Attention and consciousness/opposite effects
Can top-down attention be opposed to consciousness?
Attention enhances neuronal processing, yet, it sometimes impairs performance of the task
Attention and its neuronal correlate can be understood in the context of selection and biased competition (Desimone and Duncan, 1995): attention acts as a winner-take-all, enhancing one coalition of neurons (representing the attended object) at the expenses of others (non-attended stimuli) (Lee et al., 1999). Paradoxically though, reducing attention can enhance awareness (Olivers and Nieuwenhuis, 2005) and certain behaviors (Reber, 1976; Wong and Weisstein, 1983; Yeshurun and Carrasco, 1998; Beilock et al., 2002).
In the Rubin’s ambiguous face/vase figure (see Attention and Consciousness/How to manipulate and measure visual consciousness), the percept switches between two faces seen in profile and a vase. Discrimination of high-frequency stimuli, such as a line, presented on the face area when it is perceived as the figure is better than when it is perceived as the ground. If a blurred, low spatial frequency stimulus is presented in this region, it is better discriminated when the face is perceived as the ground. Something similar occurs when the target stimulus is presented on the vase area. In other words, a low spatial frequency stimulus is better detected on the unattended ground (Wong and Weisstein, 1982, 1983). Likewise, Yeshurun and Carrasco (Yeshurun and Carrasco, 1998) showed that attention impairs the performance of texture segregation when the subject is required to process low spatial frequency information.
Opposing effects of attention and consciousness
Note that a complete orthogonal manipulation of attention and consciousness has not been performed in any of the following examples.
Attention weakens afterimages, visibility enhances afteriamges
Consider the formation of afterimages (Fig.<ref>F1</ref>). If an item is attended during adaptation, the intensity of the subsequent afterimage becomes weaker and its duration shorter compared to an unattended item(Lou, 2001; Suzuki and Grabowecky, 2003; Wede and Francis, 2007). If, however, the image is suppressed during adaptation, the afterimage is substantially weakened (Gilroy and Blake, 2005; Tsuchiya and Koch, 2005). Thus, focal attention and consciousness have opposing effects (Tsuchiya, 2006).
|Adaptor invisible||Adoptor visible|
|Inattention to adaptor||Weaker afterimages (?)||Strong afterimages (++)|
|Attention to adaptor||Weakest afterimages (--)||Weak afterimages (+)|
Speed of perceptual switches is modulated by attention and visibility of bistable stimuli
Next, consider freezing in bistable perception (Fig.<ref>F2</ref>) (Orbach et al., 1963; Leopold et al., 2002). During continuous viewing of an ambiguous stimulus, the percept flips stochastically. Yet if the bistable figure is briefly removed (leaving the display empty), the dominant percept at the start of the new display is the same as the one when the percept disappeared. This freezing is disrupted if spatial attention is distracted from the empty display(Kanai and Verstraten, 2006), most likely by disrupting memory buildup. This can be thought of as speeding up perceptual switching. Yet distracting focal attention during bistable perception slows down the switching rate (Paffen et al., 2006; Pastukhov and Braun, 2007). In other words, withdrawing focal attention when the stimulus is invisible, not consciously seen, disrupts perceptual freezing, while withdrawing attention when the stimulus is visible slows down switching.
|Rivalry invisible||Rivalry visible|
|Inattention to rivalry|| Faster switches,
less freezing (-)
|Slower switches, more freezing (+)|
|Attention to rivalry||Slower switches, more freezing (+)||Faster switches, less freezing (-)|
Opposing effects of attention and consciousness in decision making
Finally, consider complex decision-making (Fig.<ref>F3</ref>). The Dijksterhuis’ (Dijksterhuis et al., 2006) study consisted of three phases: examination of items, deliberation, and decision. One of either 4 or 12 properties for each of 4 cars was shown one at a time during the examination phase. Subjects then deliberated for several minutes without the attributes being visible (that is, subjects had to remember them; this can be thought of as an ‘invisible’ condition) before making a purchasing decision. Dijksterhuis and colleagues manipulated whether or not subjects were cognitively engaged during the deliberation period. They concluded that when faced with working memory overload, an explicit strategy based on deliberate and rational thought leads to poor decision making for a complex decision, while distracting subjects when they decide which car to buy greatly increased the probability of a correct choice. We surmise that if the list of items would have been present throughout the decision-making period – thereby reducing working memory load – an attentional distracting task would degrade purchasing performance. For a related finding in implicit learning, see (Reber, 1976).
