BEHAVIORAL AND NEURAL BIOLOGY 25, 58-68 (1979) Learning of Visual Food Aversions by Chickens (Gallus gallus) over Long Delays GERARD M. MARTIN I AND W. P. BELLINGHAM 2 Department of Psychology, Australian National University, Canberra, Box 4, A.C.T. 2600, Australia Domestic chicks learned in one trial to associate both the color and texture of food with induced sickness even when several hours intervened between the two events. Control experiments revealed that the aversions were not mediated by taste and that they were not due to the unspecific effects of the poison. Expla- nations of long delayed learning are evaluated in the light of these data. In addition, findings on food aversion learning in other species are considered. The formation of food aversions by animals has attracted the attention of those studying learning because it challenges the assumptions that all stimuli are equally associable and that temporal contiguity between a stimulus and a consequence is an essential condition for their association (Revusky & Garcia, 1970). Such challenges have contributed to the de- velopment of new theories which point out that animals will form associa- tions over long delays when relevant stimuli do not intervene between the to-be-associated stimulus and the consequence (Revusky, 1971). Unfortunately, systematic examination of food aversion learning over delays of hours has only been studied in rats and has been limited to taste stimuli (Andrews & Braveman, 1975; Revusky, 1968; Smith & Roll, 1967). Visual aversions have not, to our knowledge, been demonstrated with delays exceeding 60 min, while at least one attempt to obtain long delayed visual aversions with rats failed (Revusky & Parker, 1976). Investigators have suggested that two factors may impede the formation of visual aversions over long delays: the lack of salience of visual cues relative to taste cues in, for example, guinea pigs (Braveman, 1975), and the fact that there are more potentially interfering visual stimuli during the delay (Czaplicki, Borrebach, & Wilcoxon, 1976). It is difficult to assess the ' Now at the Department of Psychology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada. We thank R. F. Mark, G, N. Seagrim, L. H. Storlien, L. Jones, and W. K. Timmins for helpful comments; W. Kaveney for technical assistance; and Katy Gillette and Julia Irwin for help during Experiment 4. 58 0163 - 1047/79/010058-11 $02.00/0 Copyright © 1979by AcademicPress, Inc, All rightsof reproduction in any form reserved.