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Touchscreen response precision is sensitive to the explore/exploit tradeoff

The explore/exploit tradeoff is a fundamental property of choice selection during reward-guided decision making. In perceptual decision making, higher certainty decisions are more motorically precise, even when the decision does not require motor accuracy. However, while we can parametrically control uncertainty in perceptual tasks, we do not know what variables - if any - shape motor precision and reflect subjective certainty during reward-guided decision making. Touchscreens are increasingly used across species to measure choice, but provide no tactile feedback on whether an action is precise or not, and therefore provide a valuable opportunity to determine whether actions differ in precision due to explore/exploit state, reward, or individual variables. We find all three of these factors exert independent drives towards increased precision. During exploit states, successive touches to the same choice are closer together than those made in an explore state, consistent with exploit states reflecting higher certainty and/or motor stereotypy in responding. However, exploit decisions might be expected to be rewarded more frequently than explore decisions. We find that exploit choice precision is increased independently of a separate increase in precision due to immediate past reward, suggesting multiple mechanisms regulating choice precision. Finally, we see evidence that male mice in general are less precise in their interactions with the touchscreen than females, even when exploiting a choice. These results suggest that as exploit behavior emerges in reward-guided decision making, individuals become more motorically precise reflecting increased certainty, even when decision choice does not require additional motor accuracy, but this is influenced by individual differences and prior reward. These data uncover the hidden potential for touchscreen tasks in any species to uncover the latent neural states that unite cognition and movement.

animal behavior and cognition↗

Equal performance but distinct behaviors: Astatotilapia burtoni sex differences in a novel object recognition task and spatial maze

Sex differences in behavior and cognition can be driven by differential selection pressures from the environment and in the underlying neuromolecular mechanisms of decision-making. The highly social cichlid fish Astatotilapia burtoni exhibits dynamic and complex social hierarchies, yet explicit cognitive testing (outside of social contexts) and investigations of sex differences in cognition have yet to be fully explored. Here we assessed male and female A. burtoni in two cognitive tasks: a novel object recognition task and a spatial task. We hypothesized that males outperform females in a spatial learning task and exhibit more neophilic/exploratory behavior in across both tasks. In the present study we find that both sexes prefer the familiar object in a novel object recognition task, but the time at which they exhibit this preference differs between the sexes. Females more frequently learned the spatial task, exhibiting longer decision latencies and quicker error correction, suggesting a potential speed-accuracy tradeoff. Furthermore, the sexes differ in space use in both tasks and in a principal component analysis of the spatial task. A model selection analysis finds that preference, approach, and interaction duration in the novel object recognition task that reach a threshold of importance averaged across all models. This work highlights the need to explicitly test for sex differences in cognition to better understand how individuals navigate dynamic social environments.

animal behavior and cognition↗

Transfer from number to size reveals abstract coding of magnitude in honeybees

Number discrimination has been documented in honeybees. It is not known, however, whether it reflects, as in vertebrates, the operating of an underlying general magnitude system that estimates quantities irrespective of dimensions (e.g., number, space, time) and format (discrete, continuous). We investigated whether bees spontaneously transfer discrete discrimination of number to continuous discrimination of size. Bees were trained to discriminate between different numerical comparisons having either a 0.5 (2 vs. 4 and 4 vs. 8) or 0.67 ratio (2 vs. 3 and 4 vs. 6). Half of the subjects learnt to choose the smaller quantity and the other half the larger quantity. Bees were then tested for spontaneous choice (in the absence of reward) using comparisons with identical numbers but different sizes. Irrespective of the ratio of the stimuli, bees trained to select the smaller numerical quantity chose the congruent smaller size; bees trained to choose the larger numerical quantity chose the congruent larger size. This finding provides the first evidence for a cross-dimensional transfer between discrete (numerical) and continuous (spatial) dimensions in an invertebrate species and supports the hypothesis of a cognitive universality of a coding for general magnitude.

animal behavior and cognition↗

Cognitive performance and stress responsiveness in the Trinidadian Guppy: a multivariate approach

