Psychophysiological responses to positive and negative food and nonfood visual stimuli

The aim of the study was to examine associations between psychophysiological responses and emotionally arousing visual food and nonfood stimuli. Eighteen healthy normal weight female volunteers were recruited. The stimulus materials consisted of pretested pictures which each had 2 features, valence (positive/negative) and category (food/nonfood). Pleasantness ratings and psychophysiological responses, including facial electromyography, heart rate variability (HRV), galvanic skin response (GSR), and gaze deviation, were recorded. The main findings were as follows: (a) Corrugator muscle activation and GSR were associated with valence of the pictures; and (b) HRV parameters (mean R-R interval and root mean square of the successive differences) and zygomaticus muscle activity increased more when subjects viewed positive nonfood pictures than positive food pictures. In conclusion, these relatively simple physiological measurements are sensitive to stimulus valence and category, and thus can be useful measures in the objective assessment of emotionally arousing stimuli.