Memorizing the relations between items and learning relational rules are two ways in which sets of items can be ranked. We investigated the interaction of these types of learning in a series of five experiments with six adult male rhesus monkeys. We presented monkeys with three types of image sets. Scene sets were random images of natural scenes or cityscapes with no perceptually evident pattern by which to rank them. Relations among these images had to be learned through trial and error. Patterned sets were shapes that varied systematically along a physical dimension such as size such that a single rule for ranking them could be applied across images. Disordered sets were the same as Patterned sets, but monkeys were trained to rank them in an arbitrary order that was not consistent with differences along a physical dimension. Monkeys learned Scene sets more quickly than Patterned sets and Disordered sets, suggesting that monkeys memorize the relations between images relatively easily. In follow-up experiments, we found that monkeys also learned rules for the Patterned sets, indicated by the fact that they generalized performance to novel images and reversed ranks across the whole set after training with a single reversed pair. In Experiments 4 and 5, we investigated the interaction of memorization and relational rule learning with compound image sets that included both systematic physical variation and arbitrary visual content. We found further evidence that monkeys ordered images by both memorization and rules. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Humans are capable of recognizing the temporal organization of a rhythm by perceiving its metrical structure even when it is evoked only by temporal alterations. There is also plenty of data suggesting that several animal species can track different rhythmic cues. However, there is no clear evidence that nonhuman animals can extract metrical information from an auditory rhythm. To explore this issue, we familiarized rats () to auditory rhythmic sequences. We then tested them with novel sequences that presented temporal variations at the metrical, grouping, or tone duration level. We observed that the animals responded differently to the familiar versus the novel sequences, suggesting that temporal alterations are sufficient for the animals to discriminate between auditory rhythmic sequences. Likewise, the use of temporal accents could be relevant to provide metrical information, although it is still an open issue the extent to which the animals are able to induce meter from rhythmic sequences. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

In recent decades, there has been a growing interest in exploring the cognition of domestic dogs. However, the role of olfaction and vision in dogs' perception of everyday situations has been underexplored. To investigate this topic, we used a simple food-searching paradigm. A treat was hidden in one of three locations, either (a) visible from the starting point (vision condition), (b) invisible from the starting point (smell condition), or (c) invisible with an additional decoy treat presented as a distraction (fake condition). About 87 dogs of various breeds were categorized into either the olfactory-focused or the vision-focused group based on their sniffing behavior in a pretest. It was hypothesized that olfactory-focused dogs would preferentially use their sense of smell for task solving, whereas vision-focused dogs would rely more on visual information. Thus, it was expected that dogs of each group would have an advantage in the corresponding condition. However, there was no difference between groups in the duration to find the food in the three conditions. In general, food was approached faster in the vision condition, and dogs in all groups were distracted by the presence of the fake food. Thus, for all dogs, the visual sense was more dominant than the olfactory sense, and they could easily switch between using the two senses. The results are discussed in light of breed differences and general perception skills of domestic dogs. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Uncovering the cognitive bases of egg rejection behavior in avian hosts of brood parasites carries significant comparative implications not only for our understanding of host-parasite coevolution but also for cross-species research aimed at assessing decision-making. In this study, we focused on the American robin (), a species that lays large, elongated, and immaculate blue eggs and is well studied for its robust rejection of smaller, rounder, white, and maculated eggs laid by the brood parasitic brown-headed cowbird (). Employing a randomized multiple simultaneous parasitism paradigm, we experimentally investigated how model egg color, dimensions, and maculation influenced the rejection rates of eight distinct egg types across 28 different pairings of two eggs at a time. First, we assessed whether egg rejection decisions depended on model egg features. Then, for a subset of trials (36%) where one egg was accepted and the other was rejected, we utilized a conjoint design analysis, a methodology borrowed from economics and marketing. Using the conjoint analysis, we showed that white model eggs were 50% more likely to be rejected relative to blue eggs, small-round eggs were 39% more likely to be rejected compared to large-elongated model eggs, and maculated eggs were 19% more likely to be rejected compared to immaculate eggs. These findings reaffirmed the roles of egg color, dimension, and maculation as key visual cues influencing egg rejection behavior in American robins. These findings also offer methodological advancements to study egg rejection behavior and lend themselves to future comparisons of human and nonhuman decision-making processes. