Inaptitude of the signal detection theory, useful vexation from the microgenetic view, and inevitability of neurobiological signatures in understanding perceptual (un)awareness☆
Introduction
“Subliminal Perception and its Cognates” is by no means a quick read. However if one takes his time and goes into the arguments and explanations presented, it should be concluded that a very important set of theoretical and methodological problems of the so-called subliminal perception issue are dealt with. Matt Erdelyi does this in a way that should not be overlooked or ignored. The relativity and connotativity (instead of the seeming categorical denotativity) of the set of very basic concepts is demonstrated. Adhering to the traditional ways of approaching the problem of conscious versus preconscious perceptual processing is full of pitfalls and rapid theoretical hole-in-ones seem to be impossible, given our present conceptual landscape. (“Traditional” means using concepts like available versus accessible, sensitivity versus bias, absolute versus relative sensitivity, threshold or limen versus criterion value, etc.)
For me, the most important message implicit in Erdelyi’s article is a caution against the prevailing methodological tool in empirical perception and consciousness research—the signal detection theory (SDT). Erdelyi shows its serious limitations and misleading departure points if one wants to use it for research on preconscious (subconscious, subliminal) as contrasted with conscious, cognitive processes. Invoking SDT is equal to bringing behaviorism in disguise in consciousness studies.
In what follows I will comment on the time aspect of processing by adhering to the microgenetic approach, present a Gedanken experiment that stresses the puzzle with SDT, and mention one obvious and simple (in principle), however complex (in practice) way of approaching the puzzle of subliminality.
Section snippets
Microgenesis and subliminality
According to the radical version of the microgenetic hypothesis, each conscious percept unfolds analogously to how the image imprinted into a photographic paper and which is initially invisible develops after the paper has been immersed into developer (Bachmann, 2000). At first there are coarse indistinct regions, then some fragmentary detail emerges, until finally the detailed, rich and more or less full picture has become dominant in perceptual awareness. The fair estimate is that this
Perception of illusory-contoured objects and SDT
Let us imagine that we would like to measure sensitivity of an observer to an object formed by illusory contours. We have a suitable stimulus (e.g., illusory-contoured disc shown in Fig. 1) and an experimental device that allows us to continuously increase and decrease luminance contrast between the inducing elements of the illusory object and the equiluminous background. We intermix trials with actually presented stimulus and “empty trials” and the task is to detect the illusory-contoured
The (neurobiological) way out
It seems that the principal shortcoming of the target article is its shallow reference to the data on preconscious processing versus conscious processing gathered in the most fruitful, combined neuroscientific and psychophysical, research. Respective neurophysiological explanations of preconscious versus conscious processes are quite overlooked. Yet this set of data and theory seems to present the best available evidence and theoretical discussion for providing natural-scientific foundations
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Cited by (9)
It's all in your head: Expectations create illusory perception in a dual-task setup
2018, Consciousness and CognitionCitation Excerpt :We contend that the perceptual experiences of our participants are more akin to hallucinations than to “signal” or “noise” of the SDT. Hence, while we think that SDT can still be useful for understanding objective perceptual detection behavior, we feel that the SDT is not the correct tool for analysing perceptual phenomena generated by expectations, including illusions (see also Bachmann, 2004, on this matter). Eventually new tools and experimental paradigms will be needed for dissociating perceptual phenomena from decision making (see Bang & Rahnev, 2017; Fritsche, Mostert, & de Lange, 2017 for clever experimental manipulations for dissociating perception and decision making).
Measuring consciousness: Task accuracy and awareness as sigmoid functions of stimulus duration
2011, Consciousness and CognitionCitation Excerpt :The awareness ratings above 1 simply reflect these trials, and it might even be possible that the participant experienced a vague illusion of perceiving a stimulus that is not the one presented. It is also possible that top-down influences on perception, rather than simply coincidence, bias the processing of a sensory stimulus in one direction (Bachmann, 2004). In this sense, the fact that awareness ratings are not all ones (i.e. no experience) when the participants are at chance seems logical if one assumes that the same sensory stimulus is not always processed in a same way, and part of the reason for such changes in processing could in principle be changes in either response bias or top-down bias in the perceptual system (causing illusory perception).
Occipital EEG correlates of conscious awareness when subjective target shine-through and effective visual masking are compared: Bifocal early increase in gamma power and speed-up of P1
2009, Brain ResearchCitation Excerpt :This is well justified if we remember that correct registration of and above chance responding to masked stimuli can be executed also when subjects have no direct awareness of them (Morris et al., 1998; Klotz and Neumann, 1999; Dehaene and Naccache, 2001; Moutoussis and Zeki, 2002). ( See also Bachmann, 2004, on how examples of non-veridical, but consciously clear perception may help to question the use of objective behavioral sensitivity-measures for evaluation of the distinctness and clarity of conscious experience.) Therefore, if we would base our conclusions about NCC on correct responding versus incorrect responding comparisons, we may confound unconscious, albeit correct responding with the processes necessary for consciousness.
Subliminality, consciousness, and temporal shifts in awareness: Implications within and beyond the laboratory
2004, Consciousness and CognitionHow to begin to overcome the ambiguity present in differentiation between contents and levels of consciousness?
2012, Frontiers in Psychology
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Commentary on Erdelyi, M. H. (2004). Subliminal perception and its cognates: Theory, indeterminacy, and time. Consciousness and Cognition, 13, 73–91.