In consciousness research, phenomenal consciousness (subjective experience) is often distinguished from access consciousness (cognitive availability). Some scientists, notably Ned Block, argue that phenomenal content can exceed what is cognitively accessed—a claim known as 'overflow'. This review examines the evidence and concludes that existing data do not demonstrate overflow. Overflow is theoretically possible but extremely difficult to prove if 'cognitive access' is defined as working memory or attention. However, if 'access' means information becoming 'cognitively available' in a broader sense, then a separation between subjective experience and access is impossible.
The problem of explaining how subjective experiences like colors, sounds, and tastes arise from brain processes is often considered the greatest unsolved mystery. A key question is whether the neural basis of perceptual consciousness is separate from the neural basis of cognitive access mechanisms that allow reporting and reflecting on conscious experiences. This Theme Issue critically discusses current empirical findings, identifies methodological problems, and proposes novel approaches to this central issue in consciousness research.
Phenomenal consciousness cannot overflow the availability of information for action, but it may overflow working memory, which is seen as a surface phenomenon reflecting underlying dynamic strategies. This conclusion comes from the REF (reorganization of elementary functions) framework, a neurocognitive model based on connectionist networks where advanced processing modules called elementary functions reorganize connectivity to form dynamic strategies rather than fixed cognitive functions. The neural correlate of consciousness is understood within these models as tied to such reorganizations, and working memory is influenced by both experience and situational factors.