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Apes require high volumes of energy-rich foods that tend to be patchily distributed, creating evolutionary pressures for flexible and complex cognition. Several species hunt mobile prey, placing demands on working memory and selecting for sociocognitive abilities such as predicting prey behavior. The mechanisms by which apes overcome foraging and hunting challenges are difficult to elucidate. Field investigations provide rich data sets but lack experimental control, limiting the gamut of questions they can answer, while experiments with captive subjects offer lower generalizability to real-world situations. Virtual environments (VEs) present a compromise, combining experimental specificity with proxies of realistic situations. In this study, chimpanzees and bonobos moved through a three-dimensional VE using a touchscreen. All subjects learned to chase and catch moving rabbits, some exhibiting high success rates even in the presence of large obstacles. Success in trials with a first-person (FP) viewpoint was much higher than in trials presented from overhead, suggesting that the immersive nature of FP trials helped subjects to understand their location in the environment better than when they took a top-down view. Data were analyzed using generative computational agent models, identifying that subjects occasionally employed anticipatory hunting strategies, but more often used a direct chasing strategy. This study validates the use of VEs as an experimental paradigm, demonstrating that apes can understand the behavior of moving agents in situations of varying complexity and that computational modeling can be utilized to delve into behavioral data at a fine-grained level and identify which of several cognitive strategies they fit best. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Recent research has shown that personality similarity between pair-bonded individuals can lead to better compatibility and well-being in humans. In our study, we explored the personality of 27 pairs of captive coppery titi monkeys (), using a Hominoid Personality Questionnaire of 54 personality items. We also examined the effect of pair duration, pair affiliation, and the presence of offspring on the personality of these pairs. We built a model with five components to describe titi monkey personality structure in our colony and labeled these components as aggressive, cool, cautious, innovative, and helpful. Helpful, which we relate to "agreeableness," was significantly higher in males than in females. Aggressive and helpful were correlated within couples. Helpful was also negatively related to the time spent since pairing. Innovative was higher for pairs with higher affiliation. Additionally, we compared personality similarity between a group of pairs that were created based on initial compatibility (determined via a "speed-dating" experiment), and a group of tenure-matched pairs that were determined quasirandomly. Pairs determined from speed dating were more helpful than pairs from the colony comparison group, which suggests that high levels of initial attraction may facilitate an increase in prosocial personality traits. Our findings, including the negative correlation of "helpful" with time since pairing and the heightened "innovative" trait in pairs with stronger affiliation, may suggest subtle dynamics within titi monkey personalities. These insights contribute to a broader understanding of nonhuman primate personalities. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

To investigate same-different conceptualization in nonhuman animals, researchers have used the multiple-item array task (MIAT), which requires discriminating whether icons in an array are the same or different from one another. Although entropy-based explanations for MIAT performance have been influential, their validity is debatable. In Experiment 1, budgerigars and pigeons were trained to discriminate whether 16 icons were the same or different from one another. When the number of icons was reduced, the discrimination tendency of both species was correlated with the entropy value, replicating previous findings. Experiment 2 further supported this correlation by controlling for the number of icons and icon patterns. However, Experiment 3 revealed that when entropy was constant, the subjects judged different more frequently for arrays with more icons per pattern, which contradicts entropy-based predictions. Notably, the response patterns of the subjects in Experiment 3 were inconsistent with logical same-different judgments, suggesting that these animals perform the MIAT based on criteria distinct from those of same-different conceptualization. These findings challenge the validity of typical MIAT for examining same-different concepts in animals and indicate the need to develop more reliable alternative methods. