Orienting Attention

• Posner Cue - Target Paradigm:

Subject presses a button as soon as x appears

Orienting Attention

• Posner Cue - Target Paradigm:

Orienting Attention

• Posner Cue - Target Paradigm:

Orienting Attention

• Posner Cue - Target Paradigm:

Orienting Attention

• Posner Cue - Target Paradigm:

X

Orienting Attention

• Posner Cue - Target Paradigm:

Orienting Attention

• Posner Cue - Target Paradigm:

That was a validly cued trial because the x appeared in the box that flashed

Orienting Attention

• Posner Cue - Target Paradigm:

Orienting Attention

• Posner Cue - Target Paradigm:

Orienting Attention

• Posner Cue - Target Paradigm:

Orienting Attention

• Posner Cue - Target Paradigm:

X

Orienting Attention

• Posner Cue - Target Paradigm:

Orienting Attention

• Posner Cue - Target Paradigm:

That was an invalidly cued trial because the x appeared in the box that didn’t flash

Paradigms Used To Study Attention

• Posner Cue - Target Paradigm:

Attention Effect = Valid RT - Invalid RT

Voluntary Orienting

• Under what circumstances would a cue lead to a voluntary shift of attention?

Voluntary Orienting

• Under what circumstances would a cue lead to a voluntary shift of attention?– Informative cue– Validity = greater than 50%

Voluntary Orienting

• Under what circumstances would a cue lead to a voluntary shift of attention?– Informative cue– Validity = greater than 50%

• What is another way to make this paradigm a voluntary orienting paradigm?

Voluntary Orienting

• What is another way to make this paradigm a voluntary orienting paradigm?

Symbolic cues may orient attention towards another location.Stimulus cues orient attention to the stimulated location.

Symbolic Cue

Voluntary Orienting

• What is the time course of voluntary orienting?

Cue - Target Interval

ResponseTime

Invalidly Cued Targets

Validly Cued Targets

About 200 ms

Reflexive Orienting

• Attention can be automatically “summoned” to a location at which an important event has occurred:

Reflexive Orienting

• Attention can be automatically “summoned” to a location at which an important event has occurred:– Loud noise– Motion– New Object

• We call this attentional capture

Transients

Reflexive Orienting

• The Posner cueing paradigm (with blinking boxes) confounds reflexive and voluntary orienting

… in what way?

Reflexive Orienting

• The Posner cueing paradigm (with blinking boxes) confounds reflexive and voluntary orienting

• How could we change the Posner cueing paradigm to make it asses only reflexive orienting?

Reflexive Orienting

• The Posner cueing paradigm (with blinking boxes) confounds reflexive and voluntary orienting

• How could we change the Posner cueing paradigm to make it asses only reflexive orienting?

• Make validity 50% (non-informative cue)

Reflexive Orienting

• Time course of reflexive orienting is counterintuitive

Cue - Target Interval (ms)

ResponseTime

Valid

Invalid

0 500 1000About 50 ms

Reflexive Orienting

• Time course of reflexive orienting is counterintuitive

• Delayed response at validly cued location after long cue-target interval is known as inhibition of return (IOR)

Reflexive Orienting

• Time course of reflexive orienting is counterintuitive

• Delayed response at validly cued location after long cue-target interval is known as inhibition of return (IOR)

• Thought to occur because attention goes to cued location, then leaves and is inhibited from returning

Reflexive Orienting

• Can symbolic cues be reflexive?

Almost never but …

Reflexive Orienting

• Can symbolic cues be reflexive?

Reflexive orienting to direction of eye gaze

Reflexive Orienting

• Potential cues for Reflexive Orienting– Loud noise– Motion– New Object

• New Objects are powerful attention grabbers!

Transients

New Objects Capture Attention

IS THERE AN “H”?

Initial scene viewed for several hundred ms

Yantis & Jonides (1990): New-Object Paradigm

New Objects Capture Attention

New scene: search for target letter

IS THERE AN “H”?

Yantis & Jonides (1990): New-Object Paradigm

H may be revealed from and 8 or may appear as a new object

Reflexive Orienting

• Steven Yantis and colleagues– Result:

Reflexive Orienting

• Steven Yantis and colleagues– Result:

Targets are found faster when they are “new objects” than when they are revealed from “old” objects

Reflexive Orienting

• Steven Yantis and colleagues– Interpretation:

The visual system prioritizes in dealing with visual objects - relatively recent objects are “flagged” while older objects are disregarded

The Physiology of Attention

Physiology of Attention

• Neural systems involved in orienting

• Neural correlates of selection

Disorders of Orienting

• Lesions to parietal cortex can produce some strange behavioural consequences

ParietalLobe

Disorders of Orienting

• Lesions to parietal cortex can produce some strange behavioural consequences

– patients fail to notice events on the contralesional side

– Patients behave as if they are blind in the contralesional hemifield but they are not blind

Disorders of Orienting

• Lesions to parietal cortex can produce some strange behavioural consequences

– patients fail to notice events on the contralesional side

– Patients behave as if they are blind in the contralesional hemifield but they are not blind

Disorders of Orienting

• Called Hemispatial Neglect - patients appear unable to process information in the contralesional hemifield

Disorders of Orienting

• Hypothesis: Parietal cortex somehow involved in orienting attention into contralesional space

Disorders of Orienting

• Posner and colleagues

– Use cue-target paradigm to investigate attentional abilities of parietal lesion patients

Contralesional Ipsilesional

Disorders of Orienting

Results: Valid cue in contralesional field is effective

invalid- contralesional target

valid - contralesional target

invalid - ispilesional target

valid - ipsilesional target

Results: Severe difficulty with invalidly cued contralesional target

Disorders of Orienting

• Interpretation:– Patients have difficulty disengaging

attention from good hemifield so that it can be shifted to contralesional hemifield

Disorders of Orienting

• Interpretation:

– Patients have difficulty disengaging attention from good hemifield so that it can be shifted to contralesional hemifield

– Parietal cortex is somehow involved in disengaging attention

Disorders of Orienting

• Disengage - Shift - Engage Model– Parietal Cortex notices events and

disengages attention

Disorders of Orienting

• Disengage - Shift - Engage Model– Parietal Cortex notices events and

disengages attention– Superior Colliculus moves attention

Disorders of Orienting

• Disengage - Shift - Engage Model– Parietal Cortex notices events and

disengages attention– Superior Colliculus moves attention– Pulvinar Nucleus reengages attention

Disorders of Orienting

• Disengage - Shift - Engage Model– Parietal Cortex notices events and

disengages attention– Superior Colliculus moves attention– Pulvinar Nucleus reengages attention– Entire process is under some top-down

control from Frontal Cortex

Disorders of Orienting

• Orienting mechanism can be interfered with in normal brains

Disorders of Orienting

• Orienting mechanism can be interfered with in normal brains– changes that are not accompanied by transients are hard to

detect

Disorders of Orienting

• Orienting mechanism can be interfered with in normal brains– changes that are not accompanied by transients are hard to

detect• e.g. building appearing slowly

• orienting mechanism scans the scene aimlessly

Disorders of Orienting

• Orienting mechanism can be interfered with in normal brains– changes that are not accompanied by transients are hard to

detect• e.g. building appearing slowly

• orienting mechanism scans the scene aimlessly

– changes accompanied by full-field transients are hard to detect

• e.g. change blindness

• orienting mechanism is blinded by the transient