Theoretical Models of Attention

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Theoretical Models of Attention
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Theoretical Models of Attention
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• Broadbent (1958) conceptualized attention as
  information processing
• Used a cuing paradigm to show that attentional
  selection of one channel dramatically biased
  perception
• Initially believed that unattended inputs were
  filtered out altogether

o
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x
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"Was there an o in the bottom left square?"
"Was there an x in the bottom left square?"
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Early Selection

• Early Selection model postulated that attention
  acted as a strict gate at the lowest levels of
  sensory processing
• Based on concept of a limited capacity bottleneck

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Early Selection

• Early Selection model failed to explain some
  findings
• Shadowing studies found that certain information
  could intrude into the attended stream
• Subjects name, loud noises, etc.

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Late Selection

• Late Selection models postulated that attention
  acted on later processing stages (not sensory)

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Late vs. Early

• Various hybrid models have been proposed
• Early attenuation of non-attended input
• Late enhancement of attended input

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Electrophysiological Investigations of Attention
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Modulation of Auditory Pathways

• The theory is that attention acts as an early
  selection filter
• The prediction is that selective auditory
  attention modulates early responses in the
  auditory pathway
• Hernandez-Peon (1956)
• Electrodes in cats
• Attended tones elicited more rapid spike trains

What was the critical confound?
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Modulation of Auditory Pathways

• Failed to rule out overt orienting
• Cats can orient their ears without moving their
  heads
• Not surprising that auditory responses went up
  when cat swiveled its ears
• Solution was to carefully monitor subjects
  orienting with eye trackers and present stimuli
  through headphones

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Modulation of Auditory Pathways

• Hillyard et al. (1970s) attention effects in
  human auditory pathway using ERP
• Selective listening task using headphones
• Every few minutes the attended side was reversed
• Thus they could measure the brain response to
  identical stimuli when attended or unattended

attending LEFT Ignoring RIGHT
beep beep beep beep boop beep
beep beep beep boop beep beep
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Modulation of Auditory Pathways

• Result ERP elicited by attended and unattended
  stimuli diverges by about 90ms post stimulus
• Long before response is made
• Probably in primary or nearby auditory cortex

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Modulation of Auditory Pathways

• Other groups have found ERP modulation even
  earlier as early as Brainstem Auditory Response
• Probably no robust modulation as low as cochlea
• 40 ms is consistent w/ attention affecting a
  feed forward sweep
• Does focused auditory attention always affect the
  feed forward sweep? What if attention is
  reoriented just before the target occurs?

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Modulation of Auditory Pathways

• Different ways to use attention in space

attending LEFT Ignoring RIGHT
now left, now right, now left, now right
beep beep beep beep boop beep
beep beep beep boop beep beep
beep beep beep beep boop beep
beep beep beep boop beep beep
SUSTAINED
TRANSIENT
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Modulation of Auditory Pathways

• Response times are faster for attended relative
  to unattended targets
• The theory is that transient and sustained
  attention act on auditory pathways the same way

now left, now right, now left, now right
beep beep beep beep boop beep
beep beep beep boop beep beep
TRANSIENT
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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• Three speakers
• Steady stream of tones
• Respond to each tone

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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• Three speakers
• Steady stream of tones
• Respond to each tone

BEEP
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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• Three speakers
• Steady stream of tones
• Respond to each tone

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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• Three speakers
• Steady stream of tones
• Respond to each tone

BEEP
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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• Three speakers
• Steady stream of tones
• Respond to each tone

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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• Three speakers
• Steady stream of tones
• Respond to each tone

BEEP
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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• Three speakers
• Steady stream of tones
• Respond to each tone

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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• Three speakers
• Steady stream of tones
• Respond to each tone

BEEP
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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• We can compare targets preceded by targets at the
  same location with targets preceded by targets on
  the other side

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Modulation of Auditory Pathways

• Transient Attention The Target-Target Paradigm
• We can compare targets preceded by targets at the
  same location with targets preceded by targets on
  the other side
• Does transient attention modulate auditory system
  like sustained attention?

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Modulation of Auditory Pathways

• ERP is markedly different in the two situations!

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Modulation of Auditory Pathways

• ERP is markedly different in the two situations!
• One possibility
• sustained attention allows for attentional
  configuration of sensory cortex to modulate
  feed-forward sweep but
• Transient attention can only modulate recurrent
  processes

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Modulation of Auditory Pathways

• Earliest attention-related component (called the
  Nd1) is over contralateral posterior scalp - not
  primary cortex

Tata Ward (2005)
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Next Time

• Electrophysiology of visual attention
• Read Chellazi paper for the 18th