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Photophobia, aversion for brightly lit environments, is commonly observed in laboratory nocturnal rodents such as mice and rats, as indicated, for example, by the light-dark box test. The universality of photophobia in laboratory nocturnal rodents rises questions on its corresponding behavior in nature and on what adaptive value may have led to the selection of this behavior during biological evolution. Nocturnality alone is insufficient to explain photophobic behavior, as nocturnal rodents show reduced roaming in the day just because they are sleeping and not because they are choosing to avoid a possibly aversive daylight. On the other hand, a natural behavior more directly related to the photophobia observed in the laboratory is selenophobia (moonlight avoidance), which in free-ranging rodents can be operatively defined as the reduction of exploratory and foraging activities in moonlit nights compared with dark nights. In the case of selenophobia, factors related to nocturnality are ruled out, and light-related factors can be easily isolated. Selenophobia has been found in a wide variety of nocturnal rodents, for which it may represent an antipredatory adaptation. A technology-aided study of selenophobia may strongly contribute to a better understanding of its nature, of the relative contributions of instinct and learning to this behavior, and of its neural underpinnings. In particular, new behavioral and neurophysiological technologies, for example, miniaturized radiocollars, freely accessible testing chambers equipped with infrared video cameras, animal-borne miniaturized video cameras, and noninvasive electrophysiological recordings, may be of particular usefulness to shed light on selenophobia. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Sharing food with immature individuals is costly and should therefore only occur when the benefits outweigh the costs. Accordingly, sharing typically decreases when immature individuals get older and become more proficient independent foragers. Providers would gain more if they could adjust food sharing not only to immature age but also to their skill level. Such sensitivity to others' skill deficits is expected to be rare, but may be found in species with high prosociality and other-regarding preferences, such as cooperative breeders. Here, we compared the food-sharing patterns of cooperatively breeding common marmosets () and closely related but independently breeding squirrel monkeys () under two conditions. In the baseline condition, food was easily accessible whereas in the experimental condition, individuals had to solve a puzzle to access the food. We found that the cooperatively breeding marmosets, but not the independently breeding squirrel monkeys, shared more when immatures lacked the skill to obtain the food from the apparatuses. Skill sensitivity might be associated with the presence of other-regarding preferences and a strong proclivity to proactively share food during baseline conditions. This proclivity has evolved in marmosets, but not squirrel monkeys, in the context of cooperative breeding and may facilitate the emergence of skill recognition, information donation, and teaching. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Drugs, bomb materials, fruits, and even medical conditions such as cancer are all stimuli that a dog's nose can be trained to detect, and the dog then can report reliable information about those stimuli in terms of presence or absence. This essay discusses the tremendous effort that goes into training expert detection dogs, highlighting different ways of instantiate training. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Music is a ubiquitous feature of human behavior. Yet the origins of human musicality remain poorly understood. One attractive approach has investigated the distribution and components of musicality among nonhuman animals. Here I tested four highly trained pigeons in three experiments for their capacity to discriminate the intervals of the chromatic scale. Using an auditory go/no-go same/different task, the pigeons discriminated intervals spanning different numbers of semitones on each trial as synthesized with two musical instruments (cello and organ). Experiment 1 examined this discrimination using a successive melodic context, while Experiment 2 used a simultaneous harmonic context. Experiment 3 tested pure tones in both contexts. The pigeons were sensitive to the distance among the pitch intervals, but examination of specific diagnostic intervals revealed little evidence for any contribution of human-like musical consonance (perfect fifth and octave) and dissonance (tritone and major seventh) to the discrimination. Although more accomplished in the auditory modality than widely assumed, the current state of the evidence suggests pigeons, while sensitive to the pitched nature of sound, lack essential capacities needed for music perception. The evolutionary implications for the comparative psychology of music are considered. