Perceptual Load

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<ul><li> 1. Perceptual load as a major determinant of the locus of selection in visual attention Lavie, N.,&amp; Tsal, Y.(1994).Perception &amp; Psychophysics, Vol.56(2),183-197.</li></ul> <p> 2. Overview </p> <ul><li>Theoretical discussion</li></ul> <ul><li><ul><li>perceptual load </li></ul></li></ul> <ul><li>Literature review</li></ul> <ul><li><ul><li>Early and late selection </li></ul></li></ul> <ul><li>Conclusion </li></ul> <p> 3. Background </p> <ul><li>Broadbent (1958): </li></ul> <ul><li><ul><li>Early selection: </li></ul></li></ul> <ul><li><ul><li><ul><li>Limited process </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>Analysis of physical features </li></ul></li></ul></li></ul> <p> 4. Background </p> <ul><li>Deutsch and Deutschs (1963): </li></ul> <ul><li><ul><li>Late selection: </li></ul></li></ul> <ul><li><ul><li><ul><li>Unlimited process </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>Parallel </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>Relevant response </li></ul></li></ul></li></ul> <p> 5. Background </p> <ul><li>Kahneman and Treisman (1984): </li></ul> <ul><li><ul><li>Paradigmatic shift </li></ul></li></ul> <ul><li><ul><li><ul><li>Filtering paradigm </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li><ul><li>Shadowing task (Cherry,1953) </li></ul></li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li><ul><li>Partial-report technique (Sperling,1960 ) </li></ul></li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>Selective set paradigm </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li><ul><li>Spatial and semantic priming </li></ul></li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li><ul><li>Visual search experiment </li></ul></li></ul></li></ul></li></ul> <p> 6. Some debate about early selection </p> <ul><li>Broadbents filter model limited capacity channel </li></ul> <ul><li>Physical distinction rather than info load </li></ul> <ul><li>Clear physical distinction of relevant info is insufficient for early selection </li></ul> <p> 7. </p> <ul><li>Lavie:</li></ul> <ul><li><ul><li>Physical distinction-&gt;priority-&gt;cannot prevent irrelevantinfo processing </li></ul></li></ul> <ul><li><ul><li>Perceptual load of relevant info </li></ul></li></ul> <ul><li><ul><li>prevent irrelevant processing </li></ul></li></ul> <p> 8. The proposed model for selective attention </p> <ul><li>Lavies premise: </li></ul> <ul><li><ul><li>Limited capacity : </li></ul></li></ul> <ul><li><ul><li><ul><li>early selection </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>late selection (automatic process) </li></ul></li></ul></li></ul> <p> 9. Literature review </p> <ul><li>Structural approach </li></ul> <ul><li>Perceptual load </li></ul> <ul><li>Physical distinctiveness between relevant and irrelevant items </li></ul> <p> 10. Literature review </p> <ul><li>Qualitative </li></ul> <ul><li><ul><li>Unlimited perception when one irrelevant stimulus is processed </li></ul></li></ul> <ul><li>Quantitative </li></ul> <ul><li>Limited perception but at the same time can accommodate more than one item </li></ul> <ul><li>early selection =high perceptual load </li></ul> <ul><li>Late selection = low perceptual load </li></ul> <p> 11. Perceptual loadOperational definition</p> <ul><li>No. of units/itemsin the display </li></ul> <ul><li><ul><li>Ex. A string of letters</li></ul></li></ul> <ul><li><ul><li>word= 1 unit </li></ul></li></ul> <ul><li><ul><li>letters = many units </li></ul></li></ul> <ul><li>Nature of processing for each unit </li></ul> <p> 12. Physical distinctiveness </p> <ul><li>Major factor in determining nature of selection </li></ul> <ul><li>Focus on location </li></ul> <ul><li>Low load poor distinction / clear distinction between target and distractor </li></ul> <p> 13. Low perceptual load + poor physical distinction </p> <ul><li>Poor distinction: </li></ul> <ul><li><ul><li>relevant and irrelevant stimuli occupy the same location </li></ul></li></ul> <ul><li><ul><li>Ex. Stroop task </li></ul></li></ul> <ul><li><ul><li>Parallel processing of relevant and irrelevant dimensions </li></ul></li></ul> <ul><li><ul><li>Asymmetric interference. ex.: word -&gt; color </li></ul></li></ul> <p> 14. Low perceptual load + poor physical distinction </p> <ul><li><ul><li>Logan (1980): manipulate expectancy </li></ul></li></ul> <ul><li><ul><li>Eriksens (1974):</li></ul></li></ul> <ul><li><ul><li><ul><li>AUAAAUAA </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>irrelevant distractor is identified </li></ul></li></ul></li></ul> <p> 15. 16. 17. 18. Low perceptual load + poor physical distinction </p> <ul><li><ul><li>Eriksens and Schultz (1979): </li></ul></li></ul> <ul><li><ul><li><ul><li>Prolong the process of target-&gt; increase distractor effect </li></ul></li></ul></li></ul> <p> 19. Low perceptual load + poor physical distinction </p> <ul><li><ul><li>Miller (1987): </li></ul></li></ul> <ul><li><ul><li>Flank X target appear left </li></ul></li></ul> <ul><li><ul><li>Flank O target appear right </li></ul></li></ul> <ul><li><ul><li><ul><li>High correclation:88valid cue </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>8invalid cue </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>Low correclation:56valid cue </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>40invalid cue </li></ul></li></ul></li></ul> <p> 20. Low perceptual load + poor physical distinction 21. 