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Undergraduate Research Project Management System

Effects of Fixed and Variable Schedules of Reinforcement on Within-Session Decreases of Response Rates and Food Consumption in Dwarf Hamsters

Status Complete
Seeking Researchers No
Start Date 11/01/2009
End Date 06/30/2010
Funding Source Undergraduate Research Grant
Funding Amount
Community Partner
Related Course
Last Updated 09/21/2011 11:05PM
Keywords dwarf hamster


  Gwen Lupfer

Student Researchers
  Christie Flanagan


Food provides strong motivation for humans and animals alike; it is a basic need that must be fulfilled. However, with an increase in agricultural and industrial activity, food has secondarily become an excessive indulgence. Obesity has become increasingly problematic in the United States; therefore, it is important to understand motivation as it pertains to food. Operant conditioning, in which food delivery is contingent upon behavior, is a common procedure used to study food-related motivation. During this procedure both human and non-human subjects typically increase and decrease their response rates within sessions. Utilizing dwarf hamsters (Phodopus campbelli), I will employ fixed and variable interval schedules of reinforcement in order to examine subjects' within-session response rate decreases during the differing schedules of reinforcement. Additionally, the use of dwarf hamsters will experimentally distinguish
habituation, rather than satiation, as the reason for within session decreases because they store food in their cheek pouches, rather than consuming it immediately. I predict that during the variable schedules of reinforcement: (1) subjects' rate of responding to reinforcement will decrease more slowly, and (2) subjects will consume (as opposed to storing in cheek pouches) a greater proportion of reinforcers earned. These results would indicate that receiving food at unpredictable times increases motivation to earn and consume food.

Specific Aims: To record a slower within-session decrease in response rates among subjects during a variable interval schedule of reinforcement rather than a fixed interval schedule of reinforcement. To record more pellets consumed, compared to hoarded, on a variable interval schedule of reinforcement than on a fixed interval schedule or reinforcement. To record and document the hoarding of food pellets in each hamster's cheek pouches, rather than consumption of the food pellets, in order to support habituation rather than satiation as an explanation for within-session decreases in response rates.

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