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Striped skunks are omnivorous generalists with patchily distributed food-two selection pressures that are purported to drive the evolution of cognition. Despite this, the cognitive abilities of skunks have rarely been tested. Using the slat-pulling task, we assessed the ability of three striped skunks to reason about the visual patterns of support when two slats were presented (one supporting a food item). We used both functional slats (real wooden slats that gave subjects both visual and functional information when manipulated) and purely representational slats in an arbitrary version of the task (painted lines that provided only visual information). All three skunks found the arbitrary task difficult to learn but nevertheless learned to solve it after thousands of trials. They appeared to respond to visual patterns of contact and perceptual containment between food and painted lines to solve several configurations of the task. Interestingly, only one of three skunks learned to pull supportive over unsupportive slats (despite the addition of functional information). This subject had first learned the visual pattern associated with reward in the arbitrary version, thus showing the transfer of visual patterns from the arbitrary to the functional task. Overall, striped skunks demonstrated the ability to use visual patterns to solve problems despite their relatively poor vision and difficulty in learning the tasks. These findings provide further support for the idea that slat-pulling tasks can be solved by visual pattern learning alone and that this possibility needs to be controlled for in tasks assessing abstract causal reasoning. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Typical approaches to study self-control present subjects with a simultaneous choice between a larger-later (LL) reinforcer and a smaller-sooner (SS) reinforcer. In contrast, in patch-leaving tasks, subjects choose between staying at a patch for an SS (or LL) reinforcer and leaving for an LL (or SS) reinforcer. Previous studies show that blue jays, monkeys, humans, and rats prefer the SS reinforcer in binary-choice tasks, whereas the same subjects prefer the LL reinforcer in equivalent patch-leaving tasks. The current study systematically replicated this research using pigeons. Six pigeons responded in a binary-choice task and in two patch-leaving tasks in which staying led to an LL (Patch-L) or SS (Patch-S) reinforcer. Across conditions, the SS reinforcer delay varied from 5 to 55 s; the LL reinforcer delay was always 60 s. In binary-choice conditions, subjects preferred the SS reinforcer. In Patch-L and Patch-S conditions, subjects preferred the LL and SS reinforcer, respectively, reflecting a bias to stay at the patch. This bias persisted when the stay response was more effortful and when the delays to both reinforcers were equal. This may reflect a species-specific win-stay bias and the differential consequences of staying (which led to a stimulus signaling food) versus leaving (which led to a stimulus never associated with food). Thus, we propose a conditioned-reinforcement account of intertemporal choice in patch-leaving contexts. We suggest several avenues for further investigations of the mechanisms underlying intertemporal choice in different contexts and question the economic equivalence of the operant and patch-leaving procedures. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Play behavior has been extensively studied across species, but its direct role in social relationships remains unclear. Here we use an "isolation versus separation" protocol to identify behaviors associated with relationship renewal in adolescent female rats. Members of a dyad that had been separated for 24 hr, without isolation from other peers, initially increased investigative behaviors relative to nonseparated peers; however, in contrast with social isolation, separation by itself did not increase rough-and-tumble play. The data suggest that increased play following isolation depends on general motivations, rather than a "peer-specific" drive to renew relationships with an individual. This is consistent with a role of play in more general social learning rather than reestablishing bonds or expectations. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Associative learning models typically reflect statistical relationships between experienced events. Causal models can go beyond this information to specify the ways in which events are related. This meta-representational aspect of causal models allows them to reflect uncertainty about relationships between events: for example, if a light initially leads to sucrose but subsequently the light is experienced without sucrose, this might first support formation of a light-causes-sucrose model and subsequently lead to uncertainty over whether the model remained accurate. Prior studies of Pavlovian conditioning in rats manipulated sucrose-magazine access during extinction to produce uncertainty about reward presence or absence. Rats were sensitive to covering of the site of reward delivery, which was interpreted as evidence for a causal-model account reflecting uncertainty. However, associative accounts-based on the direct impact of the dipper mechanism used to deliver sucrose through secondary reinforcement or contextual renewal of responding-can also explain the results. In two new experiments, manipulation of the dipper mechanism through extinction and test phases resulted in behavior consistent with these associative accounts. However, demonstration of the importance of the sucrose dipper suggests that the reward delivery mechanism should be included in a causal model. Such a revised causal model also provides an account of the impact of manipulating the sucrose dipper. While these experiments do not conclusively decide between associative and causal models as explanations of rodent behavior, they do illustrate the value of incremental experimental study and the importance of methodological detail in addressing questions of comparative cognition. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Detection dogs are required to learn and alert to multiple different odors during training and to generalize this learning to similar odors when working. They should be both sensitive to variation in the target odors and specific enough to avoid false alerts, but how readily they achieve this is likely to depend on the training method employed. The majority of agencies train by presenting single target odors in isolation, and adding additional odors consecutively, although recent research with rats suggests intermixing the target odors concurrently throughout training may be a more effective approach. This study therefore tested the relative efficacy of intermixed training in dogs. Using an odor-detection lineup, pet dogs were trained to detect two target odors, A and B. Those allocated to the "sequential" group were trained to criterion on odor A and then trained on odor B (or vice versa), the "compound" group were trained on a mixture of AB, and the "intermixed" group trained on A and B concurrently. Each dog was then tested on all combinations of the test stimuli (A, B, and AB), as well as combinations containing a novel interferent (AC, BC, and ABC). Results revealed that dogs trained by the intermixed method made significantly more correct (true positive) indications, and significantly fewer miss (false negative) indications than the other two methods, suggesting that intermixed training is more effective than currently used alternative training methods. Thus, for improved performance and generalization, we recommend detection dog training should use an intermixed method of training. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Like many other species, dogs have a natural quantity judgment system to assist with decision making to maximize resources. Additionally, dogs are highly sensitive to, and influenced by, human-delivered ostensive (i.e., social) cues. Here, we assessed the influence of one such cue-a high, rising, positive "Oooh!" sound-on dogs' choice of differing quantities of pieces of food presented on two different plates. Subjects ( = 29) received 16 randomized trials of four conditions: 1 versus 1 paired with experimenter "Oooh!" while looking at the one plate, 1 versus 3, 3 versus 1 paired with experimenter "Oooh!," and 1 versus 1. As predicted, dogs chose the larger quantity more often in 1 versus 3 conditions. Contrary to one of our predictions, subjects chose the 1 versus 1+ "Oooh!" at chance levels. However, in support of another prediction, pairing the smaller reward with a positive intonation in 3 versus 1+ "Oooh!" significantly reduced dogs' choice of the larger reward. That is to say, without the presence of words, eye contact, or facial expressions, dogs followed a misguiding cue and chose a smaller reward that a stranger had deemed more valuable than a larger one. Local enhancement as well as a drive to increase social capital with the human are discussed as possible explanations. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Decreasing responsiveness to repeated visual stimuli (i.e., the inability to sustain attention) in jumping spiders (Salticidae) parallels that found in humans. In humans, drugs affect vigilance, and previous work on salticids has shown that the "vigilance decrement" is unlikely to be sensory habituation and that caffeine ameliorates reductions in attention. We exposed to delta-9 tetrahydrocannabinol (THC) and methamphetamine before presenting them with a repeated visual stimulus. In the THC experiment, spiders were given a THC solution, water, or a vehicle solution, using a within-subjects design. The orienting response (i.e., "interest") of salticids on a track ball to face a fly stimulus presented peripherally on a monitor was scored, as well as "general movement" (e.g., walking, as a control for physical fatigue) and "no movement." The methamphetamine experiment was identical except that salticids were given methamphetamine solution or water. In both the THC and methamphetamine treatments, general movement dropped over time, while in control treatments, this was constant. Additionally, due to an initial stimulating effect of methamphetamine on interest, the response decrement was significantly steeper when spiders were administered methamphetamine compared with water. Our results suggest that the modulation of sustained attention, and possibly motivation, is likely in salticids. basic local alignment search tool genome queries on a closely related species and pharmacological radioligand experiments suggested that salticids do not possess cannabinoid receptors, but the presence of transient receptor potential proteins may help explain the small behavioral changes observed with THC. In contrast, how methamphetamine affects salticids remains unknown. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

