Automatic processing of visual food stimuli during hunger: a visual mismatch response study

Abstract

The aim of this thesis was to investigate whether the presentation of visual food stimuli elicits visual mismatch negativity (vMMN) in an oddball paradigm and whether the amplitude of the vMMN is modulated by hunger. For this purpose, 18 right-handed women underwent two experimental sessions: hunger and fed conditions. Participants were instructed to complete a 2- back working memory task while stimuli depicting high fat savoury (HFSA) and high fat sweet (HFSW) foods were presented as deviants in a stream of neutral standard stimuli in the periphery of the screen. To examine whether the effect of hunger was food-specific, neutral deviants were used as control stimuli. Further, emotional blink of attention (EBA) was used to validate the vMMN. Deviant minus standard difference waveforms yielded significant mismatch responses in the early, mid-latency, and late time windows. In HFSA, the modulation of hunger was evident in the early and mid-latency time windows pertaining to automatic stimulus detection. In HFSW, the modulation of hunger was not observed. In addition to the food deviants, hunger also modulated the responses to the neutral stimulus. Therefore, the modulation of hunger pertaining to general information processing cannot be ruled out. As the EBA task did not yield anticipated results, the mismatch response paradigm could not be validated via EBA. In conclusion, vMMN might prove to be a reliable measure in investigating automatic food-cue processing after additional attempts at vMMN validation with different food stimuli have been made.