Animal Cognition

Most catarrhine primates are considered to be strongly visually oriented, obtaining information about conspecifics and their environment from a diversity of visual cues. Other sensory modalities may provide information that is redundant and/or complimentary to visual cues. When cues from multiple sensory modalities are available, these may reinforce or suppress each other, as shown in several taxa ranging from insects to humans. Here, we tested how the presence and ambiguity of visual information affects the use of olfactory cues when exploring food and non-food items in semi-free ranging Barbary macaques at Affenberg Salem, Germany. We presented monkeys with pipes containing food (peanuts, popcorn), non-food (stones, feces) or no items in transparent or opaque containers, and assessed whether animals looked, sniffed and/or grabbed into the pipes depending on visibility of the contents (experiment 1). Visual information had no robust effect on sniffing probability, but it did affect sniffing behavior with respect to the timing of olfactory inspections (i.e. whether sniffing occurred first). Both visual and olfactory information affected, whether or not monkeys attempted to retrieve the items from the pipes. Furthermore, we manipulated the visual appearance of familiar food items (popcorn) with food colorant (experiment 2), which resulted in substantially increased olfactory inspections compared to unmanipulated popcorn. Taken together, reliance on the olfactory sense was modulated by the available visual information, emphasizing the interplay between different sensory modalities for obtaining information about the environment.

The extraordinary olfactory capabilities in detection and rescue dogs are well-known. However, the olfactory performance varies by breed and search environment (Jezierski et al., 2014), as well as by the quantity of training (Horowitz et al., 2013). While detection of an olfactory cue inherently demands a judgment regarding the presence or absence of a cue at a given location, olfactory discrimination requires an assessment of quantity, a task demanding more attention and, hence, decreasing reliability as an informational source (Horowitz et al., 2013). This study aims at gaining more clarity on detection and discrimination of olfactory cues in untrained dogs and in a variety of dog breeds. Using a two-alternative forced choice (2AFC) paradigm, we assessed olfactory detection scores by presenting a varied quantity of food reward under one or the other hidden cup, and discrimination scores by presenting two varied quantities of food reward under both hidden cups. We found relatively reliable detection performances across all breeds and limited discrimination abilities, modulated by breed. We discuss our findings in relation to the cognitive demands imposed by the tasks and the cephalic index of the dog breeds.

Two related methods have been widely used to test animals capacity to reason by exclusion: Calls (2004) 2-cups task, where subjects choose between two cups in which one reward was hidden and the empty cup is revealed; and Premack & Premacks task (1994) where one reward goes in each of the two cups and one reward is removed. In both cases, success is identifying the cup with the reward. It has been suggested that among corvids, the demands associated with caching may foster exclusion abilities by reinforcing the experience of relevant contraries (e.g., empty vs. full), or by supporting domain general capacities that support caching and exclusion inferences. However, Shaw et al. (2013) found that Eurasian jays, proficient cachers, failed a version of Calls 2-cups task. To further test the caching hypothesis, we amended the procedure using invisible displacement to hide rewards, removing aspects of Shaw et al.s procedure that may have masked competence of Eurasian jays. We tested seven Eurasian jays, who showed spontaneous success on both Calls 1-reward/show-empty (80% correct) and Premack and Premacks 2-reward/remove-1 (85% correct). These results align with the hypothesis that corvids exclusion reasoning is related to caching behaviour.

Spatiotemporal dynamics of behavior is key to understanding the organism-environment relationship. While often implicitly addressed, its relation to Pavlovian contingencies remains understudied in domestic dogs. This study quantitatively examined the spatial dimension of behavior of three freely moving dogs under pairing and extinction of a tone-food Pavlovian contingency. In pairing, a tone (CS) was paired with food delivery (US) on a fixed-time 60-second (FT 60 s) schedule; in extinction, only the tone was presented. Locomotion was recorded using two-dimensional tracking based on center of mass. During pairing, dogs moved closer to the dispenser, covered greater distances, displayed extended trajectories, and showed a conditional approach pattern to the dispenser during CS presentation. In extinction, they stayed closer to the owner or room periphery, traveled shorter distances, and exhibited more restricted trajectories. These findings show that spatial segments (dispenser area) are integrated into the CS-US relationship, demonstrate the usefulness of continuous recording of spatial behavior in the analysis of Pavlovian contingencies, and suggest potential application in contexts relevant to animal welfare. HighlightsO_LISpatial behavior remains largely unexplored in studies of Pavlovian contingencies C_LIO_LIDog locomotion was continuously tracked during pairing and extinction phases C_LIO_LIDistinct spatial patterns emerged across pairing and extinction phases C_LIO_LIIncorporating space into CS-US relations clarifies behavioral organization C_LIO_LITracking tools expand the experimental and applied scope of Pavlovian research C_LI

