Cognition - Selective Attention

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Selective Attention - Metaphors of attention

Attention as a mental process

  • Concentrating effort into a stimulus or mental event (thought)
  • The process by which we actively process information in the sensory registers (sensation caused by light hitting the eyes, in the case of perception)

Attention as a limited mental resource

  • Attention as a kind of fuel/mental energy that powers cognition.
  • It gets used up when we pay attention.
  • Attention is limited - there are limits to our attention - to the amount of information we can pay attention to at once.
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Why is attention necessary?

We are constantly presented with information from the external word:

  •  Audition: Numerous overlapping sounds simultaneously reach your ears. The busy street, the conversation in the noisy pub.
  • Vision: Complexity and information overload characterize most visual environments.
  • Your own thoughts: Even what you are thinking competes for your attention.

Our attentional capacity is severely limited - there is only so much we can attend to at one time - effective selection of information is critical.

Various factors impact on our ability to divide attention (practice, automaticity of the task in question). Effectively dividing your attention is also critical, as is knowing the limitations.

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Selective attention - How much do we hear?

We are constantly subjected to different sounds simultaneously - sometimes we have to focus on a singular point, whilst the rest of the stimulus being subjected towards us. 

Some kind of filtering is needed to select the important information and filter out the unimportant information. 

Cherry (1953) - Cocktail party problem 

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Auditory selective attention - Dichotic listening

Early studies - Shadowing task

  • Participants hear a recording of someone speaking delievered to one ear and must repeat this speech back while they are listening to it (the attended channel).
  • At the same time, a second message is played to the other ear, which is to be ignored (the unattended channel).
  • This overall setup is called dichotic listening.

Typical outcome: High performance in attended channel;normally little recall in unattended channel.

> Cherry (1953)

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ASA: The fate of unattended information

The fate of unattended information: Treisman (1964)

  • Participants shadowed coherent prose in the attended channel, but were presented with a text in Czech, read with an english accent in the unattended channel.
  • The individual sounds resemble English, but the message is in gibberish.

Results:

  • Good shadowing - 4/30 noticed the unattended channel (after 1 minute) was peculiar. This shows that we process little else when attention is attended.

Some characteristics of the unattended channel were recognized - participants would be able to pick up the physical characteristics, but do not process the semantics.

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ASA - Cherry, 1953

  • Participants can report the physical characteristics of the voice in the unattended channel (speaker sex, voice, pitch, voice loudness). 
  • Even if the semantic content is not processed to any degree. 
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ASA: When information breaks through - Moray, 1959

Shadowing task with participants name embedded in the unattended channel.

  • Overall, participants heard very little of the unattended message, in keeping with the other studies. 
  • However, 1/3 heard their own name!
  • Implication: Some bits of the unattended (semantic) input seem to leak through. 
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ASA: The cocktail party effect

  • These results are often referred to under the banner of the cocktail party effect.
  • Other stimuli you might notice in an unattended channel:
  • 1) Mention of a movie you just saw
  • 2) Mention of your favourite restaurant

We generally notice things of personal importance in the unattended channel.

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ASA: Summary

  • Attention mediates to a great extent what we hear of the external world.
  • When our attention is focused on one stream of information we hear remarkably small amounts of the unattended information.
  • This demonstrates our limited capacity of attention.
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Visual Selective Attention

Limitations of visual selective attention

  • Visual selective attention has been likened to a torch beam (Spatial attention; Posner, 1980).
  • Information that falls under the beam is processed with priority.
  • Information outside of the beam recieves far less processing.

Metaphors of visual attention

  • Spotlight
  • Zoom lens
  • Multiple spotlights.
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VA: Change blindness

Rensink, O'Regan & Clark, 1997

  • Pairs of pictures separated by a brief blank interval.
  • Identical except for some single aspect that is missing in one picture but present in the other. 

Characteristics

  • If the change involves something central to the scene, observers may need as many as a dozen alternations between the pictures before they detect the change.
  • If the change involves some peripheral aspect of the scene, then as many as 25 alternations are required. 

Implication

  • We see far less of a visual scene than we think we do in the absence of attention.
  • Highlights aagain the limited capacity of attention - we cannot attend to everything!
  • These studies demonstrate failure to detect changes we are looking for.
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VA: Inattentional blindness

Mack and Rock (1998)

  • Participants presented with a large '+' for 200ms followed by a pattern mask.

Task

  • Indicate which bar was longest, using two response buttons.
  • Maintained central fixation throughout the experiment and the '+' was shown off to one side.

Results

  • Performance at detecting line length: 78% accuracy.
  • But - on trial 4, while the target cross was on screen, the fixation target disappeared and was replaced by one of three shapes - a triangle, a rectange or a cross.
  • Immediately after the trial: asked if anything different had happened during this trial:
  • > 89% noticed no change. Failed to see anything else.
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VA: Inattentional blindness

Mack and Rock (1998)

  • To probe the participants further; told that a shape had replaced the fixation cross.
  • They were then asked what shape they had seen out of a triangle, rectangle or cross.
  • Found: responses were random - participants had not seen the shape that had been directly in front of their eyes!
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Inattentional blindness

  • Mack and Rock (1998): as participants were not expecting any shapes to appear they were not prepared - their attention was elsewhere (judging the lines).
  • Shapes not seen although in plain sight.

Implication - what we see if dramatically diminshed in the absence of attention. Again, this demonstrates our limited amount of attentional resources. 

Moore and Egeth (1997)

  • Participants shown displays containing two horizontal ines surrounded by a pattern of black dots - asked 'which line is longest?'. 
  • First three trials: Background dots were random. 
  • On trial 4, the pattern of dots formed a figure like the muller-lyer. 
  • Participants did not percieve the dot pattern.
  • Asked after the trial to decide which dot pattern there had been from 4 choices, 90% got it wrong. 
  • Finding 1 - Replicates inattentional blindess. Finding 2 (muller lyer): 95% participants reported line 2 as longer. 
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Inattentional blindness

  • Mack and Rock (1998): as participants were not expecting any shapes to appear they were not prepared - their attention was elsewhere (judging the lines).
  • Shapes not seen although in plain sight.

Implication - what we see if dramatically diminshed in the absence of attention. Again, this demonstrates our limited amount of attentional resources. 

Moore and Egeth (1997)

  • Participants shown displays containing two horizontal ines surrounded by a pattern of black dots - asked 'which line is longest?'. 
  • First three trials: Background dots were random. 
  • On trial 4, the pattern of dots formed a figure like the muller-lyer. 
  • Participants did not percieve the dot pattern.
  • Asked after the trial to decide which dot pattern there had been from 4 choices, 90% got it wrong. 
  • Finding 1 - Replicates inattentional blindess. Finding 2 (muller lyer): 95% participants reported line 2 as longer. 
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Summary: Moore and Egeth

What does their results mean?

They found that even though participants were completely unaware of the fins, they influenced task performance. 

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