Previous investigations into referential use of object words by dogs have revealed limited understanding in this domain by most dogs. However, a recent study by Boros et al. (Current Biology, 34(8), 1750-1754, 2024) has provided neurological evidence suggesting that understanding of the referential nature of object words and the ability to form mental representations of objects may actually be prevalent among dogs.

A new study investigates how stingless bee colonies inherit one of two architecturally distinct types of comb and proposes the primary mechanism of inheritance as stigmergy: among-individual coordination in comb building informed by environmental cues (i.e., social artefacts). These findings highlight the importance of social information in creating and maintaining architectural variance among structures.

In a recent study, Johnson and Wynne found that dogs classically conditioned to associate electric shocks with chasing a fast-moving mechanical lure inhibited chasing behaviour at test, while dogs conditioned with food rewards did not learn any operant behaviours to substitute chasing and therefore continued to interact with the lure. Here, we raise questions about the suitability of the training protocols and challenge the conclusion that shock collars impose minimal welfare impacts.

Research has examined how stimulants affect impulsive choice in delay-discounting tasks, but little is known about whether such drugs influence how discounting varies with reward magnitude. This study sought to investigate the effects of acute and chronic methamphetamine administration on rats' responding in a rapid acquisition choice task in which reward delays were changed unpredictably across sessions. In each group of four sessions, delays were unequal (1 s/8 s, or 8 s/1 s) or equal (1 s/1 s, or 8 s/8 s) while reward magnitudes were constant and unequal (one dipper cycle/four dipper cycles). This enabled us to obtain both estimates of delay discounting (i.e., sensitivity to delay) and the magnitude effect (in which larger rewards are discounted at a lower rate). Methamphetamine was administered in increasing doses acutely and chronically. Baseline results showed that rats reliably preferred the alternative with a shorter delay and that choice for the larger reward was greater when the delays were long, consistent with the magnitude effect. Acute methamphetamine dose dependently reduced both sensitivity to delay and the magnitude effect, but not sensitivity to magnitude. Chronic administration had no systematic effect on choice. This study is the first to report a magnitude effect with rats in a rapid acquisition choice procedure similar to that found in delay discounting research with humans, and suggests that acute methamphetamine administration reduces control by contingencies that change across sessions.

Recent findings indicate that noise pollution - presented in the absence of other variables - has both immediate-term impacts on young birds' developmental rates and physiology as well as long-term effects on adult telomere length and reproductive success. This work highlights yet another set of negative impacts caused by anthropogenic noise, and suggests that the dramatic fitness consequences observed likely have implications for the evolution of learning and behavior in animals living in noisy environments.

Humans and other animals often seek instrumental information to strategically improve their decisions in the present. Our curiosity also leads us to acquire non-instrumental information that is not immediately useful but can be encoded in memory and stored for use in the future by means of episodic recall. Despite its adaptive benefits and central role in human cognition, questions remain about the cognitive mechanisms and evolutionary origins that underpin curiosity. Here, we comparatively review recent empirical studies that some authors have suggested reflects curiosity in nonhuman animals. We focus on findings from laboratory tasks in which individuals can choose to gain advanced information about uncertain future outcomes, even though the information cannot be used to increase future rewards and is often costly. We explore the prevalence of preferences in these tasks across animals, discuss the theoretical advances that they have promoted, and outline some limitations in contemporary research. We also discuss several features of human curiosity that can guide future empirical research aimed at characterising and understanding curiosity in animals. Though the prevalence of curiosity in animals is actively debated, we surmise that investigating behavioural candidates for curiosity-motivated behaviour in a broader range of species and contexts, should help promote theoretical advances in our understanding of cognitive principles and evolutionary pressures that support curiosity-driven behaviour.

Despite popular culture's promotion of the elephant's ability to "never forget," there is remarkably limited empirical research on the memory capacities of any living elephant species (Asian, Elephas maximus; African savanna, Loxodonta africana; African forest, Loxodonta cyclotis). A growing body of literature on elephant cognition and behavioral ecology has provided insight into the elephant's ability to behave flexibly in changing physical and social environments, but little direct evidence of how memory might relate to this flexibility exists. In this paper, we review and discuss the potential relationships between what we know about elephant cognition and behavior and the elephants' memory for the world around them as they navigate their physical, social, and spatial environments. We also discuss future directions for investigating elephant memory and implications for such research on elephant conservation and human-elephant conflict mitigation.