Cognition is vital for carrying out behaviours required for survival and reproduction. In animals, we now know that cognitive performance varies not just among species, but also among individuals within populations. While this variation is a prerequisite for contemporary natural selection, it is also true that selection does not act on traits in isolation. The extent to which cognitive traits covary with other aspects of phenotype (e.g. personality traits) is therefore expected to be an important factor in shaping evolutionary dynamics. Here we adopt a multivariate approach to test for spatial learning ability in a captive population of male Trinidadian guppies (Poecilia reticulata), and ask whether differences in cognitive performance are associated with (repeatable) differences in stress response behaviour. We focus on stress response for two reasons. First, functional links between cognitive traits and stress coping style have been hypothesised. Second, individual-level studies of cognitive performance typically rely on multiple testing paradigms that may themselves be a stressor. Thus, there is a risk that variation in stress responsiveness is itself a cause of apparent, but artefactual variance in cognitive ability. Using a set of fish exposed repeatedly to two distinct spatial learning tasks (maze layouts), and an acute stress response test (open field trial), we find differences among-individuals in task performance that are repeatable within- and across maze layouts. On average performance improves with experience in the first maze, consistent with spatial learning, but not in the second. In both mazes, there is among-individual variation in the trajectory of mean performance with trial number suggesting individuals differ in learning rate. Acute stress response behaviour is repeatable but predicts neither average time to solve the maze nor learning rate. We thus find no support for among-individual correlation between acute stress response and cognitive performance. However, we highlight the possibility that cumulative, chronic stress effects may nonetheless cause observed declines in performance across repeats for some individuals (leading to lack of improvement in mean time to solve the second maze). If so, this may represent a pervasive but difficult challenge for our ability to robustly estimate learning rates in studies of animal cognition.

animal behavior and cognition↗

Relative brain size and cognitive equivalence in fishes

There are two well-established facts about vertebrate brains: brains are physiologically costly organs, and both absolute and relative brain size varies greatly between and within the major vertebrate clades. While the costs are relatively clear, scientists struggle to establish how larger brains translate into higher cognitive performance. Part of the challenge is that intuitively larger brains are needed to control larger bodies without any changes in cognitive performance. Therefore, body size needs to be controlled to establish the slope of cognitive equivalence between animals of different sizes. Potentially, intraspecific slopes provide the best available estimate of how an increase in body size translates into an increase in brain size without changes in cognitive performance. Here, we provide the first evaluation of this hypothesis for fishes. First, a dataset of 51 species that included only samples of [≥] ten wild-caught individuals yielded a mean brain-body slope of 0.46 (albeit with a large range of 0.26 to 0.79). This mean slope is similar to the encephalisation quotients for ectotherm higher taxa, i.e. teleost fishes, amphibians and reptiles ([~] 0.5). However, the slope is much higher than what has been found in endotherm vertebrate species ([~] 0.3). Second, we provide slope estimates for brain-body sizes and for cognition-body sizes in wild-caught cleaner fish Labroides dimidiatus as a case study. Brain-body slopes from two datasets gave the values of 0.58 (MRI scans data) and 0.47 (dissection data). Furthermore, we have cognitive performance data from 69 individuals tested in four different cognitive tasks that estimated learning, numerical, and inhibitory control abilities. In all four tasks, the cognitive performance did not correlate significantly with body size. These results suggest that the brain-body slopes represent estimates of intraspecific cognitive equivalence for this species. While subject to further studies on various species, our results suggest that endo- and ectotherm brain organisations and resulting cognitive performances are fundamentally different.

animal behavior and cognition↗

Little evidence that Eurasian jays (Garrulus glandarius) protect their caches by responding to cues about a conspecific's desire and visual perspective

Corvids appear to be capable of adjusting their behaviour according to anothers perspective, knowledge and desire. For example, Eurasian jays have been found to employ a variety of cache protection strategies to minimise cache loss by responding to cues about the visual perspective or current desire of an observing conspecific. However, it is not known whether these jays (or any other corvid) can integrate multiple cues about different mental states and perform the optimal response accordingly. Across five experiments, we found little evidence that our Eurasian jays responded to either the visual perspective or current desire of another agent. In Experiments 1 and 2 we investigated whether Eurasian jays can limit the risk of cache loss by responding simultaneously to cues about the desire and perspective of a potential conspecific pilferer. Building on established paradigms, we used opaque and clear barriers to manipulate the observers visual access to cache locations, and specific satiety to manipulate the observers desire towards different types of food. Across both experiments the jays caching pattern provided no evidence that they could integrate information about the observers desire and perspective. Moreover, the results were also inconsistent with the previously reported effects that jays protect their caches by responding to either the visual access or specific satiety of the observer independently. To gain further insight into these unexpected results, we conducted three more experiments. In Experiments 3 and 4, we attempted to replicate the previous finding that Eurasian jays prefer to cache behind an opaque barrier over a clear barrier when observed by a conspecific than when caching in private. In Experiment 5, we further investigated the previous finding that jays preferentially cache a type of food that had been eaten to satiety by a conspecific over a food that had not been eaten by the conspecific. Experiments 3, 4 and 5 found no significant effects in the direction of the previously reported effects, questioning their robustness. We conclude by discussing the implications of our study for the field of corvid cognition and highlight several key issues that affect the reliability of comparative cognition research.

