Cue-exposure is a treatment (e.g. for addictions and phobias) that aims to extinguish conditioned responses to target cues. However, especially in the case of addiction, relapse still occurs after cue-exposure and this may be due to recovery of conditioned responses outside of the extinction context. Super-extinction and deepened-extinction are two compound-cue extinction procedures which have been assessed for their capacity to produce more robust extinction than standard single-cue extinction procedures. We carried out further assessment of super and deepened-extinction protocols but found no evidence that they produced less response recovery compared to single-cue extinction. Contrariwise, super-extinction actually produced more recovery than the other two conditions. These results can be understood in terms of configural associative models (configural Rescorla-Wagner and Pearce configural model) but not in terms of the simple elemental Rescorla-Wagner model. Furthermore, the configural models provided better fits to overall data, and the Pearce configural model was better than the configural Rescorla-Wagner model.

In Pavlovian sensitization, conditioned stimuli are said to activate response modes (e.g., feeding, sexual, or fear), which result in an increase in the response to other stimuli that activate the same response mode. Pavlovian sensitization effects are likely to result from any encounter with a highly arousing stimulus, leading to high translational relevance for investigations of anxiety disorders, cognition, and the neurobiology of learning.

Eavesdropping on heterospecific alarm calls can provide valuable information about predator presence and therefore yield survival benefits. However, if, how, and why individuals react to heterospecific alarms is poorly known. If heterospecific alarms trigger a response, individuals might either stop their own vocal activity (acoustic suppression), to avoid being detected, or start alarming (acoustic stimulation), to warn conspecifics or deter predators. Here, we performed playback experiments with the alarms of 14 common forest passerine species and tested whether heterospecifics changed their acoustic behavior after playbacks and whether this involved suppression or stimulation. Moreover, we tested whether bird behavior was influenced by species-specific attributes such as escape capability, the propensity of being predated by raptors and carnivorous mammals, and the acoustic properties of alarms affecting detectability. Birds uttered alarms more frequently after playbacks than after silent controls, gave the same alarms as they normally use in response to conspecifics, and did not suppress their acoustic activity after playbacks. These results indicate that birds perceive threat from heterospecific alarms and are contagiously stimulated to alarm, rather than inhibited. Species with morphological attributes that promote agility and suffering low predation rates were more acoustically stimulated by heterospecific alarms, irrespective of the acoustic properties of the playback or their own alarms, indicating that the propensity to join into an alarm calling bout is mediated by predation risk. This study provides evidence for contagious alarming across species, for potential costs of responding to these stimuli, and shows a facilitative role of signalers within communities.

In this commentary, we respond to Jaakkola, (2025), who raised several concerns regarding our findings on vocal labeling in marmosets (Oren et al. Science, 385, 996-1003, 2024). We address each point in turn, clarifying that marmosets use socially learned, arbitrary vocal labels for specific conspecifics - labels that are neither imitations nor acoustically derived from the receiver's own calls. We show that classifier models trained on individual callers reliably identify the intended receiver, while cross-caller models reveal family-specific label conventions. We also provide evidence that vocal accommodation does not account for the observed behavior, and we argue that the consistent, receiver-specific use of labels reflects a stable mapping between individuals and calls - indicative of an internal representation of identity. Taken together, our findings support cognitively controlled social calling in marmosets and suggest a primate precursor to name-like referential communication.

In two online experiments, we aimed to study the relationship between emotion dysregulation and persistence of incentive salience attributed to reward cues. Participants' negative urgency (NU) was assessed before they completed a value-modulated attentional capture (VMAC) task measuring incentive salience as attentional sign-tracking. This consisted of two phases - rewarded and unrewarded - to evaluate the persistence of the VMAC effect. Subsequently, a Pavlovian-to-instrumental transfer (PIT) procedure was employed as another measure of incentive salience. In Experiment 1 both outcome-specific and general PIT effects were assessed, along with the impact of instrumental outcome devaluation (OD). Experiment 2 focused on the effect of Pavlovian extinction on specific PIT. Both outcome devaluation and extinction are indices of implicit emotion regulation. In Experiment 1, the OD index showed a significant positive correlation with specific PIT and a negative correlation with the NU score. In Experiment 2, the extinction index of specific PIT, linked to the level of explicit knowledge of the contingencies, correlated negatively with NU. The VMAC effect and its persistence showed correlations with NU, positive and negative, respectively (Experiment 1). No relationships were found between any measure of VMAC and OD or PIT effects in any of the experiments. These findings suggest that difficulties in emotion regulation are associated with increased attentional sign-tracking and can hinder action control and selection. These phenomena may be governed by distinct mechanisms, with the VMAC effect being more automatic and the specific PIT effect exhibiting varying degrees of goal-directed behavior depending on the effectiveness of implicit emotion regulation strategies.

