Does Varying Item Size Act as a Determinant for Food Preference in Rats?

The purpose of the present study was to evaluate if the size of food items is an important dimension of food incentive in rats. The experiment involved training rats on a T-maze with 1, 45 mg pellet and 7, 5 mg pellets in one alternative and 8, 10 mg pellets in the other alternative. Results from this study indicated that the rats showed preference for the alternative that contained the 1, 45 mg pellet surrounded by 7, 5 mg pellets. Thus, rats preferred the food set that contained the larger sized food unit to an equicaloric food set with only smaller sized food units. In regards to running speed, no significant differences were found for either alternative of food. Results from this study indicated that the apparent size of an item could be a factor in the incentive value of food and perhaps, rats used size as a heuristic, placing a higher incentive value on the food set that contained the larger sized food unit than one containing only smaller sized food units.