In social animals, studying interactions with conspecifics is crucial for understanding even basic physiological, behavioral, and cognitive processes. Due to a visible "ecological turn" in behavioral research, we observe a rapid development of novel methods devoted to studying interaction. In this article, we offer a case study of an animal interactive behavior, which uses new methods of video-recorded

Perceptual animacy is the tendency for observers to represent inanimate objects as animate, based on simple motion cues. Several features of the chasing pattern can elicit animacy perception and, similarly to adult humans, dogs perceive dots showing this pattern as animate. Here, we used moving objects with a heading alignment (isosceles triangles) to investigate whether human and dog behavior continues

Oxytocin has been shown to be important for social behavior and emotional attachments in early life and may also mediate effects of early experiences on social motivation in adulthood. In animal models, early maternal separation results in alterations in the oxytocin system, with effects on sexual, maternal, and stress reactivity behaviors in adulthood. Studies of children experiencing parental divorce

The study of personality in nonhuman primates has increased substantially, but most studies so far have been conducted with captive animals. In addition, few studies investigated the personality of Neotropical (Platyrrhini) monkeys. If we aim at investigating the ecological and social significance of personality in nonhuman primates, conducting studies of wild populations and covering a wide range

Mirror self-recognition (MSR), usually considered a marker of self-awareness, occurs in several species and may reflect a capacity that has evolved in small incremental steps. In line with research on human development and building on previous research adopting a gradualist framework, we categorized the initial mirror responses of naïve spider monkeys (Ateles geoffroyi) according to four levels. We

Recent reviews have highlighted the tendency in the comparative literature to make claims about species' relative evolutionarily adaptive histories based on studies comparing different species tested with procedurally and methodologically different protocols. One particularly contentious area is the use of the object-choice task, used to measure an individual's ability to use referential cues, which

Human adults often envisage future events and prepare items or information in advance. Studies have shown that young children can also prepare items for upcoming events, but little is known about their ability to prepare information for such events. Here, we used nonverbal measures, which are widely used in comparative cognitive research, to ask whether children seek information for their future knowledge

Performance of honeybees resembles that of vertebrates in a variety of associative learning experiments. Recent work has focused on relational learning phenomena not easily explained by associative principles, including same/different problems, the simplest of which is the oddity problem. Free-flying bees were trained to visit a laboratory window and were rewarded for choice of the odd stimulus among

The anomalous position of gorillas (Gorilla gorilla gorilla) in the capacity for self-recognition remains puzzling. The standard measure of self-recognition is Gallup's (1970) mark test that assesses an individual's ability to recognize its altered image in a mirror following the application of paint marks to visually inaccessible areas. Here, the results of a small-scale pilot study are presented

Metacognition refers to the ability to monitor one's own mental states. In the current study, we investigate whether domesticated dogs (Canis familiaris) and nondomesticated dingoes (Canis dingo) demonstrate metacognition by seeking information to remedy their own ignorance. In 2 studies, we used a naturalistic information-seeking paradigm in which subjects observed a human experimenter hiding a food

Muszynski and Couvillon (see record 2020-37265-001) built upon their previous findings that honeybees can learn the relation among triads of trial-unique visual stimuli. In this new work, they showed that bees encountering trial-unique sets of three or four visual stimuli chose the correct stimulus at above-chance levels, replicating their previous findings and extending them to four-choice displays

Eye gaze is widespread in nonhuman primate taxa and important for social cognition and communicative signaling. Bonobos and chimpanzees, two closely related primate species, differ in social organization, behavior, and cognition. Chimpanzees' eye gaze and gaze following has been studied extensively, whereas less is known about bonobos' eye gaze. To examine species differences using a more ecologically

Humans usually assess options not in terms of absolute value, but relative to reference points. The framing of alternatives can strongly affect human decision-making, leading to different choices depending on the context within which options are presented. Similar reference-point effects have been recently reported in ants, in which foragers show contrast effects: Ants overvalue a medium-quality food

Cohabiting with humans in the same ecological space requires significant variation in the behavioral repertoire of animals. Behavioral variation can potentially improve the chances of survival of an individual. The influence of humans can be measured by quantifying specific behavioral parameters of the interacting individuals. Sociability or the tendency to be friendly toward others is one of many

Up until the middle of the 19th century, some data about plant behavior could be found in books dealing with comparative psychology. The tendency gradually faded away, and the topic was almost exclusively treated in literature dealing with plant physiology. In recent years, however, there has been a revamping of psychological terminology and theorizing to describe, explain, and formulate hypotheses

Several animal species can discriminate between different sequential patterns based on repetitions of items (e.g., ABB vs. ABA), and generalize their performance to sequences made of novel elements but following the same underlying structure. This achievement suggests that these species possess the ability to abstract the sequences structures beyond exemplars. Developmental studies in humans suggest

