cogch3 attention1 attention what is it? what control do we have over it?
TRANSCRIPT
cogch3 Attention 1
Attention
What is it?
What control do We have over it?
cogch3 Attention 2
Everyone knows what attention is. It is the taking of possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought. Focalization, concentration, of consciousness are of its essence….. It implies withdrawal from some things in order to deal more effectively with others, and is a condition which has a real opposite in the confused, dazed, scatterbrained state which …. Is called distraction. - William James (1890)- William James (1890)
cogch3 Attention 3
Read the bold print.
Somewhere Among hidden the in most the spectacular Rocky Mountains cognitive near abilities Central City is Colorado the an ability old to miner select hid one a mes sage box from of another. gold. We Although do several this hundred by people focusing have our looked attention for on it, certain they cues have such not as found type it style.
What do you remember from the regular print text?
What does this tell you about selective attention?
Focused or Selective Attention
Task: Present people with two or more stimulus at the same time and instruct them to respond to only one.
cogch3 Attention 4
cogch3 Attention 5
AttentionPerceptual processes - Parallel & Unlimited Attention - Serial and Limited
At some point there is a bottleneck.
cogch3 Attention 6
We need to select which input will be attended to (and further processed) and which will be ignored (and lost).
Questions1) Is bottleneck before or after meaning has
been processed?2) How do we select what to attend to?
cogch3 Attention 7
Dichotic Listening Task (Cherry, 1953) - two messages presented
Shadowing task - repeat message presented in one ear as you are hearing it.
Dependant Measures
1) Shadowing performance (errors, hesitations, omissions) indicate that attention has been diverted.
2) What is recalled from the unattended message?
Dichotic Listening Task
8cogch3 Attention
Dichotic Listening Results
Physical attributes of unattended channel are detected (e.g., Male . vs. female voice; Human vs. musical instruments).
Semantic (meaning) attributes of unattended channel were missed (e.g., Don’t notice switch to foreign language). No content was remembered, even when the unattended stream was the same word presented 35 times (Moray, 1959).
9cogch3 Attention
10
Broadbent’s Early Filter Model
• An early-selection model - filtering occurs before incoming stimuli are analyzed to the semantic level
cogch3 Attention
11
Parts of the filter model• Sensory store - Holds incoming information for a
short period of time• Filter - Analyzes messages based on physical
characteristics like tone of voice, pitch, location of stimulus (which ear)
• Detector - Information is processed to determine meaning
• Short-term memory - Holds information for general processing
cogch3 Attention
12
Broadbent’s Split-Scan Study
• Present letters at the same time to each ear
:-):-)
:-)
H M
R S
W Pcogch3 Attention
13
Broadbent’s Split-Scan Study
• Two conditions:1.) Repeat back all letters in any order
2.) Repeat back letters in the order they were presented
Condition 1 (Any Order):H, R, W, M, S, P
Condition 2 (In Order):H, M… P?
:-):-)
:-)
H M
R S
W Pcogch3 Attention
14
Split-Scan Results
• Condition 1 (repeat back in any order)– 65% correct letter report– Would report all letters presented to one ear first
• Condition 2 (repeat back in presented order)– 20% correct letter report
• Suggests that the letters to one ear were stored briefly while those of the other ear were processed.
cogch3 Attention
15
The early filter model explains…
• How we can pay attention to one ear and ignore stimuli coming into the other ear
• Why we prefer to process stimuli that come in to one ear all at once as opposed to switching channels
cogch3 Attention
16
Problems with early filter model
Back at the cocktail party. You’re talking to your friend and ignoring all the other conversations…
Until someone across the room says your name. Then you turn your head.
But you were supposed to be ignoring other conversations - what happened?
cogch3 Attention
Moray (1959) - “cocktail party effect”
subjects could often detect their own name “fire” or context relevant words on unattended channel. How could
this happen if unattended
information does not pass
through filter for pattern
recognition?
17cogch3 Attention
cogch3 Attention 18
Late selection models Deutsch & Deutsch, 1963) information is selected after meaning has been processed.
cogch3 Attention 19
Evidence against:(Treisman & Riley, 1969)-Used shadowing task asked subject to indicate when they detected a target in either message.
Many more targets were detected on the shadowed message.
cogch3 Attention 20
Corteen & Wood (1972): Experiment in which subjects were first given mild shocks whenever certain words--city names--were presented in a long list. This set up a conditioned autonomic response, the galvanic skin response or GSR, which measures changes in the resistance of the skin with sweating. After training, just seeing the city name increased GSR.
Then Ss SHADOWED prose in one ear and heard a list of words in the other. The list included the city names plus new city names, and neutral words. Measured GSR.
cogch3 Attention 21
Coch et al., (2005) same task as Treisman 1969 except ERPs were recorded to determine if target words were being processed. ERPs 100ms after target presentation (indication that the target has been perceived) were greater for targets in the attended compared to the unattended message.
