PSYC20007 Lecture Notes - Lecture 7: Fault Tolerance, Saccade, Peripheral Vision
10 May 2018
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Lecture 7
- Early vs Late Selection Debate (1960s)
- Developments from Filter Theory (Broadbent, 1958): attention viewed as a selective filter to
protect a limited-capacity system from overload; argument about what gets through the filter
and where the filter is located
- Summary of Evidence:
- Early Selection Theory - filter before LTM
- → evidence: reduced detection accuracy on unattended channel (Treisman & Geffen,
1967)
- Late Selection Theory - filter after entry to LTM
- → evidence: semantic activation on unattended channel (McKay, 1973; Von Wright,
Anderson & Stenman, 1975)
- Early Selection Reply:
- → Late Selection - semantic activation on unattended channel shown by indirect means
- → Early Selection - doesn’t deny weak activation of semantic material on unattended
channel, indirect measures don’t show it occurs to the same degree
- → ES: [attenuate, turn volume down] weak semantic activation on unattended channel;
LS: brief semantic activation on unattended channel [which rapidly decays unless
associated material is selected by pertinence]; Really possible to distinguish
- → Some phenomena not predicted by either?
- → Shadowing tasks investigate attentional filtering (try to exclude distracting material;
select something relevant and exclude irrelevant stuff; Cherry’s binaural listening task
where he took away sound localising cues → ask people to follow one passage of
speech). Can study divided attention instead.
- → How well can we distribute attention across multiple channels?
find more resources at oneclass.com
find more resources at oneclass.com
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- Cost of Divided Attention (Moray, 1970)
- Auditory signal detection: Pure tone stimuli
- Selective: monitor for targets on one channel only
- Exclusive OR (XOR): monitor both channels, no simultaneous targets; target on left ear or right
ear but never both at once; required to respond to either target on left or right
- Task: to monitor sequence of beeps, larger beep → respond by pressing a buzzer to
indicate detection
- Cost of dividing attention → accuracy drops
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- Inclusive OR (IOR): monitor both channels, simultaneous targets possible; compare
simultaneous targets (AND trials) and non-simultaneous (OR trials); moderate cost of divided
attention (OR < SEL); large cost of simultaneous detection (AND < OR)
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find more resources at oneclass.com
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- Implications of Moray Study: Neither early or late selection could account for both findings
- Early Selection:
- → Predicts OR < SEL because there is attenuation with divided attention
- → Doesn’t predict AND < OR because attenuation shouldn’t depend on identity of
stimulus
- → Target/nontarget distinction made in limited-capacity system, so if filtering occurs
before this, distinction shouldn’t matter
- Late Selection:
- → predicts AND < OR between two simultaneous targets will both be selected by
pertinence and compete to get through filter
- → Doesn’t predict OR < SEL because if there aren’t two targets, expect no competition
- Not consistent with either early or late selection
- Maybe need a new kind of theory
- “trutural ad Capait Theories The 70’s Vie: To as i hih attetio a liit
performance
- Structural (Bottleneck) Theories: some neural structures can only deal with one stimulus at a
time; competitio produes proessig ottleek filter theor, seletie filter; E“:
bottleneck getting into LTM, LS bottleneck getting out
- Capacity (Resource) Theories: Information processing is mental work; work requires activation
of neural structure; limited capacity to activate structure
find more resources at oneclass.com
find more resources at oneclass.com
