1 Science B44 Lecture 17 Consciousness Motion induced blindness Stare in the middle of the display on the left. After several seconds, individual yellow dots will begin to disappear. 2 1. What is it? 2. Attention and awareness 3. How much is processed without awareness? 4. Unconscious guidance 5. Neural correlates: split brain Consciousness 3 1. What is it? The gap between period of sleep Subjective experience, qualia Access, report, goals, guidance Self-awareness, second-order consciousness Zombies Functional or just a witness useful for making up stories after the fact 4 2. Attention and awareness We are only conscious of things we attend to But what about all the detail we seem to see around us? Actually attend to and represent only a few items Change blindness We don’t notice changes in unattended items in plain sight (unless alerted by low-level motion cues) 5 Rensink Program 6 Objects may fade in and out of attention Disappearing from awareness as they do Concentrate on a book and you are aware of little else Motion induced blindness
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Science B44
Lecture 17Consciousness
Motion induced blindness
Stare in the middle of thedisplay on the left. Afterseveral seconds, individualyellow dots will begin todisappear.
2
1. What is it?2. Attention and awareness3. How much is processed without
awareness?4. Unconscious guidance5. Neural correlates: split brain
Consciousness
3
1. What is it?The gap between period of sleepSubjective experience, qualiaAccess, report, goals, guidanceSelf-awareness, second-order
consciousnessZombiesFunctional or just a witness useful
for making up stories after thefact
4
2. Attention and awarenessWe are only conscious of things we
attend toBut what about all the detail we seem to
see around us?Actually attend to and represent only a
few itemsChange blindnessWe don’t notice changes in unattended
items in plain sight(unless alerted by low-level motion cues)
5
Rensink Program
6
Objects may fade in and out of attentionDisappearing from awareness as they doConcentrate on a book and you are aware
of little else
Motion induced blindness
7
RivalryCrowdingSubliminal perceptionPriming
3. How much is processedwithout awareness
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Rivalry
Left eyesees hand
Right eyesees face
through tube
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Rivalry
Left eye
Right eye viewsuppresses
hand
What is the fate of the suppressed patterns.No longer in conscious visionTrack the degree of “preattentive” processing 10
Stimulus is registered and processedwithout subject’s awareness.
Research hasrepeated shownthat subliminalmessages canaffect mood andbias memoryretrieval butcannot triggercomplex behavior
Subliminal Perception
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1950s: advertiser James Vicary flashed thesemessages between frames in a movie toobriefly to reach consciousness
Coke sales up by 18.1%Popcorn by 57.8%Raised a storm of controversy, fear and loathingFCC bans subliminal advertisingVicary later confessed it was a fraud.
DRINK COCA COLA
Famous examples of Subliminal Perception 1
HUNGRY? EAT POPCORN
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"We don't need to be manufacturingsubliminal messages to get my messageacross," Mr Bush told ABC television.
RATS. Republican ad, 2000 Bush campaign, shows AlGore then “RATS” appears for one frame(1/30 of a second, but slowed to 1/15th in clip here)
Famous examples of Subliminal Perception 2
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Self-help Subliminals
Display your own subliminal messages on yourcomputer screen
Famous examples of Subliminal Perception 3
Subliminal self-help tapesLearn languages, increase self
esteem, improve leadership,listen to tapes while asleep
"I have felt an immediate change in mind states." - Keith, NZ."This is the best subliminal messages program that I haveseen!" - Steve, USA.. 14
Subliminal mere exposure effect
Subjects show higher preference for figures orfaces seen repeatedly compared to newlyintroduced ones.
More pronounced when the repeated exposureswere subliminal
Monahan, J. L., Murphy, S. T., & Zajonc, R. B. (2000). Subliminalmere exposure:Specific, general, and diffuse effects.Psychological Science, 11, 462-466
Famous examples of Subliminal Perception 4
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While looking at the “+”, attend to the big cross thatappears briefly either on left or rightReport whether its vertical or horizontal bar is longer
Subjects unable to report word presented atfixation if attention is engaged elsewhere
Priming despite inattentional blindness
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Word brieflypresented at fixation
“GRACE”
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60% report seeing only the big +, not aware of word.Without line task, 100% report “GRACE”Later, the same subjects run in a second experimentComplete word stems with whatever comes to mindCO_ _ _Might get COUNT, COUCH, COUGH, CONCH, COLDSPL_ _ _Might get PLANT, PLANK, PLOTS, PLACE, PLEAT
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ThenGR_ _ _Might get GRUNT, GRILL, GROUP, GREATNormally, GRACE is an exceedingly rare choice (0%)EXCEPT for the 60% who did not see “GRACE” in
the first experimentThey respond “GRACE” 25% of the time.It was not seen, but it was processed to the level of
word recognitionAffected subsequent behavior
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4. Unconscious guidance
Patient DF cannot recognizeobjects or even reportorientation
Yet her hands orient correctlyto openings or for graspingobjects
Rudimentary vision in the dorsal“where” stream can directactions without recognition
Patient with damaged “what” system
--> Patient with damaged V120
Visual fieldsDamage to V1 in onehemisphere
-->Blindness in theopposite hemifield
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dorsal
ventral
Alternative route bypassing V122
Damage to right V1 makes patient blind in left visual fieldYet orients hand correctly to grasp objectsRudimentary vision in the dorsal “where” stream can direct
actions without awarenessInput through ancient visual system
Patient withdamaged V1:Blindsight
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5. Neural correlates
Frontal lobesMicrotubulesLateralization of functionSplit brain
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Visual fieldsTwo hemispheres
Different specializations
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SuperiorSpatial functions
Reading andexpressing emotion
Emotionalfunctions
Left side of bodyRight side ofbodyMotor functions
Left visual field;facesRight visual fieldVisual functions
Limited languageFull languageCognitivefunctions
Right HemisphereLeft Hemisphere
Lateralization of functions
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Lateralization not fixedCan shift in response to early brain
traumaCan shift in left-handed individuals
1/3 show reversed lateralization2/3 less lateralized: bilateral
language, spatial functions, emotionPrior to brain surgery, must establish
lateralization of functionsHandedness tests
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Wada: separate hemispheres in normals
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Ducks and dolphins can sleepone hemisphere at a time
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Split brain: severed corpus callosum
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Split brain patient twice as fast as normals whenboth hemispheres can act independently
Look at central plussign
Slap hand on side oftarget item
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Look at central plussign
Slap hand on side oftarget item
Split brain patient twice as fast as normals whenboth hemispheres can act independently
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Split brain patient twice as fast as normals whenboth hemispheres can act independently
Look at central plussign
Slap hand on side oftarget item
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Split brainpatient twice
as fast asnormals
Each hemisphereinspects its visualfield independently.
Half the work, twiceas fast.
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Summary1. Consciousness, what is it?2. Attention and awareness, change blindness,
motion-induced blindness3. What is processed without awareness: rivalry,
crowding, subliminal perception, priming4. Unconscious guidance, blindsight5. Neural correlates: split brain, dual
consciousness
Exam on MondayReview Session on Saturday1 Minute Quiz
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