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Stages of Selection
• Broadbent: Early Selection - a bottleneck exists early in the course of sensory processing that filters out all but the attended channel
• Alternative theory: Late Selection - the bottleneck exists not at the lowest stages, but at the highest - such as response planning, memory and consciousness
Stages of Selection
Stages of Selection
• Testing Early Selection Theory - what prediction can be made?
Stages of Selection
• Testing Early Selection Theory - what prediction can be made?
• Information (such as meaning of words) in unattended channel shouldn’t be processed for meaning
Stages of Selection
• Shadowing Task: ignore one input, repeat back the other
• Subjects are largely unaware of unshadowed message but…
• Certain words such as their name distract them!?
• Why is this puzzling?
Stages of Selection
• Testing Early Selection Theory - what is another prediction that can be made?
• Should be able to find differences in brain activity in primary sensory areas (A1, V1)
Stages of Selection
• Electrical activity recorded at scalp (EEG) shows differences between attended and unattended stimuli in A1 within 90 ms
Hansen & Hillyard (1980)
Stages of Selection
• Evidence exists for both early and late selection mechanisms
– One interpretation: early reduction in “sensory gain” followed by late suppression of unselected information
Orienting Attention
Control of Attention
• Major Distinctions:
Voluntary Reflexive
Control of Attention
• Major Distinctions:
Voluntary Reflexive
Overt Covert
Voluntary Orienting
• Attention can be oriented covertly – a commonly used metaphor is “the spotlight of attention”
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
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
• 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)
• Viewers are still faster and more accurate!
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 an 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
Attention and Consciousness
• The attention orienting mechanism can be confused leading to something called “change blindness”
Attention and Consciousness
