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Integrating individual actions into coherent, organised behavioural units, a process called chunking, is a fundamental, evolutionarily conserved process that renders actions automatic. In vertebrates, evidence points to the basal ganglia – a complex network believed to be involved in action selection – as a key component of action sequence encoding, although the underlying mechanisms are only just beginning to be understood. Central pattern generators control many innate automatic behavioural sequences that form some of the most basic behaviours in an animal's repertoire, and in vertebrates, brainstem and spinal pattern generators are under the control of higher order structures such as the basal ganglia. Evidence suggests that the basal ganglia play a crucial role in the concatenation of simpler behaviours into more complex chunks, in the context of innate behavioural sequences such as chain grooming in rats, as well as sequences in which innate capabilities and learning interact such as birdsong, and sequences that are learned from scratch, such as lever press sequences in operant behaviour. It has been proposed that the role of the striatum, the largest input structure of the basal ganglia, might lie in selecting and allowing the relevant central pattern generators to gain access to the motor system in the correct order, while inhibiting other behaviours. As behaviours become more complex and flexible, the pattern generators seem to become more dependent on descending signals. Indeed, during learning, the striatum itself may adopt the functional characteristics of a higher order pattern generator, facilitated at the microcircuit level by striatal neuropeptides. [ABSTRACT FROM AUTHOR]

In multicellular organisms, endocrine factors such as hormones and cytokines regulate development and homoeostasis through communication between different organs. For understanding such interorgan communications through endocrine factors, the fruit fly Drosophila melanogaster serves as an excellent model system due to conservation of essential endocrine systems between flies and mammals and availability of powerful genetic tools. In Drosophila and other insects, functions of neuropeptides or peptide hormones from the central nervous system have been extensively studied. However, a series of recent studies conducted in Drosophila revealed that peptide hormones derived from peripheral tissues also play critical roles in regulating multiple biological processes, including growth, metabolism, reproduction, and behaviour. Here, we summarise recent advances in understanding target organs/tissues and functions of peripherally derived peptide hormones in Drosophila and describe how these hormones contribute to various biological events through interorgan communications.

Reproduction involves multiple complex behaviours, and the effects of familiarity on such social interactions are seldom described in fish. This is particularly true for sound production and communication within aggressive or non-aggressive context. This study explores the effects of a common garden rearing without parental care of two closely related cichlid species (Nile tilapia Oreochromis niloticus and blackchinned tilapia Sarotherodon melanotheron) on their sound production features and social interactions. After 9 months in common garden rearing, from embryonic stage to first maturity, sound production and associated behaviours were recorded on specimens of the two species in intraspecific and interspecific pairings. The authors found that fish were able to produce the same kind of sounds as those recorded in similar context for their parents. Drum sounds were associated to chasing, lateral attack and courtship in O. niloticus and only to fleeing or avoidance in S. melanotheron. Specific grunts were produced in chasing, after biting and in nest building by O. niloticus, and specific rolling sounds were associated to courtship in S. melanotheron. Sound production and behaviours were not correlated to sex steroid levels, but the number of sounds recorded in aggressive context was correlated to dominance in O. niloticus. The authors conclude that one generation of common garden rearing does not modify sound features, which remain specific and innate in the two cichlids. Despite the familiarity, O. niloticus remained dominant on S. melanotheron, but the aggressiveness between the two species decreased. [ABSTRACT FROM AUTHOR]

Soon after hatching, the young of precocial species, such as domestic chicks or ducklings, learn to recognize their social partner by simply being exposed to it (imprinting process). Even artificial objects or stimuli displayed on monitor screens can effectively trigger filial imprinting, though learning is canalized by spontaneous preferences for animacy signals, such as certain kinds of motion or a face-like appearance. Imprinting is used as a behavioural paradigm for studies on memory formation, early learning and predispositions, as well as number and space cognition, and brain asymmetries. Here, we present an automatized setup to expose and/or test animals for a variety of imprinting experiments. The setup consists of a cage with two high-frequency screens at the opposite ends where stimuli are shown. Provided with a camera covering the whole space of the cage, the behaviour of the animal is recorded continuously. A graphic user interface implemented in Matlab allows a custom configuration of the experimental protocol, that together with Psychtoolbox drives the presentation of images on the screens, with accurate time scheduling and a highly precise framerate. The setup can be implemented into a complete workflow to analyse behaviour in a fully automatized way by combining Matlab (and Psychtoolbox) to control the monitor screens and stimuli, DeepLabCut to track animals' behaviour, Python (and R) to extract data and perform statistical analyses. The automated setup allows neuro-behavioural scientists to perform standardized protocols during their experiments, with faster data collection and analyses, and reproducible results. [ABSTRACT FROM AUTHOR]

