The Neural Substrates of Conscious Perception without Performance Confounds

Abstract

How does the brain give rise to consciousness? A common approach to addressing this question in neuroscience research involves analyzing differences in neural activity in experimental conditions where consciousness of a stimulus differs. However, unless careful measures are taken, conditions that differ in awareness typically also differ in perceptual task performance, e.g. stimulus detection and discrimination. A large body of research demonstrates that task performance and awareness can dissociate, indicating that they are separate mental processes with separate underlying mechanisms. Thus, task performance looms as a potential confound in consciousness science: computational and neural processes attributed to differences in consciousness may actually be better attributed to correlated but distinct differences in task performance. Here we present an extended exploration of the issue of task performance confounds in consciousness research. We describe the approach of performance matching (i.e. creating experimental conditions that yield identical task performance yet different levels of awareness) as a solution to the problem of performance confounds, and discuss why it is not appropriate to artificially match performance by post-hoc selection of trials (e.g. analyzing correct trials only). We review a growing literature demonstrating matched-performance / different-awareness effects using a variety of experimental designs and discuss signal detection theory models that can both explain extant results and guide the design of future research. Finally, we consider caveats and nuances for performance matching approaches and propose that future research could pool across multiple experimental designs with disjoint sets of confounds to triangulate on the confound-free neural substrates of consciousness.

Spontaneous alpha-band amplitude predicts subjective visibility but not discrimination accuracy during high-level perception

“…That is, stimuli subjectively appear more visible when alpha power is low, despite that fact this appearance does not come with more accurate decisions. If correct, dissociations such as this -between conscious perception and performance -may serve as a useful tool for further examining the neural correlates and behavioral functions of conscious perception while controlling for performance confounds (Lau & Passingham, 2006;Morales et al, 2019;Samaha, 2015)…”

The Neural Correlates of Consciousness

“…accuracy, reaction time, etc. ), such that these are matched across conscious and unconscious conditions is hard to achieve experimentally (Lau 2008;Morales et al 2015;Morales et al 2019). During imaging experiments, prerequisites (e.g.…”

“…In these cases, it is the decreased signal-to-noise ratio elicited by the stimulation conditions rather than the stimulus being unconscious that accounts for the difference in performance capacity. This is why it is crucial to insist that performance capacity is a confound that needs to be controlled for when searching for the NCC (Morales et al 2015;Morales et al 2019). This, of course, is not to deny consciousness has some function; although it does invite a rethink of what the functions of consciousness might be (e.g.…”

Among the Two Kinds of Metacognitive Evaluation, Only One Is Predictive of Illusory Object Perception

“…Here, a remark is necessary for why signal detection theory (SDT, e.g., Macmillan & Creelman, 2004) and/or type-2 SDT (e.g., Morales et al., 2019)-based analyses of sensitivity and bias were not used. Essentially, this is predetermined by the ambiguity of what must be considered signal-in-noise if we are measuring subjective experiences of a nonpresented stimulus or feature (Bachmann, 2004; see also Abid, 2019; Rausch et al., 2018, on related matters).…”