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Lecture 8

PSYB51H3 Lecture Notes - Lecture 8: Zoom Lens, Frontal Lobe, Superior Temporal Gyrus

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Matthias Niemeier

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Perception and Cognition
Week 8 – July 3 rd
, 2015
Early vs. late selection
oStream of information from earlier stages up to higher-level brain areas (several synapses) up to
executive functions (structures embedded in frontal cortex).
Metaphor of pipelines.
oEarly selection or early with adaptable filter system.
oLate selection:
Even semantic processes can remain unattended/unconscious.
Although you’re told to do something you pay attention to something else.
E.g., being told to listen to a sentence in the left ear yet process language in the
right ear.
oMultilevel filtering
oPerceptual (or cognitive) load:
E.g., every time you see ‘X’ you have to push a button, but not when you see ‘O”.
Higher perceptual load if it’s X’s and N’s.
“Spotlight” (or search light) model: attention is confined to a coherent region of space and can move
from one point to the next.
“Zoom lens” model: attention expands from fixation… grows to fill whole region… shrinks to include just
cued location.
oCan have a wide scope of attention and/or a very narrow scope of attention.
oProblems with spotlight and zoom lens models:
Attention shifts rather instantly.
Attention can split into more than one focus; not necessarily coherent region in space.
E.g., fMRI experiment
E.g., Multiple object tracking (tracking 4 dots)
Biased-competition model of attention:
oCompetition: stimuli in the visual field compete for limited processing capacity and control of
behavior (e.g., overlap in RFs).
More information entering the brain at the same time than can be processed.
Purpose of bottlenecks.
Stimuli presented simultaneously compete more than sequential stimuli.
oBias: competition biased towards certain stimuli depending on:
a) Bottom-up bias: salience (e.g., brighter, lighter, louder, etc. than something else
– higher contrast).
b) Top-down bias (e.g., instructions, spatial cues, feature cues).
Attention to one of the stimuli (vs. attention to fixation point) “overcomes” the
Pre (oculo) motor theory of attention:
1) Strict link between orienting of attention (covert attention) and programming explicit ocular
movements (overt attention).
2) Attention is oriented to a given point when the oculomotor program for moving the eyes to this
point is ready to be executed.
3) Covert orienting of attention (w/o eye movements) is achieved by inhibiting the execution of the
eye movement itself.
Can you shift attention w/o moving your eyes? SURE!
Can you move your eyes w/o shifting attention? NO!
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