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Category learning is often tested with similar images that have no significance outside of the experiment for the subjects. By contrast, in nature animals often need to generalize a behavioral response like "eat" across visually distinct stimuli, such as spiders and seeds. Forming functional categories like "food" and "predator" may require conceptual rather than purely perceptual generalization. We trained free-range chickens to classify images assigned to one of four categories based on putative functional significance: inanimate objects, predators, food, and non-competing vertebrates. Images were visually diverse within each category, discouraging classification by perceptual similarity alone. In Experiment 1, chickens classified 80 images into four categories. Chickens then generalized to 80 new exemplars in each of three successive generalization tests. In Experiment 2, chickens saw new types of images to test whether their generalization was perceptual or functional. For example, chickens saw images of skunks for the predator category after training with images of hawks and snakes. Chickens used the "predator" response with these new images for both predators and non-threatening vertebrates, but not for objects or food, and did not successfully generalize any category other than predator. In Experiment 3, chickens categorized fractals as "food," and three of four chickens categorized a range of vertebrates they had not previously encountered as "predators," suggesting that chickens did not see the images as representing real world objects and animals. These results highlight constraints on the use of computer-generated images to assess categorization of natural stimuli in chickens. [ABSTRACT FROM AUTHOR]

This study examined same/different discrimination of visual stimuli in rats. Two identical stimulus-sets, consisting of four pictures in Acquisition 1 and Transfer Test 1, then two pictures in Acquisition 2 and Transfer Test 2, were presented simultaneously in two compartments of a discrimination box. Rats were trained to stay in one of the two compartments, depending on the same/different relationship among the stimuli in the stimulus sets. Two out of three rats learned same/different discrimination of four stimuli and showed significant transfer of discrimination to novel test stimuli. These two rats also learned same/different discrimination of two stimuli and showed reliable transfer of this discrimination to novel test stimuli. Rats' performance to the test stimuli was comparable to that of the training stimuli, even though responses in the test trials were always reinforced nondifferentially, regardless of the type of stimulus set, to avoid trial-and-error learning to the test stimuli. These results suggest that rats can learn same/different relationships among simultaneously presented visual stimuli at a rather abstract level. [ABSTRACT FROM AUTHOR]

Damage to the hippocampus produces profound retrograde amnesia, but odour and object discrimination memories can be spared in the retrograde direction. Prior lesion studies testing retrograde amnesia for object/odour discriminations are problematic due to sparing of large parts of the hippocampus, which may support memory recall, and/or the presence of uncontrolled, distinctive odours that may support object discrimination. To address these issues, we used a simple object discrimination test to assess memory in male rats. Two visually distinct objects, paired with distinct odour cues, were presented. One object was associated with a reward. Following training, neurotoxic hippocampal lesions were made using N‐methyl‐D‐aspartate (NMDA). The rats were then tested on the preoperatively learned object discrimination problem, with and without the availability of odour or visual cues during testing. The rats were also postoperatively trained on a new object discrimination problem. Lesion sizes ranged from 67% to 97% of the hippocampus (average of 87%). On the preoperatively learned discrimination problem, the rats with hippocampal lesions showed preserved object discrimination memory when tested in the dark (i.e., without visual cues) but not when the explicit odour cues were removed from the objects. Hippocampal lesions increased the number of trials required to reach criterion but did not prevent rats from solving the postoperatively learned discrimination problem. Our results support the idea that long‐term memories for odours, unlike recall of visual properties of objects, do not depend on the hippocampus in rats, consistent with previous observations that hippocampal damage does not cause retrograde amnesia for odour memories. [ABSTRACT FROM AUTHOR]

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Sensory abilities and cognitive processes for honey bees, bumble bees, and stingless bees have been demonstrated through conditioning experiments using odor as a conditioned stimulus (CS) and sugar solution as an unconditioned stimulus (US). Social bee conditioning employs the proboscis extension reflex (PER) to elicit an innate response to sucrose solution. However, solitary bees fail to reliably exhibit PER in response to touching antennae or tarsi with sugar solution. Here we employ a newly established, conditioning protocol for unrestrained solitary bees, i.e., the commercially available Osmia lignaria and Megachile rotundata, that allows them to explore a rearing chamber in which training can occur to subsequently reveal the ability to discriminate between an odor associated with sugar-water and a different odor associated with no reward, using three different odor pairings. No innate preference for any trial odor was found for either species. Osmia lignaria females and males clearly showed the ability to discriminate between odors after conditioning; M. rotundata adults demonstrated discrimination learning in only one set of odor pairings. Laboratory assays to condition solitary bees to not only associate odor with reward but to also discriminate between odors could support studies that address bee behavior and motivation, bee floral specialization or flower constancy, and sublethal effects of environmental stressors on bee performance. The discrepancy we found in species responses highlights the need for comparative studies, because there is no one-size-fits-all protocol for examining cognitive and learning abilities of the many species of bees whose life histories and experiences influence their behavior. [ABSTRACT FROM AUTHOR]

Generalization allows responses acquired in one situation to be transferred to similar situations. For temporal stimuli, a discontinuity has been found between zero and non-zero durations: responses in trials with no (or 0-s) stimuli and in trials with very short stimuli differ more than what would be expected by generalization. This discontinuity may happen because 0-s durations do not belong to the same continuum as non-zero durations. Alternatively, the discontinuity may be due to generalization decrement effects: a 0-s stimulus differs from a short stimulus not only in duration, but also in its presence, thus leading to greater differences in performance. Aiming to reduce differences between trials with and without a stimulus, we used two procedures to test whether a potential reduction in generalization decrement would bring performance following zero and non-zero durations closer. In both procedures, there was a reduction in the discontinuity between 0-s and short durations, supporting the hypothesis that 0-s durations are integrated in the temporal subjective continuum. [ABSTRACT FROM AUTHOR]

Pigeons (Columba livia) were trained on a stage-wise go/no-go visual discrimination task. Sixteen compound stimuli were created from all the possible combinations of two stimulus values from four separable visual dimensions: shape (circle/square), size (large/small), line orientation (horizontal/vertical), and brightness (dark/light). Starting with 1 S + and 1 S − that differed in all four-dimensional values, in our later steps, we added S − stimuli one by one, sharing at first 1, then 2, and then 3 dimensions with S + by sorting them out. When the pigeons had clearly shown attending to each of four dimensions, we presented all 16 stimuli. In this last stage, the pigeons correctly rejected most of the S − stimuli despite seeing them for the first time. Thus, to discriminate 16 unique multidimensional stimuli, it was not necessary to learn all of them as compound stimuli in such an approach. However, the 4 learnt dimensions did not give fully comprehensive information about all the new and unique compound stimuli presented in the last stage. Mistakes were associated with similarity to S + and with the order of dimensional learning. Most pigeons made mistakes in the discrimination of S − stimuli that shared 3 (some shared two) dimensions with S +. The knowledge of the first-learned dimension of compound stimuli was less reliable than the dimensions learned in the last stage. [ABSTRACT FROM AUTHOR]

