Animal Cognition最新文献

Despite their young age, zebrafish larvae have a well-developed visual system and can distinguish between different visual stimuli. First, we investigated if the first visual surroundings the larvae experience during the first days after hatching shape their habitat preference. Indeed, these animals seem to “imprint” on the first surroundings they see and select visual stimuli accordingly at 7 days post fertilization (dpf). In particular, if zebrafish larvae experience a bar background just after hatching, they later on prefer bars over white stimuli, and vice versa. We then used this acquired preference for bars to investigate innate numerical abilities. We wanted to specifically test if the zebrafish larvae show real numerical abilities or if they rely on a lower-level mechanism—i.e. spatial frequency—to discriminate between two different numerosities. When we matched the spatial frequency in stimuli with different numbers of bars, the larvae reliably selected the higher numerosity. A previous study has ruled out that 7 dpf zebrafish larvae use convex hull, cumulative surface area and density to choose between two numerosities. Therefore, our results indicate that zebrafish larvae rely on real numerical abilities rather than other cues, including spatial frequency, when spontaneously comparing two sets with different numbers of bars.

Despite considerable research into the structure of cognition in non-human animal species, there is still much debate as to whether animal cognition is organised as a series of discrete domains or an overarching general cognitive factor. In humans, the existence of general intelligence is widely accepted, but less work has been undertaken in animal psychometrics to address this question. The relatively few studies on non-primate animal species that do investigate the structure of cognition rarely include tasks assessing social cognition and focus instead on physical cognitive tasks. In this study, we tested 36 wild Western Australian magpies (Gymnorhina tibicen dorsalis) on a battery of three physical (associative learning, spatial memory, and numerical assessment) and one social (observational spatial memory) cognitive task, to investigate if cognition in this species fits a general cognitive factor model, or instead one of separate physical and social cognitive domains. A principal component analysis (PCA) identified two principal components with eigenvalues exceeding 1; a first component onto which all three physical tasks loaded strongly and positively, and a second component onto which only the social task (observational spatial memory) loaded strongly and positively. These findings provide tentative evidence for separate physical and social cognitive domains in this species, and highlight the importance of including tasks assessing both social and physical cognition in cognitive test batteries.

While sheep can detect and discriminate human emotions through visual and vocal cues, their reaction to human body odors remains unknown. The present study aimed to determine whether sheep (Ovis aries) can detect human odors, olfactorily discriminate stressed from non-stressed individuals, and behave accordingly based on the emotional valence of the odors. Axillary secretions from 34 students were collected following an oral examination (stress odor) or a regular class (non-stress odor). Fourteen female and 15 male lambs were then exposed to these odors through a habituation-dishabituation procedure. The habituation stimulus was presented four times for one minute, followed by the dishabituation stimulus presented once for one minute. Behavioral variables included spatiality relative to target odors, approach/withdrawal, ear positioning, sniffing, ingestion, and vocalization. Both female and male lambs more often positioned their ears backwards/forwards, and asymmetrically when exposed to the dishabituation stimulus, but regardless of their stress or non-stress value. They also changed their approach behavior when exposed to the dishabituation stimuli. Lambs displayed some behavioral signs of discrimination between the habituation and dishabituation odors, but regardless of their relation to stress or non-stress of human donors. In sum, this exploratory study suggests that young sheep respond negatively to the odor of unfamiliar humans, without showing any specific emotional contagion related to the stress odor. This exploratory study suggests young ovines can detect human body odor, a further step toward understanding the human-sheep relationship.

