Effect of Interpersonal and Cognitive Stressors on Habituation and the Utility of Heart Rate Variability to Measure Habituation.

Habituation is a decrease in responding to a repeated stimulus. Operant responding and salivation measure habituation in eating behaviour research. Stress may increase eating by acting as a distractor, yielding spontaneous recovery and prolonging responding for food. Our research tested differences in the ability of cognitive and interpersonal stressors to recover responding for food. We also tested heart rate variability (HRV) as a measure of habituation. Twenty women worked for portions of macaroni and cheese for 15 trials on three separate laboratory visits. Between the 12th and 13th trial, one of three different stressor types (speech, stroop and subtraction) was presented during each visit. HRV was measured continuously throughout the laboratory visits. Responding for food declined across the 12 trials with no difference in rate of habituation by visit (p > 0.8) There was no difference between stressor type in the magnitude of spontaneous recovery after each stressor (p > 0.8). Rates of habituation of HRV variables correlated (p < 0.02) with the rate of operant responding habituation. Cognitive and interpersonal stressors do not differ in their ability to recover reduced responding for food. HRV variables may measure habituation to food similar to operant responding.