The limited evidence of complex culture in non-human primates contrasts strikingly with human behaviour. This may be because non-human primates fail to use information acquired socially as effectively as they use information acquired individually. Here, monkeys were trained on a stimulus discrimination task with a win-stay, lose-shift (WSLS) reward structure. In a social learning condition, the experimenter performed an information trial by choosing between the available stimuli; in an individual condition, monkeys made this choice themselves. The monkeys' subsequent test trials displayed the same stimulus array. They were rewarded for repetition of rewarded ('win-stay') and avoidance of unrewarded ('lose-shift') information trial selections. Nine monkeys reached our pre-determined performance criterion on the initial two-stimulus stage. Their ability to generalise the WSLS strategy was then evaluated by transfer to a three-stimulus stage. Minimal differences were found in information use between the social and individual conditions on two-stimuli. However, a bias was found towards repetition of the information trial, regardless of information source condition or whether the information trial selection was rewarded. Proficient subjects were found to generalise the strategy to three-stimuli following rewarded information trials, but performed at chance on unrewarded. Again, this was not found to vary by source condition. Overall, results suggest no fundamental barrier to non-human primates' use of information from a social source. However, the apparent struggle to learn from the absence of rewards hints at a difficulty with using information acquired from unsuccessful attempts; this could be linked to the limited evidence for cumulative culture in non-human primates. [ABSTRACT FROM AUTHOR]

A popcorn popping is almost magical. And yet, the science of popcorn is safe and clear about the steps until the pop: the components, processes, and results of making popcorn. Nature has its own way to produce surprise in the form of "pops" (i.e., emergence, qualitative shifts). Emergent features spread throughout the life of taxa and individuals. A pop can be sudden and chaotic. And so is creativity. There is no incompatibility between creativity and naturalistic endeavors in science. Creativity is no god given gift blown inside humans. When creativity is defined by originality and spontaneity, it describes a feature with no past or present. I briefly summarize how one can see non-random innovation, no free occurring spontaneity, and non-heuristic effectiveness as features of behaviors that are not necessarily considered creative. Those three features reveal how traditional views of creativity undermine its real determiners and how it can be objectively defined and observed. [ABSTRACT FROM AUTHOR]

Uncertainty is a core component of threat and associated learning processes. One methodological factor impacting uncertainty in threat learning paradigms is the threat reinforcement rate, which refers to the proportion of times a cue is reinforced with an aversive stimulus. This study tested the effect of partial vs continuous threat reinforcement on threat / safety discrimination learning, as indexed by skin conductance response (SCR). Using a within-participants design, fifty-nine participants completed a task in which three colored shapes were paired with electric shock at reinforcement schedules of 100% (CS+), 50% (CS+) and 0% (CS-). In addition, the study examined the relationship between the Intolerance of Uncertainty scale (IU) and two subscales - inhibitory and prospective IU - with threat discrimination learning. The data show heightened SCR in the continuous vs partial reinforcement condition to all stimuli, but limited evidence of enhanced discrimination learning. Furthermore, no association was observed between total IU score and threat-safety discrimination. However, using a two-factor model of IU, findings showed higher inhibitory IU and higher prospective IU were associated with diminished and heightened threat discrimination, respectively. These results contribute to a fast-growing literature exploring how the uncertainty inherent to predictors of threat, individual differences in sensitivity to uncertainty, and interactions between these two factors, can shape the acquisition of threat memory. [ABSTRACT FROM AUTHOR]

Hibernation, a hypometabolic state associated with low body temperature and reduced metabolic and activity rates, represents one adaptation to harsh seasonal environmental conditions. As a consequence of hypometabolism, energetically costly neuronal processes also ought to be reduced. Since active neuronal pathways are prerequisites for learning and memory, and because previous studies revealed variable patterns, it remains unclear whether and how hibernating animals retain memories, however. Here, we investigated the effect of seasonally reduced activity on memory retention in 36 wild grey mouse lemurs (Microcebus murinus). Data from activity loggers confirmed that female grey mouse lemurs entered hibernation during the cool dry season, whereas males exhibited episodic bursts of activity throughout the austral winter. Thus, compared to males, we predicted females to show lower memory retention of visual and spatial stimulus–reward associations learned before hibernation. In contrast to our prediction, all individuals performed worse in the post‐hibernation testing session in both types of tests, compared to the pre‐hibernation learning session, and males (N = 11) performed even worse than females (N = 14) in the post‐hibernation testing session. Although females (N = 9) equipped with activity loggers tended to be less active than males (N = 4), sex‐specific activity levels were unrelated to interindividual differences in memory retention. Hence, the post‐hibernation decrease in performance of grey mouse lemurs may reflect a more general disability to retain stimulus–reward associations than a lack of memory retention due to seasonal hypometabolism, as suggested for some species of bats or squirrels. [ABSTRACT FROM AUTHOR]

Behavioural flexibility allows animals to adjust to changes in their environment. Although the cognitive processes that explain flexibility have been relatively well studied in psychology, this is less true for animals in the wild. Here we use data collected automatically during self-administered discrimination-learning trials for two passerine species, and during four phases (habituation, initial learning, first reversal and second reversal) in order to decompose sources of consistent among-individual differences in reversal learning, a commonly used measure for cognitive flexibility. First, we found that, as expected, proactive interference was significantly repeatable and had a negative effect on reversal learning, confirming that individuals with poor ability to inhibit returning to a previously rewarded feeder were also slower to reversal learn. Second, to our knowledge for the first time in a natural population, we examined how sampling of non-rewarding options post-learning affected reversal-learning performance. Sampling quantity was moderately repeatable in blue tits but not great tits; sampling bias, the variance in the proportion of visits to each non-rewarded feeder, was not repeatable for either species. Sampling behaviour did not predict variation in reversal-learning speed to any significant extent. Finally, the repeatability of reversal learning was explained almost entirely by proactive interference for blue tits; in great tits, the effects of proactive interference and sampling bias on the repeatability of reversal learning were indistinguishable. Our results highlight the value of proactive interference as a more direct measurement of cognitive flexibility and shed light on how animals respond to changes in their environment. [ABSTRACT FROM AUTHOR]