We examined the possibility of a cross-modal effect in naïve Cotesia vestalis, a parasitoid wasp of diamondback moth larvae, by using artificial flower models of four colours (blue, green, yellow, and red) in the absence or presence of floral scent collected from Brassica rapa inflorescences. In a four-choice test, regardless of the floral scent, non-starved female wasps visited green and yellow models significantly more often than blue and red ones, although no significant difference was observed between visits to the green and yellow models. They seldom visited blue and red models. When starved, the wasps became even more particular, visiting yellow significantly more frequently than green models, irrespective of the presence of the floral scent, indicating that they preferred to use yellow visual cues in their food search. Furthermore, a factorial analysis of variance revealed a significant effect of the interaction between model colour and floral scent on the wasps’ visits to flower models. The floral scent induced starved and non-starved wasps to visit yellow and green models about twice as often as without the scent. A cross-modal effect of olfactory perception on the use of chromatic information by wasps may allow them to search efficiently for food sources.

The perception of tridimensionality is elicited by binocular disparity, motion parallax, and monocular or pictorial cues. The perception of tridimensionality arising from pictorial cues has been investigated in several non-human animal species. Although dogs can use and discriminate bidimensional images, to date there is no evidence of dogs’ ability to perceive tridimensionality in pictures and/or through pictorial cues. The aim of the present study was to assess the perception of tridimensionality in dogs elicited by two pictorial cues: linear perspective and shading. Thirty-two dogs were presented with a tridimensional stimulus (i.e., a ball) rolling onto a planar surface until eventually falling into a hole (control condition) or until reaching and rolling over an illusory hole (test condition). The illusory hole corresponded to the bidimensional pictorial representation of the real hole, in which the pictorial cues of shading and linear perspective created the impression of tridimensionality. In a violation of expectation paradigm, dogs showed a longer looking time at the scene in which the unexpected situation of a ball rolling over an illusory hole occurred. The surprise reaction observed in the test condition suggests that the pictorial cues of shading and linear perspective in the bidimensional image of the hole were able to elicit the perception of tridimensionality in dogs.

This study examines the effects of novel environmental changes on the behavior of rats in an experimental chamber. We hypothesized that newly discovered opportunities, detected by the animal’s cognitive system, would motivate greater investigation of environmental changes than comparable changes that prevent a given behavior. Three experiments differed in the emergence vs. elimination of affordances represented by open or closed tunnels. In Experiment 1, rats were habituated to a chamber with all four tunnels closed, and then two tunnels were opened. In Experiment 2, rats were habituated to a chamber where all four tunnels were open, and then two tunnels were closed. In Experiment 3, rats were habituated to a chamber with two open tunnels on one side, and two closed tunnels on the other. Then, the arrangement of open and closed tunnels was swapped. Results of the Exp. 1 show that the rats responded by spending more time near the newly opened tunnels and less time near the closed tunnels, the central zone, and the transporter. This suggests that rats are more motivated to investigate the environmental change combined with the emergent affordance (opening of the tunnels) than the environmental change alone. In Exp. 2, the rats responded by spending more time near the open tunnels and less time in the central zone. This suggests that the rats are more triggered by the available affordances (open tunnels) than by the environmental change (closed tunnels). Finally, in Exp. 3, the rats responded by spending more time near the newly opened tunnels and less near the central zone. However, they did not spend less time near the newly closed tunnels. These results suggest that rats process both the novelty itself and the emergence/disappearance of available affordances. The results are discussed regarding the cognitive asymmetry in the perception of emergent vs. disappearing affordances. It is proposed that the rat’s cognitive system is specialized for detecting newly emergent environmental opportunities/affordances rather than novelty in general.

Performance in tests of various cognitive abilities has often been compared, both within and between species. In intraspecific comparisons, habitat effects on cognition has been a popular topic, frequently with an underlying assumption that urban animals should perform better than their rural conspecifics. In this study, we tested problem-solving ability in great tits Parus major, in a string-pulling and a plug-opening test. Our aim was to compare performance between urban and rural great tits, and to compare their performance with previously published problem solving studies. Our great tits perfomed better in string-pulling than their conspecifics in previous studies (solving success: 54%), and better than their close relative, the mountain chickadee Poecile gambeli, in the plug-opening test (solving success: 70%). Solving latency became shorter over four repeated sessions, indicating learning abilities, and showed among-individual correlation between the two tests. However, the solving ability did not differ between habitat types in either test. Somewhat unexpectedly, we found marked differences between study years even though we tried to keep conditions identical. These were probably due to small changes to the experimental protocol between years, for example the unavoidable changes of observers and changes in the size and material of test devices. This has an important implication: if small changes in an otherwise identical set-up can have strong effects, meaningful comparisons of cognitive performance between different labs must be extremely hard. In a wider perspective this highlights the replicability problem often present in animal behaviour studies.

