitive to the familiarity with a dog, being more influenced by the specific situation and size of the canine partner which is likely related to the ‘cuteness factor’ and/or the baby schema in female speakers.

Cognitive flexibility - the ability to adjust previously learned associations given novel information - is hypothesized to allow animals to respond to variable conditions. While cognitive flexibility is thought to primarily rely on executive control, previous experiences may interfere with learning. In this study, we tested the hypothesis that strength of associations should improve cognitive flexibility and that birds given more time to learn different spatial associations would perform better in a serial reversal task with multiple, not binary, choices. Wild chickadees were subjected to one of three spatial learning tasks that differed in the number and duration of learned associations and then completed a serial reversal task using eight-feeder arrays. All birds learned the locations of two rewarding feeders sequentially. The control group then started the serial reversal task with reward alternating daily between those two feeders. The two experimental groups had to sequentially learn an additional two locations but differed in the time allowed to learn these associations – one day for the short exposure group and three days for the long exposure group. This was followed by the serial reversal task which involved daily alternations between these two additional feeder locations. The birds in the long exposure group showed fewer location errors and learned the reversal rule faster than birds in the short exposure group. Our results demonstrate that increased experience with specific associations improves cognitive flexibility involving these associations when animals have multiple choices.

Decision-making among prey often involves balancing fitness-related activities, such as foraging and mating, with the need to avoid predation. These trade-offs may be influenced by sex, especially among sexually dimorphic species where males and females face different selection pressures. Consistent with the ‘Distracted Male Hypothesis’, male Trinidadian guppies (Poecilia reticulata), may show a reduced response to publicly available personal risk assessment cues (i.e. chemosensory predation risk cues) relative to females due to the relatively high costs associated with lost courtship and mating opportunities. Male guppies may compensate for a reduced response to personal information by increasing their use of conspecifics as a source of social information. Here, we tested this hypothesis using wild-caught male Trinidadian guppies, examining their use of visual social cues from alarmed conspecific males in the presence vs. absence of females. We found that when stimulus females were absent, focal males increased their inspection of an alarmed male stimulus shoal, suggesting the use of social information. However, when a stimulus female was present, males did not increase inspection of the male stimulus shoal. Rather, they exhibited high rates of inspection towards the female stimulus. These suggest that male guppies may adjust their antipredator behaviour depending on social context, likely reflecting underlying reproductive trade-offs.

Three-dimensionality perception relies on the integration of various depth cues, with monocular pictorial cues playing a key role in two-dimensional representations. Previous research indicates that dogs are sensitive to a combination of shading and linear perspective when perceiving three-dimensionality, yet the individual contributions of these cues remain unclear. The aim of the present study was to disentangle the specific contribution of shading and linear perspective in promoting three-dimensional perception in dogs. In a series of four experiments involving 120 dogs, subjects were presented with a ball rolling on an apparatus and either falling inside a real hole (control condition) or keeping rolling over a depicted hole (test condition). Experiments 1 and 2 assessed the individual contribution of linear perspective and shading in dogs’ perception of three-dimensionality; Experiment 3, as a replica of previous findings, investigated the combination of both cues; Experiment 4 explored the role of more intense shading. In a violation of expectation paradigm, dogs showed no sensitivity to the pictorial cue of linear perspective or low shading level alone. Conversely, the combination of linear perspective and shading, as well as intense shading alone, successfully elicited three-dimensional perception. These results confirm that dogs can successfully integrate multiple pictorial cues to perceive three-dimensionality from two-dimensional stimuli. The perception of three-dimensionality can also occur through single cues, but only if the cue is sufficiently intense, at least in the case of shading.

Neophobia, the aversion to novelty, is a conserved survival trait that influences individuals’ decision-making. In many species, juveniles showed less avoidance of novelty than adults, likely due to their limited experience and their need to gather environmental information. A challenging question is how environmental factors shape sensory processing and behavioural responses. Due to the rapid development of their nervous system and high sensitivity to environmental conditions, zebrafish (Danio rerio) represent a valuable model for investigating the phenotypic plasticity of neophobia. Previous studies showed that two-week-old larvae are more inclined to explore novel stimuli, while older larvae exhibit neophobic responses, indicating an age-dependent shift in exploratory behaviour. Lateralization, i.e. the specialization of the left and right side of the brain to attend different sensory information, may modulate the neophobic response. Here, we investigated how environmental experience alters the relationship between neophobia response and asymmetrical visual inspection in zebrafish larvae throughout early development. After hatching, larvae were reared in either enriched or barren environments. Neophobic response was assessed at 7, 14, and 21 days post-fertilization (dpf) using a novel object test. Results showed that 21dpf larvae raised in enriched environments approached the novel stimulus more quickly and frequently than barren larvae. Enrichment also significantly influenced lateralization, with enriched larvae displaying stronger lateralization. Notably, in enriched larvae, individuals that inspected the novel object more frequently showed weaker and less consistent lateralization. Results suggest that early environmental enrichment affects not only neophobic behaviour, but also the development of lateralized cognitive processing.

