Attention Presentation

VISUALATTENTION: Control,Representation, and Time

CourseHoward E. Egeth and Steven YantisDepartment of Psychology, The Johns

Hopkins University, Baltimore, Maryland 21218

1. Attentional control

Top-down control (goal-directed)

Bottom-up control (stimulus-driven)

2. Representational basis for visual selection.

3. Time course of attention.

Deployment of attentionsometimes →exclusively depends on the properties of the image.

other times →under strict supervision according to the observer’s goals.

in a few exceptions →both 2 determine the attentional consequences.

These 2 domains of attentional control invariably interact.

STIMULUS-DRIVEN &GOAL-DIRECTED CONTROL OF ATTENTION

Deployment of attentionDistribution of attention can be controlled by the intentions of

the observer.

Two major categories of stimulus properties that could in principle capture attention can be distinguished ：

Feature Singletons

&

Abrupt Visual Onsets

STIMULUS-DRIVEN &GOAL-DIRECTED CONTROL OF ATTENTION

Feature Singletons1. Stimuli that differ substantially in one or more simple visual

attribute(e.g. color, orientation, motion) from their backgrounds.

2. Feature singletons are judged as subjectively salient.

3. Such stimuli can be found efficiently in visual search.

If feature singletons capture attention?In cited cases, the stimulus in question was itself the target of

search, and therefore presumably elicited top-down control.

One have to explicitly dissociate the observer’s attentional set from the properties of the stimulus array.

Feature Singletons & Attentional CaptureSTIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

Feature Singletons

1. Stimuli that differ substantially in one or more simple visual attribute(e.g. color, orientation, motion) from their backgrounds.

2. Feature singletons are judged as subjectively salient.

3. Such stimuli can be found efficiently in visual search.

Feature Singletons & Attentional CaptureSTIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

Singletons Capture Attention

Reaction time

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Theeuwes (1992)

Pashler (1988)

Feature Singletons & Attentional CaptureSTIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

Singletons capture attention

cue array target array

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Joseph & Optican (1996)

Feature Singletons & Attentional Capture

Attention was drawn to the cue even though it was known to be irrelevant to the task.

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

Singletons Do Not Capture Attention

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Feature Singletons & Attentional Capture

Reaction time to find the target did not differ whether the target was the unique element or not.

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

Singletons Do Not Capture Attention

Hillstrom & Yantis (1994)

Feature Singletons & Attentional Capture

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STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

Reaction time of the moving targets did not differ from the stationary ones.

Attentional Control……a possible reconciliation

Singleton Detection Mode The location of the largest or the greater contrast can be accessed,

but not the identity of the dimension(s) on which the stimuli differ.

When searching for a shape singleton, an irrelevant color singleton may win out.

Feature Search Mode Attention is directed to locations that match some task-defined visual

feature (e.g. “red” or “vertical”).

Feature Singletons & Attentional Capture

Bacon & Egeth (1994)

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

Peripheral cue draws attention automatically,

whereas a central arrowhead cue requires a deliberate shift of attention.

Peripheral cues drew attention whether they were informative about the location of the target or not, while central cues only controlled the deployment of attention when they were informative.

Abrupt Visual Onsets & Attentional Capture

Jonides (1981)

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

Peripheral cues might capture attention because they have abrupt onset.

Yantis & Jonides (1984)

Abrupt Visual Onsets & Attentional Capture

A visual search task searching for a prespecified target letter embedded in an array of nontarget letters.

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION

Yantis & Jonides (1984)

Abrupt Visual Onsets & Attentional Capture

The target happened to be the onset letter

The target was one of the no-onset letters

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Reaction time

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION Abrupt Visual Onsets & Attentional

Capture Two potential mechanisms could account for

attentional capture by abrupt onset.

1. Luminance increment activates Visual pathways, and it also direct attention to the eliciting object.

2. The appearance of a perceptual object. This might be a hard-wired response to the need to rapidly identify new objects entering the visual field.

