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 21, Issue 2, 2008

Research Paper

Relative Pattern Preferences by Bumblebees

Bumblebees were trained to discriminate between two patterns, one rewarding (S+) and another unrewarding (S-) consisting of four orthogonal bars. Training and testing conditions were manipulated in a 2 X 2 between groups design. The training patterns differed only in the positioning of the bars in the inferior or the superior portion. The same was true of the testing patterns, both of which were unrewarding. A significant interaction between training and testing conditions was obtained on preference for one pattern, the diamond, which was present at testing for all four conditions. For the groups that were trained with the patterns that differed only in the inferior portion, when tested with patterns that differed in (1) the inferior portion: the diamond, for which the inferior portion matched that of the S+, was chosen at a level significantly above chance (2) the superior portion: the preference for the diamond disappeared-- no discriminationwas found, even though the alternative to the diamond was the same as the S+. For the groups that were trained with the patterns that differed only in the superior portion, the opposite effect of testing conditions was found: when tested with patterns that differed in (1) the inferior portion: the bees avoided the very same diamond that was preferred by the bees trained differently, and favoured the alternative, which was the same as the S+ (2) the superior portion: no pattern discrimination was found (i.e. the avoidance of the diamond disappeared). Two predictions were disconfirmed: that during testing bees would only (1) approach the pattern that was the same as the S+, or (2) discriminate between patterns that differed in the same area (inferior or superior) as did the training patterns. The data were in line with the interpretation that during differential conditioning the visual field used in future pattern discriminations is expanded to include not only the inferior portion of the pattern but more of the superior portion as well.

Differing Pattern of the Development of Mother–Infant Interactions in Cynomolgus Monkeys Due to Exposure of an Environmental Chemical, Bisphenol

Recent studies have focused on the effects of low doses of Bisphenol A (BPA) on the central nervous system, which may prevent sexual dimorphism of the brain in rodents. To assess sensitivity to BPA, mother–infant behaviors in the cynomolgus monkey were studied longitudinally after treating the mothers with low-dose BPA during pregnancy. Mother–infant interaction was observed for 6 months after the birth of the infants. In conclusion, male offspring of BPA-treated females showed female-like behavior patterns. Prenatal BPA exposure altered infant behavior in the early stages of mother–infant interaction, and male infants were affected more seriously than females.

Recognition and Discrimination of Human Actions Across the Senses of Echolocation and Vision in the Bottlenose Dolphin: Evidence for Dolphin Cross-modal Integration of Dynamic Information

The ability of cetaceans to explore and interpret their world via echolocation has receivedconsiderable attention during recent years, and the resulting body of work has revealed asophisticated cetacean echolocation system. In addition, a number of recent studies suggest thatdolphins can relate information that they receive from vision with information that they obtainfrom echolocation when this information concerns stationary objects. However, the present studyis the first test of the cetacean ability to integrate dynamic information about movement acrossthe two senses. Three adult female bottlenose dolphins that had previously learned to interpretvisible movements produced by humans stationed on floating docks were asked to interpret a setof these movements produced by an underwater human located behind a visually opaque screen.Although each dolphin had previously demonstrated its ability to reliably interpret movementsproduced by a human in the air above the surface of the water, none of the dolphins had anyprevious experience with underwater humans producing movements that the dolphins could seeor with underwater humans producing movements behind an opaque screen that prevented thedolphins from using visual information to interpret these signals. The dolphins quickly learned tocorrectly respond to signals that they could not see but could observe via echolocation. Theseresults demonstrate that dolphins can relate visual and echoic representations of actions,although the amount of experience necessary for such integration has yet to be determined.