Attention 2002/03/ /03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison

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1 Cognition transforming perceptions into action and thought Perception and Cognition Attention Memory Language Cognitive Modules Consciousness Animal Cognition Cognitive Science 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Attention Attention selection, processing, and consciousness of specific sensations recognized as very important to perception how much can we do at once? why? difficult to describe in objective terms clarity of perception; intensity; consciousness recent work: emphasis on selection selective access: only certain parts of [visual] input sent on for further processing examples: selective looking and selective listening 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 1

2 Example 1: Selective Looking (Neisser; Simons) Watch two teams of players one in white shirts one in black shirts Each player throws basketball to others on their team --- teams do not interact Select one of the colours (white or black) Task: count number of times ball is exchanged Neisser; Simons Pick the white or black team Count the number of times their basketball is exchanged From /03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Neisser; Simons Result: over half the observers do not see the person in the gorilla suit inattentional blindness: if we don t attend to something we won t see it Instead of a complete, detailed world, we only see a small part of it the part we are attending to! This is how magicians make things (dis)appear Card Trick Pick a card 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 2

3 I ve removed your card Selective Looking and Inattentional Blindness Does anything get through? picture of a smiley face (but not a sad one) name of observer (Sara, George) but not close names (Sura, Geosge) highly familiar stimuli highly predictable or expected stimuli Some things draw attention to themselves processed without attention, or very easily pass perceptual filters 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Example 2: Selective Listening (Cherry and many others) Two audio streams: one input per ear repeat ( shadow ) what is being said Cherry Select one of the streams (left or right) repeat ( shadow ) what is being said brain, fruit, morning, paper, light, planet, brain paper light aircraft shirt... fruit morning planet door swan... Shadowing left right ear ear each audio stream is independent of each other (streams don t interact) 2002/03/05 Psyc , Copyright Jason Harrison after the listener has finished shadowing, test what they remember from other stream 2002/03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 3

4 Cherry Result Listeners acquire almost nothing from unattended stream Inattentional deafness: if we don t attend to something, we won t hear it Instead of a complete, detailed world, we only hear a small part of it yes dear, of course dear, you re so right dear 2002/03/05 Psyc , Copyright Jason Harrison Selective Listening and Inattentional Deafness Does anything get through from unattended channel? large change in volume change in gender of speaker not a change in language Again, some things draw attention to themselves processed without attention Related: cocktail-party problem -- multiple speakers could you repeat that? -- short term auditory memory 2002/03/05 Psyc , Copyright Jason Harrison Example 3: Selective Access (Posner) Focus visual attention to an area by using a cue Spotlight or zoom lens measure time to identify target item when: observer does not know where item will appear observer does know where item will appear cue is a briefly presented dot at the location of target Posner: Example 1 no cuing: what letter appears? 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 4

5 Posner: Example 1 no cuing: what letter appears? Posner: Example 2 with cuing: what letter appears? A 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Posner: Example 2 with cuing: what letter appears? Posner: Example 2 with cuing: what letter appears? N 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 5

6 Results: Cue versus No Cue Results: Relative position of Cue Greatest reduction at location of cue Time Cue reduces time Reduction of time Cued location No Cue Cue Advance knowledge of location improves performance 2002/03/05 Psyc , Copyright Jason Harrison Amount of reduction depends on distance from cue -attention is like a spotlight or a zoom lens 2002/03/05 Psyc , Copyright Jason Harrison Cue triggers formation of a spotlight whatever is in spotlight is attended more it is attended, the better it is processed size, shape of spotlight can be controlled Different types of cues a) exogenous (outside generating) low-level reflexes sudden changes (e.g., flash or movement) draws attention automatically b) endogenous (inside generating) high-level control instruction (via some kind of visual sign or pattern) sends attention to requested location 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 6

7 Exogenous Cuing Exogenous Cuing 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Exogenous Cuing Endogenous Cuing N No interpretation needed - cue is at target location 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 7

8 Endogenous Cuing Endogenous Cuing C Observer need to interpret the cue 2002/03/05 Psyc , Copyright Jason Harrison Observer need to interpret the cue 2002/03/05 Psyc , Copyright Jason Harrison Effect of Cues Both types of cues control the same attentional mechanism (spotlight) but reflect different strategies a) exogenous (low-level control) bottom-up control of attention based on what s actually happening in environment b) endogenous (high-level control) top-down control of attention based on what observer believes Summary of Selection Selective Looking inattentional blindness Selective Listening inattentional deafness Selective Access cuing, exogenous, endogenous 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 8

9 Attention: Selective Processing Selective Access Selection of sensations (left ear, right ear) Selective access Selective construction Only certain parts of [visual] input sent on for further processing some parts ignored, some filtered, some selected Perception: coordinated interaction of different perceptual systems Even if attention allows observer to see, how well are things put together? 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Selective Construction Only certain parts of [visual] input are put together Attention both allows conscious vision and builds up visual representations Example 1: Visual Search - what visual properties are formed immediately? - diagnostic: visual search - e.g., is there a blue dot? Severe limits to what can be accessed or constructed 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 9

