Conditioned antisickness: heat as an internal stimulus in conditioning taste aversion and aversion failure in rats.

Heat was found to be effective as a conditional stimulus in the aversion failure procedure (S. Revusky, H. K. Taukulis, L. A. Parker, & S. Coombes, 1979) and was also found to be effective as an unconditional stimulus using a taste aversion procedure in which rats exposed to high ambient temperature following saccharin consumption showed robust saccharin aversions relative to unpaired and unheated controls. The antisickness and taste aversion conditioning evidence force reexamination of the view that toxic heat effects are referred to the external environment. Together with other recent evidence from this laboratory, these data support the hypothetical antisickness mechanism of aversion failure, which requires that toxic heat serve as an internal stimulus.