Learned taste and temperature aversions due to lithium chloride sickness after temporal delays.

Abstract

Rats, reared on water, were given saccharin and then made sick with a single LiCl injection after various intervals. Similarly, animals reared on saccharin were made sick with LiCl at various times after drinking water. In both conditions, rats learned to avoid drinking the fluid which preceded sickness and the amount of aversion was a function of the sickness delaj time. Similar tests with 43° C. water as the OS also produced learned aversions, but the longest effective sickness delay time with the temperature cue was less than 1 hr. compared to several hours with the taste cues. In a third experiment, rats, experienced with water and saccharin, learned specifically to avoid the fluid which they had drunk preceding their sickness, even with sickness delay times of several hours.

A contingency analysis of taste aversion conditioning

“…Reliable signs of avoidance acquisition were not seen until the sixth trial, with most animals in Group FOR avoiding administration of the oral rinse CS by the eighth trial. By contrast, there are numerous reports of long lasting, one-trial aversions conditioned to saccharin using lithium as the US over 6-8-h delays when the CS duration was 10 or more minutes (Barker & Smith, 1974;Nachman, 1970). The present findings suggest that small amounts of a flavor probably cannot be associated over relatively long CS-US delays, given that learning even a short (Y2-h) delay required a number of trials.…”

Effects of CS amount on conditioned taste aversion at different CS-US intervals

“…It is now well established that conditioned taste aversion, although it can be obtained with CS-US intervals considerably longer than those used in other conditioning paradigms, nevertheless shows an orderly delay-of-reinforcement gradient (e.g., Garcia, Ervin, & Koelling, 1966;Nachman, 1970). The traditional explanation for delay-of-reinforcement phenomena, i.e., that the weaker conditioning at longer CS-US intervals is due to the gradual decay of the CS trace, has difficulty accounting for some of the characteristics of the delay-ofreinforcement gradient in conditioned taste aversion.…”

Food after deprivation rewards the earlier eating

“…In contrast, when a single aversive manipulation of bodily state was applied after a single bout of intake of a distinctive material, strong association to that cue (Table 1) was observed in later performance (i.e., conditioning of aversion to the cue) when the consequence had been delayed for 12 hours or more (Garcia, Ervin, Yorke & Koelling, 1967;Nachman, 1970;S. Revusky, 1968).…”