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Open Access Publications from the University of California


The International Journal of Comparative Psychology is sponsored by the International Society for Comparative Psychology. It is a peer-reviewed open-access digital journal that publishes studies on the evolution and development of behavior in all animal species. It accepts research articles and reviews, letters and audiovisual submissions.

Volume 33, 2020

Research Article

The View of Russian Students on Whether Psychology is a Science

The Psychology as Science Scale (Friedrich, 1996) was administered to 525 psychology students from nine Russian universities to assess their beliefs about the nature of the discipline. About half of students (49.6%) generally agreed that psychology may be called a scientific discipline. Specifically, 71. 5% of the students agreed that psychology is a natural science, similar to biology, chemistry, and physics, 39. 9% of students agreed that psychological research is important and training in psychological methodology is necessary, and 43.1% of students agreed that human behavior is highly predictable. Students who took three methodology courses shared significantly stronger beliefs in the need for psychological research and the importance of training in methodology compared to students who did not take any methodology courses. Furthermore, students with a specialist degree had significantly stronger beliefs that psychology is a science compared to students who have just finished school. In terms of the effect of students’ career aspirations, students who wanted to be academic psychologists and clinicians had significantly stronger beliefs that psychology is a science compared to students who did not have clarity about their future careers. Regardless of the study limitations, these findings have potential implications for Russian psychology instructors.

Personality and Affiliation in a Cooperative Task for Bottlenose Dolphin (Tursiops truncatus) Dyads

Social species can depend on each other for survival, helping in rearing of young, predator defense, and foraging. Personality dynamics between individuals may influence cooperative behaviors. Bottlenose dolphins (Tursiops truncatus) live in social communities and cooperate with other conspecifics to achieve goals both in the wild and in human care. We investigated the role that personality plays in the willingness of dolphins to work together. We tested five bottlenose dolphin pairs at the Roatan Institute for Marine Sciences, Honduras, with an apparatus previously used to experimentally test dolphin cooperation. Personality profiles of each dolphin were created using surveys completed by the caretakers, in particular noting two different categories of interactions: dolphin to dolphin and dolphin to world. We hypothesized that dyadic success in the cooperative task would differ based on specific personality traits of individuals. We also hypothesized that the most successful dyads would show similar types of conspecific sociality and different means of interacting with objects. Although none of the dolphin pairs cooperated to open the apparatus, individual personalities were analyzed in relation to the dolphins’ individual and mutual interactions with the apparatus as well as the pairs’ social behaviors. Playfulness, curiosity, and affiliation as well as agreeableness, and extraversion were positively related to affiliation with the apparatus and each other. These findings suggest that certain aspects of personality are indicative of affiliation or interaction by an individual dolphin. These results could guide future animal research on the relationship between personality, social interactions, and problem-solving.

Female and male Wistar rats (Rattus norvegicus) discriminate diets according to energetic quantity

The food choice of animals is influenced by several factors including the quantity and nutrients available. It is not known, however, whether faced with alternatives that present the same amount of food, with similar flavor and obtained with the same response cost, rats would discriminate between diets with different energetic quantities. The aim was to verify whether female and male Wistar rats (Rattus norvegicus) discriminate between three types of food that differ in their energetic content (whether or not they prefer one) and whether the flavor could affect the choice between two diets with equal energetic quantities. Twelve Wistar rats (six of each sex) underwent tests of choice between pairs of diets of different energetic values. After the tests, the animals had at their disposal, in the home cage, two diets with the same energetic content, which differed in flavor (one contained sucrose) - Flavor test. The consumption of each diet was measured for five consecutive days. All the subjects demonstrated a preference for the more energetic alternative, regardless of the combination of diets presented. In the Flavor test the animals did not show significant preference for any diet, i.e., the consumption of both the S and N diets were statistically equal for all subjects. It was concluded that the animals, regardless of sex, discriminated between the diets with different energetic values and that the flavor did not seem to be a determinant variable in the food choice.


