International Journal of Comparative Psychology

In order to test the effects of qualitatively varied reinforcement on response rates 3 experiments were conducted. The goal of the first experiment was asses the level of substitutability between two reinforcers   8 female Wistar rats kept on a diet consisting solely of turnip and millet seeds, subjects were exposed to a concurrent FR5 FR5 and then to a FR4 FR8 program, by the end of the experiment there was a swift in consumption, albeit to a small degree. During the second experiment, 8 female Wistar Rats were exposed to a three-component variable interval program which consisted of three components; one during which only millet seeds were available, one in which only turnip seeds were available and a third component in which both kinds of seeds were delivered randomly. By the end of the experiment the highest response rates were recorded during the component in which only millet seeds were available. Finally, a Third experiment was implemented in order to assess whether the particular way in which the substitutable consequences are delivered (i.e., random or simultaneously) has an effect on response rates. The program for this experiment consisted of a VI 60`s with two components. During one of the components a mixture of millet seeds was delivered when subjects responded after the interval was reached while during the second component either millet and turnip seeds were delivered randomly. By the end of the experiment no differences between components were found.  Results are discussed in terms of their implications for the study of reinforcement.

Eating is a central feature of the lives of opportunistic omnivores such as humans and Norway rats. Yet in most laboratory research with Rattus norvegicus , the food landscape is monotonous, and the studies utilizing a variety of foods shed little light on intake of individual foods or choice behavior. The present study provides the most comprehensive description to date of female and male laboratory rats’ intake of foods that they and humans encounter outside of the laboratory. In eleven experiments, test foods included varieties of peanut butter, cheese, cookies, meat, chocolate, fruits, and vegetables. Rats were given commercial products or custom versions that controlled for proportion of calories from fat and caloric density, one or two foods at a time. A final experiment examined pure macronutrient self-selection. Intraspecies diversity was modeled with rat lines selectively bred on a taste phenotype. All groups voluntarily ate every food, with intake (in grams) highest for vegetables and lowest for pure macronutrients. When Low- (LoS) and High-Saccharin-Consuming (HiS) rats differed, LoS rats ate more meat and fat and were choosier whereas HiS rats ate high-carbohydrate foods more avidly; exceptions and sex-dependent differences occurred. Using these results to enrich the food landscape for laboratory rats can enhance the comparative study of food intake and its relation to other behavioral systems.

This study investigated the relationship between monetary reward and athletes’ athletic identity. The purpose was to understand the difference in athletic identity between athletes who earned monetary compensations and those who did not earn any monetary compensations for participating in sports. Two hundred and fifty-six athletes who competed in state-organized sports competitions completed the Athletic Identity Measurement Scale (AIMS). The data collected was analyzed using Mann Whitney U tests and Linear Regression at 0.05 level of significance. The findings revealed that age did not predict athletic identity, and monetary reward did not differentiate athletes who received financial compensations or not based on their athletic identity. The results have confirmed that other factors that are not monetary may be associated with athletes’ athletic identity. Therefore sports psychologists should identify those factors to help athletes sustain their athletic personalities.

We report results of experiments using human vocal commands to investigate how well a Steller sea lion ( Eumetopias jubatus ) can discriminate different sounds. The participant, Hama, a 12-year-old female at Kinosaki Marine World, Japan, was raised by four trainers. We investigate Hama’s ability to discriminate 10 vocal commands (e.g. Iya-iya, Okay etc.) used in daily performances in two experiments: 1, commands given directly to the sea lion by trainers, but out of her sight; and 2, vocal commands given to the sea lion by trainers, but using recorded commands over a loudspeaker. In the experiment 1, Hama was able to discriminate all 10 commands, but her accuracy to discriminate one command was significantly lower than others (p < .05). In the  experiment 2, Hama was able to discriminate all but one command; accuracy rates among commands were variable, but the accuracy rate for one was significantly lower than the others, and those for three commands were significantly higher than others(p < .05). These experiments demonstrate that Hama can discriminate most commands based on their acoustic properties, regardless of which of four trainers spoke them out of her sight or if they were relayed from a recording. This ability suggest that the Steller sea lion E. jubatus might use sound for their own complex communication.