Behavioral measures of impulsivity and other traits often show weaker test-retest reliability than self-report measures. Weaker reliability impacts the assessment of individual differences in the trait or state being assessed. Behavioral tasks demonstrate greater sensitivity to state variables which may be a key reason for changes in ranked performance across time. The present study examines a single impulsivity task, the escalating interest task, and considers the design principles that may alter the within-session stability of the assessed behavior. A reanalysis of existing data is contrasted with new behavioral data to reveal that rapid changes in task contingencies produced more stable individual differences than prolonged exposure to each contingency. This outcome may be driven by expanding the number of contingencies experienced at each assessment or by keeping behavior in transition. An attempt to avoid floor or ceiling effects by increasing the ambiguity of the contingency, however, did not produce the desired result. The implications of these results for the escalating interest task as well as other behavioral tasks are considered.

Perinatal undernutrition sensitizes offspring to the development of chronic adult metabolic diseases, including cognitive dysfunction, which poses significant public health issues. Undernutrition is the most powerful condition of physiological stress, and epidemiological studies indicate detrimental effects on cognitive function and behavior in human offspring exposed to inadequate perinatal nutrition, leading to increased peroxidation of PUFAs in the brain. To address these issues, the present study investigated the protective effects of the antioxidant nutraceuticals astaxanthin (AsX) and docosahexaenoic acid (DHA) on the protective effect of DHA in the presence of antioxidants on the cognitive dysfunction and oxidative stress induced by perinatal undernutrition. Using a Wistar rat model, AsX and DHA improved learning and memory skills in perinatally undernourished offspring. The cognitive parameters included the RAM and NOR tests, and the oxidative stress parameters were assessed by the estimation of GSH, MDA, total nitrite, and TAC. This study revealed spatial learning, memory dysfunction, and abnormal exploratory behavior in offspring exposed to perinatal undernutrition at different time points in postnatal life, and these effects were ameliorated by AsX and DHA. Similarly, oxidative stress induced by perinatal undernutrition was also ameliorated by AsX and DHA. Induced oxidative stress was significantly correlated with cognitive function. This study revealed the potential of AsX and DHA supplementation during the perinatal period for the future development of cognitive dysfunction.

Dreyer et al., Proceedings of the National Academy of Sciences 122, e2414274121, (2025) challenged ant and human groups to carry an oddly shaped load through a series of narrow rooms, and found that both succeed remarkably well, but used very different tactics. While the fact that humans dumb themselves down in some groups is interesting, the discovery of a collective memory built into the interaction patterns of the ants is extremely exciting.

An experiment using a predictive learning task with college students evaluated the impact of a stimulus associated with extinction on an AAB renewal design. Four groups of participants learned a specific relationship between two cues (X and Y) and two outcomes (O1 and O2) in Context A during the first phase. Subsequently, both cues were subjected to extinction in the same Context A. During the Test, extinction was in effect for both cues; one group experienced it in Context A (AAA), while the other three groups were tested in a second Context B. We observed a reduction in the AAB renewal effect when participants received a stimulus associated with extinction (AAB*), but not when testing involved presenting a new stimulus (AAB). However, the reductive effect of the extinction reminder was not observed when the stimulus was presented only during the 75% of the extinction trials (AAB*75). These findings suggest that, under certain circumstances, the level of association of the extinction reminder with extinction might affect its efficacy in reducing response recovery.

A recent study trained three tool-naïve carrion crows (Corvus corone) to use a stick tool for getting a reward out of a crevice. Automated tracking of tool tips showed gradual changes of their trajectories, demonstrating improved efficiency in their tool dexterity over time (Moll et al. Current Biology, 35, 4845-4852, 2025).

