Consciousness: An IntroductionConsciousness: An Introductionby Susan Blackmoreby Susan Blackmore

Section 2: The WorldSection 2: The World

presented bypresented byHaley Mack & Scott Haley Mack & Scott

MackenzieMackenzie

Let’s Start at the EndLet’s Start at the End Hopefully the next slide won’t spoil the Hopefully the next slide won’t spoil the

presentation. Think about the answers we presentation. Think about the answers we provide and how the theories and data that provide and how the theories and data that follow them either support or detract from follow them either support or detract from their plausibility.their plausibility.

People usually think of attention in relation People usually think of attention in relation to vision (and a lot of studies focus on it), to vision (and a lot of studies focus on it), but remember that it can apply to any kind but remember that it can apply to any kind of sensory stimulation.of sensory stimulation.

What is Attention’s Goal?What is Attention’s Goal? Truthful perception of the world is neither Truthful perception of the world is neither

required nor necessarily attemptedrequired nor necessarily attempted Conscious experiences focus on gathering Conscious experiences focus on gathering

information quicklyinformation quickly Details are filled-in to give a sense of Details are filled-in to give a sense of

continuity to our perceptionscontinuity to our perceptions

This is the point of attention in general, This is the point of attention in general, i.e., to concentrate on what is importanti.e., to concentrate on what is important

Chapter 4: Attention & TimingChapter 4: Attention & Timing Attention vs. ConsciousnessAttention vs. Consciousness Directing AttentionDirecting Attention Libet’s Half-second DelayLibet’s Half-second Delay

From http://www.jolyon.co.uk/illustrations/vision/

William James (1842-1910)William James (1842-1910) Does consciousness cause awareness?Does consciousness cause awareness? Does awareness cause consciousness?Does awareness cause consciousness? Do they affect each other at all?Do they affect each other at all?

““It is the taking possession by the mind, in It is the taking possession by the mind, in clear and vivid form, of one out of what clear and vivid form, of one out of what seem several simultaneously possible seem several simultaneously possible objects or trains of thought.” (1890)objects or trains of thought.” (1890)

Free WillFree Will James: “My experience is what I agree to James: “My experience is what I agree to

attend to”attend to” Firmly believed we have the ability to control Firmly believed we have the ability to control

our consciousness through free willour consciousness through free will Is it possible we simply think we have Is it possible we simply think we have

control over our experiences?control over our experiences? We assume a choice was made because We assume a choice was made because

attention shifted, not because we made itattention shifted, not because we made it

Filtering AttentionFiltering Attention Dichotic listening experimentsDichotic listening experiments

Attention will switch between ears to follow a Attention will switch between ears to follow a message without subject noticingmessage without subject noticing

Broadbent’s theoryBroadbent’s theory Subconscious filters parallel processing Subconscious filters parallel processing

streams to produce focused serial outputsstreams to produce focused serial outputs Subtler models claim attention may simply Subtler models claim attention may simply

allocate more resources; not a spotlightallocate more resources; not a spotlight Attention so complicated, it may not even Attention so complicated, it may not even

exist (Pashler, 1998)exist (Pashler, 1998)

Effect and Cause TheoriesEffect and Cause Theories James: is attention decided “by other James: is attention decided “by other

brain-cells, or by some spiritual force”?brain-cells, or by some spiritual force”? Effect Theory: brain cells guide brain cellsEffect Theory: brain cells guide brain cells Cause Theory: “force” guides brain cellsCause Theory: “force” guides brain cells

Similar to the difference between Similar to the difference between physicalism and dualismphysicalism and dualism

Couldn’t defend either side well, so he Couldn’t defend either side well, so he chose cause theory due to personal biaschose cause theory due to personal bias

How Sure Are You?How Sure Are You? ““I heard the door open and so I turned I heard the door open and so I turned

around to see who it was.”around to see who it was.” Did you consciously perceive the door Did you consciously perceive the door

opening and then choose to turn?opening and then choose to turn? Or, did you turn for some other reason and Or, did you turn for some other reason and

assume it was because the door opened?assume it was because the door opened?