Causal understanding in animal cognition can be divided into two broad categories (Woodward, 2011): learned associations between cause and effect (Le Pelley et al., 2017) and understanding based on underlying mechanisms (Johnson and Ahn, 2017). One experiment that gives insight to animals use of causal mechanisms is the stone-dropping task. In this, subjects are given an opportunity to push a platform to make it collapse and are then required to innovate dropping a stone tool to recreate the platform collapsing (von Bayern et al., 2009). We describe how 16/18 subjects of two species of macaw (n=18; Ara ambiguus (n=9) & Ara glaucogularis (n=9)) were able to innovate the solution in this task. Many of the subjects were able to innovate the behaviour through exploratory object combination, but it is also possible that a mechanistic understanding of the necessity for contact with the platform influenced some subjects behaviour. All the successful subjects were able to recreate their novel stone-dropping behaviour in the first or second trial after innovation (and all trials thereafter) and they were also able to do the behaviour increasingly faster. This suggests they also rely on learned associations of cause and effect. However, in a transfer task in which subjects had to guide a stick tool to make it touch a differently positioned platform, all but one of the subjects failed. This would suggest that the majority of the subjects were not using an understanding of platform contact to solve the task, although the subjects difficulty with using stick tools may have also affected their performance in this transfer.

Episodic-like memory is considered as one of the most advanced cognitive capacities and could therefore have major implications on how animals with this capacity are treated in respect to their welfare. Yet, episodic-like memory has only been substantiated in a few vertebrate species. These species are quite diverse, originate from several taxa, and the question is raised whether episodic-like memory is indeed a rather specific capacity or whether this capacity turns out to be more common when further species are investigated. In general, intensively foraging animals that rely on some replenishing resources are promising species to investigate episodic-like memory. Here, we conducted a pilot study on minipigs (Sus scrofa f. domestica), replicating an approach used in dogs. Both, dogs and pigs are macrosmate species, making the comparison of their memory of olfactory stimuli promising. The minipigs learnt to differentiate the sequence of encountered location-smell combinations as easily as dogs. This makes minipigs a promising species and the use of smells a promising approach to investigate episodic-like memory in more detail. This study also hints towards a cognitive capacity of pigs, which raises further concerns regarding intensive and barren housing conditions.

Extractive foraging is generally studied from the perspective of behavioral flexibility, cognitive ability, innovation and social learning. Despite its potential to elucidate synanthropic adaptation in species exploiting enclosed anthropogenic food, research on extractive foraging under urban conditions is limited. Since a large extent of anthropogenic food is packaged and contains highly processed food, processes of identification/extraction of food by nonhuman species become intriguing themes of research. We studied how processing status of embedded food determined extraction decisions across groups of a species differing in exposure and familiarity to the food. Further, we tested the generalizability of extraction methods. Experimenting with wild bonnet macaques (Macaca radiata), we found exposure- and form (native/shelled/peeled)-specific familiarity to peanuts, state (raw/boiled/roasted)-specific distinction in depeeling, and exposure- and state-specific differences in methods of depeeling. Group with the highest exposure to peanut differed in its propensity to use sophisticated extraction methods, e.g. depeeling by rubbing between palms (bimanual asymmetric action) and rubbing against horizontal substrata (unimanual action). The innovative methods were also extended to roasted peas and chickpeas by the urban group. Our study establishes a causal relationship between familiarity and processing status of food and shows the generalized extension of extraction methods based on food categorization. Summary StatementNonhuman species in cities face upheaval challenges of accessing enclosed and highly processed anthropogenic food. We studied the effects of minor processing of enclosed food on its extraction decisions.

Traditionally, primates have been considered primarily visual animals. However, studies across a variety of taxa suggest that, in the context of food evaluation, the reliance on this sense might be more nuanced that previously thought, with dietary specialization and food item properties leading to differences in sensory prioritization. We performed a field-based study assessing the use of sensory cues during food evaluation as well as food-related behaviours such as muzzle contact in two mixed-sex groups of wild vervet monkeys including three age classes over a period of five months (nmonkeys = 44). Using a total of 18868 food evaluation observations collected over 44 hours of focal follows, we found that vervets mainly relied on their sense of vision when evaluating food (96.8% of all instances). Sensory usage varied according to food category and sex differences were only observed in the use of smell for a subset of these. Juveniles initiated muzzle contact and used tactile inspection more often than adults whereas females received muzzle contact more often than males. In addition, the low rejection rates suggest that most food items were familiar to the vervets regardless of age and sex. These findings are in line with optimal foraging theory according to which the food evaluation process should be adapted to the familiarity of food items and allows individuals to maximize their intake of energy and critical nutrients, while minimizing the time and effort in food evaluation.