Host preference is an important behaviour in parasitoid females as they must choose suitable hosts for their offspring. Preference includes location, recognition and acceptance of hosts. Both genetic and environmental factors can affect all those stages. Here, we focus on two factors (rearing history and experience) affecting host preference in the parasitoid wasp genus Nasonia (Hymenoptera: Chalcidoidea: Pteromalidae: Pteromalinae), which harbours both a host generalist (N. vitripennis) and several closely related specialists (N. giraulti, N. longicornis and N. oneida). We tested whether Nasonia females prefer the host that they developed in by rearing them on two different host species (Lucilia sericata and Calliphora vomitoria) for over 10 generations before testing them for their host preference. We then tested whether experience changes host preference by allowing the females to feed and oviposit on either host species before testing their host preference. Only the generalist N. vitripennis showed behavioural plasticity as the effect of rearing history on host preference was overruled by their experience with a different host species. In contrast, the three specialist species were not affected by long‐term rearing history and only shifted their host preference based on experience. In all four known Nasonia species, individual adult experience modulated host recognition, acceptance and preference. [ABSTRACT FROM AUTHOR]

Throughout the animal kingdom, antipredator mechanisms are an evolutionary driving force to enable the survival of species classified as prey. Information regarding a predator's location can be determined through chemosensory cues from urine, faeces, visual and/or acoustic signals and anal gland secretions; and in several lab and field-based studies it has been seen that these cues mediate behavioural changes within prey species. These behaviours are often linked to fear and avoidance, which will in turn increase the prey's survival rate. In many studies dogs (Canis lupus familiaris) have been used as a predator species, however, no research has addressed a dog's innate ability to detect predator scents, hence the rationale behind this study. We assessed the innate ability of the untrained domestic dog to detect faecal scents of wild Eurasian brown bear (Ursus arctos arctos) and European lynx (Lynx lynx). The study monitored 82 domestic dogs across the UK and Norway. The dogs were exposed to the two predator faecal scents from Eurasian brown bear and European lynx, a herbivore faecal scent of Eurasian beaver (Castor fiber) and water control. Measurements were taken upon the time spent within a 40 cm radius of each scent and changes in the dog's heart rate when within this 40 cm radius. We found dogs spent a decreased length of time around the predator scents and had an increased heart rate in relation to their basal heart rate. We conclude that dogs can innately sense predator scents of brown bear and lynx and elicit fear towards these odours, as shown through behavioural and physiological changes. [ABSTRACT FROM AUTHOR]

The mycotoxin deoxynivalenol (DON) has a high global prevalence in grain-based products. Biomarkers of exposure are detectable in most humans and farm animals. Considering the acute emetic and chronic anorexigenic toxicity of DON, maximum levels for food and feed have been implemented by food authorities. The tolerable daily intake (TDI) is 1 µg/kg body weight (bw)/day for the sum of DON and its main derivatives, which was based on the no-observed adverse-effect level (NOAEL) of 100 µg DON/kg bw/day for anorexic effects in rodents. Chronic exposure to a low-DON dose can, however, also cause inflammation and imbalanced neurotransmitter levels. In the present study, we therefore investigated the impact of a 2-week exposure at the NOAEL in mice by performing behavioural experiments, monitoring brain activation by c-Fos expression, and analysing changes in the metabolomes of brain and serum. We found that DON affected neuronal activity and innate behaviour in both male and female mice. Metabolite profiles were differentiable between control and treated mice. The behavioural changes evidenced at NOAEL reduce the safety margin to the established TDI and may be indicative of a risk for human health. [ABSTRACT FROM AUTHOR]

