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INF1-CG 2015Lecture 22

Attention: some laboratory

experiments

1

Richard Shillcock

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Today’s goalsTo look at attention from the perspective of laboratory experiments and to find some computational implications.

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Reading Rensink, R. A., O'Regan, J. K., & Clark, J. J. (1997). To see or not to see: The need for attention to perceive changes in scenes. Psychological Science, 8(5), 368-373.

Simons, D. J., & Rensink, R. A. (2005). Change blindness: Past, present, and future. Trends in Cognitive Sciences, 9(1), 16-20.

http://www.scholarpedia.org/article/Attention

http://www.scholarpedia.org/article/Visual_salience

http://www.scholarpedia.org/article/Saliency_map

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Attention and other sensesAlthough visual attention attracts the most research, other modalities are governed by attention, as in the dichotic listening task, which reveals “filtering” of conflicting input and the role of “higher-level processing”.A particular discourse is spontaneously followed when it switches ears in a dichotic listening task.

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A role for oscillationsFries, Womelsdorf, Oostenveld, & Desimone (2008)

Visual stimulation reduced oscillatory synchronization of V4 neurons in the alpha-frequency band (9-11 Hz) and enhanced gamma-band (30-70 Hz) synchronization.

Rhythmic neuronal synchronization seems to have a role in attention.

This also occurs for the viewing of natural scenes (Brunet et al., 2013).

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Microstructure of attentionMathewson, Gratton, Fabiani, Beck, & Ro (2009)

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Microstructure of attention

Gross electrical activity at certain points determines detection.

Mathewson, Gratton, Fabiani, Beck, & Ro (2009)

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Microstructure of attention

Precise position in the α rhythm (8–10 Hz) seems to determine detectability (first suggested by Lindsley, 1952)

Mathewson, et al. (2011)

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Attention and oscillators

There is pervasive rhythmic activity in the brain.Rhythmic activity in particular bands seems to be one way of organizing processing.Different processing, often far apart in the brain, may be grouped together by oscillating at the same frequency.

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Change blindness and the flicker paradigm

Participants try to spot the change as two very similar images rapidly alternate separated by a blank screen.

They may also be separated by a “mud splash” of briefly presented shapes across the screen.

Rensink et al. (1997)

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Ultra-rapid visual processing

Responding (120 msec) using a saccade to a high-level hemifield target.

(Kirchner & Thorpe, 2006)

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Ultra-rapid visual processing (Kirchner & Thorpe, 2006)

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Ultra-rapid visual processing

Rate coding may be too slow for such responding.

Van Rullen & Thorpe (2001)

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Change detection New et al. (2007)

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Change detection New et al. (2007)

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Computational implications There are implications for the way that the brain uses its resources – lots of rather slow processors (neurons) – in visual processing.

There are implications for the priority given to clues to the presence of important entities (other living creatures) in the visual scene.

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Types of “top down”Engel, Fries & Singer (2001)

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Change blindness Simons & Chabris (1999)

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Change blindness – the door study Simons & Levin (1998)

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Change blindness and slow change Simons, Franconeri, & Reimer (2000)

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Change blindness We have the illusion that the visual world is continually present in all its detail.

Change detection experiments show that we are overwhelmingly geared to change in the world.

If change happens to be (unnaturally) masked, then we need to be attending directly to it in order to notice it.

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Saliency “Salience” just means that something stands out from its background.

It might be salient because of shape, colour, contour, texture, etc. belonging to the image (or because of the viewer’s goals, which would be a top-down effect).

Salience has been attractive as a bottom-up (exogenous) factor in attracting attention.

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Saliency Saliency within an image is typically computed in terms of local change.

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Attention in reading Reading is one activity in which an intense debate has raged regarding the role of attention.

Some models (e.g. SWIFT, by Engbert et al.) compute a saliency map across the text that suggests good landing points for the next saccade.

Other models (e.g. E-Z Reader, by Reichle et al.) have attention as a spotlight that can move onto the next word while the current word is being processed.

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Attention in reading Miellet et al. (2009)

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Attention in reading The Miellet et al. (2009) result is a demonstration using “butterfly” words that one can tease apart simple visual acuity and attention-related effects.

Attention is typically implemented in models of reading in an abstract way.

What would it mean to be less abstract?

