Attentional modulation of contamination sensitivity: sharper perceptual boundaries for food compared to nonfood odor mixtures.

Processing of contaminants in odor mixtures is influenced by their categorization into food and nonfood categories. For example, we previously found that participants were more likely to perceive food odors as contaminated by nonfood odors than vice versa, and that this effect was robust to changes in explicit task instructions. However, due to the mixing of food and nonfood components, processing differences between categories were not captured by this task design and thus remain to be explored. In the current pre-registered study, we address this knowledge gap by determining the effects of attention on the perception of odor mixtures containing only food or nonfood components. Participants (N = 24) assessed the perceived dominance of a target odor within an odor mixture. Response times to all odors increased toward the dilution series' midpoint and were faster for food odor compared to nonfood odor mixtures. Perceived target dominance increased linearly for nonfood targets but exhibited a sigmoidal shape with a steeper slope (smaller just-noticeable difference) for food targets. This implies that distinguishing 2 food odors was easier than distinguishing between 2 nonfood odors, likely due to definitions higher relevance of distinct object category boundaries subserving contamination avoidance. At the same time, contamination sensitivity might be lower for nonfoods, allowing for greater tolerance of deviations. Attention did not influence the perception of nonfood but did so for ambivalent food mixtures and when the target was completely absent.