Effects of visual presentation near the mouth on cross-modal effects of multisensory flavor perception and ease of eating

Various studies have suggested that altering the appearance of food can impact multisensory flavor perception. The cross-modal effect of such visual changes on gustation may allow for the presentation of food tastes that are difficult to express with simple combinations of taste stimuli. This cross-modal effect of visual changes on gustation holds potential for applications in gustatory displays. However, the current limitation of existing Head-Mounted Displays (HMDs) is their restricted vertical Field of View (FoV), which prohibits the display of images near the mouth while eating. This limitation may impede the cross-modal effect of visual changes on multisensory flavor perception. Additionally, the lack of visibility around the mouth area challenges the ease of eating. To address these issues, we design a Video See-Through (VST)-HMD with an expanded vertical FoV (approx. 100 [deg]). Using the HMD, we investigated how presenting visual information near the mouth affects the cross-modal effects of flavor perception and ease of eating. In our experiment, machine learning techniques were utilized to alter the appearance of food. However, the result showed no significant differences in the amount of cross-modal effects or the ease of eating between the groups with and without visual information near the mouth. As a discussion of this result, the participants may not direct their visual attention to the food when they put the food in their mouths. The experiment also examined whether visual changes alter the taste as well as the smell and texture of the food. The findings demonstrated that visual changes could present the smell and texture of the food following the modifications. This result was confirmed irrespective of the visibility near the mouth.