animal behavior and cognition↗

A mouse model of ATRX deficiency with cognitive deficits and autistic traits

ATRX is an ATP-dependent chromatin remodeling protein with essential roles in safeguarding genome integrity and modulating gene expression. Deficiencies in this protein cause ATR-X syndrome, a condition characterized by intellectual disability and an array of developmental abnormalities, including features of autism. Previous studies demonstrated that deleting ATRX in mouse forebrain excitatory neurons postnatally resulted in male-specific memory deficits. Here, we introduce a new model where ATRX is deleted at earlier embryonic stages, resulting in a broader spectrum of impairments, including contextual fear memory deficits, decreased anxiety, hyperactivity, as well as self-injurious and stereotyped behaviours. Sex-specific alterations were also observed, with males displaying heightened aggression and impaired sensory gating, while females exhibit social avoidance. Collectively, the findings indicate that early developmental abnormalities arising from ATRX deficiency in neurons contribute to of the presentation of autistic-like behaviours. Summary StatementMice with embryonic loss of ATRX in excitatory neurons represent a clinically relevant model to study sexually dimorphic alterations in cognitive and autistic traits.

animal behavior and cognition↗

Bumblebee visual learning: simple solutions for complex stimuli

Natural visual stimuli are typically complex. This presents animals with the challenge of learning the most informative aspects of these stimuli while not being confused by variable elements. How animals might do this remains unclear. Here, we tested bumblebees ability to learn multicomponent visual stimuli composed of a simple constant bar element and a grating element that was consistent in orientation but varied in width and number of gratings. Bees rapidly and successfully learned these compound stimuli. Tests revealed learning of the single bar element was more robust than learning of the grating element. Our study highlights how even small-brained invertebrates can rapidly learn multicomponent stimuli and prioritise the most consistent elements within them. We discuss how the learning phenomena of generalisation and overshadowing may be sufficient to explain these findings, and caution that complex cognitive concepts are not necessary to explain the learning of complex stimuli. HighlightsO_LIBumblebees are highly efficient in prioritising the most consistent elements in multicomponent visual stimuli. C_LIO_LIBees trained on horizontal and vertical cues exhibit differences in how they memorise visual cues. C_LIO_LITwo phenomena can explain how bees preferentially select, memorise and use visual cues in this experiment: generalisation and overshadowing. C_LIO_LIBumblebees as generalist foragers are well-suited to study visual cognition. C_LI

animal behavior and cognition↗

Spontaneous drumming behaviour in a Galah

Drumming--rhythmic, percussive sound production using body parts or external objects--is rare among non-human animals, with confirmed tool-assisted cases previously limited to primates and Palm Cockatoos. Here, we report the first documented instance of spontaneous, tool-assisted drumming in a Galah (Eolophus roseicapilla). A captive, male Galah produced rhythmic tapping by striking a coconut shell against a metal bowl. Across 14 recorded sessions, the bird displayed consistent temporal structure characterised by two stable tapping rates (approximately 0.8 s and 0.2 s inter-onset intervals) arranged into recurring phrases. This pattern indicates a simple hierarchical rhythmic organisation with a 4:1 ratio between metrical levels. The birds behaviour emerged without training, apparent reinforcement, or known exposure to conspecific or human drumming models, suggesting an intrinsic capacity for rhythmic tool use. Although the function of the behaviour remains unclear--play, nutrient extraction, or communicative signalling--these observations extend known rhythmic and tool-using abilities within cockatoos and raise new evolutionary questions. Our findings highlight the potential for rhythmically structured, instrumental behaviour to arise in a broader range of avian taxa than previously recognised, motivating further comparative and experimental work on the cognitive and biomechanical foundations of drumming in parrots.

