Sunday, February 12, 2012

Talis Bachmann - A Mechanism that Leads from Pre-conscious Content to Conscious Experience

This interesting article comes from Frontiers in Consciousness Research - and it is open access, so free for all to read. Bachmann looks at the relationship between attention and consciousness and the tendency for researchers to see these functions as interdependent (attention is necessary for consciousness) or as completely unrelated. She sees it as more complex: "attention can have both facilitative and adverse effects on the phenomena of consciousness."

There is a lot of perceptual science employed to examine our attentional skills, and the sheer number of references is daunting, but this is an excellent article - especially for those who are interested in the neuroscience of attention and how that impacts our consciousness (or can increase our consciousness through contemplative practices).

Attention as a process of selection, perception as a process of representation, and phenomenal experience as the resulting process of perception being modulated by a dedicated consciousness mechanism

  • Department of Psychology and Institute of Law, University of Tartu, Tartu, Estonia
Equivalence of attention and consciousness is disputed and necessity of attentional effects for conscious experience has become questioned. However, the conceptual landscape and interpretations of empirical evidence as related to this issue have remained controversial. Here I present some conceptual distinctions and research strategies potentially useful for moving forward when tackling this issue. Specifically, it is argued that we should carefully differentiate between pre-conscious processes and the processes resulting in phenomenal experience, move the emphasis from studying the effects of attention on the modality-specific and feature-specific perception to studying attentional effects on panmodal universal attributes of whatever conscious experience may be the case, and acknowledge that there is a specialized mechanism for leading to conscious experience of the pre-consciously represented contents autonomous from the mechanisms of perception, attention, memory, and cognitive control.
Citation: Bachmann, T. (2011, Dec). Attention as a process of selection, perception as a process of representation, and phenomenal experience as the resulting process of perception being modulated by a dedicated consciousness mechanism. Front. Psychology 2:387. doi: 10.3389/fpsyg.2011.00387

Here is a little bit from the introduction, where she sets up the problem she examines in this article - i.e., that consciousness and attention have been treated as interdependent (we need attention to experience consciousness) when, in fact, they are not, in her opinion. She offers seven examples of why that link is specious, then she offers four reasons for why the controversy continues.


In terms of subjective intentionality, unity and integration consciousness is panmodal or supramodal, but in terms of qualitative informational contents consciousness can be modally and intra-modally varied, selective and specific (Metzinger, 1995; Searle, 1997; Koch, 2004; Tononi, 2010). Consciousness has its contents in the form of feelings and sensations, perceptions, memories, and imagery dynamically representing external and/or internal environment in subject’s experience. The representational contents can be processed by brain unconsciously or pre-consciously and only part of the processed perceptual- or memory-contents reach the status of being phenomenally/explicitly experienced (Dixon, 1981; Greenwald et al., 1996; Kinoshita and Lupker, 2003; Goodale and Milner, 2004; Dehaene et al., 2006; Dijksterhuis and Nordgren, 2006; van Gaal and Lamme, 2011). But what is the mechanism of consciousness? In the current debate the main question is: whether consciousness necessarily depends on the mechanism(s) of attention or can consciousness-level representation is possible without attention being applied. Increasingly more specialists, departing from theoretical arguments and empirical data accept that attention and consciousness are separate and different, however possibly interacting (e.g., Baars, 1997b; Hardcastle, 1997; Lamme, 2003; Bachmann, 2006; Koch and Tsuchiya, 2007; van Gaal and Fahrenfort, 2008; Wilimzig et al., 2008; Tsuchiya and Koch, 2009; Brascamp et al., 2010; van Boxtel et al., 2010a,b). Why this twist away from the earlier dominating views that consciousness needs attention? In what follows I will list the arguments in favor of attention and consciousness being dissociable, discuss why the controversy over the present issue persists, and suggest some steps for moving forward in a less confusing way.

