Temporarily Loading Visual Attention Induces Prolonged Inattentional Anosmia

Forster, S, and CJ Spence. 2018. “‘What Smell?’ Temporarily Loading Visual Attention Induces Prolonged Inattentional Anosmia.” Psychological Science, https://ora.ox.ac.uk/objects/pubs:844930

Abstract: Humans have a highly sensitive sense of smell capable of detecting a range of important biological signals. Yet, anecdotal evidence suggests that we commonly fail to notice supra-threshold environmental olfactory stimuli. The determinants of olfactory awareness are, as yet, unknown. Here, we adapted the ‘inattentional blindness’ paradigm, to test whether olfactory awareness is dependent on attention. Across three experiments, participants performed a visual search task with either a high or low perceptual load (a well-established attentional manipulation) while exposed to an ambient coffee aroma. Consistent with our hypothesis, task load modulated olfactory awareness: 42.5% fewer participants in the high (vs. low) load condition reported noticing the coffee aroma. Our final experiment demonstrates that, due to the unique characteristics of olfactory habituation, the consequences of inattentional anosmia can persist even once attention becomes available. These findings establish the phenomenon of inattentional anosmia, and have applied implications for predicting when people may miss potentially important olfactory information.