1. Exogenous attentional effects depend on the spatial match between task and cue Kat Burnett Supervisor: Ayelet Sapir Second Supervisor: Giovanni d’Avossa Chair: Steve Tipper

2. Overview Spatial Attention Models Exogenous vs. Endogenous Cueing Exogenous Experiments Conclusions Further ideas

3. 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/

4. Attention Exogenous (Automatic) From outside the person An automatic response Endogenous (Voluntary) From within the person A wilful shift of attention

5. 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)

6. 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

7. 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

10. (A) (C) (B) 0% Coherence 75% Coherence 50% Coherence ‘coherent motion’ ‘dynamic noise’ StimuliRandom-dot kinematograms

11. 500ms Time 100ms 80ms Exogenous Cue 70ms 300ms 200ms Target Display 200ms MOTION TARGET ON 100ms OFF Coherent Motion 50ms ★ (or absent) Dynamic Noise 300ms PROBE ONSET

12. Experiment 1 Large Frame Cue

13. ** p < .01

14. 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?

15. Experiment 2 Smaller cue, red dot can only be in this limited area Eliminate some of the ‘noise’ from red dot detection

16. ** p < .01 * p < .05 * p < .05

17. Is this because the smaller cue matched the task, or because participants had more information on where the red dot could appear?

18. Experiment 3 Use large exogenous cue as in Experiment 1 Limit red dot location as in Experiment 2

20. Interim Conclusion The size of the exogenous cue must match the size of the task

21. Experiment 4 Spatially matched tasks

23. 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

24. Conclusions Exogenous attention can be manipulated by changing the size of the cue. Support for zoom lens and gradient models of attention

25. 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?

26. Thank you for listening