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Attention and Consciousness
“Millions of items … are present to my senses which never
properly enter into my experience. Why? Because they
have no interest for me. My experience is what I agree to
attend to … each of us literally chooses, by his ways of
attending to things, what sort of a universe he shall appear
to himself to inhabit”
William James, 1890, Principles of Psychology
Sensory Systems modulated by
Attentional Systems
a Single Hair
Cell--”pin drop”
a Single Photon
a Single molecule
What is Attention’s Goal?
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Truthful perception of the world is neither
required nor necessarily attempted
Conscious experiences focus on gathering
information quickly
Details are filled-in to give a sense of
continuity to our perceptions
This is the point of attention in general,
i.e., to concentrate on what is important
A distinction between attention and
consciousness
A common sense distinction between attention
and consciousness:
We can ask someone to ‘please pay attention’
but not to ‘please be conscious’. In general,
however, when people pay attention to
something, they generally become conscious of
it.
The common sense distinction between
attention and consciousness suggests that there
are attentional control mechanisms that often
determine what will or will not become
conscious …
A distinction between attention and
consciousness
A common sense distinction between attention
and consciousness:
We can ask someone to ‘please pay attention’
but not to ‘please be conscious’. In general,
however, when people pay attention to
something, they generally become conscious of
it.
The common sense distinction between
attention and consciousness suggests that there
are attentional control mechanisms that often
determine what will or will not become
conscious …
Selective attention: voluntary and automatic
In the real world, voluntary
and automatic attention are
generally mixed. For example,
we can train ourselves to pay
attention to the new ringtone
we found for our cell phone.
When it rings and we suddenly
pay attention to it, is that
voluntary or automatic?
Visual areas involved in active and
passive viewing extend to the parietal
lobe
Consciousness
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William James (1890):
 Consciousness is a constantly moving stream of
thoughts, feelings, and emotions
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Consciousness can be viewed as our subjective
awareness of mental events
Functions of consciousness:
 Monitoring mental events
 Control: consciousness allows us to formulate and
reach goals
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Consciousness may have evolved to direct or
control behavior in adaptive ways
Libet’s Half-second Delay
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Electrically stimulated patients’
somatosensory cortices during surgery
 Minimum level of stimulation necessary
 At this intensity, ½ second of continuous
stimulation before any perception
 Shorter stimulation requires greater intensity
What Happens to the Lag?
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Reaction times can be 200 ms, recognition
can take 300-400 ms, but Libet’s delay is
500 ms…
 Our body responds before we are conscious
of why it is responding
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Subjective referral: after neuronal
adequacy is reached, the event is referred
back to the point at which it occurred
Cortex and Consciousness
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The dorsolateral prefrontal cortex is
activated during conscious control tasks
 Subjects asked to name the ink color in the
Stroop task below have difficulty when the
word name and color are different
 This color-naming task was associated with
activation of the dorsolateral prefrontal cortex
Stroop Task
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Stroop Task
Red
Brown
Blue
Green
Green
Blue
Yellow
Black
Brown
Green
Yellow Red Black
Red Yellow
Blue Black Yellow
Brown
Red Green
Blue Black
Brown
Stroop Task
Red
Brown
Blue
Green
Green
Blue
Yellow
Black
Brown
Green
Yellow Red Black
Red Yellow
Blue Black Yellow
Brown
Red Green
Blue Black
Brown
Attention
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Our conscious awareness is limited in capacity
and we are aware of only a small amount of the
stimuli around us at any one time
Attention refers to the process by which we focus
our awareness
Three functions of attentional processes:
 Orienting function toward the environment
 Control of the content of consciousness
• I will think about this issue but not that one…
 Maintaining alertness
The brain basis of conscious experience
Binding features into conscious objects
The concept of feature
binding -- combining
color, location, shape,
and the like into a
single neuronal
assembly -- is often
necessary for visual
consciousness.
Treisman suggested
that an attentional
spotlight was required
to combine different
aspects of a stimulus
into a reportable event.
Treisman’s spotlight for binding visual
features
END of MATERIAL FOR
MIDTERM
Divided Attention
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Divided attention refers to a
task in which a person is
asked to attend to two tasks
at the same time
 Subject may be asked to listen to
one conversation (shadowing)
delivered via the left ear
 Some information on the other
channel (right ear) is processed
(as shown in priming tasks)
Central Attention: not
just sensory/perceptual
 Message 1
Message 2
GREEN
MARK
EGGS
BACK
FINE
AND
RICE
HAM
 Subjects occasionally reported
“green eggs and ham”
 This shouldn’t happen if message 2 were
completely filtered out—no central attention
process..