Many ant species can respond to dramatic changes in local conditions by relocating the entire colony to a new location. While we know that careful learning walks enable the homing behavior of foraging ants to their original nest, we do not know whether additional learning is required to navigate to the new nest location. To answer this question, we investigated the nest relocation behavior of a colony of Australian desert ants (Melophorus bagoti) that relocated their nest in response to heavy rainfall in the semidesert terrain of Alice Springs. We identified five types of behavior: exploration between nests (Old-to-New nest and New-to-Old nest), transport from Old to New nest, and relearning walks at Old and New nests. Initially, the workers performed relearning walks at the Old nest and exploratory walks between the Old and New nests. Once they completed the exploratory walks, the workers transported resources and brood to the new nest. Finally, we observed the workers performing relearning walks at the New nest. While the relearning walks at the Old nest were slow and appear to enable exploratory walks to the New nest, the relearning walks at the new nest were faster and appeared to enable homing from foraging trips. These observations shed insight on how learning helps these ants to respond to sudden changes in their environment.

Liao et al. demonstrated that crows can count out loud, revealing a level of vocal control previously unobserved in nonhuman species. This discovery suggests that rather than being judged by primate standards, birds might represent a new benchmark for vocal and perhaps broader cognitive abilities.

With the general aim of providing more evidence for considering certain behaviors involved in the act of remembering as operant, two experiments were carried out to verify its sensitivity to differential reinforcement, and to some of the variables upon which it depends. In the first experiment, three children participated, and two variables were manipulated in a "free recall" task: the accuracy of the instructions and the magnitude of the reinforcer applied to the emission of the target words. In the second experiment, 60 was changed to one of comparison between groups. In this case, the response-reinforcer interval (immediate vs. delayed) was manipulated using a "recognition" task. In both experiments, a greater number of remembered items were found in the presence of reinforcement compared to its absence, as well as with a greater magnitude of the reinforcer and with a shorter delay. These results are discussed considering the peculiarities of verbal behavior in humans and provide evidence that operant processes have an important role in traditional human memory tasks.

The "Spoon task" is a common measure of episodic future thinking (i.e., ability to imagine hypothetical future events) in children. However, by providing items and prompting children to choose one, this task might not require deliberate and goal-driven episodic future thinking. In contrast, "spontaneous" Spoon tasks may better reflect Tulving's original conception as they minimize environmental cues and verbal prompts. We identify challenges in designing such tasks, including removing the scaffolded intention to act and giving children permission and sufficient motivation to act. Drawing on the comparative literature, we propose methods to overcome these obstacles when designing spontaneous Spoon tasks. Furthermore, sampling from the work of Clayton and colleagues, we advocate for a multipronged approach including two or more of the following methods in order to capture spontaneous behavior: naturalistic observation, virtually administered tasks within the child's home, laboratory experiments, and questionnaires. Our review highlights the importance of spontaneous episodic future thinking and establishes a foundation for future methodologies to study this complex cognitive process.

Despite birdsong being one of the most studied models of sexual selection, how it operates in birds that sing only one song remains poorly understood. A recent study using a big data approach reveals a novel aspect of song that may potentially function as an honest signal of male quality and a way to maintain listener attention.

Researchers have recently described the wing-fluttering signal of Japanese tits and eyeblink signal of concave-eared torrent frogs as bodily communication that elicits specific responses. I assess the evidence that these may be intentional, goal-directed signals using established criteria for gestural communication.

One of Clayton's major contributions to our understanding of animal minds has been her work on episodic-like memory. A central reason for the success of this work was its focus on ecological validity: rather than looking for episodic memory for arbitrary stimuli in artificial contexts, focussing on contexts in which episodic memory would serve a biological function such as food caching. This review aims to deepen this insight by surveying the numerous functions that have been proposed for episodic memory, articulating a philosophically grounded framework for understanding what exactly functions are, and drawing on these to make suggestions for future directions in the comparative cognitive psychology of episodic memory. Our review suggests four key insights. First, episodic memory may have more than one function and may have different functions in different species. Second, cross-disciplinary work is key to developing a functional account of episodic memory. Third, there is scope for further theoretical elaboration of proposals relating episodic memory to food caching and, in particular, future-oriented cognition. Finally, learning-related functions suggested by AI (artificial intelligence)-based models are a fruitful avenue for future behavioural research.

