It is known that if rats learn that a cue reliably precedes eating, its presentation can cause them to initiate a feeding bout when they are apparently sated (Weingarten, 1983, 1985). However, it is currently unclear precisely how such conditioned cues affect appetite. For example, does this type of conditioning elicit food specific appetites or do individuals merely experience a general increase in feeding motivation (Mela & Rogers, 1998)? To address this issue, the present experiment investigated the hypothesis that exposure to a cue (conditioned stimulus: CS) previously paired with a specific food biases diet selection in favour of that food when an individual is given a choice. The objective of the experiment was to enhance our understanding of the behavioural control of feeding, and hence our ability to predict diet selection and food intake.
The experimental subjects were 12 male Lister-hooded rats (initial body-weight 233; SD=20g). Throughout the experiment the subjects were maintained on a 1lh:13h light:dark cycle with lights on at 0700h, and had ad libitum access to a standard laboratory diet during the light phase.