'Bait-resistance' is defined as progressive decreases in bait efficacy in controlled pest species populations. Understanding the mechanisms by which bait-resistance can develop is important for the sustainable control of pests worldwide, for both wildlife conservation programs and agricultural production. Bait-resistance is influenced by both behavioural (innate and learned bait-avoidance behaviour) and physiological aspects of the target pest species (its natural diet, its body mass, the mode of action of the toxin, and the animal's ability to biochemically break down the toxin). In this review, we summarise the scientific literature, discuss factors that can lead to innate and learned aversion to baits, as well as physiological tolerance.Weaddress the question of whether bait avoidance or tolerance to 1080 could develop in the red fox (Vulpes vulpes), an introduced predator of significant economic and environmental importance in Australia. Sublethal poisoning has been identified as the primary cause of both bait avoidance and increased toxin-tolerance, and so, finally, we provide examples of how management actions can minimise the risk of sublethal baits in pest species populations. [ABSTRACT FROM AUTHOR]

Integrating individual actions into coherent, organised behavioural units, a process called chunking, is a fundamental, evolutionarily conserved process that renders actions automatic. In vertebrates, evidence points to the basal ganglia - a complex network believed to be involved in action selection - as a key component of action sequence encoding, although the underlying mechanisms are only just beginning to be understood. Central pattern generators control many innate automatic behavioural sequences that form some of the most basic behaviours in an animal's repertoire, and in vertebrates, brainstem and spinal pattern generators are under the control of higher order structures such as the basal ganglia. Evidence suggests that the basal ganglia play a crucial role in the concatenation of simpler behaviours into more complex chunks, in the context of innate behavioural sequences such as chain grooming in rats, as well as sequences in which innate capabilities and learning interact such as birdsong, and sequences that are learned from scratch, such as lever press sequences in operant behaviour. It has been proposed that the role of the striatum, the largest input structure of the basal ganglia, might lie in selecting and allowing the relevant central pattern generators to gain access to the motor system in the correct order, while inhibiting other behaviours. As behaviours become more complex and flexible, the pattern generators seem to become more dependent on descending signals. Indeed, during learning, the striatum itself may adopt the functional characteristics of a higher order pattern generator, facilitated at the microcircuit level by striatal neuropeptides., (© 2023 the author(s), published by De Gruyter, Berlin/Boston.)

An experiment was performed with two subadult otters (Lutra lutra) born in captivity that had never seen or eaten amphibians, in which they were fed a new prey with toxic substances in its skin, the Iberian common toad (Bufo spinosus). It was observed that the otters recognised a poisonous amphibian that they had never come into contact with before as a potential prey in the absence of fish, which had previously been their only diet. As from the first test, and as described for wild otters in the literature, they consumed the toads following a learning process that consisted of ventral slicing and skinning in order to avoid contact with the dermal secretions, especially on the head and back, that toads use as a defensive mechanism. We observed the skill of the otters when handling the prey with regards to both killing them and eating them; the otters also immersed their prey in the water of their pond to remove the toxic substances emanating from the toads’ skins. The amount of remains left after the attack was gradually reduced over a period of 16 test experiments. No differences between the skins rejected in the experimental conditions and those found in nature were detected, the otter mainly eating the back legs and taking special care to reject the head, the back and viscera (especially the ovaries in the case of pregnant females). When they had brown trout together with toads in the same biomass, they neither attacked nor consumed the latter. [ABSTRACT FROM AUTHOR]

In multicellular organisms, endocrine factors such as hormones and cytokines regulate development and homoeostasis through communication between different organs. For understanding such interorgan communications through endocrine factors, the fruit fly Drosophila melanogaster serves as an excellent model system due to conservation of essential endocrine systems between flies and mammals and availability of powerful genetic tools. In Drosophila and other insects, functions of neuropeptides or peptide hormones from the central nervous system have been extensively studied. However, a series of recent studies conducted in Drosophila revealed that peptide hormones derived from peripheral tissues also play critical roles in regulating multiple biological processes, including growth, metabolism, reproduction, and behaviour. Here, we summarise recent advances in understanding target organs/tissues and functions of peripherally derived peptide hormones in Drosophila and describe how these hormones contribute to various biological events through interorgan communications.