Given that domestication provided animals with more stable environmental conditions, artificial selection by humans has likely affected animals' ability to learn novel contingencies and their ability to adapt to changing environments. In addition, the selection for specific traits in domestic animals might have an additional impact on subjects' behavioural flexibility, but also their general learning performance, due to a re-allocation of resources towards parameters of productivity. To test whether animals bred for high productivity would experience a shift towards lower learning performance, we compared the performance of dwarf goats (not selected for production, 15 subjects) and dairy goats (selected for high milk yield, 18 subjects) in a visual discrimination learning and reversal learning task. Goats were tested individually in a test compartment and were rewarded by choosing either a white or a black cup presented by the experimenter on a sliding board behind a crate. Once they reached a designated learning criterion in the initial learning task, they were transferred to the reversal learning task. To increase the heterogeneity of our test sample, data was collected by two experimenters at two research stations following a similar protocol. Goats of both selection lines did not differ in the initial discrimination learning task in contrast to the subsequent reversal learning task. Dairy goats reached the learning criterion slower compared to dwarf goats (dairy goats = 9.18 sessions; dwarf goats = 7.74 sessions; P = 0.016). Our results may indicate that the selection for milk production might have affected behavioural flexibility in goats. These differences in adapting to changing environmental stimuli might have an impact on animal welfare e.g., when subjects have to adapt to new environments or changes in housing and management routines. [ABSTRACT FROM AUTHOR]

We sought to provide evidence for a combined effect of two attentional mechanisms during associative learning. Participants' eye movements were recorded as they predicted the outcomes following different pairs of cues. Across the trials of an initial stage, a relevant cue in each pair was consistently followed by one of two outcomes, while an irrelevant cue was equally followed by either of them. Thus, the relevant cue should have been associated with small relative prediction errors, compared to the irrelevant cue. In a later stage, each pair came to be followed by one outcome on a random half of the trials and by the other outcome on the remaining half, and thus there should have been a rise in the overall prediction error. Consistent with an attentional mechanism based on relative prediction error, an attentional advantage for the relevant cue was evident in the first stage. However, in accordance with a mechanism linked to overall prediction error, the attention paid to both types of cues increased at the beginning of the second stage. These results showed up in both dwell times and within-trial patterns of fixations, and they were predicted by a hybrid model of attention. [ABSTRACT FROM AUTHOR]

Both humans and nonhuman animals need to show self-control and wait for a larger or better reward instead of a smaller or less preferred but instant reward on an everyday basis. We investigated whether this ability undergoes ontogenetic development in domestic pigs (similar to what is known in human infants) by testing if and for how long nine- and 16-week-old pigs wait for a larger amount of their preferred reward. In a delay-of-gratification task, animals first learned that a small reward was hidden under a white cup and a large reward under a black cup, and then the delay to deliver the large reward was gradually increased. The results show that older pigs could wait longer for a larger reward than younger pigs (10.6 ± 1.3 s vs. 5.2 ± 1.5 s), thereby confirming our hypothesis of ontogenetic development of self-control in pigs. This self-control is likely to be regulated by the behavioural inhibition system and associated systems. Self-control or, more specifically the lack of it may be involved in the development of abnormal behaviours, not only in humans but also in animals. Therefore, research on self-control in decision-making might provide a new perspective on abnormal behaviours in captive animals. [ABSTRACT FROM AUTHOR]

In experimental tasks that involve stimuli that vary along a quantitative continuum, some choice biases are commonly found. Take, for instance, a matching-to-sample task where animals must, following the presentation of sample stimuli (that differ in duration), choose between two or more comparison stimuli. In tests where no sample is presented there is usually a bias towards the comparison that is correct following the shortest sample. To examine some aspects of these choice biases, pigeons were trained in a symbolic matching-to-sample task with two durations of keylight as samples, where key pecking had to be maintained during sample presentation. Firstly, even though animals were required to attend to the sample, a preference for the "short" comparison in no-sample testing was found. This result disproves an account where this effect was hypothesized to happen due to non-programmed learning resulting from the animals failing to attend to some trials. Secondly, even though a bias for "short" was found in both no-sample and delay testing, the extent of the biases differed between tasks, thus suggesting that forgetting the sample presented during a delay does not necessarily land the animal in a state similar to presenting no sample at all to begin with. [ABSTRACT FROM AUTHOR]

This work studies the evolution of cortical networks during the transition from escape strategy to avoidance strategy in auditory discrimination learning in Mongolian gerbils trained by the well-established two-way active avoidance learning paradigm. The animals were implanted with electrode arrays centered on the surface of the primary auditory cortex and electrocorticogram (ECoG) recordings were made during performance of an auditory Go/NoGo discrimination task. Our experiments confirm previous results on a sudden behavioral change from the initial naïve state to an avoidance strategy as learning progresses. We employed two causality metrics using Granger Causality (GC) and New Causality (NC) to quantify changes in the causality flow between ECoG channels as the animals switched to avoidance strategy. We found that the number of channel pairs with inverse causal interaction significantly increased after the animal acquired successful discrimination, which indicates structural changes in the cortical networks as a result of learning. A suitable graph-theoretical model is developed to interpret the findings in terms of cortical networks evolving during cognitive state transitions. Structural changes lead to changes in the dynamics of neural populations, which are described as phase transitions in the network graph model with small-world connections. Overall, our findings underscore the importance of functional reorganization in sensory cortical areas as a possible neural contributor to behavioral changes. [ABSTRACT FROM AUTHOR]

Categorical perception (CP) is the phenomenon by which a smoothly varying stimulus property undergoes a nonlinear transformation during processing in the brain. Consequently, the stimuli are perceived as belonging to distinct categories separated by a sharp boundary. Originally thought to be largely innate, the discovery of CP in tasks such as novel image discrimination has piqued the interest of cognitive scientists because it provides compelling evidence that learning can shape a category's perceptual boundaries. CP has been particularly closely studied in human face perception. In nonprimates, there is evidence for CP for sound and color discrimination, but not for image or face discrimination. Here, we investigate the potential for learned CP in a lower vertebrate, the damselfish Pomacentrus amboinensis. Specifically, we tested whether the ability of these fish to discriminate complex facial patterns tracked categorical rather than metric differences in the stimuli. We first trained the fish to discriminate sets of two facial patterns. Next, we morphed between these patterns and determined the just noticeable difference (JND) between a morph and original image. Finally, we tested for CP by analyzing the discrimination ability of the fish for pairs of JND stimuli along the spectrum of morphs between two original images. Discrimination performance was significant for the image pair straddling the boundary between categories, and chance for equivalent stimulus pairs on either side, thus producing the classic "category boundary" effect. Our results reveal how perception can be influenced in a top‐down manner even in the absence of a visual cortex. [ABSTRACT FROM AUTHOR]