Cognitive enrichment is essential for improving the welfare of animals in kennels, shelters, and laboratory environments. Whereas touchscreens have been used to engage dogs cognitively, they are limited in functionality. This study tested whether a domestic dog could use a four-button computerized gaming system adapted from the Enclosure Video Enrichment (EVE) system originally designed for sea lions. We trained Orlo, a therapy dog in training, to operate the Canine Experimental Video Enrichment (CEVE) system, which is the first documented instance of a dog engaging with a nontouchscreen gaming interface. Over 11 months, Orlo completed 66 training sessions (~ 21 h), demonstrating steady improvement in both response time and accuracy. He consistently met the button press efficiency criterion (fewer than seven presses per trial) but had longer latencies than sea lions, which trainer observations suggest reflected active engagement rather than misunderstanding. This study provides proof of concept that dogs can operate a four-button interface for gaming; however, the substantial training investment may limit immediate applicability in many shelter or multidog settings. Future research should evaluate strategies to streamline training, incorporate formal welfare measures, expand the sample size to assess breed and individual differences, and determine whether dogs voluntarily engage with the system in the absence of external rewards or in the presence of other enrichment options.

The study of animal cognition has hosted a long debate about the nature of mental representation. Specifically, whether spatial (map-like) or associative (node-like) models better explain learning and behavior. To explore this, the present experiments tested three pigeons using a novel spatial discrimination task to assess how they learn to discriminate different multidimensional geometric structures. Each trial involved a go/no-go procedure in which a 1.5 cm green target appeared at a random location in an unmarked 15 × 15 cm touchscreen display area. Food reinforcement depended on the target's location. Across experiments, pigeons were tested on discriminations defined by three invisible spatial structures of varying complexity. In the first two experiments, they successfully learned discriminations based on well-formed geometric divisions involving either a vertical or a diagonal discriminative boundary, respectively. In contrast, they failed to learn a mosaic discrimination involving complex, irregular, non-linear divisions of the space. These findings indicate pigeons can learn invisible multidimensional visuospatial discriminations and do so better when the underlying structure is geometrically coherent. Further, this learning appears independent of the discriminative boundary's orientation. The latter matches previous findings testing analogous rule-based (vertical) and information-integration (diagonal) organizations using visual dimensions. It is consistent with the hypothesis that a single non-analytic associative mechanism mediates learning in both cases. Implications for understanding the discriminative representations used by pigeons in solving problems involving fundamental dimensions, like space, are considered.

Motivated behavior is characterized by a high degree of behavioral activation and effort. Preclinical models of operant effort-based decision-making are useful for studying motivational symptoms seen in many psychopathologies as well as observing individual vulnerability. In this study, we evaluated the impact of having alternative reward choices with different effort demands on the decision-making process that may lead to individual differences in working. Adult CD1 male mice, trained on a fixed ratio (FR) 8, were divided into two groups: the no-choice (FR8 for 10% sucrose) and choice (FR8 for 10% sucrose plus concurrent free access to 3% sucrose) conditions. After 5 weeks, a progressive ratio (PROG) schedule was introduced under the same choice conditions. Results indicate that only the no-choice group adjusted their work-output after changing from FR8 to PROG. The choice group did not increase lever pressing when PROG was introduced, but it maintained total fluid intake (10% plus 3%). Water restriction increased intake of all fluids in both choice conditions, independently of the effort required. Additionally, a median split based on PROG performance was used to compare high and low performers. Individual differences in lever pressing were seen under both choice conditions, but only high-performers significantly increased work output when PROG was introduced. Among the choice group, high-PROG performers did not increase total volume obtained compared with low-performers. Thus, the choice condition induced individual differences based mostly on willingness to work rather than to obtain the maximum amount of reinforcer. Further studies in both sexes should characterize this "high-worker" profile.

The ability to visually recognize objects despite differences in orientation would be advantageous for fish because they see objects from many viewpoints as they navigate their three-dimensional aquatic environment. We tested the ability of goldfish to recognize 3D chromatic and achromatic stimuli from four aspect angles in three rotation planes using a two-alternative forced-choice task. The fish were trained to discriminate between plastic models of a frog and turtle at 0°, then tested with the same objects at 0°, 90°, 180°, and 270°. In Experiments 1 and 2, the stimuli were presented in color, whereas in Experiment 3, the same stimuli were painted black. In Experiment 1, the fish performed significantly better than chance at all aspect angles (0°, ±90°, 180°) and in all three rotation planes. The goldfish displayed viewpoint-invariant performance in the picture plane, but showed enhanced performance at 0° for the two depth plane rotations, which suggests some viewpoint-dependent processes. In Experiment 2, performance accuracy was high regardless of whether the reinforced stimulus (S+) or the non-reinforced stimulus (S-) was rotated in the picture plane. In Experiment 3, two of four fish were successful in recognizing rotated achromatic stimuli. These results, taken together with other studies, suggest that goldfish more easily achieve visual object constancy when the stimuli contain surface features (color, texture, shading).

