Signal detection theory, the exclusion failure paradigm and weak consciousness--evidence for the access/phenomenal distinction?

Summary

Claims that qualitative difference paradigms reveal phenomenal consciousness without access consciousness are unwarranted. Partial cognitive access, not a total lack, can explain exclusion failure results. The Objective Threshold/Strategic model relies on a problematic 'enable' approach that denies intentional control of unconscious perception. Qualitative difference paradigms may only index a subset of access consciousness, so they cannot isolate phenomenal consciousness, and attempts to do so face serious methodological problems.

Study at a glance

Abstract

Block [Block, N. (2005). Two neural correlates of consciousness. Trends in Cognitive Science, 9, 46-52] and Snodgrass (2006) claim that a signal detection theory (SDT) analysis of qualitative difference paradigms, in particular the exclusion failure paradigm, reveals cases of phenomenal consciousness without access consciousness. This claim is unwarranted on several grounds. First, partial cognitive access rather than a total lack of cognitive access can account for exclusion failure results. Second, Snodgrass's Objective Threshold/Strategic (OT/S) model of perception relies on a problematic 'enable' approach to perception that denies the possibility of intentional control of unconscious perception and any effect of following different task instructions on the presence/absence of phenomenal consciousness. Many of Block's purported examples of phenomenal consciousness without cognitive access also rely on this problematic approach. Third, qualitative difference paradigms may index only a subset of access consciousness. Thus, qualitative difference paradigms like exclusion failure cannot be used to isolate phenomenal consciousness, any attempt to do so still faces serious methodological problems.