The effects of expectancy information on cephalic phase responses to food

Abstract

It is well-established that exposure to the sight and smell of food enhances motivation to eat and initiates cephalic phase responses (CPRs) such as increased salivation, heart rate and blood flow to the liver. However, the effect of expectancy information in food-cue reactivity studies is not well-understood; that is, whether the participants expect to subsequently eat the cued food. Because CPRs prepare the body for consumption of food, these responses might be reduced when participants are explicitly told that they will not receive the cued food. The current study tested this proposition in a within-subjects design where female participants (i) expected to eat the cued food, (ii) did not expect to eat the cued food, and (iii) took part in a no-food-cue control condition. Measures of salivation and appetite were taken before and after exposure to the food cue. A novel continuous measure of liver temperature (a proxy for blood flow) was also taken using wireless monitoring devices (iButtons®); these devices were placed in the vicinity of the liver using ultrasonography. Results indicated no effects of expectancy information on rated hunger and salivation following food-cue exposure. However, subsequent food consumption was associated with significant increases in liver temperature. These findings provide novel insight into changes in liver temperature that occur during food-cue exposure and post-prandially.