Attention and the Brain
Michael I. Posner
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Two attention systems; two functions
 Anterior frontal lobe system
• Tasks requiring awareness (planning or writing)
 Posterior parietal lobe system
• Tasks involving visuospatial abilities (playing Tetris,
vigilance tasks)
Reticular Activating System RAS
Arousal
Flow of Consciousness
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Day-dreams are shifts in attention
toward internal thoughts and imagined
scenarios
 College students may spend as much as
50% of their waking time in a day-dream
 Beeper studies of high-school students
have noted the predominance of negative
thoughts when students are with their
families as opposed to others
Psychodynamic View of
Consciousness
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Freud argued that three mental
systems form consciousness
 Conscious: mental events that you
are aware of
 Preconscious: Mental events that
can be brought into awareness
 Unconscious: Mental events that are
inaccessible to awareness; events
are actively kept out of awareness
TOT Demonstration
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Heavy, broad-bladed knife or hatchet used
especially by butchers
Crystalline sugar occurring naturally in fruits,
honey, etc.
The independent candidate that ran against
Clinton and Bush I.
Do any of these questions put the answer on the
tip of your tongue?
Subliminal Perception
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Notion that brief exposure to sub-threshold stimuli can
influence awareness
Study: subjects are shown aggressive (A) or positive (B)
stimuli
 and then rate a neutral stimulus (C)
 Subjects shown panel A first subsequently rated the boy in
panel C more negatively
(Figure adapted from Eagle, 1959)
Unconscious Cognitive Processes
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Information-processing view can be extended to
analyses of unconscious processes
Notion is that many brain mechanisms operate
in parallel
 Some of these mechanisms operate outside of the
level of consciousness
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Functional significance of unconscious
mechanisms:
 Are efficient and rapid
 Can operate simultaneously
 Operate in the absence of consciousness?
The brain basis of conscious experience
Unconscious comparisons
How can we investigate conscious
experience?
Consciousness has been used a a
variable, with experiments designed to
compare conscious and unconscious
conditions in the same experiment
using the same stimuli.
Backward masking is used to
compare conscious and
unconscious perception. Subjects
do not perceive the smiling face,
but the unconscious face still
primes behavior and brain activity
Blindsight
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People with damage to the central portion
of the occipital cortex
 are blind in the sense that they are unable to
see objects placed before them
 are able to provide partial information about
the geometric shape of an object (blindsight)
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Blindsight may involve a primitive visual
system in the midbrain
Neurology of Consciousness
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Consciousness is distributed
throughout the brain
 Hindbrain and midbrain are
important for arousal and for
sleep
 Damage to the reticular
formation can lead to coma
 Prefrontal cortex is key for
conscious control of
information processing
Sleep and Dreaming
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Behavioral characteristics of sleep
 Minimal movement
 Stereotyped prone posture
 Require a high degree of stimulation to
arouse organism
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Physiological characteristics of sleep
 Brain wave activity (seen in the EEG)
 Paralysis of muscles (seen in the EMG)
 Cardiovascular changes (alternating cycles
of arousal)
Species Variation in Sleep
(Figure adapted from Kripke et al., 1979)
Function of Sleep
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Memory consolidation
Energy conservation
Preservation from predators
Restoring bodily functions
 Sleep deprivation can alter immune
function and lead to early death
 Sleep deprivation can also lead to
hallucinations and perceptual disorder
EEG Stages of Sleep
(Figure adapted from Cartwright, 1978)
REM Sleep
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Characteristics of REM sleep
Presence of rapid-eye-movements
Presence of dreaming
Increased autonomic nervous system activity
EEG resembles that of awake state (beta
wave)
 Motor paralysis (except for diaphragm)
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Dreaming
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Psychoanalytic view: Dreams represent a window
into the unconscious
 The latent content (meaning) can be inferred from the
manifest content (the actual dream)
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Cognitive view: Dreams are constructed from the
daily issues of the dreamer
Biological view: Dreams represent the attempt of
the cortex to interpret the random neural firing of
the brain during sleep
Altered States of Consciousness
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Changes in consciousness can be
brought on by
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Meditation
Hypnosis
Drug ingestion
Religious experiences
The brain basis of conscious experience
Conscious events recruit widespread brain
activation
There are many sources of
evidence suggesting that the more
we are conscious of some event,
from visual perception to motor
control, the more cortical activity
we are likely to find.
Results of an fMRI experiment:
brain activation during a
sensorimotor task where subjects
were asked to tap along with the
sound of a metronome. Once
trained on the task, the scientists
varied the pace of the metronome
by 3, 7, or 20%. Cortical activity
increased dramatically as a
function of the unpredictability of
the tapping task.
The brain basis of conscious experience
Fast cortical interactions may be needed for conscious events
It is believed that rhythmic synchrony between different brain regions may
signal cooperative and competitive interactions between neuronal
populations needed to perform tasks, particularly those that are conscious
and under voluntary control.
A summary and some hypotheses
Selective attention to a visual stimulus seems to be guided by parts
of the frontal and parietal lobes
Conscious cognition can be shown to recruit frontoparietal regions
Thus selective attention can be thought of as an act of focusing brain
resources on visual cortex -- particularly the region where feature
analysis and construction seems to take place.
Conscious cognition can be seen as going in the opposite direction, a
visual object serving to mobilize cortical regions far beyond visual
cortex alone.