1Objects are the fundamental building blocks of how we create a representation of the external 2 world. One major distinction amongst objects is between those that are animate versus 3 inanimate. Many objects are specified by more than a single sense, yet the nature by which 4 multisensory objects are represented by the brain remains poorly understood. Using 5 representational similarity analysis of human EEG signals, we show enhanced encoding of 6 audiovisual objects when compared to their corresponding visual and auditory objects. 7Surprisingly, we discovered the often-found processing advantages for animate objects was not 8 evident in a multisensory context due to greater neural enhancement of inanimate objects-the 9 more weakly encoded objects under unisensory conditions. Further analysis showed that the 10 selective enhancement of inanimate audiovisual objects corresponded with an increase in shared 11representations across brain areas, suggesting that neural enhancement was mediated by 12 multisensory integration. Moreover, a distance-to-bound analysis provided critical links between 13 neural findings and behavior. Improvements in neural decoding at the individual exemplar level 14 for audiovisual inanimate objects predicted reaction time differences between multisensory and 15 unisensory presentations during a go/no-go animate categorization task. Interestingly, links 16 between neural activity and behavioral measures were most prominent 100 to 200ms and 350 to 17 500ms after stimulus presentation, corresponding to time periods associated with sensory 18 evidence accumulation and decision-making, respectively. Collectively, these findings provide 19 key insights into a fundamental process the brain uses to maximize information it captures across 20 sensory systems to perform object recognition.
Significance Statement 1Our world is filled with an ever-changing milieu of sensory information that we are able to 2 seamlessly transform into meaningful perceptual experience. We accomplish this feat by 3 combining different features from our senses to construct objects. However, despite the fact that 4 our senses do not work in isolation but rather in concert with each other, little is known about 5 how the brain combines the senses together to form object representations. Here, we used EEG 6 and machine learning to study how the brain processes auditory, visual, and audiovisual objects. 7Surprisingly, we found that non-living objects, the objects which were more difficult to process 8 with one sense alone, benefited the most from engaging multiple senses.