Humans use tools with specific functions to solve tasks more efficiently. However, functional specialization often comes at a cost: It can hinder the production of actions that are not usually performed with those tools, thus resulting in a fixation effect (functional fixedness). Little is known about whether our closest living relatives, the nonhuman great apes, are vulnerable to this detrimental

The mirror mark test is generally considered to be an indicator of an animal's ability to recognize itself in the mirror. For this test, an animal is confronted with a mirror and has a mark placed where it can see the mark only with the help of the mirror. When the animal extensively touches or interacts with the mark, compared with control conditions, the mirror mark test is passed. Many nonhuman

One of the challenges of collaboration is to coordinate decisions with others, and recent theories have proposed that humans, in particular, evolved skills to address this challenge. To test this hypothesis, we compared the coordination abilities of 4-year-old children and chimpanzees with a simple coordination problem. To retrieve a reward from a "puzzle box," pairs of individuals were simply required

Probabilistic categorization tasks present the learner with a set of possible responses and imperfect cue evidence of which response will be rewarded. A single, optimal integration of all available cues into an optimal response is possible given any set of evidence. In contrast, there are many possible uses of the cues that offer the learner suboptimal (but better than chance) responding. We presented

Self-recognition in animals is demonstrated when individuals pass the mark test. Formerly, it was thought that self-recognition was restricted to humans, great apes, and certain mammals with large brains and highly evolved social cognition. However, 1 study showed that 2 out of 5 magpies (Pica pica) passed the mark test, suggesting that magpies have a similar level of cognitive abilities to great apes

What is the origin of visual symbols? The artifacts that are viewed as the first visual symbols-or at least their prototypes-are the remains of stones and other objects with engravings and colorful markings. Our only access to the origin of this behavior that we share with our ancestors within the genus Homo is through skeletons, artifacts, and genetic testing, and we can only draw indirect conclusions

The rejection of parasitic eggs by hosts of avian brood parasites is one of the most common and effective defenses against parasitism. Despite its adaptive significance, egg rejection often shows substantial intraspecific variation: some individuals are more likely to remove or abandon parasitic eggs than others. Understanding variation in egg rejection requires that we study factors linked to the

To explain animal learning, researchers invoke a dominant associative construct. In contrast, researchers freely acknowledge humans' explicit-declarative learning capacity. Here, we stretched animals' learning performance toward the explicit pole of cognition. We tested four macaques (Macaca mulatta) in new discrimination-learning paradigms. Monkeys learned a series of two-choice discrimination tasks

One way to address questions about the origins and adaptive significance of personality dimensions is by comparing the personality structures of closely related species that differ in their socioecological circumstances. For the present study, we compared the personalities of captive golden-handed tamarins (Saguinus midas; N = 28), cotton-top tamarins (Saguinus oedipus; N = 20), and common marmosets

Mirror reflections can elicit various behavioral responses ranging from social behavior, which suggests that an animal treats its own reflection as a conspecific, to mirror-guided self-directed behaviors, which appears to be an indication for mirror self-recognition (MSR). MSR is scarcely spread in the animal kingdom. Until recently, only great apes, dolphins, and elephants had successfully passed

In the current work, we investigated whether capuchin monkeys preferred densely distributed resources to sparsely distributed resources in a 2-choice discrimination task with edible rewards. Capuchin monkeys were biased to select a denser food set over the same number of food items in a sparsely arranged set. Furthermore, increased density of the larger food set facilitated discrimination performance

One approach that is starting to reveal interesting variation in social interactions assesses how familiarity of individuals affects their behavior toward one another. This was studied by Prior, Smith, Dooling, and Ball (2020) with a model songbird species, zebra finches (Taeniopygia guttata). This work is important in that it reveals how fundamental simple familiarity-repeated social experience with

Disagreement has arisen in the scientific literature regarding the relative olfactory ability of humans relative to other mammals, specifically canines and rodents. A series of experiments are reported in which memory for multiple olfactory discriminations was measured in dogs, rats, and humans. Participants from all three species learned a sequence of 20 different discriminations between an S + odor

Chimpanzees have been found to show the inversion effect to visual stimuli of intact chimpanzee bodies, suggesting that they have a specific way of body processing. In this study, we examined how changes of body structures affect the inversion effect to reveal the properties of their body processing. We focused on two aspects of body structures: the first-order relations (i.e., body part arrangements)

A total of 16 lemurs, including representatives from three species (Lemur catta, Eulemur rubriventer, and Varecia variegata), were presented with a food-seeking task in which information about the rewards location, in one of two plastic tubes, was either known or not known. We evaluated whether lemurs would first look into the tube before making a choice. This information-seeking task aimed to assess