Preliminary study of discrimination of human vocal commands in walrus (Odobenus rosmarus divergens)

Walruses seem to use various acoustic signals in social context. So, the auditory faculty is seems to be important for walruses. Can walruses understand another animals' vocal information using auditory sense? This study tested whether a male walrus could discriminate human vocal words and perform different actions corresponding to each one under various conditions. The subject, a male walrus (Odobenus rosmarus) named Pou, was set on the ground, and the experimenter spoke one of the ten words to the subject under the following conditions; (1) The experimenter stood close to the subject and spoke each vocal stimulus wearing a black cloak and goggles so that the experimenter's eye and body movements would not influence the subject's behavior, (2) A wooden board was placed between the experimenter and the subject so that the subject could not see the experimenter, (3) A wooden board was placed between the experimenter and the subject so that the subject could not to see the experimenter, and the experimenter uttered each vocal stimulus through an audio speaker. Under each condition, when the subject performed the correct action corresponding to the vocal stimulus, he was rewarded with a piece of fish. As a result, the subject responded correctly to almost all the human vocal stimuli in every condition, including when the speaker was not visible. This means that he was indeed responding to the vocal words and not the experimenter's cues. This study demonstrated that walruses can hear and identify human vocal words using their auditory sense and can form correspondence between vocal words and their meanings.

Do honey bees (Apis mellifera) form cognitive representations of unconditioned stimuli?

Previous research looking at expectancy in animals has used various experimental designs focusing on appetitive and avoidance behaviors. In this study, honey bees (Apis mellifera) were tested ina series of three proboscis extension response (PER) experiments to determine to what degree honey bees’ form a cognitive-representation of an unconditioned stimulus (US). Tthe first experiment, bees were presented with either a 2 sec. sucrose US or 2 sec. honey US appetitive reward and the proboscis-extension duration was measured under each scenario. The PER duration was longer for the honey US even though each US was presented for just 2 sec.   Honey bees in the second experiment were tested during extinction trials on a conditioned stimulus (CS) of cinnamon or lavender that was paired with either the sucrose US or honey US in the acquisition trials.  The proportion of bees showing the PER response to the CS was recorded for each extinction trial for each US scenario, as was the duration of the proboscis extension for each bee.  Neither measure differed between the honey US and sucrose US scenarios,  In experiment three, bees were presented with a cinnamon or lavender CS paired with either honey US or sucrose US in a set of acquisition trials, but here the US was not given until after the proboscis was retracted. The PER duration after the CS, and again subsequent after the US, were recorded. While the PER duration after the US was longer for honey, the PER duration after the CS did not differ between honey US and sucrose US.

Special Issue: Revisiting The Legacy of Stan Kuczaj

Laterality of Eye Use by Bottlenose (Tursiops truncatus) and Rough-toothed (Steno bredanensis) Dolphins While Viewing Predictable and Unpredictable Stimuli

Laterality of eye use has been increasingly studied in cetaceans. Research supports that many cetacean species keep prey on the right side while feeding and preferentially view unfamiliar objects with the right eye. In contrast, the left eye has been used more by calves while in close proximity to their mothers. Despite some discrepancies across and within species, laterality of eye use generally indicates functional specialization of brain hemispheres in cetaceans. The present study aimed to examine laterality of eye use in bottlenose dolphins (Tursiops truncatus) and rough-toothed dolphins (Steno bredanensis) under managed care. Subjects were video-recorded through an underwater window while viewing two different stimuli, one predictable and static and the other unpredictable and moving. Bottlenose dolphins displayed an overall right-eye preference, especially while viewing the unpredictable, moving stimulus. Rough-toothed dolphins did not display eye preference while viewing stimuli. No significant correlations between degree of laterality and behavioral interest in the stimuli were found. Only for bottlenose dolphins were the degree of laterality and curiosity ratings correlated. This study extends research on cetacean lateralization to a species not extensively examined and to stimuli that varied in movement and degree of predictability. Further research is needed to make conclusions regarding lateralization in cetaceans.