Directing AttentionDirecting Attention Visual saccades can be voluntary, but Visual saccades can be voluntary, but

usually we aren’t aware of themusually we aren’t aware of them Smooth pursuit is never voluntary even Smooth pursuit is never voluntary even

though we are tracking the object!though we are tracking the object! The target it kept on the fovea automaticallyThe target it kept on the fovea automatically

Lots of other involuntary body movements Lots of other involuntary body movements occur, like rotating the head or torsooccur, like rotating the head or torso

Selective AttentionSelective Attention Covert attention scanning (Helmholtz)Covert attention scanning (Helmholtz)

Look directly at one place but pay attention to Look directly at one place but pay attention to someplace elsesomeplace else

Premotor theory (Rizzolati et al)Premotor theory (Rizzolati et al) Giving attention to a certain spatial location Giving attention to a certain spatial location

involves neurons that guide actions toward itinvolves neurons that guide actions toward it Example: if attending to a location on your Example: if attending to a location on your

right, neurons are activated that would used right, neurons are activated that would used to turn to the right and do somethingto turn to the right and do something

Pop-outsPop-outs Usually do a serial search to find one Usually do a serial search to find one

stimulus among many other similar onesstimulus among many other similar ones Takes a long time to evaluate each in turnTakes a long time to evaluate each in turn

Sometimes the slight difference is a key Sometimes the slight difference is a key characteristic, so it is immediately obviouscharacteristic, so it is immediately obvious

From www.awa.com/norton/figures/

Libet’s Half-second DelayLibet’s Half-second Delay Electrically stimulated patients’ Electrically stimulated patients’

somatosensory cortices during surgerysomatosensory cortices during surgery Minimum level of stimulation necessaryMinimum level of stimulation necessary At this intensity, ½ second of continuous At this intensity, ½ second of continuous

stimulation before any perceptionstimulation before any perception Shorter stimulation requires greater intensityShorter stimulation requires greater intensity

What Happens to the Lag?What Happens to the Lag? Reaction times can be 200 ms, recognition Reaction times can be 200 ms, recognition

can take 300-400 ms, but Libet’s delay is can take 300-400 ms, but Libet’s delay is 500 ms…500 ms… Our body responds before we are conscious Our body responds before we are conscious

of why it is respondingof why it is responding Subjective referral: after neuronal Subjective referral: after neuronal

adequacy is reached, the event is referred adequacy is reached, the event is referred back to the point at which it occurredback to the point at which it occurred

Libet’s ConclusionsLibet’s Conclusions Consciousness requires neuronal Consciousness requires neuronal

adequacy to occuradequacy to occur Backward referral challenges materialism Backward referral challenges materialism

and the idea that consciousness equals and the idea that consciousness equals certain brain activitycertain brain activity Believes data supports dualismBelieves data supports dualism

When a noise is heard, it is processed When a noise is heard, it is processed unconsciously very quicklyunconsciously very quickly We become conscious of it only after turningWe become conscious of it only after turning

Can still make some decisions consciouslyCan still make some decisions consciously

Test Libet’s Delay Yourself!Test Libet’s Delay Yourself! Cutaneous Rabbit: tap a pointed object Cutaneous Rabbit: tap a pointed object

(quickly and evenly) five times on another (quickly and evenly) five times on another person’s wrist, three times at the elbow, person’s wrist, three times at the elbow, and twice on the upper armand twice on the upper arm

The taps should feel spread out along the The taps should feel spread out along the entire arm instead of in only three spotsentire arm instead of in only three spots This phenomenon should occur BEFORE all This phenomenon should occur BEFORE all

the taps have been completedthe taps have been completed

The Phi PhenomenonThe Phi Phenomenon Same principle as the cutaneous rabbitSame principle as the cutaneous rabbit Two lights in different positions are flashed Two lights in different positions are flashed

one after the otherone after the other Creates illusion of movementCreates illusion of movement

If the lights are different colors, the color If the lights are different colors, the color seems to change as the light movesseems to change as the light moves Notice that this means the first light appears Notice that this means the first light appears

to have an in-between hue before the actual to have an in-between hue before the actual change to the second lightchange to the second light

Chapter 5: Theater of the MindChapter 5: Theater of the Mind Cartesian DualismCartesian Dualism Global Workspace TheoryGlobal Workspace Theory Consciousness without a TheaterConsciousness without a Theater

©2005 Dan L. Henderson

Thinking about ExperienceThinking about Experience John Cage: “Writing about music is like John Cage: “Writing about music is like

dancing about architecture.”dancing about architecture.”

Closed eye exercise…Closed eye exercise… An journey to the ‘theater of the mind’An journey to the ‘theater of the mind’

The Cartesian TheaterThe Cartesian Theater Hume: “The mind is a kind of theatre, Hume: “The mind is a kind of theatre,

where several perceptions successively where several perceptions successively make their appearance” (1739)make their appearance” (1739) What is on stage is in consciousnessWhat is on stage is in consciousness

Does it feel like you just sit in your head Does it feel like you just sit in your head and watch the world outside?and watch the world outside?

Is imagining like playing a fictional film Is imagining like playing a fictional film instead of the real world?instead of the real world?