New research is shedding light on the nuances and complexity of social relationships in our closest relatives, revealing cooperative intergroup relationships in bonobos, in contrast to lethal intergroup violence in chimpanzees. At the same time, intragroup relationships, at least among males, are characterized by higher frequencies of aggression and lower rates of coalitionary cooperation in bonobos than chimpanzees.

Domestic dogs (Canis familiaris) have been documented to 'overimitate' humans - a form of social learning - by copying their causally-irrelevant actions. It is suggested that this behaviour results from social, affiliative motivations. Dogs have also been known to behave differently when they are being watched (or not) by humans, such as by following commands better (or worse). In this study, we tested whether dogs' copying behaviour would also be sensitive to their caregiver's attentional states. The subject's caregiver demonstrated irrelevant and relevant actions in the dot-touching overimitation task, then during trials the caregiver was either watching their dog or turned away. Our results revealed no difference in dogs' irrelevant-action copying; however, we found that dogs approached the dots less per trial when their caregiver was watching them. Dogs also copied their caregiver's leftward sliding of a door (to obtain a food reward) more accurately when they were being watched by their caregiver. Finally, dogs who copied the irrelevant action did so more often after obtaining their food reward, which supports that these dogs may have had two separate goals: a primary instrumental goal and a secondary social goal.

The order of stimuli within sequences and the transitional probabilities (TPs) it generates are central information in sequence processing. However, less is known about what type of information and how it is extracted by general learning mechanisms. The present study focused on statistical learning of second-order TPs. Second-order TPs are involved when only the combination of two stimuli predicts the third. In a first experiment, TPs depended crucially on the order of presentation of a pair , which led to different predictions depending on the order of the stimuli (i.e., ABC vs. BAF). Eight visuomotor sequences governed by second-order TPs were used and response times (RTs) were recorded for each transition. The task included a learning phase followed by a switch phase during which the second-order TP were reversed (e.g., the sequences ABC and BAF became respectively ABF and BAC). A decrease of RTs between the second and the third stimulus during the learning phase and an increase of RTs during the switch phase suggested that variations of orders within second-order TPs could be learned. Further analyses, however, indicated that such learning was difficult for most participants. A second experiment showed that the difficulty of learning was not solely due to the difficulty to pick up the effect of order of presentation, but that learning second-order transitional probabilities in addition to order would be the main obstacle. These experiments suggest that statistical learning is capable of learning complex associations, even if this remains a challenge for human cognition.

Piagetian object permanence (OP) refers to the ability to know that an object continues to exist when out of sight: In humans, it develops in six stages. Species of great apes, other mammals, and birds (parrots, corvids, and pigeons) have been shown to possess partial or full OP, which is a prerequisite for more complex physical cognition abilities they may possess. In birds, the greatest variation is in Stage 6 (invisible displacements) and in "A-not-B" errors-incorrectly persevering in searching an empty location rewarded previously. Caching abilities have been invoked as holding explanatory power over results in corvids, for which this error is sometimes completely absent. The rook (Corvus frugilegus), a cognitively advanced, social, caching corvid, has not yet been studied for OP. This study applies tasks of one OP scale commonly adapted for nonhuman animals, Uzgiris and Hunt's Scale 1, as well as later-conceived tasks 16 and S, to a sample of adult, captive rooks. One rook demonstrated full OP (Stage 6b, multiple invisible displacements), whereas other individuals varied, attaining between Stages 5a (single visible displacements) and 6a (single invisible displacements). Like some corvids, a few made transient "A-not-B" errors. Behavioral considerations potentially underlying observed individual variation in results in rooks, including dominance, neophobia, past experiences, and individual idiosyncrasies, are examined. Rooks, like other corvids, possess well-developed OP abilities, and these results support the idea that exertion of executive control is required to avoid "A-not-B" errors, rather than caching abilities or developmental age, as previously suggested.

The New York Declaration on Animal Consciousness (Andrews et al., 2024) highlights increasing empirical evidence supporting the existence of sentience in many animal species. The views in the declaration rest on an increasingly popular theoretical approach that comparative psychologists could use to guide research on non-human consciousness.