10 Example 1: Visual Search -Result: for some targets, search always fast - target pops out of display - e.g., is there a blue dot? Search slope = 0 ( pop-out ) Example 1: Visual Search -Explanation: - for some properties, a unique value will draw attention (exogenous cue) - e.g., where s the blue dot? -e.g., a single large item among small ones -e.g., a single curved item among straight ones Search slope = 0 Proposed application: data ( pop-out ) visualization 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Example 1: Visual Search -However, this is not always the case Example 1: Visual Search -Result: for some targets, search is slow - effort needed - e.g., is there a blue vertical line? - e.g., is there a blue vertical line? 600 Reaction time (ms) search slope ( ms/item) 300 Number of items (set size) 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 10

11 Example 1: Visual Search Explanation - need to combine properties to detect target -combination is not automatic Example 2: Perception of Scenes Recall: -visual input via high-resolution fovea 180 -spotlight of attention is needed to weld properties together -search is a serial process - time needed depends on number of items 4 Eye Retina Fovea -highest density of cones -spotlight travels at about 50 ms/item Retina has good acuity only in central 4 of vision - clear vision only in this range 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Example 2: Perception of Scenes When perceiving a scene, can only get pieces of it at any instant -need to move eyes around to see scene 2002/03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 11

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13 Saccades Need to move eyes around to see the world - eye movements make jumps called saccades Saccades made about 3 times / second - jump to various parts of the world -eyes are almost always moving (unless something really interesting is seen) -by moving eyes around, a complete scan of world is made Construction of whole from saccades Question: How do the pieces (individual fixations) get put together? Visual Buffer Accumulates information Possible answer: The information from each fixation is collected into a visual buffer somewhere in the brain 2002/03/05 Psyc , Copyright Jason Harrison (eyes being moved around) Psyc , Copyright Jason Harrison 13

14 Visual Buffer Accumulates information Visual Buffer: Does not exist If it did, it should be easy to see any changes made to the image However, no evidence of this has ever been found Seeing changes sometimes very difficult to do insert brief blank interval between original and changed images eye blink saccade or eye movement occlusion movie scene cut see examples at Seeing changes in real-life Observers have great difficultly seeing a change made during an interruption Change Blindness This can happen in real life /03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 14

15 Explanation of Change Blindness Attention is needed to see change without it, observers are change blind Attention combines pieces of the image forms them into a coherent representation: token tokens support perception (detection) of change tokens describe actual objects in world (basis for action, e.g., grasping) tokens can be mis-mapped across an interruption Notes on Change Blindness 1. In everyday life, we usually see change -if something changes, creates a motion signal -motion is an exogenous cue; draws attention -if something interferes with drawing of attention (flicker, occlusion) then attention doesn t go to change -> won t see it -attentional distraction is a major cause of traffic accidents (e.g., cell phone usage) 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Notes on Change Blindness 2. There is no accumulation of built-up representation -if observer looks at picture for several seconds before flicker sequence begins -> no effect - representation built up by attention (token) stays built up only as long as attention stays on it -token dissolves after attention withdrawn -token remapped after flicker/blind/saccade Attention acts like a hand: -token exists as long as pieces of input are held -if hand picks up drops and later picks up something else, token remapped to new item Notes on Change Blindness 3. If we only see a few objects at a time, why do we have the impression of seeing lots? -representation of object formed on demand -whenever it is needed, it is built -virtual representation -> just in time system -example: refrigerator light -only on when needed -> looks like it s always on -example: object representation -only there when needed -> looks like it s always there 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 15

16 Summary of Attention You might be wondering Selection is key: selection of stimuli: looking, listening processing of stimuli: access, construction Blindness comes in many forms inattentional blindness change blindness Tasks: counting passes of ball, shadowing words, letter recognition, visual search, changes across blinks, flashes and interruptions. 2002/03/05 Psyc , Copyright Jason Harrison Where in my head does this all happen? How do we know about these locations? Time for Neural Sites of Visual Attention! Michael Posner 2002/03/05 Psyc , Copyright Jason Harrison Neural Sites of Visual Attention Posterior Network Studied via human brain lesions (strokes, traumas) brain scans of humans cell recordings in monkeys Two different networks (Posner) Posterior: expression of attention Anterior: control of attention parietal lobe (and south) movement and engagement of attention unconscious processing three interacting systems: disengagement movement engagement 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 16

17 Posterior Systems disengagement posterior parietal lobe permits processing of attended source to end movement superior colliculus eye movements: location map for tectopulvinar system allows attention to be drawn to new location engagement thalamus (pulvinar) blocks input from unattended sources Anterior Network control of attention provides contents of awareness conscious processing network includes: anterior cingulare cortex (prefrontal) frontal eye fields handles executive control voluntary shifts of attention responses to endogenous cues location of free will? 2002/03/05 Psyc , Copyright Jason Harrison /03/05 Psyc , Copyright Jason Harrison Summary of Neural Sites Posterior automatic movement and engagement of attention Anterior voluntary shifts of attention 2002/03/05 Psyc , Copyright Jason Harrison Psyc , Copyright Jason Harrison 17