All species perceive sensory stimuli from the environment through dedicated sensory modalities, and respond with appropriate behaviours designed to maximize fitness and reproductive success. In most mammalian species, information regarding sex, age and other species-specific social and reproductive characteristics is conveyed by pheromones, which are detected by the vomeronasal and olfactory systems. Traditionally, pheromone signals have been thought to possess intrinsic rewarding meanings and to trigger ‘innate’ hardwired social behavioural responses. In contrast, odorants are considered to possess mostly neutral reward value, but may induce approach or avoidance behaviours as a result of experience or through conditioning following pairing with stimuli that possess intrinsic rewarding properties. This review describes studies demonstrating that innate behavioural responses, with particular emphasis on reproductive responses mediated by pheromonal signals, are actually flexible and substantially influenced by past experience and associative learning. These attributes allow the animal to assign new motivational incentives to pheromones associated with social and reproductive behaviours, thus providing adaptive ability to cope with unique changes in internal and external environmental conditions. We argue that responses to pheromones are far more easily modified by experience than would be expected from hardwired innate responses, and that the behaviours they elicit are chiefly plastic and sensitive to modification throughout life by sensory-mediated emotional experience. [ABSTRACT FROM AUTHOR]

Reproductive success in ducks is strongly influenced by prédation on the breeding grounds. Ducklings are targeted by a range of terrestrial, aerial and aquatic predators, giving a strong selective advantage to individuals and broods that have effective ways to avoid prédation. In experiments on naive mallard (Anas platyrhynchos) ducklings without an accompanying adult female we investigated the innate ability to identify and avoid threats at varying intensity from aerial, aquatic and terrestrial predators. Ducklings displayed increased vigilance in response to pre-recorded calls of predatory birds, representing a low level of threat. They did not react to visual and olfactory stimuli generated by motionless northern pike {Esox lucius). Neither did they show a strong response to caged American mink {Neovison vison) (visual and olfactory stimuli), although they avoided the area with the mink, indicating a certain level of recognition. High intensity threats were simulated by staging attacks from aerial (goshawk, Accipiter gentilis) and aquatic predators (northern pike). The aerial attack made ducklings dive and scatter under water, whereas the response to attack by pike was to run on the water and scatter in different directions. The lack of response to a 'passive' pike and the rather weak avoidance of mink indicate that olfactory cues are not as important in identifying a potential predatory threat by ducklings as are auditory cues. Visual cues appear to be of little importance unless they are combined with movement, and a clear response is only triggered when the intensity of predator threat is high. Mallard ducklings, thus, show an innate capacity to adjust anti-predator behaviour to different predator types and to threat intensity. Our study highlights the general trade-off between foraging needs and predator avoidance, but also second-order trade-offs in which innate avoidance behaviour towards one type of predator may increase prédation risk from another. [ABSTRACT FROM AUTHOR]

1. Non-native predators might inflict proportionally higher mortality on prey that have no previous experience of them, compared to species that have coexisted with the predator for some time. 2. We tested whether juvenile Chinook salmon ( Oncorhynchus tshawytscha) were less able to recognise a non-native than a native predator, by investigating behavioural responses to the chemical cues of the invasive smallmouth bass ( Micropterus dolomieu) and the native northern pikeminnow ( Ptychocheilus oregonensis) in both laboratory and field experiments. 3. Laboratory results demonstrated strong innate antipredator responses of individual juvenile Chinook salmon to northern pikeminnow; fish spent 70% of time motionless and exhibited 100% greater panic response than in controls. By contrast, antipredator responses to the chemical cues of smallmouth bass did not differ from controls. 4. These results were supported by similar differences in recognition of these predator odours by groups of juvenile Chinook salmon in fully natural conditions, though responses reflected a greater range of antipredator behaviours by individuals. In field trials, responses to northern pikeminnow odour resulted in increased flight or absence, reductions in swimming and foraging, and increased time spent near the substratum, compared to smallmouth bass odour. 5. Given that survival of juvenile fish is facilitated by predator recognition, our results support the hypothesis that naivety may be an important factor determining the effect of non-native predators on prey populations. Efforts to manage the effect of native and non-native predators may benefit by considering complex behavioural interactions, such as these at the individual and group levels. [ABSTRACT FROM AUTHOR]

