DETOUR TESTS REVEAL TASK-SPECIFIC AND STIMULUS-SPECIFIC BEHAVIORAL LATERALIZATION IN MOSQUITOFISH (GAMBUSIA-HOLBROOKI)

We studied detour responses of male mosquitofish faced with a vertical -bar barrier through which a group of females was visible. Mosquitofis h showed a consistent population bias to detour the barrier preferenti ally leftwise when a straight barrier was used, whilst the asymmetry d isappeared if a U-shaped barrier was used. The leftward bias was appar ent even when using a simulated-predator as a target (which induced de tour behaviour for predatory-inspection responses), but not when using an empty environment or a group of males as a target. Moreover, when faced with an opaque barrier, mosquitofish tended to turn on their rig ht side. These lateral biases could be accounted for in terms of a rig ht eye preference during lateral (monocular) fixation of any stimulus of interest, suggesting functional lateralization in a teleost species for the analysis of visual information. (C) 1997 Elsevier Science B.V .