animal behavior and cognition↗

SK609, a novel dopamine D3 receptor agonist and norepinephrine transporter blocker with pro-cognitive actions, does not induce psychostimulant-like increases in risky choice during probabilistic discounting

RationalePsychostimulants, such as amphetamine (AMPH) and methylphenidate (MPH), non-selectively elevate extracellular concentrations of the catecholamine neurotransmitters, dopamine (DA) and norepinephrine (NE), and are common pharmacological strategies used to improve prefrontal cortex (PFC)-dependent cognitive dysfunction. However, this approach can be problematic given AMPH has been shown to increase preference for risky choices in a rodent assay of risk/reward decision making. SK609 is a novel NE reuptake blocker that selectively activates DA D3 receptors without affinity for the DA transporter. SK609 has been shown to improve cognitive performance without increasing psychostimulant-like spontaneous locomotor activity, suggesting SK609 may benefit neurocognitive function without psychostimulant-like side effect liability. ObjectivesWe compared AMPH, MPH, and SK609 within dose ranges that display their cognitive enhancing properties in a probabilistic discounting task (PDT) of risk/reward decision making behavior to assess their potential to increase risky choice preference. MethodsRats chose between small/certain rewards delivered with 100% certainty and large/risky rewards delivered with descending probabilities across a session (100-6.25%) following administration of AMPH (0.25-1 mg/kg), MPH (2-8 mg/kg), and SK609 (4 mg/kg). ResultsAMPH and MPH increased risky choice behavior at doses previously reported to enhance cognition, whereas SK609 did not. AMPH and MPH also reduced sensitivity to non-rewarded risky choices. ConclusionsThese data highlight the combination of NE transporter blockade and selective D3 activation in pro-cognitive action without psychostimulant-like side effect liability. The absence of DA transporter blockade and non-selective dopaminergic activation are beneficial properties of SK609 that differentiates it from the traditional pro-cognitive psychostimulants.

animal behavior and cognition↗

Habitat complexity alters the strength of sexual selection on brain size in a livebearing fish

Animals often reproduce in complex environments, which should generate selection for both enhanced detectability in signaling traits and improved cognitive processing abilities. However, the extent to which signaling and cognitive traits have evolved to overcome the challenges of interacting in complex habitats remains understudied. We examined whether habitat complexity influences sexual selection in the pygmy halfbeak, Dermogenys collettei, a small livebearing freshwater fish. Using free-swimming arenas, we created low- and high-complexity environments and observed mating behaviors in mixed-sex groups. While the opportunity for sexual selection did not differ significantly between environments for either sex, we observed positive selection gradients for both male and female brain size in open arenas, but not in complex habitats. Interestingly, no clear selection on male or female ornamentation was detected in either environment. Our findings suggest that habitat complexity may limit selection pressures on cognitive traits, such as brain size, without significantly affecting visual ornamentations role in mating success.

animal behavior and cognition↗

Transfer Entropy Based Causality from Head Motion to Eye Movement for Visual Scanning in Virtual Driving

Visual scanning is achieved by eye movement control for visual information acquisition and cognitive processing, which plays a critical role in undertaking common sensorimotor tasks such as driving. The specific coordination of the head and eyes, with head motions temporally preceding eye movements, is an important human behavior to make a key contribution to goal-directed visual scanning and sensorimotor driving. In this paper, we put forward a proposal of philosophy that this specific coordination of the head and eyes essentially indicates a unidirectional causality from head motion to eye movement. We propose to investigate transfer entropy for defining a quantitative measure of this unidirectional head-eye causality. A normalized version of the proposed causality measure is introduced for taking a role as an assessment proxy of driving. The plain transfer entropy-based definition has shown its statistical significance as the measure of causality and, the normalized version has demonstrated its good effectiveness for the evaluation of driving performance, with the verification in virtual reality-based psychophysical studies. This paper successfully suggests that the quantitative exploitation of causality based on the specific coordination of the head and eyes offers an effective approach to behaviometrics of visual scanning and sensorimotor activity. Author summaryThe coordination of head and eyes always exists in everyday sensorimotor driving tasks. Specifically, in goal-directed tasks, preparatory head motions guide eye movements to obtain and process relevant visual information for interacting with the surrounding environment. That is, the specific coordination of head and eyes involving head motions temporally preceding eye movement provides a mechanism for drivers to rely on prior knowledge for performing the tasks. As a matter of fact, this specific coordination of head and eyes essentially indicates, theoretically, a unidirectional causality from head motion to eye movement, leading to our proposal of causality philosophy. In this paper, an information-theoretic tool, transfer entropy, is exploited to capture the complex relationship between head motion and eye movement for obtaining the proposed measure of unidirectional causality. Furthermore, considering that the specific coordination of the head and eyes reflects the attention and cognitive state affecting the performance of sensorimotor tasks, we develop a normalized unidirectional causality measure as a proxy for the evaluation of driving performance. Psychophysical studies for goal-directed driving tasks are conducted based on virtual reality experimentation. Extensive results demonstrate a statistically significant correlation between the proposed normalized measure of causality and driving performance, which may provide a new and effective avenue for behaviometric applications. Practically, the merit of our proposed causality philosophy is that it is simple but effective, for obtaining an evaluation of the attentional and cognitive processes in driving tasks.