Stimulus-fading (SF) involves the presentation of increasingly difficult sets of discriminations arrayed along some continuum, where progress from one to the next depends on mastering the current discrimination. Response accuracy is correlated with two reinforcement contingencies: (1) the trial-based presentation of a consequential stimulus (e.g., a short-duration video-clip for a correct response), and (2) the response-contingent change in discriminative stimuli (RPCIDS) produced by correct responding on the trials at a fading level. This experiment isolated the effects of both contingencies by comparing learning in SF and in yoked-control (YC) version of fading wherein video-clip reinforcers were presented independent of response accuracy, but response accuracy determined advancement across fading levels. Discriminations at all fading levels were acquired by 90% and 10% of participants in the SF and YC conditions, respectively. Although many of the YC participants did not learn all of the discriminations, they did learn some of them, which reflected the reinforcing effects of response-contingent-change in discriminative stimuli. Because this contingency occurs in all fading protocols, it could influence learning in all of them. At some fading levels in the YC condition, response accuracy was unexpectedly correlated with video-clip reinforcement: a finding that did not compromise the effect of response produced change in discriminative stimuli on discrimination learning in the YC condition. This methodological limitation might be cured by substituting a truly-random-control version of fading for the YC condition. [ABSTRACT FROM AUTHOR]

Background: Fear overgeneralization is a central feature of anxiety disorders and can lead to excessive avoidance. As perceptual discrimination is a key component of fear overgeneralization, a perceptual discrimination training task was created aimed at improving perceptual discrimination and reducing fear overgeneralization.Methods: Participants with high spider fear were randomized into training or placebo conditions. After completing their assigned task, perceptual discrimination was tested. Thereafter, participants completed a behavioral avoidance test, consisting of five stimuli ranging from a paper spider to a live tarantula. Last, participants completed a threat/safety discrimination task using schematic morphs ranging from a flower to a spider, while self-report and skin conductance responses were collected.Results: The training group showed better perceptual discrimination during the test than did the placebo group. Furthermore, as stimuli became increasingly similar to a live spider, participants in the training group exhibited decreased avoidance behavior. Finally, participants in the training group indicated that schematic morphs were less similar to a spider and showed less physiological arousal than did the placebo group.Conclusions: Together, these results attest to the possible clinical relevance of the perceptual discrimination training. [ABSTRACT FROM AUTHOR]

One of Mackintosh's many contributions to the comparative psychology of associative learning was in developing the distinction between the mental processes responsible for learning about features and learning about relations. His research on discrimination learning and generalisation served to highlight differences and commonalities in learning mechanisms across species and paradigms. In one such example, Wills and Mackintosh trained both pigeons and humans to discriminate between two categories of complex patterns comprising overlapping sets of abstract visual features. They demonstrated that pigeons and humans produced similar "peak-shifted" generalisation gradients when the proportion of shared features was systemically varied across a set of transfer stimuli, providing support for an elemental feature-based analysis of discrimination and generalisation. Here, we report a series of experiments inspired by this work, investigating the processes involved in post-discrimination generalisation in human category learning. We investigate how post-discrimination generalisation is affected by variability in the spatial arrangement and probability of occurrence of the visual features and develop an associative learning model that builds on Mackintosh's theoretical approach to elemental associative learning. [ABSTRACT FROM AUTHOR]

Several studies on age-related cognitive decline in dogs involve laboratory dogs and prolonged training. We developed two spatial tasks that required a single 1-h session. We tested 107 medium-large sized dogs: “young” (N=41, aged 2.5-6.5 years) and “old” (N=66, aged 8-14.5 years). Our results indicated that, in a discrimination learning task and in a reversal learning task, young dogs learned significantly faster than the old dogs, indicating that these two tasks could successfully be used to investigate differences in spatial learning between young and old dogs. We also provide two novel findings. First, in the reversal learning, the dogs trained based on the location of stimuli learned faster than the dogs trained based on stimulus characteristics. Most old dogs did not learn the task within our cut-off of 50 trials. Training based on an object’s location is therefore more appropriate for reversal learning tasks. Second, the contrast between the response to the positive and negative stimuli was narrower in old dogs, compared to young dogs, during the reversal learning task, as well as the cognitive bias test. This measure favors comparability between tasks and between studies. Following the cognitive bias test, we could not find any indication of differences in the positive and negative expectations between young and old dogs. Taken together, these findings do not support the hypothesis that old dogs have more negative expectations than young dogs and the use of the cognitive bias test in older dogs requires further investigation. [ABSTRACT FROM AUTHOR]

Delay-of-gratification paradigms, such as the famous "Marshmallow Test," are designed to investigate the complex cognitive concepts of self-control and impulse control in humans and animals. Such tests determine whether a subject will demonstrate impulse control by choosing a large, delayed reward over an immediate, but smaller reward. Documented relationships between impulsive behavior and aggression in humans and animals suggest important implications for farm animal husbandry and welfare, especially in terms of inadequate social behavior, tail biting and maternal behavior. In a preliminary study, we investigated whether the extent of impulse control would differ between quantitatively and qualitatively different aspects of reward in pigs. Twenty female piglets were randomly divided into two groups, with 10 piglets each. After a preference test to determine individual reward preference among six different food items, a discrimination test was conducted to train for successful discrimination between different amounts of reward (one piece vs. four pieces) and different qualitative aspects of reward (highly preferred vs. least preferred food item). Then, an increasing delay (2, 4, 8, 16, 24, 32 s) was introduced for the larger/highly preferred reward. Each piglet could choose to get the smaller/least preferred reward immediately or to wait for the larger/highly preferred reward. Piglets showed clear differences in their preference for food items. Moreover, the "quality group" displayed faster learning in the discrimination test (number of sessions until 90% of the animals completed the discrimination test: "quality group"−3 days vs. "quantity group"−5 days) and reached a higher level of impulse control in the delay-of-gratification test compared to the "quantity group" (maximum delay that was mastered: "quality group"−24 s vs. "quantity group"−8 s). These results demonstrate that impulse control is present in piglets but that the opportunity to get a highly preferred reward is more valued than the opportunity to get more of a given reward. This outcome also underlines the crucial role of motivation in cognitive test paradigms. Further investigations will examine whether impulse control is related to traits that are relevant to animal husbandry and welfare. [ABSTRACT FROM AUTHOR]

The zebrafish is a model organism to study olfactory information processing, but efficient behavioral procedures to analyze olfactory discrimination and memory are lacking. We devised an automated odor discrimination task for adult zebrafish based on olfactory conditioning of feeding behavior. Presentation of a conditioned odor (CS+), but not a neutral odor (CS−) was followed by food delivery at a specific location. Fish developed differential behavioral responses to CS+ and CS− within a few trials. The behavioral response to the CS+ was complex and included components reminiscent of food search such as increased swimming speed and water surface sampling. Appetitive behavior was therefore quantified by a composite score that combined measurements of multiple behavioral parameters. Robust discrimination behavior was observed in different strains, even when odors were chemically similar, and learned preferences could overcome innate odor preferences. These results confirm that zebrafish can rapidly learn to make fine odor discriminations. The procedure is efficient and provides novel opportunities to dissect the neural mechanisms underlying olfactory discrimination and memory. [ABSTRACT FROM AUTHOR]