We examined giant panda paw use while feeding on bamboo to determine if this species exhibits manual lateralization. Video recordings of 21 captive giant pandas (15 females and six males) were used to measure two unimanual behaviors: 1) duration of grasping and manipulating bamboo culm during feeding bouts and 2) number of reaches. We did not find paw preferences at the population level but found significant sex differences in paw use. Male giant pandas used their right paw significantly more than their left paw while manipulating bamboo culm, whereas females used their left paw more for both manipulating and reaching for bamboo. Our results differ from previous studies, in which males of most placental quadrupeds have been found to favor the left forelimb more so than females. This preliminary study also suggests that task differences influence the degree of manual lateralization in the giant panda, and challenges the hypothesis that a lack of a corpus callosum leads to sex differences in marsupial forelimb biases. Considering the giant panda's distinctive behavioral ecology, morphology, and evolutionary history, this species provides a valuable model for investigating manual lateralization. We recommend further research on giant pandas, to test our preliminary findings, as well as comparative studies across other ursid species, which exhibit substantial variation in habitat and feeding ecology.

Successive negative contrast (SNC) is a procedure in which animals trained with a large reward consume less of a subsequent smaller reward than animals always trained with the small reward. Studies of SNC in rats have emerged as an important tool in understanding the affective neuroscience of unexpected loss. Establishing a similar procedure in a murine model would allow access to a greater toolbox of neuroscience techniques (e.g., optogenetics, transgenics) that are more readily available in mice than rats. While the rat SNC literature has been thriving for decades, only a few studies report SNC effects in mice. This paper critically reviews the current literature on SNC in mice and presents a failure to replicate SNC using procedures commonly used in rats. Overall, the limited evidence available in mice and a lack of consistent findings suggest that mice may not be the most suitable model for studying the neurobiology of frustration, particularly when compared to the more established rat model.

Cognitive (or behavioral) flexibility is considered an executive function characterized by patterns of behavioral adjustment in response to changes in environmental demands, which tends to decline with aging. The simple discrimination reversal task is a useful way to evaluate this function, as it directly measures processes related to performance change, such as sensitivity to consequences, learning set formation, and concept formation. Few studies on aging have employed this task, and those that have did not examine its component processes or include middle-aged adults. This study aimed to evaluate cognitive flexibility and its component processes through a simple discrimination reversal task, applied to 100 participants divided into four age groups: emerging adults, younger adults, middle-aged adults, and older adults. After learning three simple simultaneous visual discriminations, the function of the positive and negative stimuli was reversed three times, with participants needing to meet a performance criterion each time. Older participants were more likely to fail to meet the performance criterion in some of the reversals, a pattern consistent with reduced sensitivity to consequences and failure in class formation. Moreover, older individuals who succeeded in the task learned the new function assigned to stimuli more slowly during reversals and were less likely to form classes in the second reversal. However, all participants who met the criterion across the three reversals showed evidence of learning-set formation, regardless of age.

Disgust is a basic emotion that motivates avoidance behaviors to protect organisms from pathogens. Objects of disgust are acquired through classical conditioning mechanisms. Oculomotor avoidance serves as an objective marker of disgust, yet previous studies have relied on repeated presentations to establish disgust conditioning. This study aimed to adapt the category-conditioning paradigm (Dunsmoor et al., Cerebral Cortex, 24, 2859-2872, 2014) for disgust learning by employing trial-unique presentations, offering a novel tool for future research. In our experiment, items of two categories - furniture and vehicles - were paired with either disgusting or neutral scenes. Participants' eye movements were tracked, and self-reported measures were collected. The results demonstrated that the category-conditioning task with trial-unique stimuli effectively induced oculomotor avoidance. Participants exhibited both unconditioned avoidance responses to disgusting scenes and conditioned avoidance responses to category items associated with disgust. Eye-tracking data further revealed that disgust-associated stimuli motivated avoidance beyond their role as mere predictors of an aversive stimulus. Interestingly, participants initially exhibited a tendency to view the disgusting image before engaging in avoidance behavior. In conclusion, this study demonstrates that the adapted category-conditioning paradigm successfully elicits conditioned responses using trial-unique stimuli. We believe that this paradigm will provide a valuable tool for future research on disgust learning.

