The effects of imaginary eating on visual food cue reactivity: An event-related potential study.

Previous research has demonstrated that imagining consumption of a specific type of food helps individuals to consume less of that food. The present event-related potential study aimed at investigating the underlying neural correlates of this appetite-reducing strategy. A total of 86 women (mean age = 23.65 years) were randomly assigned to one of three imagination conditions. In each condition, they listened to a guided imagery script that either described the eating of 30 colorful button-shaped chocolates (M&Ms), the sorting of 30 M&Ms by color, or the sorting of 30 marbles by color. Subsequently to the imagery task, the participants were presented with images of M&Ms and marbles while their electroencephalogram and craving ratings were recorded. The results showed that imaginary eating did not reduce the appetitive value of M&M pictures. The M&M sorting group reported enhanced craving and showed increased late positivity toward M&M pictures (300-600 ms after picture onset) compared to the two other groups. The present findings indicate that the imagined handling of food increases food cue reactivity and that imaginary eating is not a reliable method to reduce appetite.

Placebos can change affective contexts: An event-related potential study.

An unpleasant context (bitter aftertaste) is able to reduce the late positive potential (LPP) elicited by affective pictures. This study attempted to influence this context with a placebo. Sixty-eight women were randomly assigned to three groups: Water, Bitter/No-Placebo, Bitter/Placebo. Participants in the 'bitter groups' first rinsed their mouth with wormwood tea that caused a bitter aftertaste. Subsequently, the placebo group received sham light therapy on the tongue to 'reduce the sensitivity of the taste buds'. All groups viewed disgusting and non-disgusting pictures while their electroencephalogram was recorded. The Bitter/Placebo group reported reduced bitterness and disgust for the aftertaste after the sham treatment. The LPP reduction (300-600 ms after picture onset) associated with the bitter aftertaste (as shown by the Bitter/No-Placebo group) was attenuated due to the placebo treatment. This is the first EEG study to demonstrate that a context-targeting placebo is able to change automatic attention allocation.

Disgust evoked by strong wormwood bitterness influences the processing of visual food cues in women: An ERP study.

The perception of intense bitterness is associated with disgust and food rejection. The present cross-modal event-related potential (ERP) study investigated whether a bitter aftertaste is able to influence affective ratings and the neuronal processing of visual food cues. We presented 39 healthy normal-weight women (mean age: 22.5 years) with images depicting high-caloric meat dishes, high-caloric sweets, and low-caloric vegetables after they had either rinsed their mouth with wormwood tea (bitter group; n = 20) or water (control group; n = 19) for 30s. The bitter aftertaste of wormwood enhanced fronto-central early potentials (N100, N200) and reduced P300 amplitudes for all food types (meat, sweets, vegetables). Moreover, meat and sweets elicited higher fronto-central LPPs than vegetables in the water group. This differentiation was absent in the bitter group, which gave lower arousal ratings for the high-caloric food. We found that a minor intervention ('bitter rinse') was sufficient to induce changes in the neuronal processing of food images reflecting increased early attention (N100, N200) as well as reduced affective value (P300, LPP). Future studies should investigate whether this intervention is able to influence eating behavior.