The pace-of-life syndrome (POLS) suggests that behavioral traits are correlated and integrate within a fast-slow physiological continuum. At the fast extreme, individuals having higher metabolic rates are more active, exploratory, and bold with the opposite suite of traits characterizing those at the slow physiological extreme. A recent framework suggests that behavioral types may also differ consistently in their cognitive style. Accordingly, we propose that cognition could be further incorporated into the POLS framework comprised of behavioral and thermal physiological traits. Under this premise, fast behavioral types having high thermal traits are predicted to acquire a novel task faster but at the cost of accuracy while slow behavioral types with low thermal traits would be more attentive, responding to cues at a slower rate leading to higher accuracy and flexibility. This was tested by measuring physiological and behavioral traits in delicate skinks (Lampropholis delicata) and testing their learning ability. Correlations were detected between cognition and behavior but not thermal physiology. Contrary to our predictions, individual positioning along these axes opposed our predicted directions along the fast-slow continuum. Fast lizards preferring lower body temperatures expressed higher activity, exploration, sociality, and boldness levels, and learned the discrimination learning task at a slower rate but made the most errors. Additionally, modelling results indicated that neither thermal physiology, behavior, or their interaction influenced cognitive performance. Although the small number of animals completing the final stages of the learning assays limits the strength of these findings. Thus, we propose that future research involving a greater sample size and number of trials be conducted so as to enhance our understanding into how the integration of cognitive style, behavior, and physiology may influence individual fitness within natural populations. [ABSTRACT FROM AUTHOR]

The last decade has seen the emergence of new views about the mechanisms underlying specificity (or, conversely, generalization) of visual skill learning. Here, we trained participants at orientation discrimination paradigm at a peripheral position to induce position and orientation specificity and to test its underlying mechanisms. Specifically, we aimed to test whether the within-quadrant spatial gradient of generalization is determined by cortical magnification, which would show that retinotopic plasticity contributes to learning and specificity. Additionally, we aimed to test whether late parts of the learning relate differently to specificity compared to early parts. This is relevant in the context of double training papers, which suggest that rule-based mechanisms of specificity in fast, early learning also would apply to late, slower learning. Our data showed partial but significant position and orientation specificity within quadrants. Interestingly, specificity was greatest for those participants who had continued to show threshold decreases during the last five sessions of training (late, asymptotic learning). Performance gains during early learning were less related to specificity. A trend for skill to spread over larger distances towards periphery than towards central vision suggested contributions to transfer of early visual areas showing cortical magnification of central vision. Control experiments however did not support this hypothesis. In summary, our study demonstrates significant specificity after extensive perceptual learning, and indicates that asymptotic learning recruits specific mechanisms that promote specificity, and that may not be recruited yet in early parts of the learning. The contributions of different mechanisms to early and late learning suggests that following these different learning periods, generalization relies on different principles and is subjected to different limits. [ABSTRACT FROM AUTHOR]

Abstract: Batesian mimicry evolution involves an initial major mutation that produces a rough resemblance to the model, followed by smaller improving changes. To examine the learning psychology of this process, we applied established ideas about mimicry in Papilio polyxenes asterius of the model Battus philenor. We performed experiments with wild birds as predators and butterfly wings as semiartificial prey. Wings of hybrids of P. p. asterius and Papilio machaon were used to approximate the first mutant, with melanism as the hypothesized first mimetic trait. Based on previous results about learning psychology and imperfect mimicry, we predicted that: melanism should have high salience (i.e., being noticeable and prominent), meaning that predators readily discriminate a melanistic mutant from appearances similar to P. machaon; the difference between the first mutant and the model should have intermediate salience to allow further improvement of mimicry; and the final difference in appearance between P. p. asterius and B. philenor should have very low salience, causing improvement to level off. Our results supported both the traditional hypothesis and all our predictions about relative salience. We conclude that there is good agreement between long‐held ideas about how Batesian mimicry evolves and recent insights from learning psychology about the role of salience in mimicry evolution. [ABSTRACT FROM AUTHOR]

In three experiments, we investigated the contextual control of attention in human discrimination learning. In each experiment, participants initially received discrimination training in which the cues from Dimension A were relevant in Context 1 but irrelevant in Context 2, whereas the cues from Dimension B were irrelevant in Context 1 but relevant in Context 2. In Experiment 1, the same cues from each dimension were used in Contexts 1 and 2, whereas in Experiments 2 and 3, the cues from each dimension were changed across contexts. In each experiment, participants were subsequently shifted to a transfer discrimination involving novel cues from either dimension, to assess the contextual control of attention. In Experiment 1, measures of eye gaze during the transfer discrimination revealed that Dimension A received more attention than Dimension B in Context 1, whereas the reverse occurred in Context 2. Corresponding results indicating the contextual control of attention were found in Experiments 2 and 3, in which we used the speed of learning (associability) as an indirect marker of learned attentional changes. Implications of our results for current theories of learning and attention are discussed. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel fine-grained dictionary learning method for image classification. To learn a high-quality discriminative dictionary, three types of multispecific subdictionaries, i.e., class-specific dictionaries (CSDs), universal dictionary (UD), and family-specific dictionaries (FSDs), are simultaneously uncovered. Here, CSDs and UD, respectively, model the patterns for each class and the patterns irrespective of any class. FSDs can help reveal the shared patterns between multiple image classes, by filling the gap between the patterns in CSDs and UD. The dependence among image classes is revealed by the shared FSDs, and a common FSD can be assigned to several classes to represent their residual. Finally, the most discriminative FSD for each class is identified by minimizing the sparse reconstruction error. Extensive experiments are conducted on different widely used data sets for image classification. The results demonstrate the superior performance of the proposed method over some state-of-the-art methods. [ABSTRACT FROM AUTHOR]