SI: ISCP bienniel meeting (2018)

Comparisons of Animal “Smarts” Using the First Four Stages of the Model of Hierarchical Complexity

The Model of Hierarchical Complexity is a behavioral model of development and evolution of the complexity of behavior. It is based on task analysis. Tasks are ordered in terms of their hierarchical complexity, which is an ordinal scale that measures difficulty. The hierarchical difficulty of tasks is categorized as the order of hierarchical complexity. Successful performance on a task is called the behavioral stage. This model can be applied to non-human animals, and humans. Using data from some of the simplest animals and also somewhat more complex ones, this analysis describes the four lowest behavioral stages and illustrate them using the behaviors of a range of simple organisms. For example, Stage 1 tasks, and performance on them, are addressed with automatic unconditioned responses. Behavior at this Stage includes sensing, tropisms, habituation and, other automatic behaviors. Single cell organisms operate at this Stage. Stage 2 tasks include these earlier behaviors, but also include respondent conditioning but not operant conditioning. Animals such as some simple invertebrates have shown respondent conditioning, but not operant conditioning. Stage 3 tasks coordinate three instances of these earlier tasks to make possible operant conditioning. These stage 3 performances are similar to those of some invertebrates and also insects. Stage 4 tasks organisms coordinate 2 or more circular sensory-motor task actions into a superordinate “concept”. This explanation of the early stages of the Model of Hierarchical Complexity may help future research in animal behavior, and comparative psychology.


Special Issue: Canine Research

Discrimination of person odor by owned domestic dogs

In the field of dog cognition research, many studies assume that their subjects have multimodal recognition of their owner: Experiments using the face or voice of the person have proliferated. An outstanding question is whether owned domestic dogs represent the people with whom they live via smell. Olfaction is a principle sensory modality for dogs, and there is evidence that it is integral to recognition of conspecifics. In the current study, we investigated whether owned dogs spontaneously (without training) distinguished their owner's odor from a stranger's odor. Using natural body odor captured on a t-shirt, we found that dogs habituated to a familiar odor and dishabituated to an unfamiliar odor. This finding begins to answer the question of how dogs recognize and represent humans, including their owners.

Assessment of Canine Temperament: Predictive or Prescriptive?

Canine temperament testing has historically been linked to the predictability of future behavior. A predictive model of canine temperament testing assumes that a dog’s behavior in one situation will likely be similar to its behavior in a variety of other situations. An alternative model is proposed for a canine temperament test that could identify areas in which a dog might fail to perform certain test items, but by using modern behavior analysis techniques, behaviors could be modified through a prescriptive approach. This article describes the AKC Temperament Test (ATT), which is the first prescriptive canine temperament test. The ATT is designed to provide pet dog owners with information about potential problem areas that can be modified through training.



Distinguishing personal belief from scientific knowledge for the betterment of killer whale welfare – a commentary

We contest publication of Marino et al. regarding captive killer whale (Orcinus orca) welfare because of misrepresentations of available data and the use of citations that do not support assertions. Marino et al. misrepresent stress response concepts and erroneously cite studies, which appear to support Marino et al.’s philosophical beliefs regarding the cetacean hypothalamic–pituitary–adrenal axis. To be clear, these misrepresentations are not differences of scientific opinion, as the authors’ conclusions lack any scientific basis. More extensive review of Marino et al.’s citations reveal a dearth of empirical evidence to support their assertions. Further, Marino et al.’s approach to animal welfare is not consistent with conventional veterinary approaches to animal welfare, including their apparent opposition to use of preventative and therapeutic veterinary interventions. While Marino et al. argue that killer whales’ cognitive and spatial needs preclude management of this species under human care, misrepresentation of the citations used to support this opinion invalidates their arguments. Misleading interpretations of data relative to killer whales’ cognitive and emotional needs and specious and unsubstantiated comparisons with states experienced by humans with posttraumatic stress disorder and other conditions, represent a number of strategies used to misrepresent knowledge regarding killer whale welfare. These misrepresentations and fallacies are inconsistent with scientific ethical standards for credible, peer-reviewed journals (ICMJE, 2018), and are barriers to rigorous discourse and identification of strategies for optimizing killer whale welfare. Assertions in the paper amount to nothing more than a compilation of conclusory, philosophical statements. We would also like to mention that manuscripts such as Marino et al.’s do great damage to the fields of comparative psychology and to behavioral science as a whole.

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