Skip to main content
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 22, Issue 4, 2009

Research Paper

The Judder of the Cricket: The Variance Underlying the Invariance in Behavior

While the behavior of many animals can be identified as involving discrete and stereotyped actions, there is a persistent tension between emphasizing the fixedness of the actions (“Fixed Action Patterns”) and emphasizing the variation in the components comprising those actions (“Modal ActionPatterns”). One such action, the back and forward judder of crickets often exhibited in agonistic interactions, was analyzed. Judders occurring on a horizontal surface by Gryllus bimaculatus were compared to those occurring on an inclined platform. Although the body movements involved were variable, that variability occurred in the context of maintaining some features of judder invariant. For example, the crickets maintained their bodies so that they were horizontal relative to the substrate, not to gravity, and most features of the back and forward movement (e.g., distance moved, velocity) were maintained as fixed despite differences in posture and movement. At a theoretical level, what these findings suggest is that behavior patterns involve a combination of fixedness and variation in the service of that fixedness. It becomes an empirical issue to discern these complementary components.

Perceptual Learning in a Human Conditioned Suppression Task

The present experiment demonstrated a “perceptual learning” effect found in the animal literaturewith human participants. The common finding in animal work is that intermixed exposures to twostimuli prior to conditioning facilitates their subsequent discrimination on a generalization test morethan the same amount of exposure to the stimuli in a blocked arrangement. The method was asuppression task implemented in a video game. Participants learned to suppress a baseline response(mouse clicking) when a colored sensor (i.e., CS) predicted an attack (i.e., US). First, prior toconditioning, they received either intermixed pre-exposures to two sensor CSs, blocked preexposures,no pre-exposures, or pre-exposure to the individual visual elements of the CSs. Second, inconditioning, one of the sensor CSs was paired with an attack US. Finally, generalization ofsuppression to the other sensor CS was assessed. Pre-exposures to the sensor CSs reducedgeneralization relative to no-exposure at all, with intermixed pre-exposures producing the greatestreduction in generalization. The importance of the present work is that it reduces the possibleidiosyncrasy of existing results with humans that used evaluative-conditioning methods bydemonstrating the effect with a method that has been used to reproduce a variety of associativelearningphenomena and is easily amenable to associative-learning explanations

Siamangs (Hylobates syndactylus) Recognize their Mirror Image

The ability to recognize oneself in the mirror is assumed to represent an important step towards a higher level of animal intelligence that, ultimately, can lead to human-like self-awareness and empathy. Even though rarely successful in the classical mark test, the siamang’s spontaneous behavior in front of the mirror, a visually controlled manipulation of its face, suggests that it interprets the reflection as belonging to itself. As a consequence, the cognitive status of the gibbons may need a serious reevaluation since, in total, at least three species (Hylobates syndactylus, H.gabriellae, H. leucogenys) seem to be capable of self-recognition. Their, nonetheless, weak interest in the mirror image is hypothesized to be caused by the comparatively low level of sexual competition in the lesser apes.

The Behavioral Development of Two Beluga Calves During the First Year of Life

Currently, very little formal research exists regarding the behavioral development of beluga calves (Delphinapterus leucas). The behaviors and interactions of two beluga calves born into the care of humans were observed consistently from birth to 12 months. Changes in behavior were recorded continuously for 20 minutes for each mother-calf pair 2 to 4 times a week. As expected, the primary calf activity involved swimming with mother, which gradually decreased over the first year of life. Calves initiated the majority of their separations from and reunions with their mothers. Unexpectedly,the calves demonstrated an early independence and primary responsibility for proximity maintenance to their mothers. The calves also engaged in more solitary swims, object play, and interactions with each other across the year. In summary, the two calves followed developmental trends that were similar to each other and to other cetaceans in the care of humans.

Multiple Cue Extinction Effects on Recovery of Responding in Causal Judgments

Many experiments have demonstrated recovery of extinguished responding following a context change and some experiments have shown that extinction in multiple contexts can reduce this response recovery. We report two additional experiments which both showed reduced response recovery following extinction in the presence of multiple partner cues. These experiments also showed reduced response recovery following acquisition in the presence of multiple partner cues. The effect of the multiple extinction treatment was present in tests carried out in presence of the original training cue (ABA design) as well as in the presence of a novel test cue (ABC design), suggesting the effect was mediated by the associative strength of the target cue, rather than by the strength of the partner cue. However, the effect of the multiple acquisition treatment was only present in the ABA design, suggesting this effect was mediated by the associative strength of the partner cues, not by the strength of the target cue.