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Lecture

Psychology 3325 Lecture Notes - Visual Cortex, Positron Emission Tomography, Sensory System


Department
Psychology
Course Code
Psychology 3325
Professor
John Usher

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Brain Mechanisms of Selective Attention
possible explanation for selective attention is that some components of brain's sensory system
are temporarily sensitized, which enhances their ability to detect particular categories of
stimuli
eg. if person were watching shape we would see increased acitvity in portion of visual
cortex devoted to analysis of shape
Corbetta had people look at computerized display containing 30 colured rectangles which
could change in shape, colour, or speed of movement and ask them to pay attention to one
attribute (same display every time)
used PET scanner to measure brain activity and found that paying attention to different
attributes caused different appropriate regions of visual cortex to be activated
Luckm, Chelazzi, Hillyard and Desimone obtained similar results in study using monkeys
recorded activity of single neurons in visual association cortex
when cue indicated that monkey should be watching for stimulus to be presented in
particular location, neurons that received input from that visual field fired more rapidly
even before stimuli was presented neurons were primed for detecting stimulus in their
part of visual field
Biology and Culture: Control of Consciousness
expectations and customs of society substantially influence effects that drugs have on
person's consciousness
can alter, expand or escape own consciousness without use of drugs
function that all methods of changing consciousness have in common is alteration of attention
various exercises can be divided into those that withdraw attention from stimuli around us
and those that increase attention to events that have become so commonplace that we no
longer notice them exercises called meditation
Techniques for withdrawing attention:
goal of most meditation exercises is to remove attention from all sensory stimuli to think of
nothing
direct attention to specific object, spoken of imagined word or phrase, monotonous sound, or
to repetitive movement by doing this we learn to ignore other stimuli
two primary goals: to reduce verbal control over non-verbal functioning of brain and to
produce afterwards a rebound phenomenon - heightening of awareness and an increase in
attention (conscious increasing exercises)
Techniques for Increasing and Dishabituating Consciousness:
habituation to most stimuli in our environment enables us to concentrate on stimuli that are
important to survival
techniques for reducing awareness help reduce habituation
easiest way to reduce habituation and automatic functioning is to encounter novel stimuli, do
things differently, do something dangerous or something that demands skill and coordination,
or remove oneself from world temporarily suppressed attention mechnisms rebound
Consciousness and the Brain
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