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Location- vs. object-based attention Egly, Driver & Rafal (1994)

Cueing is more effective when the target is in the same object, compared with a different object.LH damage impairs switching between objects, RH damage impairs switching between locations.

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Different attentional systems Corbetta & Shulman (2002)

Goal directed – dorsal fronto-parietal.Stimulus driven – RH ventral fronto-parietal.

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Challenges To appreciate the flexibility of attention, in terms of how we think about it.

To see if the neuropsychology can give us some insight into it.

To think what a box labelled “attention” actually is, in a model.

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Secondary referencesMathewson, K. E., Gratton, G., Fabiani, M., Beck, D. M., & Ro, T. (2009). To see or not to see:

prestimulus α phase predicts visual awareness. The Journal of Neuroscience, 29(9), 2725-2732.

Mathewson, K. E., Lleras, A., Beck, D. M., Fabiani, M., Ro, T., & Gratton, G. (2011). Pulsed out of awareness: EEG alpha oscillations represent a pulsed-inhibition of ongoing cortical processing. Frontiers in Psychology, 2, 99. doi:  10.3389/fpsyg.2011.00099

Engel, A. K., Fries, P., & Singer, W. (2001). Dynamic predictions: oscillations and synchrony in top–down processing. Nature Reviews Neuroscience, 2(10), 704-716.

Fries, P., Womelsdorf, T., Oostenveld, R., & Desimone, R. (2008). The effects of visual stimulation and selective visual attention on rhythmic neuronal synchronization in macaque area V4. The Journal of Neuroscience, 28(18), 4823-4835.

Brunet, N., Bosman, C. A., Roberts, M., Oostenveld, R., Womelsdorf, T., De Weerd, P., & Fries, P. (2013). Visual Cortical Gamma-Band Activity During Free Viewing of Natural Images. Cerebral Cortex. doi:10.1093/cercor/bht280

Egly, R., Driver, J., & Rafal, R. D. (1994). Shifting visual attention between objects and locations: evidence from normal and parietal lesion subjects. Journal of Experimental Psychology: General, 123(2), 161–177.

Corbetta, M., & Shulman, G. L. (2002). Control of goal-directed and stimulus-driven attention in the brain. Nature Reviews Neuroscience, 3(3), 201-215.

Rensink, R. A., O'Regan, J. K., & Clark, J. J. (1997). To see or not to see: The need for attention to perceive changes in scenes. Psychological Science, 8(5), 368-373.

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Secondary referencesKirchner, H., & Thorpe, S. J. (2006). Ultra-rapid object detection with saccadic eye movements:

Visual processing speed revisited. Vision Research, 46(11), 1762-1776.

Van Rullen, R., & Thorpe, S. J. (2001). Rate coding versus temporal order coding: what the retinal ganglion cells tell the visual cortex. Neural Computation, 13(6), 1255-1283.

New, J., Cosmides, L., & Tooby, J. (2007). Category-specific attention for animals reflects ancestral priorities, not expertise. Proceedings of the National Academy of Sciences, 104(42), 16598-16603.

Simons, D. J., & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28(9), 1059-1074.

Simons, D. J., & Levin, D. T. (1998). Failure to detect changes to people during a real-world interaction. Psychonomic Bulletin & Review, 5(4), 644-649.

Simons, D. J., Franconeri, S. L., & Reimer, R. L. (2000). Change blindness in the absence of a visual disruption. Perception, 29(10), 1143-1154.

Reichle, E. D., Rayner, K., & Pollatsek, A. (2003). The EZ Reader model of eye-movement control in reading: Comparisons to other models. Behavioral and Brain Sciences, 26(04), 445-476.

Engbert, R., Nuthmann, A., Richter, E. M., & Kliegl, R. (2005). SWIFT: a dynamical model of saccade generation during reading. Psychological Review, 112(4), 777-813.

Miellet, S., O'Donnell, P. J., & Sereno, S. C. (2009). Parafoveal magnification visual acuity does not modulate the perceptual span in reading. Psychological Science, 20(6), 721-728.

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Secondary referencesThe Door study: http://www.youtube.com/watch?v=FWSxSQsspiQ

Slow change study: http://www.youtube.com/watch?v=1nL5ulsWMYc

Gorilla study: http://www.youtube.com/watch?v=vJG698U2Mvo

There are many flicker-paradigm/change-blindness videos available: http://www.youtube.com/watch?v=NSCliuAqIG8