Inhibitory control, the ability to suppress an automatic response in favour of a contextually appropriate alternative, is crucial for adaptive behaviour across animal species. While extensively studied in mammals and birds, research on reptiles remains limited, with comparisons hindered by methodological inconsistencies. Here, we assessed inhibitory control in two reptile species, Hermanns tortoise (Testudo hermanni) and the bearded dragon (Pogona vitticeps), using the transparent cylinder test--a method widely employed with mammals, birds, and fish. This test evaluates the ability to inhibit reaching directly for visible food through a transparent barrier. Both species exhibited lower inhibitory control than most amniotes, supporting the prevalent hypothesis linking inhibitory capacity to brain size. However, exceptions observed in various species suggest ecological and non-cognitive factors also shape these abilities. Notably, bearded dragons outperformed tortoises, despite their smaller size. In tortoises, females surpassed males, highlighting sex-based inhibitory differences in non-avian reptiles. Additionally, a positive correlation between lateralization and inhibitory control was observed in both species, providing the first evidence of such a link in reptiles. These findings emphasize the role of lateralization in reptilian cognition and suggest that inhibitory control across vertebrates is influenced by diverse factors, including brain size, ecology, and sex.

Reports of honeybees demonstrating abstract concepts like sameness and difference marked a pivotal development in comparative psychology. Subsequent studies expanded the scope of concept learning in honeybee cognition, yet most evidence relies on a single method: the delayed-matching-to-sample task using a Y-maze. Whether this setup is uniquely effective or if alternative approaches could yield similar results remains unresolved. Additionally, the failure of bumblebees (Bombus spp.) to complete this task, despite honeybees demonstrating success, remains unexplained. This study compared the performance of honeybees (Apis mellifera) and bumblebees (Bombus terrestris) across matching-to-sample tasks with varying degrees of physical continuity between sample and target stimuli. The objectives were twofold: to evaluate an alternative method for assessing concept learning in both species and to investigate potential species differences in such tasks. Contrary to prior findings, neither species succeeded at the reported proficiency levels in simultaneous matching-to-sample tasks. Moreover, bumblebees outperformed honeybees in one task. These results are consistent with an explanation based on species-specific differences in visual attention mechanisms, and underscore the need for further research on concept learning in social bees.

The extent to which dogs (Canis familiaris) as a domesticated species understand human intentions is still a matter of debate. The unwilling-unable paradigm has been developed to examine whether nonhuman animals are sensitive to intentions underlying human actions. In this paradigm, subjects tended to show more patience toward a human that appears willing but unable to transfer food to them compared to an unwilling (teasing) human. In the present study, we conducted the unwilling-unable paradigm with dogs using a detailed behavioural analysis based on machine-learning driven 3D tracking. Throughout two preregistered experiments, we found evidence, in line with our prediction, that dogs reacted more impatiently to actions signalling unwillingness to transfer food rather than inability. These differences were consistent through two different samples of pet dogs (total N=96) and they were evident also in the machine-learning generated 3D tracking data. Our results, therefore, provide robust evidence that dogs distinguish between similar actions (leading to the same outcome) associated with different intentions. However, their reactions did not lead to any measurable preference for one experimenter over the other in a subsequent transfer phase. We discuss different cognitive mechanisms that might underlie dogs performance in this paradigm.

Young precocial birds benefit from staying close to both their mother and siblings, while prioritising adults, which provide better care. Which features of the stimuli are used by young birds to prioritise attachment to adults over siblings is unknown. We started to address this question in newly hatched domestic chicks (Gallus gallus), focusing on their spontaneous preferences for visual stimuli that systematically vary between adult and juvenile chickens: size (larger in adults than in juveniles) and colour (darker and redder in adults than in juveniles). Overall, chicks at their first visual experience, that had never seen a conspecific beforehand, were most attracted to the red and large stimuli (two adult features) and interacted with red stimuli more than with yellow stimuli. When tested with red large vs. small objects (Exp. 1), chicks preferred the large shape. When tested with yellow large and small objects (Exp. 2), chicks did not show a preference. These results suggest that the combination of size and colour form the predisposition that helps chicks to spontaneously discriminate between adult and juvenile features from the first stages of life, in the absence of previous experience.

