Interocular transfer of a visually mediated conditioned food aversion in chicks

Young chicks with one eye occluded were subjected to a food aversion conditioning procedure in which an unfamiliar colored liquid (the conditioned stimulus) was paired with delayed LiCl-induced illness (the unconditioned stimulus). In a subsequent preference test, chicks displayed marked avoidance of the liquid whether tested with the trained or the untrained eye open, demonstrating substantial interocular transfer of the monocularly acquired visual food aversion after the single conditioning session and despite the long interstimulus interval. A possible role of the unconditioned stimulus in determining interocular transfer of avoidance habits in birds is discussed.