Abstract
In complex natural environments, the ability to simultaneously attend to multiple sensory modalities and distinguish relevant information from irrelevant is essential for adaptive behavior. For example, deciding what to eat in a crowded street market may require attending to the sights, sounds, and smells of potential options. Divided attention tasks are an effective experimental model of multisensory processing. However, these tasks tend to utilize only two modalities, almost exclusively involving auditory and visual domains. By comparison, the olfactory modality has received less focus despite being a significant part of daily sensory experience. Here we designed a study in which human participants (n = 50) experienced simultaneous presentation of odors, visual images, and sounds in a multisensory divided attention task. On each trial, prior to stimulus presentation participants were cued to attend to one, two, or all three modalities, and then after stimulation were probed on the specific identity of one of the attended modalities. Interestingly, we found that performance was significantly above chance in all attention conditions, with significantly decreased accuracy in any condition with olfactory attention. Additionally, increasing the modalities attended did not have a negative impact on performance — in fact, the opposite was true for unimodal and bimodal conditions. These results indicate that humans have the capacity to simultaneously attend to auditory, visual, and olfactory information in multisensory conditions, with decreased accuracy for olfactory stimuli.