Cartesian MaterialismCartesian Materialism Daniel Dennett rejects the Cartesian Daniel Dennett rejects the Cartesian

theater and Cartesian materialismtheater and Cartesian materialism Claims most materialists still believe in Claims most materialists still believe in

something like the CTsomething like the CT CM is what he calls the implied belief in CT CM is what he calls the implied belief in CT

despite materialists’ rejection of dualismdespite materialists’ rejection of dualism Any notion that there is a place where Any notion that there is a place where

“consciousness happens” suggests the “consciousness happens” suggests the belief in Cartesian dualismbelief in Cartesian dualism

Locating ConsciousnessLocating Consciousness Many areas of the brain are correlated Many areas of the brain are correlated

with certain kinds of processingwith certain kinds of processing Stimuli enter the brain through the senses, Stimuli enter the brain through the senses,

the brain processes it, & behavior resultsthe brain processes it, & behavior results Consciousness does not appear in a placeConsciousness does not appear in a place Consciousness does not appear at a timeConsciousness does not appear at a time

Dennett says we cannot ask these Dennett says we cannot ask these questions without believing in the CTquestions without believing in the CT

Mental ScreenMental Screen Roger Shepard’s 1971 experiment: the Roger Shepard’s 1971 experiment: the

time to rotate a block in the mind is time to rotate a block in the mind is proportional to the degree of rotationproportional to the degree of rotation Suggests we recreate the world in our head, Suggests we recreate the world in our head,

just like the idea of a Cartesian theaterjust like the idea of a Cartesian theater Not proof of conscious imagining; we Not proof of conscious imagining; we

rotate objects every day without noticingrotate objects every day without noticing Same part of brain active whether imagining Same part of brain active whether imagining

or consciously viewingor consciously viewing

Examples of different degrees of mental rotation. Try to figure out which sets are of the same block and which are not.

Notice how relatively little time is necessary for (A) while a lot more is needed for greater rotations present in (B) and (C).

From http://www.mphy.lu.se/avd/nf/hesslow/philosophy/

Global Workspace TheoryGlobal Workspace Theory Barrs, 1988: continues with the theater Barrs, 1988: continues with the theater

metaphor with a bright spot on stagemetaphor with a bright spot on stage Unconscious contextual systems process Unconscious contextual systems process

information in the shadows to affect the information in the shadows to affect the events that occur in the bright spotevents that occur in the bright spot

Each part of the “theater” is a different Each part of the “theater” is a different aspect of consciousnessaspect of consciousness Senses and ideas are “actors”Senses and ideas are “actors” Memories, interpretations, and automatisms Memories, interpretations, and automatisms

are the “audience”are the “audience”

Consciousness w/out Consciousness w/out TheaterTheater

Libet’s theory of neuronal adequacyLibet’s theory of neuronal adequacy Most events do not reach the level necessary Most events do not reach the level necessary

for conscious experiencefor conscious experience Crick’s “astonishing hypothesis”Crick’s “astonishing hypothesis”

One’s sense of self is merely the result of One’s sense of self is merely the result of interactions between neurons and moleculesinteractions between neurons and molecules

Stimuli are consciously perceived if cells fire Stimuli are consciously perceived if cells fire in synchrony to create reverberatory circuitsin synchrony to create reverberatory circuits

Multiple DraftsMultiple Drafts Dennett proposes that everything in the Dennett proposes that everything in the

brain is under constant revisionbrain is under constant revision Perceptions and ideas are always present Perceptions and ideas are always present

as multiple drafts at various stagesas multiple drafts at various stages There is no point in asking which are There is no point in asking which are

conscious because this implies the CT existsconscious because this implies the CT exists The sense of a narrative stream arises only The sense of a narrative stream arises only

when a question is presented and answeredwhen a question is presented and answered Drafts can affect behavior in this way and Drafts can affect behavior in this way and

leave traces in memory, but there is no actual leave traces in memory, but there is no actual experienceexperience that occurs that occurs

Chapter 6: The Grand IllusionChapter 6: The Grand Illusion Filling in GapsFilling in Gaps Change BlindnessChange Blindness Inattentional BlindnessInattentional Blindness

From http://www.cogsci.uci.edu/%7Eddhoff/whites-illusion-color.html

What do we really see?What do we really see? Illusions are things that are not what they Illusions are things that are not what they

appear to beappear to be Most people believe that “seeing” Most people believe that “seeing”

(1) is a conscious stream of moving images(1) is a conscious stream of moving images (2) represents the world(2) represents the world

Why do only parts of our visual experience Why do only parts of our visual experience become conscious?become conscious?

Why should any of what we see be an Why should any of what we see be an authentic representation?authentic representation?