Cognitive capacity for quantity discrimination is highly adaptive in various ecological contexts and subject to convergent evolution across diverse animal species, yet the underlying mechanism involved is not fully understood. Discrimination accuracy generally increases with the ratio between two quantities; however, this ability is expected to differ across ratio ranges. To test this we presented a novel symbol system to 28 rosy-faced lovebirds (Agapornis roseicollis), associating additive tally marks with symbols representing a one-to-one correspondence with different food quantities. Trained lovebirds could spontaneously infer the relative food quantities represented by other symbols. Lovebirds proved capable of (1) associating symbols (i.e., object-file symbolism); with (2) "more-less" quantity inference, by deducing food quantities based on their knowledge of this symbol-quantity association; and (3) enhancing their performance in relation to disparity ratio (conforming to Webers law) and absolute difference. Furthermore (4), the influence of food ratio and absolute difference varied with different ratio ranges. Within a small ratio range ([≤] 3) discrimination performance improved with increments of ratio or absolute difference, whereas within a higher ratio range (> 3), the effect of these factors diminished. We conclude that rosy-faced lovebirds are capable of advanced numeracy and quantity discrimination, similar to larger parrot species.

Animals use learning to adaptively adjust their behaviour to conditions taking advantage of previous experiences. While individual learning is advantageous, it includes risks and costs that can be overcome by learning from others. Despite its relevance, the ability to learn from observing others behaviour was tested in only a limited number of birds species, of which only a few feeds mainly on plants. There is still much to be learn what kind of information birds are interested and capable of gathering from conspecifics in the foraging context. We set out to test the social learning skills of a granivorous gregarious species of cardueline finch, the Serin (Serinus serinus), because they likely follow conspecifics cues to forage. We used an observer-demonstrator paradigm where observers were given the opportunity to learn to reach hidden food from observation of demonstrators that were previously trained to perform the task. Almost half of the birds tested were capable of learning (40%) from a conspecific in a colour-food association experiment, and learners were able to remember the association after fifteen days. Also, almost half of the birds tested for this revealed to be capable of reversal learning. The ability to learn was not influenced by sex or age, of both demonstrators and learners, but learners had longer wings than non-learners. We investigated whether personality could explain the differences in learning ability of these birds. We assessed individual boldness and sociability through the novel object test and mirror personality tests respectively. Although we found repeatability those personality traits we found no association with social learning ability.

The decoy effect, a bias in choice between two options when a third, inferior option is introduced, has been observed across various organisms, from slime molds to humans. In this study, we investigated whether zebrafish (Danio rerio), a widely used biological model organism, exhibit the decoy effect in their shoaling group choices, specifically examining this effect by varying only shoal size. Using spatial trajectory analysis of freely swimming zebrafish interacting with conspecifics in adjacent display tanks, we tested how shoaling decisions varied between dichotomous (two-option) and trichotomous (three-option) choice sets. Our experiments compared preferences for 4 versus 2 and 6 versus 3 shoal sizes, with a single fish serving as a decoy in the trichotomous sets. The results revealed sex-specific differences in the decoy effect: males exhibited a shift in preference only in the Trichotomous-first condition, where prior exposure to the decoy led to a significant preference for the larger shoal. In contrast, females displayed the decoy effect exclusively in the Dichotomous-first condition, shifting from a significant preference for the larger shoal to showing no clear preference in the presence of the decoy. Notably, our findings demonstrate that the decoy effect can occur even when studied unidimensionally, with both sex and the order of presentation influencing zebrafish shoaling preferences. These results offer new insights into decision-making processes and highlight the importance of considering order effects in studies of choice behavior, with potential methodological implications for research in other species.

Relatively little is known about the influence of maternal care on dog behaviour, despite the prominence of dogs in our lives and the established importance of early experiences in other species. While recent observational research has begun to document associations between canine maternal behaviour and later offspring outcomes, there is still much to learn--particularly regarding what factors impact maternal behaviour and the enduring effects of maternal care on puppy behavioural development. Understanding how early experiences shape future behaviour is of practical importance for companion and working dogs. We characterized the early rearing environment of 235 individual puppies from 59 litters bred by a service dog provider and explored whether offspring cognitive and behavioural traits through 16 months of age were associated with early mothering behaviour. We also investigated whether maternal behaviour could be predicted by pre-pregnancy dam behaviour and how the rearing location (private home or professional breeding centre) influenced maternal behaviour and/or puppy behaviour. We identified dam behavioural characteristics measured pre-pregnancy that were related to subsequent maternal care. While time of year was associated with maternal behaviour scores, parity, litter size, breed composition, and rearing location were not. We found that rearing location was related to puppy performance on the Dog Cognitive Development Battery (DCDB) at 8 weeks of age. Finally, maternal behaviour was associated with certain puppy cognitive and behavioural measures, assessed via the DCDB at 8 weeks of age and via questionnaires at 6, 10, 12 and 16 months of age. Our results indicate that experiences within the first few weeks of life, particularly maternal care and rearing location, may influence several aspects of dog behaviour relevant to both working and companion animals. HighlightsO_LIWe tracked early maternal interactions across 59 litters C_LIO_LISome traits measured pre-pregnancy were associated with subsequent maternal care C_LIO_LIRearing location was associated with some puppy behaviour but not maternal care C_LIO_LIMaternal care was associated with some aspects of puppy behaviour at 8 weeks C_LIO_LIMaternal care was associated with reports of puppy behaviour through 16 months C_LI

