Enduring Interest in Perceptual Ambiguity: Alternating Views of Reversible Figures

Research favoring the so-called bottom-up and top-down classes of explanations for reversible figures that dominated the literature in last half of the 20th century is reviewed. Two conclusions are offered. First, any single-process model is extremely unlikely to be able to accommodate the wide array of empirical findings, suggesting that the "final" explanation will almost certainly involve a hybrid conceptualization of interacting sensory and cognitive processes. Second, the utility of distinguishing between 2 components of the observer's experience with reversible figures is emphasized. This distinction between the observer's ability to access multiple representations from the single stimulus pattern ( ambiguity ) and the observer's phenomenal experience of oscillation between those representations ( reversibility ) permits the literature to be segregated into useful categories of research that expose overlapping but distinctive cortical processes.