Alterations in the social and cognitive domain are considered important indicators for increased disability in many stress-related disorders. Similar impairments have been observed in rodents chronically exposed to stress, mimicking potential endophenotypes of stress-related psychopathologies such as major depression disorder (MDD), anxiety, conduct disorder, and posttraumatic stress disorder (PTSD). Data from numerous studies suggest that deficient plasticity mechanisms in hippocampus (HC) and prefrontal cortex (PFC) might underlie these social and cognitive deficits. Specifically, stress-induced deficiencies in neural plasticity have been associated with a hypodopaminergic state and reduced neural plasticity persistence. Here we assessed the effects of unpredictable chronic mild stress (UCMS) on exploratory, social and cognitive behavior of females of two inbred mouse strains (C57BL/6J and DBA/2J) that differ in their dopaminergic profile. Exposure to chronic stress resulted in impaired circadian rhythmicity, sociability and social cognition in both inbred strains, but differentially affected activity patterns and contextual discrimination performance. These stress-induced behavioral impairments were accompanied by reduced expression levels of brain derived neurotrophic factor (BDNF) in the prefrontal cortex. The strain-specific cognitive impairment was coexistent with enhanced plasma corticosterone levels and reduced expression of genes related to dopamine signaling in hippocampus. These results underline the importance of assessing different strains with multiple test batteries to elucidate the neural and genetic basis of social and cognitive impairments related to chronic stress. [ABSTRACT FROM AUTHOR]

The ability to identify stimuli that signal important events is fundamental for an organism to adapt to its environment. In the present paper, we investigated how more than one stimulus could be used jointly to learn a temporal discrimination task. Ten pigeons were exposed to a symbolic matching-to-sample procedure with three durations as samples (2, 6, and 18 s of keylight) and two colors as comparisons (red and green hues). A 30-s intertrial interval (ITI), illuminated with a houselight, separated the trials. Both the houselight and the sample keylight could control responding, so two tests were run to assess how these stimuli influenced choice. In the no-sample test, the keylight was not presented; in the dark-ITI test, the houselight was not illuminated. Results suggest that both houselight and keylight controlled choice, and with the exception of one animal, the more a pigeon relied on one of these stimuli, the less it appeared to rely on the other. [ABSTRACT FROM AUTHOR]

Iridescence--change of colour with changes in the angle of view or of illumination--is widespread in the living world, but its functions remain poorly understood. The presence of iridescence has been suggested in flowers where diffraction gratings generate iridescent colours. Such colours have been suggested to serve plant-pollinator communication. Here we tested whether a higher iridescence relative to corolla pigmentation would facilitate discrimination, learning and retention of iridescent visual targets. We conditioned bumblebees (Bombus terrestris) to discriminate iridescent from non-iridescent artificial flowers and we varied iridescence detectability by varying target iridescent relative to pigment optical effect. We show that bees rewarded on targets with higher iridescent relative to pigment effect required fewer choices to complete learning, showed faster generalization to novel targets exhibiting the same iridescence-to-pigment level and had better long-term memory retention. Along with optical measurements, behavioural results thus demonstrate that bees can learn iridescence-related cues as bona fide signals for flower reward. They also suggest that floral advertising may be shaped by competition between iridescence and corolla pigmentation, a fact that has important evolutionary implications for pollinators. Optical measurements narrow down the type of cues that bees may have used for learning. Beyond pollinator-plant communication, our experiments help understanding how receivers influence the evolution of iridescence signals generated by gratings. [ABSTRACT FROM AUTHOR]

Anxiety disorders are the most common mental disorder worldwide. Although anxiety disorders differ in the nature of feared objects or situations, they share a common mechanism by which fear generalizes to related but innocuous objects, eliciting avoidance of objects and situations that pose no objective risk. This overgeneralization appears to be a crucial mechanism in the persistence of anxiety psychopathology. In this study we test whether an intervention that promotes discrimination learning reduces generalization of fear, in particular, harm expectancy and avoidance compared to an irrelevant (control) training. Healthy participants (N = 80) were randomly allocated to a training condition. Using a fear conditioning paradigm, participants first learned visual danger and safety signals (set 1). Baseline level of stimulus generalization was tested with ambiguous stimuli on a spectrum between the danger and safety signals. There were no differences between the training groups. Participants then received the stimulus discrimination training or a control training. After training, participants learned a new set of danger and safety signals (set 2), and the level of harm expectancy generalization and behavioural avoidance of ambiguous stimuli was tested. Although the training groups did not differ in fear generalization on a cognitive level (harm expectancy), the results showed a different pattern of avoidance of ambiguous stimuli, with the discrimination training group showing less avoidance of stimuli that resembled the safety signals. These results support the potential of interventions that promote discrimination learning in the treatment of anxiety disorders. [ABSTRACT FROM AUTHOR]

Medical diagnoses are often made on the basis of the presence of multiple symptoms. However, little is known about how the presence of multiple simultaneous symptoms may influence a bias in determining which symptoms are identified, in part due to a lack of an experimental analogue of this process. The current article presents a laboratory analogue of this process and explores whether over-selectivity influences the ability to identify symptoms indicative of particular illnesses. In two experiments, participants completed a diagnosis task that required them to rate the degree to which symptoms predicted illnesses, with predictor symptoms being presented either singly or in compound. In both experiments, over-selectivity was observed; one symptom of the compound received lower ratings, compared to the other element of the compound and the single predictor, while the other component received comparable ratings with the element. These findings are discussed in relation to associative accounts of over-selectivity and as a procedure to study biases in medical decision making.Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Individuals learn to classify percepts effectively when the task is initially easy and then gradually increases in difficulty. Some suggest that this is because easy-to-discriminate events help learners focus attention on discrimination-relevant dimensions. Here, we tested whether such attentional-spotlighting accounts are sufficient to explain easy-to-hard effects in auditory perceptual learning. In two experiments, participants were trained to discriminate periodic, frequency-modulated (FM) tones in two separate frequency ranges (300–600 Hz or 3000–6000 Hz). In one frequency range, sounds gradually increased in similarity as training progressed. In the other, stimulus similarity was constant throughout training. After training, participants showed better performance in their progressively trained frequency range, even though the discrimination-relevant dimension across ranges was the same. Learning theories that posit experience-dependent changes in stimulus representations and/or the strengthening of associations with differential responses, predict the observed specificity of easy-to-hard effects, whereas attentional-spotlighting theories do not. Calibrating the difficulty and temporal sequencing of training experiences to support more incremental representation-based learning can enhance the effectiveness of practice beyond any benefits gained from explicitly highlighting relevant dimensions. [ABSTRACT FROM AUTHOR]

A fundamental property of visual cortex is to enhance the representation of those stimuli that are relevant for behavior, but it remains poorly understood how such enhanced representations arise during learning. Using classical conditioning in adult mice of either sex, we show that orientation discrimination is learned in a sequence of distinct behavioral stages, in which animals first rely on stimulus appearance before exploiting its orientation to guide behavior. After confirming that orientation discrimination under classical conditioning requires primary visual cortex (V1), we measured, during learning, response properties ofV1neurons. Learning improved neural discriminability, sharpened orientation tuning, and led to higher contrast sensitivity. Remarkably, these learning-related improvements in the V1 representation were fully expressed before successful orientation discrimination was evident in the animals; behavior. We propose that V1 plays a key role early in discrimination learning to enhance behaviorally relevant sensory information. [ABSTRACT FROM AUTHOR]