Yantis & Hillstrom (1994)

EXP3

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTION Abrupt Visual Onsets & Attentional

Capture Yantis & Hillstrom used stimuli that were equiluminant with

their background. These displays thus exhibited no change in mean luminance, but they did include the appearance of a new perceptual object.

Attention was captured by new perceptual objects even though they didn’t exhibit a luminance increment.

Yantis & Hillstrom (1994)

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTIONInteraction of Goal-Driven & Stimulus-Driven

Capture Irrelevant feature singletons capture attention only when

subjects enter singleton detection mode.

Attentional capture by abrupt onset can be modulated by focused attention elsewhere in the display.

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTIONInteraction of Goal-Driven & Stimulus-Driven

Capture Any given perceptual act entail an attentional control setting.

The attentional control setting is part of the explicit or implicit set of perceptual goals held by the observer at the specific moment.

The visual features that are of current interest(e.g. “red” or “vertical”) will control the distribution of attention.

Folk.Remington.Johnston(1992)

EXP1

TABLE

EXP2

TABLE

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTIONInteraction of Goal-Driven & Stimulus-Driven

Capture The deployment of attention depends critically on what the

subject is set for.

When the cue and target were of the same type, i.e. both color or both onset, cue validity had a large effect.

Whereas the cue and target were of different types, then the cue had little or no influence on response time.

The state of attentional readiness adopted by the observer determines what sort of feature singletons will capture attention.

Folk.Remington.Johnston(1992)

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTIONInteraction of Goal-Driven & Stimulus-Driven

Capture Wolfe’s Guided search model Attention is directed to objects serially in order of priority.

Top-down activationHow closely an object matches the current attentional set.

Bottom-up activationHow much a given object differs from neighboring objects within

any given perceptual dimension.

Attention mapDetermines the order in which objects are visited during visual

search.

Wolfe (1994)

STIMULUS-DRIVEN & GOAL-DIRECTED CONTROL OF ATTENTIONInteraction of Goal-Driven & Stimulus-Driven

Capture The deployment of attention depends jointly on properties

of the image and the goals and expectation of the observer.

William James

exp1

exp2

THE REPRESENTATIONAL BASIS OF VISUAL SELECTION

“If attention selects a stimulus, what is the stimulus that it selects?”

Viewpoint 1

Hoffman & Nelson (1981):identify a target and then identify a secondary shape

Downing & Pinker (1985):cued box & target event

Viewpoint 2

Kahneman & Henik (1981): attention

might be directed not only to spatial

locations but also to perceptual objects.

the Gestalt psychologists

Overlap and Grouping

Rock & Guttman (1981):

1.The judgment task of the object drawn

2. A surprise recognition test

Overlap and Grouping

Duncan (1984): a display

consisting of a rectangle with a

tilted line drawn through the

middle.

Overlap and Grouping

when attention is directed to one part of an

object, other parts of the object enjoy an

attentional benefit, whereas equally distant

locations in other objects do not.

Egly et al (1994)

Overlap and Grouping

Eriksen & Eriksen (1974):the noise

letters were assigned to a response that

conflicted with the response associated

with the target letter, responses were

significantly slowed

Baylis & Driver (1992)

X H S H X H X S X H

Motion

Kahneman et al (1992)

An object file: a temporary

episodic representation of a

visual object, containing a record

of its location, its various

attributes, and its recent history

Motion

The target follows the onset of the cue by 150 ms or less(speed) ; or more than 300 ms(slow), inhibition of return (IOR) paradigm(Posner et al,1985)

Tipper et al (1991)

Motion

Gibson & Egeth(1994) argued that the conception of an object as independent of location should not be understood to imply that an object is devoid of location.

