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Lecture

BIO330H5 Lecture Notes - Lateralized Readiness Potential, Bereitschaftspotential, Explicit Memory


Department
Biology
Course Code
BIO330H5
Professor
Dolderman

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Chapter 9: Consciousness
Consciousness as a Social Phenomenon
first position on consciousness is that it is not a natural phenomenon and that it is
supernatural and miraculous not to be understood by human mind
second position is tha consciousness is natural phenomenon but also that we cannot
understand it for various reasons – exists because of nature of human brain
our brains cannot grasp concept
do not have methods to study it yet
poorly defined
third position is that consciousness is produced by activity of brain and that we should
be optimistic about our ability to understand it (Hebb)
The Adaptive Significance of Consciousness
consciousness is awareness of processes in brain, not processes themselves
consciousness does not exist – humans have ability to be conscious
most likley explanation for consciousness lies in its relation to deliberate, symbollic
communicaion – our ability to communicate (words, signs, other symbollic meaning)
provides us with self-awareness --> social phenomenon (like communication)
Consciousness and the Ability to Communicate
through communicating symbolically we can express our needs, thoughts,
perceptions, memories, intentions, and feelings to other people
require 2 general capacities:
must be able to translate private events (needs, thoughts, etc) into symbolic
expressions
brain mechanisms we use to communicate with others must receive input from
systems of brain involved in perceiving, thinking , remembering, etc
our symbols (words) must have effect on other person listening
once words are decoded in listener's brain they must affect listener's own
thoughts, perceptions, memories and behaviour
having both of these capabilities allows us to communicate with ourselves
thinking in words involves subvocal ariculation – brain mechanisms that permit us to
understand words and produce speech are same ones we use to think in words
ability to communicate with ourselves symbolically gives rise to consciousness
conscious of private events we can talk about to others or ourselves: our needs,
perceptions, intentions, memories, and feelings
people who are deaf sometimes think with their hands
people mouth words to themselves
experiment by Cheesman and Merikle – presented people with word (primer) that
was either congruent or incongruent with coloour of subsequent stimulus (target) and
people were asked to name target; between primer and target on some trials there
was random jumble of visual lines
found that incongruent primers produced Stroop-like interference even when
jumble interfered with ability to consciously identify word
presented same experiment with many more congruent than incongruent primes
so that by using primer people could predict what colour was about to come
when primer was consciously perceivable people used it to predict target but when

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it was not consciously perceived people failed to use it
consclusions: we become able to describe and thereby use psychological events
tha are private to ourselves
some animals are conscious – dogs can learn to communicate with owner by
communicating symbolically
underlying brain mechanisms, such as those of explicit memory system may be
present in species closely related to us – behaviour of primates in mirror suggest they
have concept of self-awareness
computer could learn to communicate symbolically with itself and us
Evaluating Scientific Issues: Does Conscious Thought Control Behaviour
previously psychologists would not study consciousness because it was not observable
behaviour – Descartes thought human actions were controlled by non-material mind
(dualism); William James thought emotional awareness came after reaction
recent evidence from cognitive psychology and neuropsychology provides way of
thinking about issue of conscious control of behaviour – some evidence uses
phenomenon of visual illusions
2 crayons – horizontal looks shorter (“top hat illusion” - because it is often
demonstrated using judgments about crown vs brim of hat)
Ganel and Goodalecompared perceptual judgments of object shape with ability
to pick up object and showed people wooden block on table and asked them
whether block was wider or narrow and repeated with different blocks
easy to judge width if blocks are all same length but if length was different then
task was difficult
grasping actions was not affected by variation in length
perceptual awareness of objects may be based on different visual system than one we
use for actions
Ebbinghau illusion – circle surrounded by big circles looks smaller than circle
surrounded by small circles but if you were to reach for them your behaviour would be
unaffected by relative size
introspective experiences would tell us that they were diferent in size but
behaviour would reflect otherwise
thought and action go together but is correlation – could be third action of brain that
causes action and thought
Libet – asked people to make hand motion while watching rapidly moving clock hand
and were to report where clock hand was at time they became aware of an intention
to move
reports indicated that they experienced awareness of intention 3/10 of a second
before motion
also measured “readiness potential” - electrical brain activity of motor cortex prior
to movement
occured about 7/10 of a second before motion
Haggard and Eimer – reasoned that if readiness potential was cause of movement
then it should show covariation in time with awareness
asked participants to move right or left mand and to report when they were aware
of intention to move
looked at occasions where report of awareness was late (closer in time to actual
movement) to see if readiness potential was also late and found that it was not

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also looked at lateralized readiness potential (measures activity specific to side
where movement occurs) and found that it did covary with report of awareness
when awareness was late/early so was lateralized readiness potential
lateralized readiness potential may reflect brain acitvity that leads to awareness about
action – but is specific to one side of cody that moves, which presumably means that it
must follow more general decision to make any movement; may be only part of
sequence of brain activity leading up to conscious awareness
Haggard, Clark, and Kalogeras – looked at awareness of voluntary and involuntary
movement
induced muscle twitches (moved hand) by magnetic impulses delivered through
surface of scalp
watched clock hand spin around dial and reported where hand was when they felt
intention to move or involutnary movement produced by simulation
some trials were operant trials – tone came ¼ of a second after movement and
person was asked to report time of tone
on operant trials – reported times of voluntary movement were late and reported
times of following tone were early: opposite of involuntary trials where reported
time of movement was ealry and reported time of tone was late
people's subjective experience of sequence was that, on voluntary tirals,
movement and tone were close together and on involuntary trials perception was
that they were further apart
brain must bind together experience of voluntary movement with its external
consequences
binding perhaps helps us recognize those external events that are consequences of
our behaviours
Consciousness and Moral Reasoning
Anderson – reported case of 2 individuals who suffered brain damage to prefrontal
area of brain before they were 2 years old
had normal intellectual functioning but no moral or social reasoning
inability to recall social and moral knowledge
history of poor social and moral adjustment
Selective Attention
not conscious of all stimuli detected by our sense organs
selective attention – process that controls our awareness of, and readiness to
respond to, particular categories of stimuli or stimuli in a particular location
sensory memory receives moreinformation than it can transfer into short-term
memory
Sperling – found that although people couldn't remember all letters he flashed, they
could direct their attention to any of 3 lines and identify them with perfect accuracy
process of selective attention determines which events we become conscious of
attention may be controlled automatically (intense stimuli), instructions, or by
demands of particular task we are performing
attention to visual events in particular tends to act like spotlight that highlights events
within some spatially contained area
our attentional mechanisms serve to enhance our responsivness to certain stimuli and
to tune out irrelevant information – determines what is stored in short term memory
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