The Mind ’ s Eye Mapped Onto the Brain ’ s Matter

Research on visual mental imagery has been fueled recently by the development of new behavioral and neurosci-entific techniques. This review focuses on two major topics in light of these developments. The first concerns the extent to which visual mental imagery and visual perception share common psychological and neural mechanisms; although the research findings largely support convergence between these two processes, there are data that qualify the degree of overlap between them. The second issue involves the neu-ral substrate mediating the process of imagery generation. The data suggest a slight left-hemisphere advantage for this process, although there is considerable variability across and within subjects. There also remain many unanswered questions in this field, including what the relationship is between imagery and working memory and what representa-tional differences, if any, exist between imagery and perception. Consider sitting in your office and answering the question " How many windows do you have in your living room? " To decide how to answer, you might construct an internal visual representation of your living room from the stored information you possess about your home, inspect this image so as to locate the windows, and then count them. This type of internal visual representation (or " seeing with the mind's eye "), derived in the absence of retinal stimulation, is known as visual mental imagery, and is thought to be engaged in a range of cognitive tasks including learning, reasoning, problem solving , and language. Although much of the research on mental imagery has been concerned specifically with visual mental imagery, and hence the scope of this review is restricted to this topic, similar internal mental representations exist in the auditory and tactile modalities and in the motor domain. The past decade has witnessed considerable progress in our understanding of the psychological and neural mechanisms underlying mental imagery. This is particularly dramatic because, in the not-too-distant past, during the heyday of behaviorism, discussions of mental imagery were almost banished from scientific discourse: Given that there was no obvious way of measuring so private an event as a mental image and there was no homunculus available for viewing the pictures in the head even if they did exist, the study of mental imagery fell into disrepute. Indeed, through the 1940s and 1950s, Psychological Abstracts recorded only five references to imagery. The study of mental imagery was revived in the 1970s, through advances such as the experiments of …