Journal of Comparative Psychology最新文献

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).

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).

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).

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).

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).

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).

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).

Organisms are believed to attempt to maximize their net energy intake while foraging. The paradoxical choice task shows that they may instead prefer to obtain information rather than primary reward when the outcome is uncertain. That is, they prefer stimuli that consistently predict food or no food (informative option), to stimuli that inconsistently predict both food and no food in larger amounts (noninformative option). This task also seems to indicate that some species (like pigeons, Columba livia, and starlings, Sturnus vulgaris) are more prone to choose the informative option, while other species (like rats, Rattus norvegicus, and humans, Homo sapiens) tend to favor reward procurement through the noninformative option. There is empirical evidence for and against this view. However, an analysis of the literature suggests that species differences in paradoxical choice might be less pronounced than often believed. We argue that pigeons and rats are usually not tested under conditions that are motivationally equivalent for both species-in particular, the opportunities to track consistent stimulus-food pairings are less often met in the rat studies than in the pigeon studies. (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).

Animals navigate complex environments that present both hazards and essential resources. The prioritization of perceptual information that is relevant to their next actions, such as accessing or avoiding different resources, poses a potential challenge to animals, one that can impact survival. While animals' attentional biases toward negatively valanced and threatening stimuli have been explored, parallel biases toward differently valued resources remain understudied. Here, we assessed whether three primate species (chimpanzees [Pan troglodytes], gorillas [Gorilla gorilla gorilla], and Japanese macaques [Macaca fuscata]) prioritized their attention to positively valued resources-preferred foods compared to unpreferred foods. We employed a computerized dot probe attentional bias task in which we presented participants with paired images of their preferred and unpreferred foods in randomized locations (left or right). Latencies to touch the "probe" that replaced either image revealed that all three species responded faster to the probe when it replaced the preferred option (χ²(1) = 284.50, SE² = .03, p < .001). The uniformity of the primates' responses hints that a propensity to prioritize highly preferred items is rooted in these primates' evolutionary past, one that may serve as a mechanism to rapidly detect and locate resources such as highly valued foods. Future research will help disentangle the role that color plays in these biases. (PsycInfo Database Record (c) 2024 APA, all rights reserved).