LATERALITY OF AGGRESSIVE RESPONSES IN ANOLIS

This experiment examined whether or not aggression in the Lizard Anolis (suborder Lacertilia, family Iguanidae) is lateralized. Five pair of adult Anolis were subjected to several 20 min behavioral trials, during which one animal was placed in the cage of the other. Behaviors were captured on video and coded according to eye preference, motor activity, posture, and color. Analysis of the data found that the most aggressive behaviors, including biting, threatened biting, and aggressive movements, were done under the guidance of the left eye. Both left and right eyes were used with equal frequency during non-aggressive movements. Most of these aggressive episodes were done while the animals were ''lightly'' colored. Because of an almost complete crossing-over of the optic tract in Anolis, along with the absence of a corpus callosum, it is likely that most, if not all, of the information in the left eye was processed by the right hemisphere. These results suggest that the lizard Anolis, like humans, rats, and chicks, may mediate aggressive responses predominantly through right-hemispheric brain mechanisms. (C) 1995 Wiley-Liss, Inc.