To examine (1) the effect of experience and rearing environment on learning and behaviour over time, and (2) when (or if) newly-emerged young begin to incorporate experience into their choices, we compared the activity levels and hunting-site preferences of newly-emerged laboratory and field-reared crab spiders (Misumena vatia (Clerck, 1757)). We split spiderlings from eight broods into cohorts (1) released on goldenrod (Solidago canadensis) in the field and (2) retained individually in the laboratory, but provisioned with Drosophila melanogaster. We then tested both field-retrieved and laboratory-reared individuals at days 3, 7, 14 and 21 for their (1) rate of activity in cages over 15 min and (2) choice of either goldenrod or wild carrot (Daucus carota), two frequent hunting sites in the field. The rearing environment clearly influenced the spiderlings' activity levels: field-reared spiderlings became more active than laboratory-reared spiders over time; however, their choice of flowers did not change, even though their experience differed. Thus, innate mechanisms dominated the spiders' early hunting-site choices, and experience only informed their decisions at later stages in ontogeny. The spiders may, therefore, have multiple mechanisms for learning that begin to operate at different times, since spiderlings improve their locomotor performance through experience, while failing to use early experience in choosing hunting sites at this early point in ontogeny. [ABSTRACT FROM AUTHOR]

While ocean acidification is predicted to threaten marine biodiversity, the processes that directly impact species persistence are not well understood. For marine species, early life history stages are inherently vulnerable to predators and an innate ability to detect predators can be critical for survival. However, whether or not acidification inhibits predator detection is unknown. Here, we show that newly hatched larvae of the marine fish Amphiprion percula innately detect predators using olfactory cues and this ability is retained through to settlement. Aquarium-reared larvae, not previously exposed to predators, were able to distinguish between the olfactory cues of predatory and non-predatory species. However, when eggs and larvae were exposed to seawater simulating ocean acidification (pH 7.8 and 1000 p.p.m. CO2) settlement-stage larvae became strongly attracted to the smell of predators and the ability to discriminate between predators and non-predators was lost. Newly hatched larvae were unaffected by CO2 exposure and were still able to distinguish between predatory and non-predatory fish. If this impairment of olfactory preferences in settlement-stage larvae translates to higher mortality as a result of increased predation risk, there could be direct consequences for the replenishment and the sustainability of marine populations. Ecology Letters (2010) 13: 68–75 [ABSTRACT FROM AUTHOR]

The evolutionary history of most behaviours remains unknown. Here, we assay burrowing behaviour of seven species of deer mice in standardized environments to determine how burrowing evolved in this genus (Peromyscus). We found that several, but not all, species burrow even after many generations of captive breeding. Specifically, there were significant and repeatable differences in both the frequency of burrowing and burrow shape between species. Moreover, these observed species-specific behaviours resemble those reported in wild mice. These results suggest that there is probably a strong genetic component to burrowing in deer mice. We also generated a phylogeny for these seven species using characters from four mtDNA and two autosomal loci. Mapping burrowing behaviour onto this phylogeny suggests a sequence for how complex burrowing evolves: from small, simple burrows to long, multitunnel burrows with defined entrance and escape tunnels. In particular, the most ‘complex’ burrows of P. polionotus appear to be derived. These behavioural data, when examined in a phylogenetic context, show that even closely related species differ in their burrowing behaviours and that the most complex burrows probably evolved by the gradual accumulation of genetic change over time. [Copyright &y& Elsevier]

The goal of ‘life skills training’ is to improve survival of captive-reared animals after release to the wild. Our study tested the hypothesis that learned predator recognition in hatchery-reared fish is favoured at ecologically appropriate periods during ontogeny. We began by asking whether the innate response of Atlantic salmon to predator odour (from high- and low-risk predators) declines during hatchery rearing. Next, we used classical conditioning to assess the capacity of fish in different age groups to learn to recognize predator odour. The first experiment showed that innate predator recognition is retained by fish for at least 8 months in a hatchery environment. However, the response of 10- to 15-week-old salmon to predator odour was significantly greater than that of younger (3-week-old) or older (28- to 36-week-old) fish. This is consistent with a period of heightened receptivity to predator odour cues. The second experiment provided evidence for age-dependent learning because salmon aged 16–20 weeks showed learned predator recognition abilities, whereas 3-week-old fish relied on innate responses. The onset of learning occurred at the age when wild fish undergo a habitat shift that greatly increases their encounters with predators. Future attempts to improve predator recognition skills of fish should take greater account of life history and focus on the ontogenetic stage where learning is favoured. [Copyright &y& Elsevier]