Episodic memory is the ability to recollect specific past events belonging to our personal experience, and it is one of the most crucial human abilities, allowing us to mentally travel through time. In animals, however, evidence of what-where-when memory (hereafter, WWW memory) is limited to very few taxa, mostly reflecting the socioecological challenges faced in their environment. In this article

Piagetian liquid overconservation was investigated in four grey parrots (Psittacus erithacus). Birds tracked the larger of two quantities that had undergone various manipulations. Experiment 1 involved controls to ensure birds could track movement of the quantities, including direct and diagonal cross-transfers. All birds succeeded. In Experiment 2, different amounts in the same transparent or opaque

An individual's ability to respond to and align with the behavior of others is a fundamental component of social behavior. Zebra finches form lifelong monogamous pair bonds; however, zebra finches are also gregarious and can form strong social bonds with same-sex conspecifics. Here, we quantified behavior during brief 10-min reunions for males and females in five types of social conditions: monogamously

In both the wild and captivity, chimpanzees engage in reciprocal patterns of prosocial behavior. However, the proximate mechanisms underlying these patterns are unclear. In the current study, we investigated whether chimpanzees prefer to act prosocially toward conspecifics who have directly benefited them (perhaps based on an affective bond) or whether they simply observe the prosocial behavior of

Cooperative hunting is generally considered to be a cognitively challenging activity, as individuals have to coordinate movements along with a partner and at the same time react to the prey. Wolves are said to engage in cooperative hunting regularly, whereas dogs could have maintained, improved, or reduced their cooperative skills during the domestication process. We compared the performance of individuals

Aquatic species such as bottlenose dolphins can move in 3 dimensions and frequently view objects from different orientations. This study examined their ability to identify 2-D objects visually despite changes in orientation across 2 rotation planes. A dolphin performed a matching-to-sample task in which a sample was presented at a different orientation from its match in a 3-alternative choice array

Visual illusions have been widely used to compare visual perception among birds and mammals to assess whether animals interpret and alter visual inputs like humans, or if they detect them with little or no variability. Here, we investigated whether a nonavian reptile (Pogona vitticeps) perceives the Müller-Lyer illusion, an illusion that causes a misperception of the relative length of 2 line segments

The current study takes a holistic view of cross-species comparative research and investigates the dissemination of the term intention as representative of the so-called "cognitive revolution." All references from 641 articles, published from 1948 to 2017, are used to analyze a citation network. The analysis visualizes and identifies prominent articles in the scientific debate and locates them structurally

Animal personality, consistent interindividual differences in behavior through time, has been intensively studied across animal taxa and particularly in nonhuman primates. Two different methods have been used to study personality: questionnaires filled out by trusted raters, following the research tradition in human personality psychology, and behavioral observations or testing, based on the behavioral

Humans and other apes represent magnitudes spatially, demonstrated by their responding faster and more accurately to one side of space when presented with small quantities and to the other side of space when presented with large quantities. This representation is flexible and shows substantial variability between cultural groups in humans and between and within individuals in great apes. In contrast

Within human problem-solving, the propensity to use a familiar approach, rather than switch to a more efficient alternative is pervasive. This susceptibility to "cognitive set" prevents optimization by biasing response patterns toward known solutions. In a recent study, which used a nonverbal touch screen task, baboons exhibited a striking ability to deviate from their learned strategy to use a more

Humans use eye- and head-gaze cues to facilitate social interactions among members of their own species. Research examining nonhuman animal-to-human cueing effects has received little attention, but may provide valuable insight into the mechanisms that have enabled species to coexist and thrive in shared environments. The objective of the current studies was to determine how gaze cues influence the

Bats and dolphins echolocate ultrasonically while foraging, an active mode of perception that is effective for intercepting small, fast-moving targets, but less so for tracking large targets from long distances. Unlike toothed whales, humpback whales and other baleen whales are widely assumed not to echolocate. Echoes generated by humpback whale vocalizations often have been viewed either as low-level

The perception of temporal regularities is essential to synchronize to music and dance. Here, we explore the detection of isochrony in two mammal species. We trained rats (Rattus norvegicus) and humans (Homo sapiens) to discriminate sound sequences with regular intervals from sound sequences with irregular intervals using a go/no-go paradigm. We used four different tempi in the training sessions and

Adjustment of percussive movements to match the energetic requirements of the task serves as an index of skill in stone-knapping and nut-cracking. In this study, we compared strike-by-strike adjustment of percussive movements in expert bearded capuchin monkeys (Sapajus libidinosus) and (novice and expert) humans cracking palm nuts (Astrocaryum spp.) using stone hammers of varying mass. The monkeys