animal behavior and cognition↗

Compulsivity is linked to maladaptive choice variability but unaltered reinforcement learning under uncertainty

Compulsivity has been associated with variable behavior under uncertainty. However, previous work has not distinguished between two main sources of behavioral variability: the stochastic selection of choice options that do not maximize expected reward (choice variability), and random noise in the reinforcement learning process that updates option values from choice outcomes (learning variability). Here we studied the relation between dimensional compulsivity and behavioral variability, using a computational model which dissociates its two sources. We found that compulsivity is associated with more frequent switches between options, triggered by increased choice variability but no change in learning variability. This effect of compulsivity on the trait component of choice variability is observed even in conditions where this source of behavioral variability yields no cognitive benefits. These findings indicate that compulsive individuals make variable and maladaptive choices under uncertainty, but do not hold degraded representations of option values.

animal behavior and cognition↗

Hypoglycemia Aggravated Cognitive Degeneration by activating Endothelial ZBP1-mediated PANoptosis in Type 2 Diabetes

Recurrent hypoglycemia increases cognitive impairment in diabetes mellitus patients. Following cerebral neuron injury, endothelial cells provide morphological, metabolic and immune support to damaged neurons. We investigated the inflammatory mechanism involved in hippocampal neuron degeneration. Behavioral experiments, including the open field test (OFT) and the Morris water maze test, were performed to measure cognitive changes. Using a vascular ring experiment, we evaluated vasodilation of the carotid artery. ZBP1 expression was knocked down after transfection with small interfering RNA in a brain endothelial cell line (bEnd3). In this study, PANoptosis, a recently defined form of programmed cell death (PCD), was found to be increased by hypoglycemia in the hippocampus of type 2 diabetic mice in vivo and by low glucose in bEnd3 cells in vitro. ZBP1 knockdown decreased PANoptosis induced by low-glucose stimulation in high-glucose-cultivated bEnd3 cells. RNA transcriptomics sequencing revealed that AGE-RAGE signaling significantly changed after ZBP1 was knocked down in bEnd3 cells. Corresponding biochemical data confirmed that ZBP1 knockdown regulated the advanced glycation end products (AGEs)-Receptor for Advanced Glycation End Products (RAGE) axis in bEnd3 cells. We present the first evidence that hypoglycemia impaired cognition in mice with type 2 diabetes by activating brain endothelial ZBP1-mediated PANoptosis via the AGE-RAGE axis. ARTICLE HIGHLIGHTSO_LIPANoptosis, a newly defined form of programmed cell death, is induced in the hippocampus after recurrent hypoglycemia in male db/db mice. C_LIO_LIZBP1, a sensor of the PANoptosome, was activated in low glucose cultured brain endothelial cells. C_LIO_LIHypoglycemia impairs vasodilation and cognitive function in type 2 diabetic mice. C_LIO_LIOur study indicates that inhibiting ZBP1-PANoptosis and the AGE-RAGE axis may be a potential approach to prevent hypoglycemia-induced cognitive degeneration in individuals with type 2 diabetes. C_LI

animal behavior and cognition↗

Apparent sunk cost effect in rational agents

Rational decision makers aim to maximize their gains, but humans and other animals often fail to do so, exhibiting biases and distortions in their choice behavior. In a recent study of economic decisions, humans, mice, and rats have been reported to succumb to the sunk cost fallacy, making decisions based on irrecoverable past investments in detriment of expected future returns. We challenge this interpretation because it is subject to a statistical fallacy, a form of attrition bias, and the observed behavior can be explained without invoking a sunk cost-dependent mechanism. Using a computational model, we illustrate how a rational decision maker with a reward-maximizing decision strategy reproduces the reported behavioral pattern and propose an improved task design to dissociate sunk costs from fluctuations in decision valuation. Similar statistical confounds may be common in analyses of cognitive behaviors, highlighting the need to use causal statistical inference and generative models for interpretation.

