An Examination of the Roles of Sensory Preconditioning and Higher Order Conditioning in Taste Aversion Learning in Rats

Abstract

This study investigated whether or not the exteroceptive cue of a tone could be conditioned to a taste aversion using the procedures of sensory preconditioning and higher order conditioning. Four conditions – each having a pre (sensory preconditioned) and a post (higher order conditioned) - phase were employed (a total of eight groups with eight subjects per group). Experimental groups received pairings of a tone with the taste of saccharin either prior to (pre groups) or after (post groups) a conditioning phase in which a LiCl injection was paired with saccharin therefore making the subject ill. The Control l (Cl) groups received pairings of no tone and saccharin either before or afterthe conditioning phase of saccharin and LiCl. Control 2 (C2) groups received the tone and saccharin pairings either prior to or after the conditioning phase, but conditioning for this group paired a saline (NaCl) injection with the taste of saccharin. Control 3 (C3) groups had pairings of no tone with saccharin either before or after the pairing of NaCl with saccharin in the conditioning phase. In the Test I phase, suppression of bar pressing to the tone was measured as an index of a conditioned emotional response. The Test II phase was a two bottle choice test with water and saccharin. It was hypothesized that exteroceptive cues could become higher order conditioned stimuli and/or sensory preconditioned stimuli for internal events, and could influence performance. More specifically it was predicted that the experimental groups would evidence suppression of bar pressing when exposed to the exteroceptive higher order conditioned or sensory preconditioned stimulus (the tone). Suppression of bar pressing was not expected in any other group. In the second phase of testing (Test II) the groups made ill to the taste of saccharin during conditioning (Pre-E, Post-E, Pre-Cl, and Post-Cl) were expected to consume significantly less saccharin than the remaining groups. Results did not demonstrate the establishment of a higher order or sensory preconditioned conditioned emotional response, although an aversion to saccharin was evidenced in groups which were made ill to its taste. Results are discussed in terms of ''prepared" learning (Seligman, 1970) or a more general set of laws for all kinds of learning.