The concept of fear in animals, particularly its manifestation and measurement, remains a focal point in psychological research. This study builds on the systematic review and meta-analysis work of Bao et al. (Neuroscience & Biobehavioral Reviews, 157: 105537, 2024), which posits that freezing behavior and 22-kHz ultrasonic vocalizations (USVs) may represent objective and subjective fear states in rodents, respectively. We further investigated how these responses are modulated by shock intensity, tone-duration matching, and individual anxiety levels in rodent fear-conditioning paradigms. Experiment 1 manipulated shock intensity during fear learning and tone-duration matching between learning and cue tests, revealing that while freezing behavior was consistent across conditions, 22-kHz USVs varied significantly and appeared later than freezing. This divergence was more pronounced in fear generalization tests. Experiment 2 explored the response differences in rodents with high and low anxiety, demonstrating that highly anxious individuals exhibited more 22-kHz USVs but not increased freezing during cue tests. These findings suggest that while freezing may reflect automatic defensive reactions, 22-kHz USVs are more indicative of rodents' cognitive appraisal and their subjective experience of fear. This distinction provides valuable insights that could improve the translation of animal fear models to human psychiatric conditions related to fear and anxiety.

Two sentence summary: In this response to a recent commentary by Bastos et al. (2024) on our study showing a superiority of aversive over positive reinforcement training to inhibit chasing in dogs under specific conditions, we emphasize three points: (1) failing to inhibit chasing can result in injuries and fatalities to dogs and people, (2) dog owners want and need rapid solutions (more time-consuming approaches are less likely to be implemented), and (3) the existing literature favoring positive reinforcement is based on correlational and quasi-experimental methods that cannot determine causality.

The Spatial Numerical Association of Response Codes (SNARC) effect reflects an association of magnitude with space. For example, humans typically map small numbers to one side of space and large numbers to the other. Research with a variety of animal species has revealed similar spatial-magnitude associations in species without relevant cultural practices, suggesting ancient origins. Human spatial-numeric associations are known to be modified by cultural practices, such as reading direction. Some studies of nonhumans have suggested that spatial-numeric associations are fixed, with small quantities represented to the left, while others suggest this relationship is not preprogrammed. Here, we report variable and flexible spatial-numeric associations in rhesus monkeys. Monkeys were required to pick both the smaller and the larger array of dots across counterbalanced conditions. We found clear spatial-numeric associations that varied among individuals and reversed between the Pick Small and Pick Large quantity conditions-indicating flexible rather than fixed associations. We found similar but nonsignificant patterns in subsequent tests using size rather than quantity. These results, like those from adult birds and apes, suggest that while the cognitive architecture for spatial-magnitude mapping is evolutionarily conserved, the specific spatial associations shown by individuals likely result from experience.

Many plant populations are dependent on animal-mediated seed dispersal; however, in the study of mutualistic processes, animals are generally thought of as unselective consumers. This approach is problematic as it does not consider the decisions of the foraging animals, and little attention is given to the cognitive processes that underpin these behaviors. One such process is the ability to predict fruit availability, as this would allow animals to direct their foraging towards productive food sources and would ensure rapid seed removal when fruits are ready to be eaten. This is particularly important for species that cannot move rapidly between resources, such as tortoises. This study investigated temporal (24-h cycle) and visual cues use during food anticipation in captive red-footed tortoise (Chelonoidis carbonaria), an important seed disperser in its natural environment. A significant increase in activity was observed in the hour immediately preceding food delivery, suggesting that the tortoises learned to predict the availability of food. Test trials, in which the visual and temporal cues were put in conflict or removed, revealed that the tortoises used both sources of information to predict food availability. Moreover, extinction trials, in which the tortoises did not have reliable temporal or visual cues prior to feeding, resulted in a rapid loss of anticipatory behavior. These findings provide insights into the cognitive processes that control anticipatory foraging behavior and, as such, have important implications for both animal and plant fitness, furthering our knowledge of mutualistic services such as seed dispersal.

