International Journal of Comparative Psychology

I report an observation of possible play behavior in an individual captive Vlaming's unicornfish (Naso vlamingii). The fish was documented performing locomotory interactions with the filtered stream of water from the return nozzle in its aquarium. Such behaviors conform to existing definitions of play behavior. Animal play is traditionally imagined to be restricted to mammals and birds, with research on this type of behavior remaining scarce within other animals. This finding thus expands upon the ubiquity of play in understudied vertebrate taxa. 

The Laboratory of Comparative Psychology and Behavioral Biology at Oklahoma State University has been developing comparative psychology teaching exercises for over 30 years. In this paper, we provide suggestions for using the dwarf octopus (Octopus joubini) to teach students about the importance of observation, and the relationship of observation in the creation of ethograms and experimental design. Throughout this paper, students learn how to properly make an observation of a novel animal, create an ethogram, and conduct an experiment. We present a sample observation activity and three additional experiments, during which students will observe and record behaviors and environmental conditions. Students learn saltwater tank upkeep, time management, creation and coding of operational definitions, attention to changes in animal behavior, and the experimental process. These observation studies allow students to observe and record behavioral data to understand comparative psychology and experimental design. 

The purpose of this study was to examine the responses of a Steller sea lion to two consecutive commands. We conducted this study on one same subject, Hama, as a continuation of Sasaki et al. (2022), which examined whether the Steller sea lion can discriminate human vocal commands. In Sasaki et al. (2022), commands were presented individually to examine the accuracy rate for each command. In the present study, we observed how Hama responded to the rapid presentation of two consecutive commands. The commands were presented in 20 different orders and combinations as 20 command combination patterns using five different commands. The results showed that Hama responded to 12 command combination patterns by performing behaviors corresponding to two consecutive commands. Hama performed the two behaviors in sequence in 8 of the 12 command combination patterns. The responses to the other four command combination patterns were combined single behaviors that combined the behaviors indicated by the two consecutive commands and that were already connected to different single commands. Although the combined single behaviors were not simple combinations of behaviors induced by the two consecutive commands, the combined single behaviors included the common body parts (e.g., fore flippers) or common action types (e.g., rotation) of behaviors induced by each command in the two consecutive commands. These results not only indicate that Hama could understand multiple linguistic information, but also suggest the possibility that Hama spontaneously formed categories based on the learned commands. 

Reversal learning has been studied in many species, often as an indicator of their behavioral flexibility. Although this research typically focuses on individuals, groups of social animals, especially social insects, are often considered to have similar learning capabilities. Associative learning has been rarely studied in ant colonies and their behavioral flexibility is still to be assessed. In this study, ant colonies readily learned to discriminate between compound visuotactile cues and subsequently learned their reversal. Reversal performance was maintained after a 5-day retention interval, but not after a 10-day interval. Although this study does not differentiate learning processes at the individual vs. colony levels, it is the first demonstration of reversal learning conducted in ant colonies. These results show that the two-corridor maze can serve to assess colony-level learning in ants. This is a first step to investigate key mechanisms underlying collective learning and cognition in ants. 

Laterality is defined as the occurrence of each cerebral hemisphere having asymmetric control over the different sides of the body, leading to preferences to use one side of the body over the other for various behaviors. Many types of laterality exist, but handedness is the form that is most predominantly assessed. Handedness in animals is of special interest to laterality researchers, as humans were once thought to be the only species that exhibited lateralized hand preferences. The aim of the current study was to determine if Asian small-clawed otters (Aonyx cinerea) exhibit significant paw preferences in behaviors associated with completing a specific tool-use task. Video data of the otters completing the task was analyzed for specific paw interactions with the tool-use apparatus, and the percentage of correct completion of the task was documented for each otter. Overall, no significant population level paw preference was present. However, individual differences in paw preference and differing trends in handedness on each focal behavior was present.  The results showed that paw preference (or lack thereof) did affect the tool-use task completion for some otters, and for others, the preference did not seem to have an effect. The main implications of this study are that paw preferences in Asian small-clawed otters are present on an individual level when solving a novel tool-use task. 

Guinea pigs (Cavia porcellus) are popular pets and used as laboratory animals, however, their dietary preferences are under-studied. It is important for guinea pig owners and carers to increase the opportunity for good animal welfare by providing personalized and enriching dietary options. Thus, this study aimed to assess the use of paired-stimulus and multiple-stimulus-without-replacement preference assessments to determine the food preferences of seven male guinea pigs and test the validity of the methods by testing the demand for the most- and least preferred foods as reinforcers for climbing an elevated ramp. Generally, the preference assessments identified the same foods as the most preferred for each guinea pig, but not the least preferred foods. Guinea pigs climbed up to the steepest angle for both most and least preferred foods, but a non-linear least squares regression and demand analysis indicated faster climbing and inelastic demand for most preferred foods compared to slower climbing and elastic demand for least preferred foods. Both preference assessment methods were valid in identifying a preferred food, however, the multiple-stimulus-without-replacement assessment was more efficient to conduct. High-preference foods such as parsley and dandelion are recommended as future training reinforcers for guinea pigs and as foods to consider using as enrichment in captive guinea pig systems to encourage good welfare. 

We investigated dominance in two groups of captive painted turtles, each over a period of 8 weeks. In each case, we began with five turtles, then added a sixth after 6 weeks. One group was run in the fall, the other in the spring, and the makeup of males and females differed in the two seasons. We measured two behaviors while they were feeding: mounting, defined as placing a claw or head above the carapace of the other turtle for at least one second, where the mounter was stationary, and biting, defined as snapping at another turtle. We hypothesized that the turtles would demonstrate a dominance hierarchy. Our results showed that painted turtles show individual differences in behavior. These differences are consistent over time and allow dominance hierarchies to be established. Both mounting and biting demonstrated consistency, but mounting was more consistent than biting. The amount of mounting and biting differed by sex and season, but turtle size did not seem to influence their activities. Finally, the introduction of a new turtle disrupted the dominance behaviors of the turtles, suggesting that turtles recognize a new turtle as unfamiliar. Understanding the complex dynamics of captive turtle populations has implications for the management and welfare of turtles in captivity and in the wild. 

Humans and other vocal-learning species engage in solo vocalizations. Such vocalizations in the human literature are referred to as private speech and have been hypothesized to play a role in vocal repertoire development both in humans and nonhumans, alike. The current study used corpus linguistics techniques to quantitatively and qualitatively compare the private speech of a two-year-old child and an enculturated, home-reared African Grey parrot to identify similarities and differences in the composition and function of their private speech. Both speakers exhibited previously documented human private speech functions, including sound- and word-play and repetitive practice of new words. The composition of the utterances, however, was different between the two speakers. The child’s private speech contained a larger vocabulary, more frequent use of function words (i.e., prepositions, articles, pronouns, conjunctions) to string together ideas, and the use of multiple verb tenses. The cross-species finding that a home-reared parrot’s private speech is similar in function—including evidence of play and possible intrinsically-motivated practice—to that of a language-learning child offers unique insights into the evolution of human language. 

Primates have been studied extensively to understand their behavior and the mechanisms that allow information processing. However, when we closely analyze the species studied and the different projects and topics carried out with them, we found that some species have been highly studied, while others have only a few studies. These differences create a significant underrepresentation of some primate species that could be especially problematic when we use the available information to track the evolution and the diversification of behavior and the mechanisms for information processing. With this in mind, this review aims to show the state-of-the-art of different topics studied in Mexican primates and identify topics that could be studied in the future. The review also aims to demonstrate why working with native species is a path that many low- and middle-income countries like Mexico can follow to develop research programs in their homelands.