There is no shortage of anecdotal evidence that domestic dogs ( Canis lupus familiaris ) can solve problems in individual or creative ways. Whether it is figuring out a new way to knock over the trash can or combining puppy-dog eyes with a whine for some table scraps, dogs approach their world in many ways. In recent years, dogs have been studied for a number of cognitive functions but their ability to demonstrate creative behaviors has not been empirically studied. The present study extends training of the create behavior, as previously trained in dolphins, to dogs. The criteria of the create behavior required the dog to present a behavior that had yet to be performed in the session, therefore, the only incorrect response was a repeated behavior. Mastery of the create command was coded on three components: repetition, energy, and novelty. Possible implications of this research will be discussed. This study adds to the literature on dog cognition and supports the utilization of citizen science for canine cognition research.

The Monty Hall dilemma (MHD) is a probability puzzle in which humans consistently fail to adopt the optimal winning strategy. The participant chooses between three identical doors, behind one of which is a valuable prize. After the participant makes their initial decision, the host reveals that there is nothing behind one of the two remaining doors, then asks the participant if they would like to stay with their originally selected door or switch to the remaining unopened door. The optimal choice is to switch to the previously unchosen door, which increases the probability of winning from 33% to 67%. Despite this basic solution, humans repeatedly perform suboptimally. Previous attempts to improve performance by increasing the number of available doors have been successful (Burns & Weith, 2004; Franko-Watkins et al., 2003; Saenen et al., 2015; Stibel et al., 2009; Watzek et al., 2018). However, prior studies that examined whether this improved performance could generalize to different contexts have been inconclusive (Franko-Watkins et al., 2003; Watzek et al., 2018). To examine whether human performance can generalize across two computerized variations of the MHD, the present study explored how previous experience involving trials presented with eight options affects switching percentages in subsequent trials with three options. The results replicated findings from previous studies, which demonstrated that switching rates increased as a function of more available options. The findings also revealed participants can successfully generalize their behavior when returning to three-option trials. Further exploration of the MHD is needed to determine why performance generalization occurs in certain contexts, but not others.

Identifying meaningful vocalizations in nonhuman animals can help explain the evolution of human communications. However, non-speech-like sounds, including laughter equivalents, are not well studied, although they may be meaningful. In this pilot study we investigate whether dogs perform a domain-specific pant during play by capturing vocalizations and behaviors during three interactions: training, play, and rest. Sixteen human and dog dyads participated in a session that included all three interactions in the same order: training, play, rest. During these sessions, each partner wore wireless microphones that transmitted to a receiver and digital recorder, while a standalone digital camera captured video of the interactions. A one-way ANOVA demonstrates that dogs do perform a domain-specific "play pant," which was almost completely absent during training and rest. These vocalizations mostly co-occurred with play behaviors (e.g., play bow) or tickling and cuddling. These preliminary findings suggest that a laugh-like play pant is used by dogs during play; future research should explore other interspecific acoustic signals as derived from conspecific signals and having communicative function.

The aim of this study was to compare two different types of feeding enrichment (vegetarian vs. carnivore) through the daily activity, space use and inter-individual distances in a captive Iberian wolf ( Canis lupus signatus ) pack housed at the Barcelona Zoo. Multifocal sampling methods were used for data collection and instantaneous scans were made at 15-min intervals during sessions of varying duration. The enrichment sessions were carried out once a day, three days per week –Monday, Wednesday, and Friday- repeating the delivered schedule of items every two weeks. Thus, both feeding phases included six different enrichment sessions; the vegetarian phase included chopped fruit – apples inside a burlap sack, scattered bananas, peaches, frozen pears, and oranges, and kiwis inside a frozen water block; the carnivore phase included animal products -beef raw lean meat inside a burlap sack or inside a frozen water block, horse leg, live carp, frozen rabbit skin and live grasshoppers-. There were individual differences in the response to both feeding enrichments. Only the carnivore enrichment provoked statistically significant differences in exploration, locomotion, inactivity and not visible. Only the indeterminate zone showed changes during both enrichment phases. The inter-individual distance between Iberian wolves was statistically significantly lower during both feeding enrichment phases –especially during the carnivore as compared to the vegetarian phase- than during the baseline phase. Enrichment items designed more according to the natural history of these animals seem to have a greater capacity to improve the wolf welfare. Future studies on this species are necessary to improve husbandry techniques, welfare, and conservation programs.

This article introduces the little-known contributions of Alfred Binet to comparative psychology. While Binet’s contributions to intelligence testing are well known and widely discussed in introductory psychology and history of psychology texts, his contributions to comparative psychology are largely forgotten. To acquaint textbook writers and students with Binet’s contributions, we review his 1889 book The Psychic Life of Micro-Organisms: A Study in Experimental Psychology . This book details his observations of the behavior of microscopic organisms. We discuss each of the nine chapters and close with speculation of how his book may have helped develop his problem solving tests.