22. Low perceptual load + poor physical distinction </p> <ul><li><ul><li>Lavie: </li></ul></li></ul> <ul><li><ul><li><ul><li>Low load-&gt; spare attentional capacity-&gt; irrelevantstimuli </li></ul></li></ul></li></ul> <p> 23. Low perceptual load + poor physical distinction </p> <ul><li><ul><li>Paquet and Lortie (1990): </li></ul></li></ul> <ul><li><ul><li><ul><li> + attenuates associated-flanker effect </li></ul></li></ul></li></ul> <ul><li><ul><li><ul><li>Spatial precue reduced distractor effect but not eliminated it </li></ul></li></ul></li></ul> <p> 24. Low perceptual load + clear physical distinction </p> <ul><li>Eriksen (1974): </li></ul> <ul><li><ul><li>Contour-to-contour distance </li></ul></li></ul> <p> 25. </p> <ul><li>Keren, OHara, and Skelton (1977): </li></ul> <ul><li><ul><li>Same-different matching task </li></ul></li></ul> <ul><li><ul><li>Flanking targets </li></ul></li></ul> <p> 26. 27. 28. </p> <ul><li>Tipper (1985): </li></ul> <ul><li><ul><li>Negative priming (NP) </li></ul></li></ul> <ul><li><ul><li>Same identity, different shape(letter) -&gt; NP still occurred </li></ul></li></ul> <ul><li>Tipper &amp; Cranston (1985): </li></ul> <ul><li><ul><li>Pictures and names -&gt; NP still occurred </li></ul></li></ul> <ul><li>Distractor was processed to the semantic level </li></ul> <ul><li>low load-&gt; clear distinction-&gt; irrelevant processing </li></ul> <p> 29. 30. </p> <ul><li>Merikle and Gorewich (1979): </li></ul> <ul><li><ul><li>Size, distance-&gt; incompatible distractor-&gt; interfere </li></ul></li></ul> <ul><li>Hagenaar and van der Heijden (1986): </li></ul> <ul><li><ul><li>Color patch-&gt; compatibility </li></ul></li></ul> <p> 31. Manipulating display size Studies with high perceptual load 32. Manipulating display size </p> <ul><li>Clearer evidence that early selection is foundonlyunder conditions of high perceptual load </li></ul> <ul><li>Navon(1989) </li></ul> <ul><li> possibility of early selection among all possible combinations of </li></ul> <ul><li><ul><li>physical properties{color , size} </li></ul></li></ul> <ul><li><ul><li>Semantic property {relevant item: letter / digit} </li></ul></li></ul> <p> 33. Items : letters + digits </p> <ul><li>Low load display </li></ul> <ul><li><ul><li>2 item</li></ul></li></ul> <ul><li>High load display </li></ul> <ul><li><ul><li>4 item </li></ul></li></ul> <ul><li><ul><li>Distractor could be compatible/incompatible </li></ul></li></ul> <p>1 Target`1 Distractor 1 Target`3Distractors 34. Results </p> <ul><li>Color=no effect of display size nor ofdistractor compatibility </li></ul> <ul><li>Category=display size interacted withdistractorcompatibility effect </li></ul> <p> 35. 2- item4-item</p> <ul><li>responses when the distractor was incompatible than when it was neutral or compatible </li></ul> <ul><li>Late selection </li></ul> <ul><li>No effect on distractor compatibility</li></ul> <ul><li>Distractor interference was reduced when the load was relatively high </li></ul> <ul><li>Thus early selection </li></ul> <p> 36. </p> <ul><li>2. Kahneman and Chajczyk (1983) </li></ul> <ul><li> manipulated perceptual load in a variation of the stroop task </li></ul> <ul><li>RT for naming color of a central patch appearing together with a black word directly above or below it. </li></ul> <p> 37. 38. Experiment . 39. 40. Results </p> <ul><li>Word spelt a compatible color naming responses were faster </li></ul> <ul><li>Compatibility effect was reduced when:1. second neutral word</li></ul> <ul><li>2. array of Xs was added </li></ul> <ul><li>Reduction of attn. resources by neutral stimulus to capture incompatible distracting stimulus </li></ul> <ul><li> Attn. resources are involuntarily allocated to irrelevant stimuli only when relevant processing is not sufficiently demanding. </li></ul> <p> 41. Possible extensions to other modalities (auditory) </p> <ul><li>Zelinker (1971) </li></ul> <ul><li>Shadowlist of digits (4) </li></ul> <ul><li>Ignore feedback of their voices (0.2s delay) </li></ul> <ul><li>3 groups of shadowing </li></ul> <p> 42. Results </p> <ul><li>Easy shadowing</li></ul> <ul><li>Difficult shadowing </li></ul> <ul><li>Resourcesinterference </li></ul> <p>Delayed feedback difficult to ignore More stuttering Reduced interference 43. </p> <ul><li>Barr and Kapadnis (1986) </li></ul> <ul><li> manipulating difficulty of the relevant task affects the ability to ignore an irrelevant auditory message </li></ul> <ul><li>Standard shadowing test (English) </li></ul> <ul><li>Native speakers and non native speakers </li></ul> <p> 44. Results </p> <ul><li>Native speakers noticed more changes in unattended channel </li></ul> <ul><li>Ex. Speech interruptions </li></ul> <ul><li>reduction in voice intensity </li></ul> <ul><li>Changes caused more interferences in shadowing </li></ul> <ul><li>Non-native speakersresources</li></ul> <ul><li>processing of irrelevant message </li></ul> <p> 45. Summary </p> <ul><li>Early or late selection is determined by:</li></ul> <ul><li>1) perceptual load</li></ul> <ul><li>2)physical distinctiveness. </li></ul> <ul><li>Early selection : </li></ul> <ul><li><ul><li>desirableperceptual loads </li></ul></li></ul> <ul><li><ul><li>possible when there is a clear distinction between relevant and irrelevant items </li></ul></li></ul>