In social foraging situations, some group members actively engage in behaviors associated with searching for patch zones (produce), while others join previously discovered patch zones (scrounge). Pavlovian conditioning enables individuals to anticipate a biologically significant event or unconditioned stimulus, such as resource availability, when paired with another event, such as a blue light, also known as a conditioned stimulus (CS). Considering that individuals' prior experiences with habitat features may influence their preference for producer or scrounger responses, this study aims to assess the impact of resource-associated signals on the group produce index. Specifically, the study seeks to (a) outline a setup for goldfish () incorporating renewable patch zones, (b) evaluate the CS's effect on the proportion of producers, and (c) develop an agent-based model capturing the CS's effect on the proportion of producers. Eight goldfish were used, with half undergoing a delayed Pavlovian acquisition protocol. Pavlovian-trained and control fish were assessed under signal and nonsignal conditions. The findings reveal that the producer index in the signal condition was higher for the Pavlovian group than the control group. To simulate conditions to those observed in fish, we developed an agent-based model where Pavlovian agents oriented themselves toward the nearest patch zone when the CS was present. The results mirrored those observed in fish, indicating an advantage derived from preexposure to the CS. This study contributes to the investigation of individual disparities and the impact of learning within the framework of the producer-scrounger game. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Song sessions produced by humpback whales recorded off the coasts of Hawaii and Colombia show recurrent patterns of acoustic variation across consecutive songs. Analyses of intra-individual variations within continuous song sessions revealed that songs consistently cycled through stages of acoustic complexity. At time scales spanning tens of minutes, cyclical variations likely reflected the diving behavior of singers. Changes over shorter time frames suggest that singing humpback whales may also systematically modulate the acoustic complexity of individual sounds during song production, both by gradually morphing units and by varying the number of times they repeat sound patterns. Comparable cycles were evident across years and populations. Cyclical variations within song sessions can reveal how much time and energy singers spend producing tonal versus frequency-modulated/broadband elements. Tonal components are generally more difficult to localize spatially but easier to detect over long distances, suggesting that singing humpback whales may dynamically vary sound production in ways that affect both sound transmission and auditory spatial processing. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Understanding conspecifics' age classes is crucial for animals, facilitating adaptive behavioral responses to their social environment. This may include gathering and integrating information through multiple modalities. Using a cross-modal preferential-looking paradigm, we investigated whether dogs possess a cross-modal mental representation of conspecific age classes. In Experiment 1, dogs were presented with images of an adult dog and a puppy projected side by side on a wall while a vocalization of either an adult dog or a puppy was played back simultaneously. To test the effect of relative body size between adult dog and puppy images, two size conditions (natural size and same size) were employed for visual stimuli. We examined dogs' looking behavior in response to cross-modally matched versus mismatched stimuli. We predicted that if dogs have cross-modal representations of age classes, they would exhibit prolonged attention toward matched images compared to mismatched ones. In Experiment 2, we administered the same paradigm within an eye-tracking experiment to further improve the measurement quality of dogs' looking times. However, dogs' looking times in either experiment did not demonstrate significant differences based on the match or mismatch between image and vocalization. Instead, we observed a size effect, indicating dogs' increased attention toward larger adult dog images compared to smaller puppy images. Consequently, we found no evidence of cross-modal representation of age class in dogs. Nonetheless, we found increased looking time and pupil size upon hearing puppy vocalizations compared to adult vocalizations in Experiment 2, suggesting that dogs exhibited heightened arousal when hearing puppy whining. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Dolphins are known to recognize their environment through echolocation. Previous studies have reported that they can discriminate the shape, size, thickness, and even material of objects through echolocation. However, little is known about the discrimination of quantities other than size and thickness (e.g., the number of objects). It is also unclear whether Weber's law (i.e., ratio dependency) holds for quantity discrimination through echolocation. In this study, we examined relative quantity judgments of visually occluded objects presented underwater by bottlenose dolphins. We found that they could discriminate pairs of same-sized objects ranging from one to eight, with performance improving as the difference ratio between the two numbers increased. In addition, their performance also improved as the magnitude of the number of objects involved increased. An additional test revealed that the accuracy of discrimination through echolocation was comparable to that of visual relative quantity judgments of the objects presented above water. On the other hand, under the condition that the overall size of each object (i.e., the sum of areas) was incongruent with the number of objects, performance was lower than when number and size were covarying. However, even within the incongruent condition, the effect of the number ratio was still observed, suggesting that the dolphins might have used various types of quantity information, such as number and size, flexibly to solve the task. