Archive for November 18, 2008

End of Phase 1– Separate Hoarding

After making the previously described changes in our apparatus, we set out to gather data regarding number of pellets hoarded when each individual rat is alone on her particular side of the mesh divider. After 8 trials ( we would have liked to do more but couldn’t given our time constraint–it’s almost the end of the semester!) Louise has hoarded an average of 30.8 pellets and eaten an average of 6.3 grams per trial. Penelope has hoarded an average of 28.9 pellets and eaten an average of 6.2 grams per trial.

Thus, it is clear that the changes we made on our apparatus really made a difference. We’ve been doing some research and have found some possible explanations for the success of our changes.

1) Larger space: Many of the studies we have read use long “alleys” attached to the rats main cage. The food was placed at the end of these alleys, allowing the rats to travel a ways to retrieve the food, as they would in a more natural, wild situation.

2) Familiar environment: A study done by Miller and Viek (1944) suggested that rats may hoard more in their home cages because they see their cages as a place of maximum security. This study worked off the basis of a concept proposed by Bindra (1948b) called the security hypothesis. This hypothesis assumed that rats are relatively “anxious” and “insecure” when outside of their home cages, which would interfere with natural hoarding behavior. Bindra also suggested that the amount of anxiety experienced by the rat depended on its individual characteristics, as well as the characteristics of the situation. Thus, different rats could react differently in different situations. It is also interesting to note that the characteristics of the “home cage” that make it familiar to the rat are unknown. However, it seems as if we were successful in assuming that a familiar smell (their own urine) and object (the wash cloth) would make the box seem more familiar.

We have begun the second phase of the experiment which includes gathering data on the number of pellets hoarded while the rats are together in the tank, but separated by the wire mesh divider. We will attempt to get in at least 8 trials during this phase as well.

alone-graph-12

November 18, 2008 at 2:02 pm Leave a comment


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