Date Approved


Degree Type

Open Access Senior Honors Thesis



First Advisor

Silvia von Kluge

Second Advisor

Joseph Breza

Third Advisor

Carol Freedman-Doan


The purpose of this study is to investigate the food preferences of rats when given food with either a high protein or a high sugar content. We hoped to compare initial preferences and long-term exposure to determine the role of taste, and then post-ingestive effects, to examine if taste preferences are formed on the basis of taste alone or caused by the body's absorption of nutrients. To achieve this goal, we studied rats' food choices when presented with high protein yogurt or yogurt with a high sugar content. For half the rats two dishes were placed into the home container (simultaneous condition), for the other half there was only one container {sequential condition). In the simultaneous condition rats were presented with a choice between sweet yogurt and protein yogurt (n = 4). In the sequential condition they were presented with either the sweet or protein yogurt on one day, followed by the opposite on the next day, alternating every day for the duration of the trial. The initial condition was counterbalanced (n = 5 for each initial condition). It was hypothesized that rats would show an initial preference for sugar, which would shift to a preference for protein over the two-week trial period. 1 The results from this experiment show that our initial hypothesis was not supported. Rats simultaneously offered sugar and protein generally preferred sugar, both initially and habitually. However, rats offered only one of the mixtures have an initial preference for protein that rapidly switches over to a preference for sugar. Regardless of testing condition, this preference generally becomes stronger over a two-week testing period. Not only does the interest in sugar increase over time under all conditions, the interest for protein decreases significantly for those in the simultaneous condition. To better substantiate these results, this study should be repeated with a sample size of at least 10 rats per testing condition. A longer timeframe to show changes in consumption would also be advised.

Included in

Psychology Commons