Katherine E. Burnett
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Transcript of Katherine E. Burnett
Exogenous attentional effects depend on the spatial match between task and cue
Kat BurnettSupervisor: Ayelet Sapir
Second Supervisor: Giovanni d’AvossaChair: Steve Tipper
Overview• Spatial Attention– Models– Exogenous vs. Endogenous– Cueing
• Exogenous Experiments• Conclusions• Further ideas
Models of Spatial Attention• Spotlight
• (Posner et al., 1980; LaBerge, 1983)
• Zoom lens• (Eriksen & St James, 1986)
• Gradient• (Henderson, 1991)
http://www.spotadventures.com/picture/view?picture_id=332559
http://crystalearthworks.blogspot.com/
Attention• Exogenous
(Automatic)
• From outside the person
• An automatic response
• Endogenous (Voluntary)
• From within the person• A wilful shift of
attention
Cueing Attention• Exogenous– Sudden grab, near target– Bright e.g. Flash
– Just before the stimulus (100ms)
– Does not need to be informative
• Endogenous– In centre of display– Symbolic e.g. Arrow
– Give the participant time to wilfully move attention there (300ms)
– Needs to be useful for the participant or they will not move attention (Jonides, 1980)
• Cue validity– A valid trial is one in which the target appears at the
cued location.– On an invalid trial, the target appears at an uncued
location.• Validity effect– The difference in performance at the cued and uncued
locations.– Therefore a validity effect is indicative of cue utilisation.
Validity effect
Yeshurun & Carrasco, 1998
• Resolution Hypothesis– Target Enhancement
• Texture Segmentation Task– 2 interval forced choice– Both intervals cued and
masked– “Which interval did the
target appear in?”
• Cue– 54ms line above
the target location
Yeshurun & Carrasco, 1998
Exogenous Results• Benefit for peripheral locations• Impairment at foveal locations
Exogenous Spatial Attention
Does cue size matter?
‘coherent motion’0% Coherence
‘dynamic noise’
(A)
75% Coherence
(C)
50% Coherence
(B)
StimuliRandom-dot kinematograms
Time500ms
200ms
80ms
100ms
300ms
70ms
300msMOTION TARGET
200ms
ON
OFF
Target Display
★50ms
(or absent)
PROBE ONSET
100ms
Coherent Motion
Dynamic Noise
ExogenousCue
Experiment 1Large Frame Cue
Motion Probe-5
0
5
10
15
20No
rm V
alid
ity E
ffect ** p < .01
Why might we get a validity effect for coherent motion and not for probe?
Spatial mis-match?Any part of window is showing motion but only one dot is red – where is attention?
Target enhancement?
Experiment 2Smaller cue, red dot can only be in this limited areaEliminate some of the ‘noise’ from red dot detection
Motion Probe Motion ProbeExperiment 1 Experiment 2
-5
0
5
10
15
20No
rm V
alid
ity E
ffect
** p < .01
* p < .05 * p < .05
Is this because the smaller cue matched the task, or because participants had more
information on where the red dot could appear?
Experiment 3Use large exogenous cue as in Experiment 1Limit red dot location as in Experiment 2
Motion Probe Motion Probe Motion ProbeExperiment 1 Experiment 2 Experiment 3
-10
-5
0
5
10
15
20
25
30
35N
orm
Val
idity
Effe
ct
Interim Conclusion
The size of the exogenous cue must match the size of the task
Experiment 4Spatially matched tasks
Motion Probe Motion Probe Motion Probe Motion ProbeExperiment 1 Experiment 2 Experiment 3 Experiment 4
-10
-5
0
5
10
15
20
25
30
35N
orm
Val
idity
Effe
ct
Conclusions• Exogenous attention operates through target
enhancement.– The large cue may not have evoked optimal
resolution for the probe detection task.– OR the white dots were interfering with the red dot
Conclusions• Exogenous attention can be manipulated by
changing the size of the cue.– Support for zoom lens and gradient models of
attention
Further Work• Multiple Cue Sizes within participants– Is this a modulation or a case of match/no match?
• Motion as the small task, probe discrimination as the large task– Do the effects swap?
• Colour Cue– Motion perception uses luminance channels: Could
this be why the motion validity effect is bigger?
Thank you for listening