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Serial pattern learning describes behavior in which a subject anticipates not only the time and effort needed for the next reinforcer but also the pattern of time and effort to reinforcers after the first. Chandel et al. (2021) found that pigeons left a progressive (increasing ratio) schedule earlier than would have been optimal. They argued that the pigeons anticipated the harder-to-obtain reinforcers beyond the next one. In the present experiments, pigeons were trained on a progressive schedule for which each reinforcer was successively easier to obtain. However, the initial choice was between a fixed ratio schedule (FR23) for which a reinforcer was easier to obtain than the first reinforcer on the improving progressive schedule (32 pecks). Delayed discounting theory suggests that the pigeons would prefer the FR23 because more immediate reinforcers should be preferred, whereas serial pattern learning suggests that the progressive schedule might be preferred because easier-to-obtain reinforcers would follow the initially harder 32 pecks. In Experiment 1, a preference for the fixed ratio schedule was not found, however, in Experiment 2, when the two alternatives were equated for the number of reinforcers that could be obtained on each trial, a significant preference for the improving progressive schedule was found. The results of Experiment 2 were consistent with the serial pattern learning hypothesis. The pigeons did not choose the more immediate reinforcer associated with fixed ratio alternative. Rather, they showed a preference for the improving progressive schedule for which later reinforcers would be easier to obtain. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The featured article by Sakurai and Tomonaga (2024) in this issue has set out to test to what extent dolphins can estimate relative differences between pairs of object numbers by echolocation. For this they used three consecutive experiments with multiple controls and compared their data statistically to existing data from visual experiments done on other species. Previous studies already indicate that dolphins can visually estimate relative numerosity (e.g., Jaakkola et al., 2005; Yaman et al., 2012). Therefore, the goal of the present study was to investigate the dolphin's capacity to apply Weber's law (quantity judgments are more accurate proportional to the quantities investigated) to two sets of object quantities under sonar evaluation. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Many parrot species exhibit a high degree of limb lateralization on both the individual and species levels. In particular, the members of the cockatoo family are left-footed for food-holding at proportions reminiscent of right-handedness in humans. Here, we examine the limb lateralization of the Goffin's cockatoo (), a tool-using and technically proficient species used as a model of parrot cognition. First, we investigated the postural origins theory, originally proposed in primates to explain handedness. According to this theory, the hand that was used by ancestral primates to cling to trees developed finer motor control. Using a series of problem-solving tasks, we tested the possibility that the parrot's postural foot, which is similarly used to grasp tree branches, could be more motorically skilled. Although we did not find support for this idea, we did discover that task type does affect foot use, as subjects switched from using their food-holding dominant foot to their other foot during reaching tasks. We also found that the cockatoos more flexibly switched and used both feet when faced with more challenging tasks. Secondly, we attempted a partial replication of a previous study with parrots derived from the enhanced cognition hypothesis, which claimed that more lateralized individuals were better problem solvers. However, we did not find this relationship to be significant in any of our tasks. We did confirm that individual Goffin's cockatoos are extremely limb lateralized for food-holding in addition to other tasks, which may play a role in their approaches to problem-solving. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Utilizing Automated Cognitive Testing Systems (ACTS) with group-housed nonhuman primates offers a number of advantages over manual testing and computerized testing of singly housed subjects. To date, ACTS usage has been limited to great apes or African monkeys. Here, we detail what we have learned while implementing ACTS with socially housed squirrel monkeys and rhesus macaques and provide information about the training process. In addition, we examined the effects of age on learning acquisition. We found age differences in learning for both squirrel monkeys and rhesus monkeys. Older monkeys were not as proficient as younger monkeys on learning to use the touch screens (squirrel monkeys only), discrimination learning (rhesus monkeys only; note: squirrel monkeys were not trained to criterion on this task), and recognition learning (both species). Overall, ACTS provide a number of advantages for studying cognition in socially living nonhuman primates and can be used to further investigate cognitive decline whether related to natural aging processes or disease pathology. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Maze studies have provided substantial information about nonhuman cognition, such as insights on navigational strategies, spatial memory, and choice discriminations. This knowledge can aid in how we understand the foraging strategies of many animals, particularly understudied and endangered species, such as the Guatemalan beaded lizard (). These actively foraging lizards rely on chemoreception to locate prey, but it is unknown to what extent they engage in olfaction and vomerolfaction to hunt and navigate their environment. We investigated how Guatemalan beaded lizards moved through a physical maze. When navigating an eight-arm radial maze with all arms baited, lizards tended to turn into the immediately adjacent arm in a single direction, similar to other reptiles that have been tested in radial arm mazes. In a T-maze, the lizards had to discriminate between arms that contained scent and no-scent from a distance. They were generally unable to choose the baited (correct) arm at levels greater than chance, indicating an inability for this discrimination. With the addition of a scent trail, however, all lizards chose the baited arm at levels significantly above chance, and this increased accuracy was correlated with increased latency to make the arm choice. The lizards also demonstrated a decreased rate of tongue flicking as proximity to reward increased. Guatemalan beaded lizards can efficiently navigate a radial arm maze and can successfully use vomerolfaction with substrate-borne cues to locate prey, but they appear to have minimal olfaction abilities when sensing from a distance. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Surface chemical cues from prey elicit elevated levels of tongue-flicking and striking behavior in many species of snakes and lizards. These responses are mediated by the vomeronasal system, and they may even occur in the absence of other sensory cues. How individuals of a species respond to prey chemical cues can reflect developmental, ecological, and evolutionary processes. Our focus in this study was ecologically based, and involved testing whether levels of chemosensory responding reflect the putative relative intake of prey types in nature. We tested 11 wild-caught adult gopher snakes () for their chemosensory responses, namely tongue flicking, in response to surface chemicals of natural prey items (rodent and bird) and to two control stimuli (distilled water and hexane). On average the snakes had significantly higher rates of tongue flicking toward prey cues than to control stimuli ( = .001). Responses to rodent and bird surface chemicals did not significantly differ from each other ( = .35). Tongue-flick responses to rodent surface chemicals were significantly higher than to both water and hexane (s < .01), while responses to bird surface chemicals were significantly higher than to water ( < .05) but not to hexane ( = .12). (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Contrafreeloading is defined as choosing to perform work to obtain a reward, despite the presence of an identical, freely available alternative. According to standard learning and optimal foraging theories, it should not exist. Thus, any evidence of such behavior is noteworthy. We briefly review the recently introduced play hypothesis, which proposes that contrafreeloading is more likely if the action involved is viewed as play rather than work (i.e., agreeable rather than aversive). One might consequently expect species that are relatively more playful to be more likely to engage in contrafreeloading. We evaluated this possibility by testing purportedly playful umbrella cockatoos ); we studied four residents of a bird sanctuary in upstate New York (Dudley, JJ, Poly, and Teddy Bear). The task involved choosing between shelled and deshelled almonds; the former choice constituting evidence of contrafreeloading. We documented contrafreeloading in a novel species and then compared our results with previously published data on the reportedly less playful Grey parrots (). Individually, a higher percentage of cockatoos engaged in contrafreeloading on more than half the trials than did the Greys, with statistically similar levels of individual variation, but the overall amount of contrafreeloading was not statistically significantly different between the species at a group level. We discuss possible reasons for these findings. Additionally, we examine similarities in the behavioral expression of play and contrafreeloading. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

This article discusses the ephemeral reward task and how it is not always a clear and concise choice. This is demonstrated through some animal studies involving birds and primates. This article also shows that when compared to human studies, that there are positive correlations between the BART and optimal choice in the ephemeral reward task, meaning that those who took more risks also were more inclined to be optimal. (PsycInfo Database Record (c) 2024 APA, all rights reserved).