There is growing concern that infectious disease can impair the cognitive performance of wild animals, but the mechanisms by which this may occur are unclear. Here, we examined the apparent contributions of cognitive and motivational factors to the poor performance on a string-pulling task among American crows (Corvus brachyrhynchos) infected with a common bacterial pathogen (Campylobacter spp.). In a sample of 57 crows, of which 65% were infected with Campylobacter, we found that infected crows were significantly less likely to solve a string-pulling task with a food reward and took longer to solve it after engaging with the task. However, their poor performance appeared largely motivational. Infected birds exhibited longer latency to attempt the task (9.0 ± 2.8 vs. 22.8 ± 3.4 min when uninfected vs. infected, respectively). They also had a slower attempt rate after initial engagement (lower persistence) than uninfected crows: on average, the attempt rate of infected birds was 61% lower than for uninfected birds. Anorexia may have played a role in this lower motivation, as infected crows consumed significantly fewer calories when food was provided ad libitum than uninfected crows: birds with the highest apparent infection intensity ate 43.4% fewer calories/day than uninfected birds. Our study provides a framework for distinguishing among the potential mechanisms underlying impaired performance on a problem-solving task among infected individuals. It also sheds light on some of the potential downstream fitness and survival consequences for animals exhibiting disease-linked changes in behavior and cognitive performance.

For social species, the ability to identify individual group members is crucial. Vocalizations often carry individual signatures that can serve as cues for the caller’s identity. However, it is still unclear how consistent these signatures are and how early they develop. Here, we investigate the development of vocal individuality in hand-raised carrion crows. Over the course of four weeks, spanning both the nestling and fledgling stage, we recorded vocalisations of known individuals across various behavioural contexts. We show that vocal individuality is present early on and is encoded by several acoustic parameters whose importance remains consistent as the birds age. Additionally, while vocal dissimilarity between individuals generally increased over time, the pattern of change varied across contexts. Our findings highlight the dynamic nature of vocal individuality coding during early life and provide new insights into the relationship between vocal and social development in corvids.

Fishes are among the oldest and most diverse groups of vertebrates, encompassing a vast array of species that differ in morphology, ecology, and behavior. While such diversity can pose challenges to comparative cognition research, it can also offer valuable insights into how different ecological and evolutionary pressures shape cognitive abilities. As the earliest diverging extant vertebrates, and the simplest neural architecture, fishes also provide a critical window into the origins and evolution of vertebrate intelligence. However, despite their potential, we have only just begun to scratch the surface of what fish cognition can reveal, in part due to practical limitations that have constrained cross-species comparisons, including the use of small, single-species samples and a lack of standardized testing procedures. To address these challenges, we introduce ManyFishes, the first big team science collaboration dedicated to comparative cognition and behavior in fishes. Here, we discuss the benefits, potential, challenges and solutions, and impact of this large-scale collaborative effort. Like other big team science initiatives, ManyFishes relies on the ability to establish an infrastructure that facilitates communication and coordination among collaborators from diverse backgrounds, while promoting openness, transparency, and reproducibility in fish cognition research. With this paper, we aim to raise awareness of the ManyFishes initiative and invite researchers to join, contribute to, and benefit from this large-scale collaborative effort in future projects.

In socially complex species, vocal signals often convey individual identity, enabling recognition and coordination of individualized groups. Jackdaws (Corvus monedula) are highly social corvids that form life-long monogamous pair bonds. They frequently produce ‘tchak’ contact calls while foraging in loose ground-based heterospecific flocks where maintaining cohesion without visual contact may be advantageous. We recorded tchak contact calls from nine adult males during natural foraging and analysed their acoustic structure using both conventional acoustic methods and machine learning approaches. Unsupervised classification revealed two structurally distinct call variants, a harmonic and a noisy form, which differed in spectral and temporal properties. While the harmonic variant occurred in eight out of the nine males, the noisy form was only recorded in five individuals. Both variants encoded individual identity, and spectrogram-based analyses yielded higher classification accuracy. These results suggest that tchak calls convey stable identity cues which facilitate individual recognition. The coexistence of two structurally and individually distinctive call forms within a single call type highlights the flexibility of jackdaw vocal communication.