Behavioral, neuroimaging, and neuropsychological approaches to implicit perception

For well over a century, the idea that rich, complex perceptual processes can occur outside the realm of awareness has either intrigued or exasperated researchers. Although popular notions of implicit processing largely focus on the practical consequences of implicit perception, the empirical literature has addressed more focused, basic questions: (a) Does perception occur in the absence of awareness? (b) what types of information are perceived in the absence of awareness? and (c) what forms of processing occur outside of awareness? This chapter discusses recent advances in the study of implicit perception, considering the ways in which they do and do not improve on earlier approaches. We contrast the conclusions a skeptic and a believer might draw from this literature. Our review considers three distinct but related classes of evidence: behavioral studies, neuroimaging, and brain-damaged patient case studies. We conclude by arguing that qualitative differences between perceptual mechanisms are interesting regardless of whether or not they demonstrate the existence of perception without awareness.