The social facilitation of feeding, where individuals increase their feeding behavior in the presence of conspecifics, is widely documented, but the underlying mechanisms remain unclear, particularly regarding passive versus active facilitation and the role of individual differences, such as sex and personality. We investigated how visual exposure to non-feeding conspecifics influenced feeding behavior in zebrafish (Danio rerio), examining food consumption and other feeding related behaviors, while also assessing individual variation in boldness and sociability. Zebrafish consumed significantly more food pellets and manipulated food differently when conspecifics were present, indicating that passive social facilitation due to the mere presence of conspecifics was sufficient to increase feeding behavior. Males exhibited stronger socially facilitated feeding responses, consuming more pellets, spitting pellets more frequently, and orienting food spitting away from stimulus fish, suggesting competitive motivations. Females showed more cautious feeding behavior, holding pellets in their mouths for longer. Contrary to predictions, neither boldness nor sociability predicted individual differences in feeding behavior or responses to social context. Our findings demonstrate that social facilitation due to a passive audience and sex-specific competitive strategies influence the feeding behaviors of zebrafish.

Despite numerous studies on individual recognition having been carried out on lizards, a clear demonstration that lizards are able to identify conspecifics is still lacking. Individual recognition in lizards involves identifying conspecifics based on distinctive characteristics, including physical, acoustic, and chemical cues. Lizards use specialized epidermal glands for intraspecific communication, which secrete a mixture of proteins and lipids. To demonstrate individual recognition, a training period needs to be devised to establish associations between traits and memories of interactions with other individuals. We thus performed a 3-week study on the common wall lizards (Podarcis muralis) to assess whether lizards are able to associate between previous experience with conspecifics and their chemical signals. Further, we investigated whether proteins played a role in this association. We acclimated 40 males to laboratory conditions during the first week. In the second week, we trained lizards to develop familiarity with odors (feces, urine, skin, femoral gland secretion) from previously unknown individuals. During the third week, we tested lizards by exposing them to odors from familiar and unfamiliar individuals. Lizards examined unfamiliar signals for longer in terms of time and frequency compared to familiar ones. These results form the basis of showing that lizards may be capable of recognizing conspecifics as different individuals, based on their chemical signals, even if the observed discrimination remains at the level of familiarity and unfamiliarity. The experiment does, however, demonstrate evidence of learned responses in common wall lizards.

This study investigates learning transfer processes in the teaching of pure tacts and intraverbals within the context of verbal behavior. The objectives were: to assess whether training pure tacts and intraverbals, through the inclusion of different stimuli, facilitates learning transfer to new impure tacts, and to determine whether one of these verbal operants (pure tact or intraverbal) better promotes learning transfer. The sample included 54 children aged 11-12 years, using a within-subjects experimental design with pre-post measures. The research was divided into 17 phases and six cycles, with two levels of the independent variable: (1) different stimuli in pure tacts and same in intraverbals, and (2) same stimuli in pure tacts and different in intraverbals. The presentation order was counterbalanced to control for order effects in training. Analyses using repeated-measures ANOVAs revealed that while participants could learn with either type of training, the training of pure tacts facilitated a greater learning transfer toward new impure tacts. In fact, training with pure tacts significantly increased the accuracy of responses in impure tact tests compared to intraverbal training, promoting greater generalization of learning (Pure tacts: M = 80.25%; SD = 4.04; F(1,26) = 5.44, p = .028, ηp = .173; Intraverbals: M = 51.54%; SD = 3.65; F(1,26) = 8.33, p = .008, ηp = .243). This finding suggests that pure tacts play a key role in promoting generative behavior, allowing the acquisition of new behavioral repertoires without explicit instruction. Theoretically, this study contributes to isolating the effect of pure tacts in learning transfer, while, practically, it offers relevant educational strategies to improve learning in populations with verbal and cognitive developmental limitations.

Townrow and Krupenye (PNAS, 122(6), Article e2412450122, 2025) found that bonobos understand the mental states of others and can attribute ignorance to a social partner. In an elegantly simple design, the authors found bonobos to communicate more often, and more quickly, when a social partner is ignorant, rather than knowledgeable, of the location of a hidden food item.

The study of animal play has grown popular in recent years and its occurrence in diverse taxa documented. Two recent papers describe detailed experimental research on play in Drosophila and the effects of domestication on play in red junglefowl and domestic chickens, furthering the need to understand the role of play in behavioral evolution throughout the animal kingdom.

Sun et al. (2025) reveal the progressive, dynamic changes in the response properties of thousands of hippocampal neurons as mice learn a conditional discrimination while moving along a virtual linear track. At the end of training, separate orthogonalized ensemble codes, reflecting the properties of a state machine, capture the inherent structure of the task while dissociating the discrimination outcomes.