Top-Down and Bottom-Up Processes in the Perception of Reversible Figures: Toward a Hybrid Model

Summary

Reversible figures such as the Necker cube are ambiguous visual patterns that support at least two markedly different perceptual organizations. During a period of continuous viewing, observers’ conscious experience fluctuates, alternating between the possible interpretations. Attempts to explain this multistable perceptual character of reversible figures traditionally have attributed reversals to either bottom-up (stimulus driven) or top-down (conceptually-driven) processes. In the former case, perceptual fluctuations are attributed to the alternating fatigue and recovery of competing cortical organizations. In the latter case, perception is thought to be analogous to a hypothesis-testing or problem-solving process that successively considers alternative “solutions” to the perceptual puzzle represented by a reversible figure. We argue for a hybrid theoretical framework in which both types of processes contribute to figure reversals. By explicitly recognizing the contributions of both lower-level sensory processes and higher-level cognitive processes, the hybrid approach can resolve apparent conflicts in the reversible figure literature by calling attention to the fact that different viewing conditions can differentially engage top-down and bottom-up processes. The approach also provides a framework for future research, encouraging work that addresses how bottom-up and top-down processes are coordinated and how their effects are integrated in determining conscious perceptual experience.