Treisman (1960)
Found that attention could be easily switched to the unattended ear when semantic content of the message shifted
cogch3 Attention 22
23
Treisman’s attenuation model
• Still an early-selection theory
• Instead of a filter, an attenuator analyzes incoming messages– Physical characteristics– Language - Groups of syllables/words
• Attended messages are given more priority
cogch3 Attention
24
Attenuation = loss of signal strength
cogch3 Attention
25
The Dictionary Unit
• Both messages gets passed on to the dictionary unit
Threshold = Smallest signal strength that can just be detected
Easily detected
cogch3 Attention
26
Attenuation explains…
• Hearing your own name when that stream is supposed to be ignored
• Switching channels in order to make a complete sentence
• But a specific dictionary unit? That seems like a cop-out.
cogch3 Attention
27
Problems with early selection
• MacKay (1973)
• Ambiguous sentences: “They were throwing stones at the bank”– Bank = Financial institution or side of a river?
cogch3 Attention
28
MacKay Method & Results
• Dichotic listening– Attended stream: Ambiguous sentence
• “They were throwing stones at the bank.”
– Unattended stream: Biasing word• “River” or “Money”
• The biasing word had an effect!– If “money”, the ambiguous sentence was more
likely interpreted as financial institution
cogch3 Attention
29
What does this mean?
• The unattended stream was being processed, and it wasn’t a name or another low-threshold word– Not early-selection– Not an attenuator
• The word was actually being processed to the semantic level (to its meaning)
cogch3 Attention
30
So what’s right?
• There’s evidence for EVERYTHING!
• That’s no good.
• Lavie (1995) - Where the filtering occurs depends on task load– How much of a person’s cognitive resources
are used in a task
cogch3 Attention
31
Perceptual Load Theory:The location of the filter is Flexible
• High-load task: Difficult, requiring most of someone’s cognitive resources– Only selected items are processed
• Low-load task: Easier, cognitive resources are left over– Can process additional information
cogch3 Attention
cogch3 Attention 32
Johnston & Heinz (1978) Multimode attention theory:Selective attention can operate anywhere, early or late, but the later it operates the more costly in terms of resources (mental effort) it is
Demonstrated this using a task which showed that processing difficulty increased as the lateness of attention selection increased
cogch3 Attention 33
Dual Task Procedure1) Dichotic listening with shadowing
Independent Variables: messages physically differ (different sexSpeakers or do not (same sex speakers).2) Detect light stimuli on a computer screen.Dependent Measure: time to respond to presence of light
Results: Early (physical) differences created much less slow down than Late (semantic) differences.
cogch3 Attention 34
More than 2 messages (created sothey appear to come from different sources), does not increase response times. Processing unattended message does not take resources, selecting it does.
cogch3 Attention 35
Summary1. Filter is flexible - depends on the task2. Later selection takes more effort.3. Effort depends on selection not
on amount of background.
cogch3 Attention 36
Selective Visual Attention
cogch3 Attention 37
Spot Light/Zoom Lens Metaphor
• Can be directed to specific areas• Can be diffuse or focused
- trade off in concentration• Concentrated at the center, fuzzy at
the borders• Limited capacity
Muller et al., 2003Zoom Lens Theory predicts that if you are focusing on two items, your attention should also be good for any item that falls between the two items.
cogch3 Attention 38
Evidence show that if attention is split between two cued locations, detections of items falling between is poor.
Figure 3.1 (a) Shaded areas indicate the cued locations and the near and far locations are not cued. (b) Probability of target detection at valid (left or right) and invalid (near or far) locations. Based on information in Awh and Pashler (2000).
When attention is split,
it can act like multiple spot lights. With unattended areas falling in spaces between attended areas.
cogch3 Attention 40
What Happens to Unattended Stimuli?What Happens to Unattended Stimuli?
Evidence from Neglect Patients.
Shown some pictures to the non-neglected visual field and others to the neglected visual field.
Later asked to identify the same pictures in a degraded version. They are just as fast with those that had been presented to the neglected as the non-neglected visual field (priming).
cogch3 Attention 41
Neurological evidence also indicates that when the overall attentional load of a task was low, neglect patients showed increased brain activity to task irrelevant items presented in the neglected visual field (some processing is going on) even though the patients are not consciously aware of the stimuli.