Cognitive adaptations for processing causal information are fundamental to flexible problem-solving across species. Patterned-string tasks offer a classic means-end problem, requiring subjects to identify the functional connection between an action and its distal outcome. This study investigated patterned-string pulling in East Asian hornbills, a cognitively underexplored avian taxon, to assess their problem-solving abilities and underlying cognitive mechanisms. Nine hornbills were presented with three string configurations of increasing complexity: parallel (baseline), broken (contact/no-contact), and crossed strings. Subjects reliably selected the correct string in the baseline and contact conditions, demonstrating sensitivity to physical continuity cues. In contrast, accuracy declined significantly in the crossed condition, which required recognition of spatial displacement between the baited and accessible string ends. Reaction time (RT) analyses revealed prolonged latencies in the crossed condition, likely reflecting increased cognitive demands or limited habituation. Individuals who failed often adopted suboptimal strategies, such as proximity or side biases. We also observed lateralisation effects, with a left-side RT advantage, suggesting hemispheric specialisation. These findings support the hypothesis that task complexity modulates both decision accuracy and response speed, highlight RT as a useful proxy for interim cognitive processing, and establish hornbills as a valuable comparative model for studying causal cognition in birds.

Whether and how dolphins can engage in spontaneous, untrained social learning to solve novel tool problems via action- or result- (or other) social learning remains debated. In the present study we tested the spontaneous social learning abilities of six dolphins (all not trained to copy) on two tool-using tasks (what we call the ball-up / ball-down task) - using a dolphin demonstrator and a human demonstrator. Regardless of task type and demonstrator type none of the tested dolphins reproduced the demonstrated tool solutions. We experienced several issues regarding our test apparatus, and so these negative results may be due to apparatus failures. However, these findings may also fully or partially indicate that untrained dolphins are not generalized, spontaneous social learners across information types, especially regarding the acquisition of tool solutions in puzzle tasks. More studies are required to precisely determine the capacity for spontaneous tool solution copying in dolphins.

Risk, or variance over outcomes, features prominently in many decisions, but the factors that determine when and how risk modulates decision making remain unclear. We tested how risk affected rats strategies for exploiting a diminishing food source as the overall richness of the environment was manipulated. Long-Evans rats earned food by sequentially visiting two foraging patches with different reward schedules--a low-variance standard option and a high-variance risky option--that provided the same average rate of reward. When rats switched between options, they encountered either a long or short delay during which no food was available to simulate the cost of travelling between patches. When the travel delay was short rats allocated more time to the low-variance standard reward schedule than the high-variance risky option. When the travel time was long rats spent the same amount of time in risky and standard patches. Consistent with previous work, rats "overharvested" patches, remaining for longer than the optimal patch residence duration. Overharvesting was prevalent in both risky and standard patches, and the magnitude of overharvesting increased with successive visits to the same patch, suggesting that overharvesting was not driven by uncertainty about the reward statistics of patches.

Zebrafish (Danio rerio) constitute an excellent model system to investigate the neural and genetic basis of quantitative cognition because of the single neuron resolution of calcium imaging of awake, behaving fish. While nonsymbolic numerical cognition has been investigated across many taxa, symbolic numerical cognition has not been investigated among fish. We developed a novel quantitative symbolic test for zebrafish using an operant conditioning paradigm in which the number of horizontal lines zebrafish approached in a 2-alternative forced choice task predicted the number of food reward pellets they would receive. Zebrafish did not at the population level learn a preference for the 2-line stimulus predictive of receiving 2 food pellets. However, they performed significantly above chance in a nonsymbolic discrimination task with the same apparatus, in which the 2-line stimulus was associated with the same reward but the choice of the 1-line stimulus was not rewarded. We also explored the explanatory value of alternative spatial learning hypotheses such as a Win-Stay, Lose-Shift (WSLS) strategy at the individual level for fish in navigating these spatially randomised tasks. The implications of this for symbolic versus nonsymbolic quantitative cognition in this model system are discussed relative to reward type and stimulus modality.