Citizen science approaches have grown in popularity over the years, partly due to their ability to reach a wider audience and produce more generalizable samples. In dogs, these studies, though, have been limited in their controls over materials or experimental protocols, with guardians typically reporting results without researcher supervision. Over two studies, we explored and validated a synchronous citizen science approach. We had dog guardians act as experimenters while being supervised by a researcher over Zoom. In study 1, we demonstrated that synchronous citizen science produced equivalent levels of performance to in-lab designs in a choice task. Consistent with past in-lab research, dogs selected a treat (vs. an empty plate) in a two-alternative forced-choice task. In study 2, we showed that Zoom methods are also appropriate for studies utilizing looking time measures. We explored dogs’ looking behaviors when a bag of treats was placed in an unreachable location, and dogs’ guardians were either attentive or inattentive while dogs attempted to retrieve the treats. Consistent with past work, dogs in the attentive condition looked at their guardian for longer periods and had a shorter latency to first look than dogs in the inattentive condition. Overall, we have demonstrated that synchronous citizen science studies with dogs are feasible and produce valid results consistent with those found in a typical lab setting.

Due to their outstanding ability of vocal imitation, parrots are often kept as pets. Research has shown that they do not just repeat human words. They can use words purposefully to label objects, persons, and animals, and they can even use conversational phrases in appropriate contexts. So far, the structure of pet parrots’ vocabularies and the difference between them and human vocabulary acquisition has been studied only in one individual. This study quantitatively analyses parrot and child vocabularies in a larger sample using a vocabulary coding method suitable for assessing the vocabulary structure in both species. We have explored the composition of word-like sounds produced by 21 grey parrots (Psittacus erithacus) kept as pets in Czech- or Slovak-speaking homes, and compared it to the composition of early productive vocabularies of 21 children acquiring Czech (aged 8–18 months), who were matched to the parrots by vocabulary size. The results show that the ‘vocabularies’ of talking grey parrots and children differ: children use significantly more object labels, activity and situation labels, and emotional expressions, while parrots produce significantly more conversational expressions, greetings, and multiword utterances in general. These differences could reflect a strong link between learning spoken words and understanding the underlying concepts, an ability seemingly unique to human children (and absent in parrots), but also different communicative goals of the two species.

The blank comparison (BLC) task was developed to assess stimulus relations in discrimination learning; that is, are subjects learning to “select” the correct stimulus (S+) or “reject” the incorrect stimulus (S-) or both? This task has been used to study exclusion learning, mostly in humans and monkeys, and the present study extends the procedure to rats. The BLC task uses an ambiguous stimulus (BLC+/-) that replaces S+ (in the presence of S-) and replaces S- (in the presence of S+). In the current experiment, four rats were trained to remove session-novel scented lids from sand-filled cups in a two-choice, simultaneous presentation procedure called the Odor Span Task (OST) before being trained on the BLC procedure using odors as the discriminative stimuli. The BLC training procedure utilized simple discrimination training (S+ and S-) and added select (S+ and BLC-) and reject (BLC+ and S-) trial types. All rats demonstrated accurate performance in sessions with both select and reject type trials. Next, BLC probe trials were interspersed in standard OST sessions to assess the form of stimulus control in the OST. Rats performed accurately on select type probe trials (similar to baseline OST performance) and also showed above chance accuracy on reject type trials. Thus, we demonstrated that rats could acquire an odor-based version of the BLC task and that both select and exclusion-based (reject) relations were active in the OST. The finding of exclusion in rats under the rigorous BLC task conditions confirms that exclusion-based responding is not limited to humans and non-human primates.