Investigation of eye tracking, electrodermal activity and facial expressions as biometric signatures of food reward and intake in adults with normal weight

Introduction: Pervasive exposure to a vast and varied food repertoire has contributed to the obesity epidemic. A better understanding of the psychophysiological responses to food cues that precede food choice and food intake is therefore needed. Biometric measures such as eye tracking, electrodermal activity and facial expressions may separately or collectively provide deeper insight into the psychophysiological processes underlying food reward and food intake. We examined how biometric responses differed in foods varying in fat and taste and explored how these biometric signatures to food cues were related to food preference behaviors, food choice, and food intake.
Methods: This study involved three parts: 1) we developed and validated a Danish food image database representing foods and food categories commonly encountered in the Danish culture; 2) we developed the Steno Biometric Food Preference Task based on a validated behavioral methodology (The Leeds Food Preference Questionnaire) including implicit and explicit responses to foods; and 3) we conducted a cross-sectional study in 100 adults with normal weight to test the biometric food preference task by assessing biometric responses (concurrent eye tracking, electrodermal activity and facial expressions) and food reward to visual food stimuli from different food categories. Food intake and selection was examined using a simultaneous choice ad libitum buffet.
Results: The results from this cross-sectional study showed significant differences in visual attention towards foods varying in fat content and taste prior to making rapid food choice decisions. Furthermore, the study found positive associations between maintained attention during a forced choice paradigm and subsequent food reward and food intake measures (Figure 1). Attention, arousal and facial expression during passive viewing were not associated with food reward or intake measures, except for an association between negative valence and explicit liking such that less liked foods also elicited stronger negative facial expressions.
Conclusions: The findings indicate that implicit, biometric responses to food cues predict both food reward and actual food intake.