This study will examine differences in habituation to foods high in sugar and fat content versus those that are not, in normal weight women.

Participants will complete two experimental sessions, in which habituation to chocolate cake and dried apricots will be measured, with each session measuring habituation rate to one food. Upon arrival to the session, participants will write down what they have consumed and the minutes of physical activity they have engaged in during the previous 24 hours. Participants will rate their feelings of hunger and fullness using a 100mm VAS. They will also rank their liking of the food being used in the session using a 100mm VAS. Participants will be given a peanut butter flavored granola bar, containing 190 kcal, and be instructed to consume all of the bar.

Next, participants will complete a computer generated task to measure habituation to a food (chocolate cake or apricots). The computer task will be programmed at a variable interval of 120 ± 42 seconds (VI-120) reinforcement schedule, so that participants will be rewarded one point for the first response made after approximately 120s have passed. The computer task consists of two squares, one that flashes red every time a mouse button is pressed and another square that flashes green when a point is earned. The habituation phase will be 24 minutes, divided into 12, 2-minute trials, during which participants can earn points towards access to 75 kcal portions of the food that is being measured. Participants will receive the food immediately after each point is earned to consume and can continue to play the computer task while eating. Participants will be instructed that when they no longer want to earn access to the food they can go to another table and engage in the activities provided (i.e., reading magazines). After the computer task, participants will rate their feeling of hunger, fullness, and liking of the food. During the computer task the number of consecutive two-minute time blocks before responding ceases, as well as the overall pattern of responding, will be measured.

Inclusion Criteria:

• body mass index (BMI) 18.5 to 24.9 kg/m2
• nonsmokers
• not allergic to the foods used in the investigation
• must like the foods in the investigation (scoring > 50 mm on a visual analogue scale [VAS])
• be willing to consume the foods
• not have dietary restrictions
• not be a restrained eater (scoring > 12 on the Three Factor Eating Scale)
• not be on medications that influence appetite
• not planning to change their diet or physical activity during the time frame of their study participation
• not dieting or trying to lose weight.

Exclusion Criteria:

• BMI outside of the range 18.5-24.9
• smoker
• food allergies
• does not like the foods used in the study
• has dietary restrictions
• is a restrained eater
• on medications that may influence appetite
• planning on changing diet or physical activity during time frame of the study
• dieting
• trying to lose weight