|List invisible||List visible|
|Inattention to decision making||Better decision (+)||Worse decision (?)|
|Attention to decision making||Chance performance (-)||Best decision (?)|
- Beilock SL, Carr TH, MacMahon C, Starkes JL (2002) When paying attention becomes counterproductive: impact of divided versus skill-focused attention on novice and experienced performance of sensorimotor skills. J Exp Psychol Appl 8:6-16.
- Desimone R, Duncan J (1995) Neural mechanisms of selective visual attention. Annu Rev Neurosci 18:193-222.
- Dijksterhuis A, Bos MW, Nordgren LF, van Baaren RB (2006) On making the right choice: the deliberation-without-attention effect. Science 311:1005-1007.
- Gilroy LA, Blake R (2005) The interaction between binocular rivalry and negative afterimages. Curr Biol 15:1740-1744.
- Kanai R, Verstraten FA (2006) Attentional modulation of perceptual stabilization. Proc Biol Sci 273:1217-1222.
- Koch C, Tsuchiya N (2007) Attention and consciousness: two distinct brain processes. Trends Cogn Sci 11:16-22.
- Lee DK, Itti L, Koch C, Braun J (1999) Attention activates winner-take-all competition among visual filters. Nat Neurosci 2:375-381.
- Leopold DA, Wilke M, Maier A, Logothetis NK (2002) Stable perception of visually ambiguous patterns. Nat Neurosci 5:605-609.
- Lou L (2001) Effects of voluntary attention on structured afterimages. Perception 30:1439-1448.
- Olivers CN, Nieuwenhuis S (2005) The beneficial effect of concurrent task-irrelevant mental activity on temporal attention. Psychol Sci 16:265-269.
- Orbach J, Ehrlich D, Heath HA (1963) Reversibility of the Necker Cube. I. an Examination of the Concept of "Satiation of Orientation". Percept Mot Skills 17:439-458.
- Paffen CL, Alais D, Verstraten FA (2006) Attention speeds binocular rivalry. Psychol Sci 17:752-756.
- Pastukhov A, Braun J (2007) Perceptual reversals need no prompting by attention. Journal of Vision.
- Reber (1976) Implicit Learning of Synthetic Languages: The Role of Instructional Set Journal of Exp Psych: Human Leaning and Memory 2:88-94.
- Suzuki S, Grabowecky M (2003) Attention during adaptation weakens negative afterimages. J Exp Psychol Hum Percept Perform 29:793-807.
- Tsuchiya N (2006) Attention and Awareness: Visual Psychophysics and Aversive Conditioning in Humans. Ph.D. Thesis, California Institute of Technology, Pasadena, California.
- Tsuchiya N, Koch C (2005) Continuous flash suppression reduces negative afterimages. Nat Neurosci 8:1096-1101.
- Wede J, Francis G (2007) Attentional effects on afterimages: Theory and data. Vision Res 47:2249-2258.
- Wong E, Weisstein N (1982) A new perceptual context-superiority effect: line segments are more visible against a figure than against a ground. Science 218:587-589.
- Wong E, Weisstein N (1983) Sharp targets are detected better against a figure, and blurred targets are detected better against a background. J Exp Psychol Hum Percept Perform 9:194-201.
- Yeshurun Y, Carrasco M (1998) Attention improves or impairs visual performance by enhancing spatial resolution. Nature 396:72-75.