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