Filling-in the GapsFilling-in the Gaps When part of an object is obscured, we When part of an object is obscured, we

infer the missing informationinfer the missing information Visual stimuli are pixilated spatially and Visual stimuli are pixilated spatially and

temporally but our perception is nottemporally but our perception is not Rods and cones are individual cellsRods and cones are individual cells Cells’ responses to changing stimuli take timeCells’ responses to changing stimuli take time

Blind spot is a significant gap, but we Blind spot is a significant gap, but we never see a black holenever see a black hole

Implication for the CTImplication for the CT Imagine a room full of identical pictures Imagine a room full of identical pictures

repeated over and overrepeated over and over The visual perception is that all are in The visual perception is that all are in

focus, even though that is impossiblefocus, even though that is impossible Dennett: there is no photocopy effect; the Dennett: there is no photocopy effect; the

brain just guesses after the first fewbrain just guesses after the first few If one picture is different, a brief glance is not If one picture is different, a brief glance is not

long enough to notice itlong enough to notice it

Even More Filling-inEven More Filling-in V.S. Ramachandran’s subject Josh has a V.S. Ramachandran’s subject Josh has a

very large blind spot (scotoma)very large blind spot (scotoma) Presented with vertical lines above and Presented with vertical lines above and

below, he could actually see the gap closebelow, he could actually see the gap close Offset lines took ~5 s to line up and closeOffset lines took ~5 s to line up and close A row of numbers was filled in with numbers A row of numbers was filled in with numbers

that couldn’t be readthat couldn’t be read Twinkling black dots on a red background: Twinkling black dots on a red background:

each feature was filled-in individuallyeach feature was filled-in individually

Change BlindnessChange Blindness People often don’t notice minor changes People often don’t notice minor changes

between two picturesbetween two pictures This is especially true if you don’t see them at This is especially true if you don’t see them at

the same timethe same time A subject scanning text will not notice A subject scanning text will not notice

changes outside his focus that are very changes outside his focus that are very obvious to others (Grimes, 1996)obvious to others (Grimes, 1996)

Differences in alternating images are Differences in alternating images are found more quickly if the change is in an found more quickly if the change is in an area of interest (Rensink et al, 1997)area of interest (Rensink et al, 1997)

Examples of Rensink’s FilmsExamples of Rensink’s Films

Java Applet Versions (can change settings)Java Applet Versions (can change settings)

http://www.usd.edu/psyc301/ChangeBlindness.htmhttp://www.usd.edu/psyc301/ChangeBlindness.htm

Downloadable QuickTime VersionsDownloadable QuickTime Versions

http://http://www.psych.ubc.ca/~rensink/flicker/downloadwww.psych.ubc.ca/~rensink/flicker/download

Inattentional BlindnessInattentional Blindness Subjects told to attend to one area will Subjects told to attend to one area will

actively inhibit attention elsewhereactively inhibit attention elsewhere Focus and attention are not the same!Focus and attention are not the same!

If the fovea is centered on a fixation point, If the fovea is centered on a fixation point, attention can still be directed to the sideattention can still be directed to the side

Will not notice a stimulus at the fixation point, Will not notice a stimulus at the fixation point, even though the eye is directed right at iteven though the eye is directed right at it

Gorillas in our MidstGorillas in our Midst Subject watched teams dressed in black Subject watched teams dressed in black

and white throw a ball in a film (Simons and white throw a ball in a film (Simons and Chabris, 1999)and Chabris, 1999) Told to pay attention to white team’s passesTold to pay attention to white team’s passes 50% had no memory of seeing a person in a 50% had no memory of seeing a person in a

black gorilla suit walk aroundblack gorilla suit walk around

Vision TheoriesVision Theories Simons & Levin: from each fixation we get Simons & Levin: from each fixation we get

a gist, which we compare to later gistsa gist, which we compare to later gists If the gists are similar, we don’t notice any If the gists are similar, we don’t notice any

changes in the detailschanges in the details Rensink: low-level processing creates a Rensink: low-level processing creates a

“coherence field” for each object“coherence field” for each object ““Virtual representation” creates a rich Virtual representation” creates a rich

experience without utilizing all informationexperience without utilizing all information O’Regan: no need to store everything O’Regan: no need to store everything

because the brain can call on the world as because the brain can call on the world as a kind of external memorya kind of external memory

What is Vision’s Goal?What is Vision’s Goal? Truthful perception of the world is neither Truthful perception of the world is neither

required nor necessarily attemptedrequired nor necessarily attempted Conscious experiences focus on gathering Conscious experiences focus on gathering

information quicklyinformation quickly Details are filled-in to give a sense of Details are filled-in to give a sense of

continuity to our perceptionscontinuity to our perceptions

This is the point of attention in general, This is the point of attention in general, i.e., to concentrate on what is importanti.e., to concentrate on what is important