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Attention

What is it?

What control do We have over it?

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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)

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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.

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AttentionPerceptual processes - Parallel & Unlimited Attention - Serial and Limited

At some point there is a bottleneck.

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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?

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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

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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).

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Broadbent’s Early Filter Model

• An early-selection model - filtering occurs before incoming stimuli are analyzed to the semantic level

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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

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Broadbent’s Split-Scan Study

• Present letters at the same time to each ear

:-):-)

:-)

H M

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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?

:-):-)

:-)

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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.

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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

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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?

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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?

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Late selection models Deutsch & Deutsch, 1963) information is selected after meaning has been processed.

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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.

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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.

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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

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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

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Attenuation = loss of signal strength

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The Dictionary Unit

• Both messages gets passed on to the dictionary unit

Threshold = Smallest signal strength that can just be detected

Easily detected

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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.

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Problems with early selection

• MacKay (1973)

• Ambiguous sentences: “They were throwing stones at the bank”– Bank = Financial institution or side of a river?

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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

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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)

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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

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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

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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

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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.

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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.

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Summary1. Filter is flexible - depends on the task2. Later selection takes more effort.3. Effort depends on selection not

on amount of background.

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Selective Visual Attention

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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.

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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.

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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).

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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.

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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

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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

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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.

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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.

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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.

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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 .

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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.

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Reducing Neglect: PhysiotherapyHemi-neglect patients when asked to point straight ahead – point several degrees to the left.

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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.

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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

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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

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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.

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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.

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Cell Phone Use

Hyman et al (2009)

Cell phone users less likely (25%) than non-users (51%) to notice a unicyling clown!!!

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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.

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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