cogch3 Attention 42
cogch3 Attention 43
Hemi neglectPatients Suffering From 'Hemi-neglect' Ignore Things On Their Left, But They See Them Nonetheless
Click here to see Science Daily article (05/15/08.)This study demonstrates that in hemi-neglect the left part of the world is not a 'blind' region: in a way, patients read unconsciously what is there. However, the patients cannot make conscious use of this information
cogch3 Attention 44
Attention as Capacity• Attention is the process of allocating mental
resources to various cognitive tasks
Factors effecting allocation of Attention-Anxiety -Salience and Distinctiveness- Relevance-Task demands
Cross- Modality Effects
Ventriloquist Illusion
Rubber Hand Illusion
Phantom Limb Pain (begin at 13:00)
Body Swap Illusion
cogch3 Attention 45
Disorders of Visual Attention
Hemi-neglect – (Historical note) President Woodrow Wilson after suffering two strokes developed hemi neglect. When colleagues came to visit him, he failed to respond to them until they were escorted to his right side. He denied he had a problem and planned to run for a third term as president until his wife finally intervened.
cogch3 Attention 46
Spatial Extinction: can detect a single item in both the left and right visual fields but, under conditions double simultaneous stimulation fail to detect the item in the left field.
cogch3 Attention 47
Presented
Perceived
When stimuli is presented in the neglected field but has no competition for attention from the non-neglected visual field, the image is perceived. When there is competition for attention from the non-neglected visual field, attention is given only to the non-neglected visual field.
cogch3 Attention 48
Two Attention Systems (Corbetta)
Goal directed system - preparing and applying goal-directed (top-down) selection for stimuli and responses. Effected by expectations, knowledge and/or intentions.
Stimulus driven – (bottom-up) specialized for the detection of behaviorally relevant stimuli, particularly when they are salient or unexpected. Circuit breaker .
cogch3 Attention 49
The area were the two attention systems combine is in the parietal lobe. There is competition for attention from the two attentional systems. Hemi- neglect can occur due to impairment in either the goal-directed or the stimulus driven systems. Results in a failure to activate the parietal cortex enough to capture attention to that visual filed.
Hemi-neglect is a disorder of Attention – not of perception.
cogch3 Attention 50
Reducing Neglect: PhysiotherapyHemi-neglect patients when asked to point straight ahead – point several degrees to the left.
cogch3 Attention 51
Prism glasses that shift the visual field 10 degrees to the right allow patients to use the Goal-directed (top-down) processes to direct more attention to the neglected left visual field.
Demonstration• I will show you a scene quickly.
• Report first the black numbers.
• Report what you see at each of the 4 locations.
+++
Mask
Illusionary conjunctions
• We tend to put different features from different objects together.
• Some brain damaged patients (parietal lobe) show illusionary conjunctions even when the patients were allowed to view the stimuli for 10 seconds.
Feature search
XX
X
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
O X
O
O O O
O
X
X
Conjunction searchTreisman & Gelade 1980
Feature Integration Theory
Find the Green X
Typical Findings & interpretation
• Feature targets pop out– flat display size function
• Conjunction targets demand serial search– non-zero slope
0
500
1000
1500
2000
2500
3000
1 5 15 30Display Size
RT
(m
s)
Feature Target
ConjunctionTarget
Find Which is more difficult?
Find Which is more difficult?
Feature integration theory
• Attention is the “glue” that combines the information from the what and where systems.
cogch3 Attention 59
Multi-tasking
Ophir et al (2009) Correlation between multitasking and distractibility.
When asked to do two tasks at once, participants who reported being multitaskers performed less well on the main task than did non-multitaskers. Perhaps multitaskers are just less able to focus attention.
cogch3 Attention 60
Cell Phone Use
Hyman et al (2009)
Cell phone users less likely (25%) than non-users (51%) to notice a unicyling clown!!!
cogch3 Attention 61
Practice and Dual Task Performance
Spelke, Neisser et al (1976)
Two subjects read short stories while writing lists of words at dictation. After some weeks of practice, they were able to write words, discover relations among dictated words, and categorize words for meaning, while reading for comprehension at normal speed. The performance of these subjects is not consistent with the notion that there are fixed limits to attentional
capacity.
cogch3 Attention 62
Automatic vs. Controlled
• Automatic Processes– Fast and efficient– Unavailable to
consciousness– Unavoidable– Unintentional
• Controlled Processes– Slow and less efficient– Available to consciousness– Controllable– Intentional
Attention as executive control
• In contrast to capacity theories (which see attention as a limitation) considering it as executive control of possibly conflicting multiple goals makes attention instead a source of efficiency
• Evidence: Psychological Refractory Period
Psychological Refractory Period
• 2 stimuli and 2 responses– Light: press button– Tone: press foot pedal
• Varying SOAs– At short SOAs, response to task 2 takes longer
• Varying stimulus processing difficulty– Lengthening processing of stimulus 1 slows RT to
stimulus 2– Lengthening processing of stimulus 2 does not slow
response to stimulus 2!!
PRP: Surprising Results
S1 R1
ProcessingOf Stimulus
Central Executive
Response to Stimulus
S2 R2
S1 R1S2 R2
S1 R1S2 R2