Participants in two human goal-tracking experiments were simultaneously trained with negative patterning (NP) and positive patterning (PP) discriminations (A+, B+, AB–, C–, D–, CD+). Both elemental and configural models of associative learning predict a PP advantage, such that NP is solved less readily than PP. However, elemental models like the unique cue approach additionally predict responding in AB– trials to be initially stronger than that in A+ and B+ trials due to summation of associative strength. Both experiments revealed a PP advantage and a strong summation effect in AB– trials in the first half of the experiments, irrespective of whether the same US was used for both discriminations (Experiment 1) or two different USs (Experiment 2). We discuss that the correct predictions of the unique cue approach are based on its assumptions of non-normalized and context-independent stimulus processing rather than elemental processing per se. [ABSTRACT FROM PUBLISHER]

Biases in judgement of ambiguous stimuli, as measured in a judgement bias task, have been proposed as a measure of the valence of affective states in animals. We recently suggested a list of criteria for behavioural tests of emotion, one of them stating that responses on the task used to assess emotionality should not be confounded by, among others, differences in learning capacity, i.e. must not simply reflect the cognitive capacity of an animal. We performed three independent studies in which pigs acquired a spatial holeboard task, a free choice maze which simultaneously assesses working memory and reference memory. Next, pigs learned a conditional discrimination between auditory stimuli predicting a large or small reward, a prerequisite for assessment of judgement bias. Once pigs had acquired the conditional discrimination task, optimistic responses to previously unheard ambiguous stimuli were measured in the judgement bias task as choices indicating expectation of the large reward. We found that optimism in the judgement bias task was independent of all three measures of learning and memory indicating that the performance is not dependent on the pig's cognitive abilities. These results support the use of biases in judgement as proxy indicators of emotional valence in animals. [ABSTRACT FROM AUTHOR]

Discrimination learning can cause improved and worsened ability to perceive differences. This subsequently affects how stimuli are associated with meanings and behaviors. Here, human listeners were trained with frequency-modulated (FM) tonal sweeps (500-1000 Hz) in a paradigm where one FM rate (8.29 octaves per second) required a 'Target' response, while a rate either slower (5.76 octaves per second) or faster (11.94 octaves per second) required a 'Non-Target' response. Training led to a shift in 'Target' responding along the FM rate dimension away from the 'Target' in a direction opposite the trained 'Non-Target'. This peak shift was paralleled by an asymmetry in acuity along the FM rate dimension in an untrained ABX task (a.k.a. match-to-sample). Performance improved relative to pre-training on trials where the 'Target' was contrasted with stimuli nearer the trained 'Non-Target'. Performance worsened on trials containing stimuli displaced along the FM dimension further from the trained 'Non-Target'. A connectionist model of perceptual learning containing non-associative representational modification and associative-based task-specific reweighting was able to simulate behavior. Simulations generated novel testable predictions regarding peak shift and worsening as a result of discrimination learning. Data have theoretical and practical consequences for predicting trends in the generalization of learned behaviors and modifiable perceptual acuities. [ABSTRACT FROM AUTHOR]

A recent study found that guppies ( Poecilia reticulata) can be trained to discriminate 4 versus 5 objects, a numerical discrimination typically achieved only by some mammals and birds. In that study, guppies were required to discriminate between two patches of small objects on the bottom of the tank that they could remove to find a food reward. It is not clear whether this species possesses exceptional numerical accuracy compared with the other ectothermic vertebrates or whether its remarkable performance was due to a specific predisposition to discriminate between differences in the quality of patches while foraging. To disentangle these possibilities, we trained guppies to the same numerical discriminations with a more conventional two-choice discrimination task. Stimuli were sets of dots presented on a computer screen, and the subjects received a food reward upon approaching the set with the larger numerosity. Though the cognitive problem was identical in the two experiments, the change in the experimental setting led to a much poorer performance as most fish failed even the 2 versus 3 discrimination. In four additional experiments, we varied the duration of the decision time, the type of stimuli, the length of training, and whether correction was allowed in order to identify the factors responsible for the difference. None of these parameters succeeded in increasing the performance to the level of the previous study, although the group trained with three-dimensional stimuli learned the easiest numerical task. We suggest that the different results with the two experimental settings might be due to constraints on learning and that guppies might be prepared to accurately estimate patch quality during foraging but not to learn an abstract stimulus-reward association. [ABSTRACT FROM AUTHOR]

Because depth information has shown its effectiveness in scene classification, RGB-D sensor-based scene classification has received wide attention. However, when images are polluted by noise in the transmission process, the recognition rate will decline significantly. Furthermore, after adopting feature representation schemes, the dimensionality of concatenated features that are extracted from the RGB image and depth image pair is very high. Therefore, a new dimensional reduction algorithm called Cauchy estimator discriminant learning (CEDL) is presented in this paper. CEDL simultaneously addresses two goals: (1) to decrease negative influences to some extent when there is noise in the input samples; (2) to preserve the local and global geometry structure of the input samples. Experiments with the frequently used NYU Depth V1 dataset suggest the effectiveness of CEDL compared with other state-of-the-art scene classification methods. [ABSTRACT FROM AUTHOR]

Establishment in urbanized environments is associated with changes in physiology, behaviour, and problem-solving. We compared the speed of learning in urban and rural female common mynas, Acridotheres tristis, using a standard visual discrimination task followed by a reversal learning phase. We also examined how quickly each bird progressed through different stages of learning, including sampling and acquisition within both initial and reversal learning, and persistence following reversal. Based on their reliance on very different food resources, we expected urban mynas to learn and reversal learn more quickly but to sample new contingencies for proportionately longer before learning them. When quantified from first presentation to criterion achievement, urban mynas took more 20-trial blocks to learn the initial discrimination, as well as the reversed contingency, than rural mynas. More detailed analyses at the level of stage revealed that this was because urban mynas explored the novel cue-outcome contingencies for longer, and despite transitioning faster through subsequent acquisition, remained overall slower than rural females. Our findings draw attention to fine adjustments in learning strategies in response to urbanization and caution against interpreting the speed to learn a task as a reflection of cognitive ability. [ABSTRACT FROM AUTHOR]