Why it Can be Said that Attention is not the Basis for Consciousness

There are many reasons for seeing why attention is not necessary for consciousness. First, maximum concentration of attention does not guarantee consciousness of a stimulus that is the focus of attention. In metacontrast masking, binocular rivalry, visual crowding, motion-induced blindness (MIB), and some other experimental phenomena of consciousness (Kim and Blake, 2005; Bachmann et al., 2011) loss of conscious experience of a target-stimulus is inevitable despite of the maximum attempts to attend to it. Binocular rivalry is perhaps the most used and discussed paradigm here.

Some recent work claiming that attention is necessary for binocular rivalry presents questionable evidence and conclusions – e.g., Zhang et al. (2011). Frequency-tagged brain responses were induced for rivalrous stimuli with the effect that for the unattended stimulus this response was weak. However, the frequency-tagged brain response did not disappear under inattentional conditions but was simply weakened. The correlation between frequency-tagged brain response and attentional condition is not a proof of a causal relation; this is especially if it is not sure that frequency-tagged EEG signature is a valid NCC. Data and discussion presented by Roeber et al. (2011) points to the controversy over electrophysiological signatures as fully reliable NCC and also reinstates that rivalry continues while attention is diverted from the competing stimuli.

Second, selective attention mechanisms are effective in improving processing of unconscious information. In many cases the nature and relative extent of the effect is comparable to those when attention improves processing of the consciously experienced stimuli. For example, attention can improve unconscious processing by augmenting priming effects or ERP components associated with pre-conscious processing (Jaśkowski et al., 2002; Naccache et al., 2002; Bahrami et al., 2007; Custers and Aarts, 2011). Conversely, unconsciously processed stimuli influence conscious attention and attention and awareness effects may be independent (Lambert and Shin, 2010; Schmidt and Schmidt, 2010; Hsieh et al., 2011; Hsu et al., 2011; Most and Wang, 2011; Tapia et al., 2011). The main difference is that in one case selective attention works on unconscious information and in the other case on consciously experienced information.

Third, attention can select between stimuli that are already, and to an equal extent, consciously perceived. Equally phenomenally salient perceptual objects precede attentional selection. Fourth, research shows that conscious awareness has specialized brain mechanisms of its own that are not the very mechanisms of selective attention (Purpura and Schiff, 1997; Jones, 2001; Koch, 2004; Ribary, 2005; Tsubomi et al., 2011). Experimental work has also shown that electrophysiological signatures of the effects of attention and awareness, especially when studied by the contrastive methods, can be different or independent (Kiefer and Brendel, 2006; Wyart and Tallon-Baudry, 2008; Aru and Bachmann, 2009a,b; Busch et al., 2009; Britz and Pitts, 2011).

The fifth argument derives from the experiments showing that in some specific conditions attention has an adverse effect on conscious experiences (Lou, 2001; Tsuchiya and Koch, 2009; Rahnev et al., 2011). Voluntary covert attention to color afterimage, afterimage of spatially modulated contrast, or spatially localized motion aftereffect tends to speed up their decay from awareness (Lou, 2001; Suzuki and Grabowecki, 2003; Wede and Francis, 2007; Bachmann and Murd, 2010; van Boxtel et al., 2010a; Murd and Bachmann, 2011). Sixth, some aspects of a scene such as the gist or animated objects can be explicitly noticed without attention and without compromising the competing focused attention task (van Boxtel et al., 2010b; see, however, Cohen et al., 2011). Seventh, consciousness-level sentience can in principle emerge spontaneously and without a preset selective attention. The typical cases are waking from sleep where one does not pay attention to the need to wake up now (while in sleep, we do not decide to begin attending to the environment) or involuntary hallucinating or tinnitus-like experiences.

On the other hand, nobody denies strong and very common examples where attention facilitates conscious experiences and often is the sine qua non-condition for conscious perception. These examples come from the phenomena of spatial and object attention, divided attention, prior entry, change blindness, inattentional blindness, working-memory analysis, understanding a demanding intellectual problem, etc. (Mack and Rock, 1998; Posner, 2004; Lavie, 2006; Srinivasan, 2007; Carrasco, 2011). Thus why the controversy over attention versus consciousness continues?
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