Although the diversification of species has fascinated researchers for centuries, we know remarkably little about how behavior influences niche adaptation and the genetic mechanisms through which behavior evolves. In their recent study, Sommer-Trembo et al. (Science, 384, 470-475, 2024) demonstrate a critical role for the regulatory gene cacng5b in modulating phenotypic variation in exploratory behavior in one of the most exceptional adaptive radiations: the African cichlid fishes of Lake Tanganyika.

In complex social environments, animals benefit from suppressing inappropriate responses (known as Response Inhibition) to avoid conflicts and maintain group cohesion. Recent research suggests that an individual's early-life social environment can shape their response inhibition. However, these findings have mostly been correlational, and results vary across species. Furthermore, the role of learning is often overlooked when measuring response inhibition, despite its potential importance to understanding group differences. We investigated the effect of early-life group size, a key determinant of social complexity, on response inhibition in Japanese quails (Coturnix japonica), whilst taking the role of learning into account. Quails (n = 120) were raised in either small groups of five or large groups of 15 individuals. Response inhibition was assessed using the cylinder task. Up to ten trials were administered to assess whether the birds' responses changed with increasing experience of the task. Among the quails that completed ten trials, we found that those raised in large groups consistently spent less time pecking the cylinder than those raised in small groups. The quails' responses were also influenced by their body condition, food motivation and sex. Importantly, the quails learned to inhibit their responses - successful trials increased, and time spent pecking the cylinder decreased, across ten trials. However, learning rates did not differ between the treatment groups. These findings suggest that early-life social group size promotes the development of response inhibition in quails, but not their learning of it, during the cylinder task.

The aim of this research was to test the effect of training impure tact versus pure tact and intraverbals on the emergence of new verbal operants (impure tacts), thus establishing a conceptual and methodological differentiation on these operants. This was done by varying the training order of intraverbal or impure tact to analyze and confirm whether or not impure tact is the mere sum of pure tact plus intraverbal and therefore has different functions and consequences in learning. An experiment was conducted with 30 participants randomly assigned to three groups. In Group 1, pure tact plus intraverbal and then impure tact were trained. In Group 3 the training order of these operants was counterbalanced. Group 2 was the control group, training only pure tact plus intraverbal. After the training phases, the emergence of impure tacts was tested. The results of this research indicate that the training of impure tacts favors the emergence of new impure tacts to a greater extent than the training of pure tact plus intraverbal and that they therefore have different functions. It is also shown that variation in the order of presentation of the type of training influences the subsequent emergence of new operants (impure tacts), so that creating a previous history of learning in impure tacts favors emergence even when the intraverbal alone is subsequently trained. This has important implications at both conceptual and methodological levels as it would contribute to the development of more effective language training technologies.

Young precocial birds benefit from staying close to both their mother and their siblings, while prioritising adults, which provide better care. Which features of the stimuli are used by young birds to prioritise approach and eventually 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 features that systematically vary between adult and juvenile chickens, and that had previously been identified as attractive: 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 spent more time in close proximity with red stimuli than with yellow stimuli. When tested with red large versus 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. Chicks had a stronger preference for large red stimuli (vs. small yellow objects) than for small red stimuli (vs. a large yellow object) (Exp. 3). 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, exhibiting a preference to approach stimuli with features associated with the presence of adult conspecifics.

Vivid episodic memories in humans have been described as the replay of the flow of past events in sequential order. Recently, Panoz-Brown et al. Current Biology, 28, 1628-1634, (2018) developed an olfactory memory task in which rats were presented with a list of trial-unique odors in an encoding context; next, in a distinctive memory assessment context, the rats were rewarded for choosing the second to last item from the list while avoiding other items from the list. In a different memory assessment context, the fourth to last item was rewarded. According to the episodic memory replay hypothesis, the rat remembers the list items and searches these items to find the item at the targeted locations in the list. However, events presented sequentially differ in memory trace strength, allowing a rat to use the relative familiarity of the memory traces, instead of episodic memory replay, to solve the task. Here, we directly manipulated memory trace strength by manipulating the odor intensity of target odors in both the list presentation and memory assessment. The rats relied on episodic memory replay to solve the memory assessment in conditions in which reliance on memory trace strength is ruled out. We conclude that rats are able to replay episodic memories.

