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Lecture

PSYB65H3 Lecture Notes - Two-Streams Hypothesis, Focal And Diffuse Brain Injury, Postcentral Gyrus


Department
Psychology
Course Code
PSYB65H3
Professor
Ted Petit

Page:
of 6
Psyb65 chapter 11
Attention and Consciousness
Attention and consciousness is studied together because attention can mediate conscious
experience.
o Your consciousness of the world is grated by attention
The different ways attention can be defined:
Studying attention:
o William James: attention doesn’t need definition – but he identifies 2 basic features of
attention
1. Selection of sensory info from several simultaneously available inputs
a. They can be sensory but does not have to be
b. It can be directed to internal mental processes
i. This is called “selective attention”
1. To let some information to be processed while ignoring
others
The shifting of attention can occur without adjusting sensory structures,
ex: I can see the letter on my left corner without moving my eyes
2. Selection of mental state
a. Allowing either internal or external flow of info
1. Voluntary attention: one intentionally shifts attention
2. Reflexive attentions: shift occurs in response to external
event
Hermann von Helmholtz studied perception using walls in his laboratory (like those in the
optometrist) he was able to identify the letter at the top right without moving his gaze
Cocktail party effect: the ability to focus one’s listening attention on a single speaker among a
bunch of conversations and background noises
o Cherry: spatial hearing was what divided auditory inputs
o But this is not the case the auditory selective attention is mediated by the
contralateral anterior temporal lobe
Early vs. late selection
Early selection
Attentional selection is quite early (early in the experiment, not in life)
o Ex: in Helmholtz experiment, he was able to remember those letters if he paid
attention to a specific spot before the light
o Its known as early selection encoding and perceptual analysis of an input does not
need to be complete before it is selected or rejected from further processing
The inner ear seems to be more vulnerable to higher perceptual and attentional processes
ERP event-related potential
o Since changes in the ERP take place at the level of the extrastriate visual cortex instead
of primary, therefore the visual system is operated later than the auditory system.
Late Selection
Attention operates after the sensory info has been perceives identified and organized
Semantic level: colors that does not match the word, people are slower at naming the color
There is semantic attention but they fail to attend to these stimuli
How does attention shift?
Voluntary shifts in attention:
Voluntary shifts in attention are the changes that you intentionally make ex: changing the focus
of your attention from one thing to another
o Invalid trial: when the cue is misleading
o Valid trial: when the cue actually leads the target to the correct location
o Neutral trial: the cue does not yield any information about the location of the target
When they are more valid trials than invalid ones, participants learn to anticipate the location of
the target.
o This leads to a reduction in their reaction time, which is a benefit
invalid cues increase average reaction time result in cost of reaction time
Reflexive shifts in attention:
many shifts of attention are not conscious decisions
reflexive changes in attention are usually adaptive
o revolutionary: it helped us survive
but it’s not always useful or adaptive
Exogenous cueing: when the participant is told to do the task in the same way and to ignore
cues that are presented randomly. This produces cost and benefits, they are both possible for
valid cues, depending on the timing
o If the flash appears before such as 300+ millisecond = results in cost
Cost is called an inhibitory aftereffect or inhibition of return
Benefit can be observed in attention are short rather than when attentional
changes must be maintained for longer periods of time
Reflexive orienting responses are normally very short, about 200 or fewer milliseconds
o Much longer duration could be life-threatening
Second possibility is when the cues tend not to provide valid information; we become reluctant
to response to changes on that side.
Neural Systems Subserving Attention
Where in the brain is attention?
o Some believed it was at the back
Every cortical cell can have its activity influences by attention
Attention is not strictly controlled by cortical structures
Baddeley’s model on memory: working memory can be thought of as having three components,
with the primary component responsible for controlling attention and supervising the 2 “slave”
subsystems.
o 2 sub systems: phonological loop, visuospatial sketchpad
The central executive is defined by what it does when performing tasks: its involved with the
allocation of attention, strategy selection, and the integration of info received from the two
slave systems
Tasks that are demanding of central executive activates the dorsolateral prefrontal cortex
Posner and Peterson proposed a model of attention which involved three visual attentional
mechanisms that are functionally and anatomically distinct attention systems that are involved
in visual attention
o PAS : posterior attentional system distinct from the 2 other systems
Involved in orienting spatial attention, such as object search and inspection of
object once it is found it’s like a zoom lens (how? And where?) it’s part of the
dorsal visual pathway
o AAS: anterior attentional system
Responsible for working memory and executive control that subserves the
conscious control of attention
Its involved in memory, semantics and motor behavior control
o VS: vigilance system
To prepare and sustain alertness toward signals that demand high priority
It is functionally lateralized
Right frontal damage compromises the ability to develop and maintain
an alert state, but this is not seen in the left hemisphere
Its selectively dependent on norepinrephrine
o The posner and Peterson system is best used to describe people with focal brain injuries
Studying consciousness
No definition for consciousness
Lucid dreaming: when you are aware that you’re dreaming
Defining consciousness
The criteria that consciousness must demonstrate:
o Selective attention, explicit memory, language and self awareness
Bisiach: there are 3 different senses of consciousness
o Nonphysical entities: the soul
o Experience of sensation, thought or action
o Monitoring of the internal representations
Damasio: there are 2 kinds of consciousness
o Core consciousness: transient process that is generated as an organism interacts with an
object
o Extended consciousness: more complication, its generated out of the gradual buildup of
autobiographical self, it requires long term memory
The process of knowing what one knows
TOM = theory of mind, which is the understanding that others can have beliefs and thoughts
that are different from their own
o Animals that have TONM understand that an individual who sees an event has
knowledge of that event
We can decide to look at consciousness as rather being a state or trait
o Trait: those who exhibit this trait does not have to always be in a conscious state
The neural basis of consciousness
Farah: proposed 3 general theoretical positions
o 1. Consider consciousness as the privileged role of particular neural structures
Descartes: activity influencing the pineal gland was experienced consciously
and other patterns of activity were not