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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 10, Issue 3, 1997


Video Display for Study of Avian Visual Cognition: From Psychophysics to Sign Language


We demonstrated four different ways of using video systems for research  in avian visual cognition: 1) recent developments of high vision TV systems made it possible to use the video system for psychophysical studies. Visual acuity measured with such a video system was comparable to those obtained by more traditional methods; 2) using image processing software, we could display unnatural animals, such as chimeras on the TV screen. We also reported that pigeons did not discriminate partially occluded conspecifics; 3) effects of exposure to visual stimuli upon on-going behavior were examined using suppression and conditioned suppression procedures; and 4) discrimination of moving images, namely two words of Japanese Sign Language, are reported.  

Spaced-trail Operant Learning with Purely Instrumental Contingencies in Pigeons (Columba Livia)


purpose of this experiment was to study persistence during extinction of key pecking performance in pigeons (Columba livia) after training with either a large (15 food pellets) or a small reward magnitude (1 food pellet). Strictly instrumental contingencies were enforced and a single trial per daily session was administered. There were 52 acquisition trials followed by 48 extinction trials. Although extinction started from similar response levels in both groups, the pigeons trained with 15 pellets exhibited significantly slower extinction than those trained with a single pellet. This result is discussed in the context of comparative research on the effects of reward magnitude and schedule on extinction in vertebrates.  

Comparative Perspectives on Pointing and Joint Attention in Children and Apes


comprehension and production of manual pointing and joint visual attention are already well developed when human infants reach their second year.  These early developmental milestones mark the infant's transition into accelerated linguistic competence and shared experiences with others. The ability to draw another's attention toward distal objects or events facilitates the development of complex cognitive processes such as language acquisition. A comparative approach allows us to examine the evolution of these phenomena. Of recent interest is whether non-human primates also gesture and manipulate the eye gaze direction of others when communicating. However,all captive apes do not use referential gestures such as pointing, or appear to understand the meaning of shared attention. Those that show evidence of these abilities differ in their expression of them, and this may be osely related to rearing history. This paper reviews the literature on the topic of pointing and joint attention in non-human primates with the goal of identifying why these abilities develop in other species, and to examine the potential sources of the existing individual variation in their expression.