This study explored long-term retention of spatial memory in rats using an eight-arm radial maze. Crystal and Babb (Learning and motivation, 39(4), 278-284, 2008) previously demonstrated that rats could retain spatial memory for up to 25 h in the radial maze. Notably, they found performance improved with 48-h intertrial intervals compared with 24-h intervals. Our study investigated the effects of extending intertrial intervals on long-term retention of spatial memory by reducing the potential for proactive interference. Each trial comprised a learning phase, during which subjects were required to sequentially visit four randomly selected arms, followed by a free-choice test that included all eight arms, conducted after increasing the retention and intertrial intervals. The retention intervals were systematically increased from 1 h to 24, 48, and, ultimately, 72 h, with corresponding intertrial intervals expanding from 24 to 48, 120, and 144 h. Performance significantly surpassed chance levels across all conditions, demonstrating that rats are capable of retaining spatial memory for up to 72 h.

Among the many important empirical and theoretical contributions in her career Clayton and her colleagues advanced the idea that comparative cognition researchers would benefit from considering the role of magic and the techniques of the magician in some areas of cross-species cognitive study. They provided compelling and exciting studies using the techniques of the magician and demonstrated how those affect nonhuman animals that rely on vision, showing that there are similarities and dissimilarities in how susceptible some nonhuman species are to the magician's effects that typically work so well on human observers.

We recently showed that food-hoarding birds use familiarity processes more than recollection processes when remembering the spatial location of their caches (Smulders et al., Animal Cognition 26:1929-1943, 2023). Pravosudov (Learning & Behavior, https://doi.org/ https://doi.org/10.3758/s13420-023-00616-x , 2023) called our findings into question, claiming that our method is unable to distinguish between recollection and familiarity, and that associative learning tasks are a better way to study the memory for cache sites. In this response, we argue that our methods would have been more likely to detect recollection than familiarity, if Pravosudov's assertions were correct. We also point out that associative learning mechanisms may be good for building semantic knowledge, but are incompatible with the needs of cache site memory, which requires the unique encoding of caching events.

To survive and reproduce, animals need to behave adaptively by adjusting their behavior to their environment, with learning facilitating some of these processes. Dogs have become a go-to model species in comparative cognition studies, making our understanding of their learning skills paramount at multiple levels, not only with regards to basic research on their cognitive skills and the effects of domestication, but also with applied purposes such as training. In order to tackle these issues, we tested similarly raised wolves and dogs in a serial learning task inspired by Harlow's "learning set." In Phase 1, different pairs of objects were presented to the animals, one of which was baited while the other was not. Both species' performance gradually improved with each new set of objects, showing that they "learnt to learn," but no differences were found between the species in their learning speed. In Phase 2, once subjects had learned the association between one of the objects and the food reward, the contingencies were reversed and the previously unrewarded object of the same pair was now rewarded. Dogs' performance in this task seemed to be better than wolves', albeit only when considering just the first session of each reversal, suggesting that the dogs might be more flexible than wolves. Further research (possibly with the aid of refined methods such as computer-based tasks) would help ascertain whether these differences between wolves and dogs are persistent across different learning tasks.

To investigate the extent of adoption of more efficient coding strategies, pigeons learned, in three experiments, a symbolic matching-to-sample task that featured an asymmetric sample-comparison mapping. In all experiments, one comparison was correct following one of the samples (one-to-one mapping), and another comparison was correct following the remaining samples (many-to-one mapping). The experiments differed in sample number; Experiment 1 featured three samples, Experiment 2 five samples, and Experiment 3 seven samples. Our goal was to assess the adoption of a single-code/default coding strategy, which establishes two response rules: one rule specific to the sample mapped one-to-one (the single code), and another rule to be applied following any other sample (the default rule). Alternatively, the animals could establish more response rules, one per sample. Thus, the single-code/default strategy allows learning a task via a reduced number of response rules, and the more samples are mapped many-to-one, the greater the savings it allows. As such, the three experiments should progressively be more amenable to the adoption of this strategy. Overall, the adoption of a single-code/default strategy was not widespread. When taken together with previous results, the present study suggests that the amount of training may affect the coding strategy pigeons adopt. Additionally, our results underscore that individual differences are a fundamental aspect to consider when studying learning flexibility.