animal behavior and cognition↗

The lemur baseline: How lemurs compare to monkeys and apes in the Primate Cognition Test Battery

Primates have relatively larger brains than other mammals even though brain tissue is energetically costly. Comparative studies of variation in cognitive skills allow testing of evolutionary hypotheses addressing socioecological factors driving the evolution of primate brain size. However, data on cognitive abilities for meaningful interspecific comparisons are only available for haplorhine primates (great apes, Old- and New World monkeys) although strepsirrhine primates (lemurs and lorises) serve as the best living models of ancestral primate cognitive skills, linking primates to other mammals. To begin filling this gap, we tested members of three lemur species (Microcebus murinus, Varecia variegata, Lemur catta) with the Primate Cognition Test Battery, a comprehensive set of experiments addressing physical and social cognitive skills that has previously been used in studies of haplorhines. We found no significant differences in cognitive performance among lemur species and, surprisingly, their average performance was not different from that of haplorhines in many aspects. Specifically, lemurs overall performance was inferior in the physical domain but matched that of haplorhines in the social domain. These results question a clear-cut link between brain size and cognitive skills, suggesting a more domain-specific distribution of cognitive abilities in primates, and indicate more continuity in cognitive abilities across primate lineages than previously thought.

animal behavior and cognition↗

Optimizing touchscreen measures of rodent cognition by eliminating image bias

For the last twenty years, the Bussey-Saksida touchscreen-based operant conditioning platform has evolved in close parallel alongside the Cambridge Neuropsychological Test Automated Battery (CANTAB) to produce batteries of tests for studying complex cognitive functions in rodents that are increasingly analogous to human diagnostic tests and greatly narrow the translational gap in cognition research. Naturally, with this increasing usefulness comes increasing use, particularly by non-experts. This necessitates a greater understanding of, and a better controlling for, confounding factors that may limit the systems ability to optimally detect cognitive deficits when used as a widely accessible and commercially available standardized task. In the present study, we show a strong image preference bias in a standard pairwise discrimination task with a widely used spider-plane image pairing in a putative animal model for intellectual disability. This bias greatly influenced the performance of our experimental mice, significantly affecting the length of time it took mice to complete the task, their progress over time, and several accessory measures usefully recorded by the Bussey-Saksida touchscreen system. We further show that this bias can be corrected by using more similar image pairings without sacrificing the animals ability to learn to distinguish the stimuli. This approach eliminated all significant stimuli specific differences seen with the spider-plane pairing. We then analyzed the pixel composition of the various stimuli to suggest that the bias is due to a difference in image brightness. These findings highlight the importance of carefully modulating paired touchscreen stimuli to ensure equivalence prior to learning and the need for more studies of visual perception in mice, particularly as it relates to their performance in cognitive assays.

animal behavior and cognition↗

Problems with comparative analyses of avian brain size

There are multiple hypotheses for the evolution of cognition. The most prominent hypotheses are the Social Intelligence Hypothesis (SIH) and the Ecological Intelligence Hypothesis (EIH), which are often pitted against one another. These hypotheses tend to be tested using broad-scale comparative studies of brain size, where brain size is used as a proxy of cognitive ability, and various social and/or ecological variables are included as predictors. Here, we test how methodologically robust such analyses are. First, we investigate variation in brain and body size measurements across >1000 species of bird. We demonstrate that there is substantial variation in brain and body size estimates across datasets, indicating that conclusions drawn from comparative brain size models are likely to differ depending on the source of the data. Following this, we subset our data to the Corvides infraorder and interrogate how modelling decisions impact results. We show that model results change substantially depending on variable inclusion, source and classification. Indeed, we could have drawn multiple contradictory conclusions about the principal drivers of brain size evolution. These results reflect recent concerns that current methods in comparative brain size studies are not robust. We add our voices to a growing community of researchers suggesting that we move on from using such methods to investigate cognitive evolution. We suggest that a more fruitful way forward is to instead use direct measures of cognitive performance to interrogate why variation in cognition arises within species and between closely related taxa.

animal behavior and cognition↗