Although objects are distinct from the spatial locations that they occupy, there exist other intraobject locations that may be fixed with respect to the overall object

The Time Course Of Attention

-Directing Attentionhow quickly attention can be directed at a particular stimulus

-Dwell Time of Attentionhow long attention remains at a particular stimulus

Visual SearchRapid Serial Visual Presentation (RSVP)- whole report, partial report, minimal sequence

-Movement of Attentionhow attention moves from location to location

Time Course of Attention

Directing Attention

Muller & Rabbitt (1989)

Directing Attention

Peripheral cue: fast, transient responseCentral cue: slow, sustained response

= deliberate shift of attention

Dwell Time of Attention (Visual Search)

Estimate amount of time spent per item in the visual display

Wolfe et al (1989)

Dwell Time of Attention (Visual Search)

Dwell Time of Attention (RSVP-whole) Sequential display of stimuli Saarinen & Julesz (1991)

SOAs: 33, 67, or 100 ms

Dwell Time of Attention (RSVP-whole)

Dwell Time of Attention (RSVP-whole) Different approach: how slowly stimuli

needed to be presented to keep report accuracy at a high level

Kolers & Katzman (1966)6 letters sequentially, same spatial locationSOA of 375 ms for over 90% accuracy

Dwell Time of Attention (RSVP-whole) Haber & Nathanson (1969)

Words that varied from 4 to 8 lettersCritical SOA for 4 letter word= 65 ms, for 8 letter

word = 110 ms

- problems

Dwell Time of Attention (RSVP-partial) Problems w/ whole report Use of words: guessing strategies Random letter strings: memory requirement > task

performance RSVP- partial report: report 1 or 2 “target items” in the

stream Broadbent & Broadbent (1987)

Dwell Time of Attention (RSVP-partial) Broadbent & Broadbent (1987)

Dwell Time of Attention (RSVP-partial)

For 1st Exp Probability of reporting first target correctly

Probability of reporting second target correctly

Probability of reporting both target correctly

Targets temporally adjacent

0.46 0.35 0.075

Targets separated by three intervening items

0.45 0.14 0.075

• consistent w/ Duncan (1980)

Rapid serial visual presentation partial report Weichselgartner and Sperling(1987)

Memory mechanismsAttentional processes Perceptual processes

Rapid serial visual presentation partial report Raymond et al.(1992)

A suppression of visual processing ○ Perceptual and attentional mechanisms blink

A dual-task RSVP experiment ○ The consequences associated with paying

attention to a target○ Posttarget performance deficits

Sensory factors

○ ％ correct detections of the probe As a function of the probe position of in the seriesAttentional blink

RSVP with a multi-item sequenceA daunting task

Duncan et al.(1994)Stimuli were close together in time

○ The first stimulus interfered with the secondDwell time of attention

○ An index of the time course of the first object’s attentional demand

○ 500ms

Rapid serial visual presentation minimal sequences-1

Why the discrepant results-1

Moore et al(1996)Dwell time

○ Depending on specific stimuli and tasks?Duncan et al(1994) and Ward et al(1995)

○ Masked stimuli○ A difficult discrimination > an easy discrimination

Why the discrepant results-1

Moore et al(1996)Masking

statusaffecting the dwell time

Dwell time in easy method ○ ↓200ms

Why the discrepant results-2

Bennett and Wolfe(1996)Visual searchRSVP

Fell only at 26 ms

The movement of attention

Attention shifting from one location to another in the visual fieldAn analog and continuous fashionAn abrupt relocation

An analog and continuous fashion-1

Shul-et al （ 1979 ）Like a spotlight

Tsal （ 1983 ）Attention takes time to move

○ ↑distance → ↑time to moveCue should be beneficial

○ Maximum benefit of the cueFurther away from fixation

An analog and continuous fashion-2

Eriksen & Murphy (1987) and Yantis (1988)Not including a control for general arousal or

alertnessAttention shifting

○ Continuous or discrete dynamics?

An abrupt relocation-1 Sagi and Julesz (1985)

Discrimination accuracy was independent of distance

Kwak et al.(1991) Remington and Piere(1984)

An abrupt relocation-2

Sagi & Julesz (1985) and Kwak et al.(1991)Tasks was accomplished preattentively

○ Being little reason to speak of reallocation of attention

An abrupt relocation-3

A serial processingAdditive

A parallel processing Subadditive

An abrupt relocation-4 Sperling and Weichselgartner(1995)

↑distance → ↑time to move Attention can skip over an intervening

obstacle without any time costQuantum

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