Context conditioning: positive reinforcing effects of various food-related stimuli

Rats were subjected to context preference tests to investigate the degree to which various manipulations involving food stimuli can be used to appetitively condition contextual cues. One manipulation consisted of placing hungry rats in a context that contained food that they could consume. A second one involved exposure to a context containing food that could only be seen and smelled, without consumption being possible. A third type of manipulation consisted of exposing animals to a context after the consumption of a small meal in the home cage. Finally, hungry, control subjects were merely exposed to a context containing an empty food tray. Preference for the context was only enhanced after the first type of manipulation, indicating that the actual consummatory act constitutes the major source of reinforcement in the present procedure. Olfactory and visual food cues, as well as postingestional aftereffects in isolation, did not function as reinforces.