Joe Lau's wiki: Courses/2015a2230notes Prinz

Prinz on attention and consciousness

Attention

@Every one knows what attention is. It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. . It implies withdrawal from some things in order to deal effectively with others.^^^William James (1890)@

The spotlight metaphor of attention

• Attention associated with pop-out, search, selection

The AIR theory (Attended Intermediate-level Representation)

@Consciousness arises when and only when intermediate-level representations are modulated by attention.@

@Consciousness arises when and only when intermediate-level representations undergo changes that allow them to become available to working memory.@

• Levels of representation
  • Low-level: disunified low-level features
  • Intermediate: whole objects with surface details and perspectives - like a 3D movie
  • High-level: perspective-independent objects
• What we are conscious of: intermediate-level contents - intermediate level theory of consciousness
• But intermediate-level representations not sufficient for consciousness. Many cases of unconscious perception.
  • Winkielman et al. (2005) - Happy faces followed by masks. "smiles caused thirsty participants to pour and consume more beverage and increased their willingness to pay and their wanting more beverage (Study 2). Subliminal frowns had the opposite effect. No feeling changes were observed, even in thirsty participants."

Another example

• Forster, Booker, Schacter, and Davis (1990) - Unconscious perception of a word influences stem completion.
• WORD1 (eg soup) --> WORD FLASHED (eg elastic, no conscious perception) --> WORD2 (eg chess) --> TASK: complete word stem (eg ela_________)
• Flashing a word increased the likelihood of its being given as a completion, even though subjects reported not being consciously aware of it.

Three lines of evidence

Unilateral neglect

• Unilateral neglect is usually caused by right hemisphere damage from stroke (right inferior parietal cortex). Seems to lack conscious experience of left visual field.
• Contrast: Patients with blindness in left visual field might turn their heads to the left to get a full view.
• Unconscious perception in unilateral neglect: "Marshall and Halligan (1988) presented a neglect patient with two vertically aligned pictures of houses that were exactly the same except one of them had flames shooting out on the left. The patient insisted that the houses were the same, but when asked which one she would rather live in, she chose the one without flames on 9 out of 11 trials."
• Activations include intermediate level visual areas, but not sufficient for consciousness.
• "Standard’ theory of neglect: Attention mechanism in right hemisphere attends to both sides; left hemisphere only controls attention to the right side.
• Proposal: Right hemisphere damage destroys attention to left side resulting in loss of visual awareness of the left visual field. Attention necessary and sufficient for consciousness.
• Normal patients: TMS to attention areas in parietal cortex can induce neglect symptoms (Meister et al., 2006).
• Comments
  • Is it possible that there is phenomenal consciousness but no attention in the neglect field?
  • The explanation assumes the standard theory about the asymmetry of attention. Are there alternative theories?

Attentional blink

https://www.youtube.com/watch?v=MH6ZSfhdIuM

Inattentional blindness

https://www.youtube.com/watch?v=vJG698U2Mvo

Comparison with Baars (1988) Global Workspace Theory

• Prinz : consciousness is information AVAILABLE to working memory, "located in sensory pathways"
• Baars: consciousness is information ACTUALLY within working memory (in the form of global workspace)

Five arguments against Baars

1. Working memory encodes high-level content. Content of consciousness more fine-grained. Color discrimination (1 million colors) more fine-grained than color memories (11-16).
2. Visual experience too complex to be encoded in working memory which has limited capacity.
3. Change blindness - Failing to notice a change shows that there is no encoding in working memory.
   • http://sites.sinauer.com/wolfe4e/wa07.05.html
   • https://www.youtube.com/watch?v=38XO7ac9eSs
   • https://www.youtube.com/watch?v=FWSxSQsspiQ
4. Subliminal perception - Consciously aware of a stimulus but not knowing what it was vs. aware and being able to report. The latter involves encoding in working memory.
5. Hasson et al. (2004) - Watching a movie "showed no significant response in frontal areas".

Objections: attention not sufficient

Kentridge (2004) on GY

• Setup: "They presented GY with an arrow in the center of a screen, followed by either a vertical or horizontal line in one of two locations in his blind visual field. The arrows were visible to him, but the oriented lines were not. At a tone, GY had to guess the orientation of the line he could not see. Kentridge et al. found that his accuracy increased if the line was located in the direction that the arrow was pointing. They concluded that the arrow leads GY to direct attention within his blind field, and it is that attention that facilitates performance. Thus, attention seems to be possible in the absence of consciousness."
• Criticism: Attention to empty space at spatial location X improves subsequent unconscious identification of object at the same location. But this does not imply attention to the object.

Jiang (2006)

• Subjects have to report on the orientation of the stripes in a patch.
• Prinz's response: Better performance due to changes in microsaccades, not attention.
  • Attentional focus need not be the same as gaze direction.
• Convincing? Maybe spontaneous microsaccades do reflect changes in attentional focus here.
• It is possible that attention is necessary but not sufficient.

Objections: attention not necessary

1. Koch: attention not necessary in ganzfeld perception

• Koch: Visual awareness is present during perception of a ganzfeld, but attention is not engaged because there is nothing in the visual field that requires selective attention.
• Prinz: Attention can still be deployed, in scanning different parts of the visual field.

2. Reddy (2006)

• Experiment: "Subjects do not report having clear experiences of the faces, but they do seem to experience something when the faces are flashed. This looks like conscious perception without attention"
• Prinz: But maybe there is some residual attention? Faces tend to pop-out in visual perception and so may capture some amount of attention.

3. Lamme (2003)

• "it seems implausible that any subjects were attending, except perhaps by chance, to the rectangle that was" later being pointed at. The subjects' performance suggests that the rectangle was consciously perceived in the first display.
• Prinz: "Lamme is right that subjects are not attending selectively to each specific rectangle, but he has no grounds for saying subjects are not attending to the full assembly. And consequently, he has no grounds for saying there is consciousness without attention."
• Comment: Can diffused attention over a large area support local object recognition?

The story continues

Video: http://www.youtube.com/v/X2sjKghOTi4