Atlantic salmon, Salmo salar, increase their ventilation rate in response to predator odour cues. We measured the ventilation response of newly hatched Atlantic salmon to odours of high- and low-risk predators at five concentrations (10–200%). Concentration may be interpreted as predator proximity and/or number of predators present and thus represents a gradation of predation risk. Predator species (pike, Esox lucius, and minnow, Phoxinus phoxinus) and predator odour concentration affected the number of individuals responding and the strength of individual response. Fewer individuals responded to minnow odour than pike odour, and the proportion of individuals responding also declined with odour concentration. Salmon responded more strongly to high-risk predator (pike) odour than the low-risk (minnow) odour for a given concentration, and ventilation rate generally increased with increasing concentrations of both odours. This study shows that Atlantic salmon have the innate ability to evaluate risk in terms of odour concentration and predator species. [Copyright &y& Elsevier]

The article talks about the European Molecular Biology Organization (EMBO) conference entitled "The Assembly and Function of Neuronal Circuits", held in Ascona, Switzerland from September 25-30, 2005. Discussions on various areas of neurobiology took place, but the focus was on the developmental logic of neuronal circuit assembly and the linking of such to the basis of information coding and behavior.

Flower colour is a major advertisement signal of zoophilous plants for pollinators. Bees, the main pollinators, exhibit innate colour preferences, which have often been attributed to only one single floral colour, though most flowers display a pattern of two or several colours. The existing studies of floral colour patterns are mostly qualitative studies. Using a model of bee colour vision we quantitatively investigate two questions: whether or not component colours of floral colour patterns may mimic pollen signals, and whether or not bumblebees exhibit innate preferences for distinct parameters of naturally existing floral colour patterns. We analysed the spectral reflectances of 162 plant species with multicoloured flowers and inflorescences, distiniguishing between inner and outer colours of floral colour patterns irrespective of the particular structures so coloured.We found that:- The inner colour of radially symmetrical flowers and inflorescences and of zygomorphic flowers appears less diverse to bees than the peripheral colour.- The inner colour of most radial flowers and inflorescences as well as the inner colour of a large number of non-related zygomorphic flowers appears to bees to be very similar to that of pollen.- Bumblebees (Bombus terrestris) exhibit innate preferences for two-coloured over single-coloured dummy flowers in a spontaneous choice test.- Bumblebees exhibit innate preferences for dummy flowers with a large over those with a small centre area.- Bumblebees exhibit innate preferences for dummy flowers with a centre colour similar to that of pollen over those with another centre colour.Our findings support the hypotheses that the inner component of floral colour patterns could be interpreted as a generalised and little recognised form of mimicry of the colour of visually displayed pollen, that bumblebees exhibit innate preferences regarding colour and size parameters of floral colour patterns, and that these correspond to visually displayed pollen. These findings together suggest a prominent role of floral colour patterns in advertisement to and guidance of naive flower visitors. [ABSTRACT FROM AUTHOR]

Freshly emerged flower visitors exhibit colour preferences prior to individual experience with flowers. The understanding of innate colour preferences in flower visitors requires a detailed analysis, as, on the one hand, colour is a multiple-signal stimulus, and, on the other hand, flower visits include a sequence of behavioural reactions each of which can be driven by a preferential behaviour. Behavioural reactions, such as the distant approach, the close-range orientation, the landing, and the extension of mouthparts can be triggered by colour stimuli. The physiological limitations of spectral sensitivity, the neuro-sensory filters, and the animals' different abilities to make use of visual information such as brightness perception, wavelength-specific behaviour and colour vision shape colour preferences. Besides these receiverbased factors, there are restrictions of flower colouration due to sender-based factors such as the absorption properties of floral pigments and the dual function of flower colours triggering both innate and learned behaviour. Recordings of the spectral reflection of coloured objects, which trigger innate colour preferences, provide an objective measure of the colour stimuli. Weighting the spectral reflection of coloured objects by the spectral composition of the ambient light and the spectral sensitivity of the flower visitors' photoreceptors allows the calculation of the effective stimuli. Perceptual dimensions are known for only a few taxa of flower visitors. [ABSTRACT FROM AUTHOR]

Innate defensive responses such as freezing or escape are essential for animal survival. Mice show defensive behaviour to stimuli sweeping overhead, like a bird cruising the sky. Here, we tested this in young male mice and found that mice reduced their defensive freezing after sessions with a stimulus passing overhead repeatedly. This habituation is stimulus specific, as mice freeze again to a novel shape. Habituation occurs regardless of the visual field location of the repeated stimulus. The mice generalized over a range of sizes and shapes, but distinguished objects when they differed in both size and shape. Innate visual defensive responses are thus strongly influenced by previous experience as mice learn to ignore specific stimuli., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)