In nonhuman animals, individuals of the same sex and age differ in their behavior patterns consistently across time, comparable with human personality differences. To draw conclusions about the adaptive value of behavior traits, it is essential to study them in the wild where animals are subject to the ecological pressures that promoted the evolution of behavior strategies. This study was conducted

In previous research, pigeons and hill mynas that performed differently on an object permanence task were presumed to attend to objects in different ways (Plowright, Reid, & Kilian, 1998). In the current study, we conducted 4 experiments to investigate if the attention of hill mynas and pigeons is object-based and if there are species differences in their visual-attentional processes. In Experiment

One logical place to start in a wider search is to look for perception of auditory rhythm in diverse species. Celma-Miralles and Toro (see record 2019-59892-001), in this issue's Featured Article, report such a study. They tested whether rats and humans could detect deviations from one component of auditory rhythm, isochrony (a constant interval between sounds; Ravignani & Madison, 2017). Rats learned

Episodic-like memory is a personal memory that contains what happened, where it happened, and when it happened. Although episodic-like memory in nonhuman animals has been shown using what-where-when memory paradigms, it has not previously been shown in dogs. Dogs are an excellent candidate for developing translational models of neurodegenerative disorders related to episodic memory, including Alzheimer's

Nonhuman primate species appear to vary markedly in inferential reasoning abilities as measured by a classic inference-by-exclusion cup task. Even within species, individuals who can solve the cup task in the visual domain often struggle to use analogous auditory cues. Here we tested five cotton-top tamarins (Saguinus oedipus), cooperatively breeding New World monkeys that use both visual and auditory

Prosocial behavior in rats is known to occur in response to a familiar rat's distress, but the motivations underlying prosocial behavior remain elusive. In this study, we adapted the experimental setting of Ben-Ami Bartal, Decety, and Mason (2011) to explore different motivations behind helping behavior in adolescent rats. In the original setting, a free rat is placed in an arena where a cagemate is

In jumping spiders (Salticidae), the vigilance decrement, or decrease in response to a repeated visual stimulus over time, directly parallels that found in humans. Explanations for the vigilance decrement in the human literature are heavily mentalistic and central nervous system (CNS) based, whereas response decrements in invertebrates are typically thought of as habituation at the sensory periphery

Across various species, infant faces share various features referred to as "baby schema"(Lorenz, 1942). Assuming that these features are indeed shared among species, it is possible that nonhuman animals may perceive age information in conspecific and heterospecific faces. We tested whether tufted capuchin monkeys (Sapajus apella) would visually categorize age from faces. In Experiment 1, we trained

Optical illusions have been widely used to compare visual perception among vertebrates because they can reveal how the system is able to adapt to visual input. Sensitivity to visual illusions has never been studied in reptiles. Here, we investigated whether red-footed tortoises, Chelonoidis carbonaria, and bearded dragons, Pogona vitticeps, perceive the Delboeuf illusion. This illusion involves the

[Correction Notice: An Erratum for this article was reported online in Journal of Comparative Psychology on May 9 2019 (see record 2019-25503-001). In the article "Embracing in a Female-Bonded Monkey Species (Theropithecus gelada)" by Virginia Pallante, Pier Francesco Ferrari, Marco Gamba, and Elisabetta Palagi (Journal of Comparative Psychology, Advance online publication. March 25, 2019. http://dx

Recently, evidence for acoustic universals in vocal communication was found by demonstrating that humans can identify levels of arousal in vocalizations produced by species across three biological classes (Filippi et al., 2017). Here, we extend this work by testing whether two vocal learning species, humans and chickadees, can discriminate vocalizations of high and low arousal using operant discrimination

Capuchins (Sapajus apella) and squirrel monkeys (Saimiri sciureus) participated in 3 experiments in which they were presented with 2 objects, one appropriately oriented and the other inappropriately oriented to retrieve a food reward by pulling, replicating prior experiments with nonhuman primates described as evaluating "tool choice." Choice patterns were analyzed to assess whether monkeys learned

Researchers and artists have long been interested in visual illusions because they illustrate the interesting, complicated, and constrained ways in which we perceive the world. Although we may not be familiar with the names of the many different visual illusions that exist (e.g., the Necker cube, the Müller-Lyer illusion, and the Hermann grid illusion, to name a few), people with typically functioning

Reciprocity and cooperation are fundamental to human society and are observed in nonhuman primates. Primates are not only sensitive to direct reciprocity and its violation but also indirect reciprocity. Recent studies demonstrated that some primate species adjusted their behavior by observing others' interactions. Capuchin, marmoset, and squirrel monkeys avoided taking food from human actors who behaved