Over the past 10 years, Cognitive Linguistics has taken a quantitative turn. Yet, concerns have been raised that this preoccupation with quantification and modelling may not bring us any closer to understanding how language works. We show that this objection is unfounded, especially if we rely on modelling techniques based on biologically and psychologically plausible learning algorithms. These make it possible to take a quantitative approach, while generating and testing specific hypotheses that will advance our understanding of how knowledge of language emerges from exposure to usage. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to focus on developing and validating a multidimensional measure of work-related age-based stereotypes (WAS) scale. Design/methodology/approach – Based upon a review of the literature, a three-dimensional stereotype content model including both negative (incompetence, inadaptability) and positive (warmth) stereotypes of older workers was created. Construct, convergent, discriminant, and criterion-related validity for the WAS scale were examined across three independent samples constituting both lab-based experimental studies and a field-based survey (total n=1,245). Findings – Across all samples, the WAS evidenced good construct, convergent, discriminant, and criterion-related validity. Originality/value – As evidenced by a review of the literature, the WAS is unique in that it measures both negative and positive stereotypes of older workers. Implications for research are discussed. [ABSTRACT FROM AUTHOR]

In many species, males and females have different reproductive roles and/or differ in their ecological niche. Since in these cases the two sexes often face different cognitive challenges, selection may promote some degree of cognitive differentiation, an issue that has received relatively little attention so far. We investigated the existence of sex differences in visual discrimination learning in the guppy, Poecilia reticulata, a fish species in which females show complex mate choice based on male colour pattern. We tested males and females for their ability to learn a discrimination between two different shapes (experiment 1) and between two identical figures with a different orientation (experiment 2). In experiment 3, guppies were required to select an object of the odd colour in a group of five objects. Colours changed daily, and therefore, the solution for this task was facilitated by concept learning. We found males' and females' accuracy practically overlapped in the three experiments, suggesting that the two sexes have similar discrimination learning abilities. Yet, males showed faster decision time than females without any evident speed-accuracy trade-off. This result indicates the existence of consistent between-sex differences in decision speed perhaps due to impulsivity rather than speed in information processing. Our results align with previous literature, indicating that sex differences in cognitive abilities are the exception rather than the rule, while sex differences in cognitive style, i.e. the way in which an individual faces a cognitive task, are much more common. [ABSTRACT FROM AUTHOR]

Judgment bias tasks (JBTs) are considered as a family of promising tools in the assessment of emotional states of animals. JBTs provide a cognitive measure of optimism and/or pessimism by recording behavioral responses to ambiguous stimuli. For instance, a negative emotional state is expected to produce a negative or pessimistic judgment of an ambiguous stimulus, whereas a positive emotional state produces a positive or optimistic judgment of the same ambiguous stimulus. Measuring an animal's emotional state or mood is relevant in both animal welfare research and biomedical research. This is reflected in the increasing use of JBTs in both research areas. We discuss the different implementations of JBTs with animals, with a focus on their potential as an accurate measure of emotional state. JBTs have been successfully applied to a very broad range of species, using many different types of testing equipment and experimental protocols. However, further validation of this test is deemed necessary. For example, the often extensive training period required for successful judgment bias testing remains a possible factor confounding results. Also, the issue of ambiguous stimuli losing their ambiguity with repeated testing requires additional attention. Possible improvements are suggested to further develop the JBTs in both animal welfare and biomedical research. [ABSTRACT FROM AUTHOR]

Background Children with autism spectrum disorder have impairments in social behaviours that require systematic intervention. The purpose of this study was to evaluate the cool versus not cool procedure implemented in a small group (dyad). Method The cool versus not cool procedure consisted of the researcher demonstrating the targeted behaviour both correctly and incorrectly and having the participants discriminate the demonstration. If the participants were unable to reach mastery, additional components were added. The researchers utilised a multiple-probe design to evaluate the cool versus not cool procedure. Results Results indicated that participants were able to reach mastery criterion on some of the social skills with the demonstration alone whereas some skills required either role-playing or feedback during probes. Conclusions The results showed that the cool versus not cool procedure was somewhat effective in increasing social behaviours; however, some skills required additional components for participants to reach mastery criterion. [ABSTRACT FROM AUTHOR]

We explored tiger salamanders' ( Ambystoma tigrinum) learning to execute a response within a maze as proximal visual cue conditions varied. In Experiment 1, salamanders learned to turn consistently in a T-maze for reinforcement before the maze was rotated. All learned the initial task and executed the trained turn during test, suggesting that they learned to demonstrate the reinforced response during training and continued to perform it during test. In a second experiment utilizing a similar procedure, two visual cues were placed consistently at the maze junction. Salamanders were reinforced for turning towards one cue. Cue placement was reversed during test. All learned the initial task, but executed the trained turn rather than turning towards the visual cue during test, evidencing response learning. In Experiment 3, we investigated whether a compound visual cue could control salamanders' behaviour when it was the only cue predictive of reinforcement in a cross-maze by varying start position and cue placement. All learned to turn in the direction indicated by the compound visual cue, indicating that visual cues can come to control their behaviour. Following training, testing revealed that salamanders attended to stimuli foreground over background features. Overall, these results suggest that salamanders learn to execute responses over learning to use visual cues but can use visual cues if required. Our success with this paradigm offers the potential in future studies to explore salamanders' cognition further, as well as to shed light on how features of the tiger salamanders' life history (e.g. hibernation and metamorphosis) impact cognition. [ABSTRACT FROM AUTHOR]

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Visual perceptual learning (VPL) can improve spatial vision in normally sighted and visually impaired individuals. Although previous studies of humans and large animals have explored the neural basis of VPL, elucidation of the underlying cellular and molecular mechanisms remains a challenge. Owing to the advantages of molecular genetic and optogenetic manipulations, the mouse is a promising model for providing a mechanistic understanding of VPL. Here, we thoroughly evaluated the effects and properties of VPL on spatial vision in C57BL/6J mice using a two-alternative, forcedchoice visual water task. Briefly, the mice underwent prolonged training at near the individual threshold of contrast or spatial frequency (SF) for pattern discrimination or visual detection for 35 consecutive days. Following training, the contrast-threshold trained mice showed an 87% improvement in contrast sensitivity (CS) and a 55% gain in visual acuity (VA). Similarly, the SF-threshold trained mice exhibited comparable and long-lasting improvements in VA and significant gains in CS over a wide range of SFs. Furthermore, learning largely transferred across eyes and stimulus orientations. Interestingly, learning could transfer from a pattern discrimination task to a visual detection task, but not vice versa. We validated that this VPL fully restored VA in adult amblyopic mice and old mice. Taken together, these data indicate that mice, as a species, exhibit reliable VPL. Intrinsic signal optical imaging revealed that mice with perceptual training had higher cut-off SFs in primary visual cortex (V1) than those without perceptual training. Moreover, perceptual training induced an increase in the dendritic spine density in layer 2/3 pyramidal neurons of V1. These results indicated functional and structural alterations in V1 during VPL. Overall, our VPL mouse model will provide a platform for investigating the neurobiological basis of VPL. [ABSTRACT FROM AUTHOR]