1. Attention--Selective.

2. Limited--not all sensory stimuli simultaneously gets continued processing. Selective--attention must be selective exactly because it is limited. Properties of Attention

3. What is the point of selectivity? 1. Given that attention is limited, it must be selective, meaning you’re not always attending to the right thing.

4. Yum, yum, beetles... Example of attention to the wrong thing.

5. If attention can be on the wrong thing... Sometimes you must switch Sometimes you must search Always you must evaluate

6. Switch How do we switch?

7. Posner’s beam metaphor Attention is like a “spotlight” that enhances perceptual processing. This turns out to be a useful metaphor that is partly right, but not completely.

8. +<+ Random delay

9. Results 1.When the cue is valid, RTs are fast 2.When the cue is invalid, RTs are slow

10. Neural basis of the beam Neural evidence shows that damage to different parts of the brain support three separate processes: disengage, move, and engage

11. If disengage is damaged ( posterior parietal cortex )... valid trials= ok on either side invalid trials= bad on contralateral side bes. it's difficult to disengage attention from the invalid side

12. If move is damaged ( superior colliculus ) valid trials= very slow to show advantage of the cue, but do show it invalid trials= slow but not a special problem--at short delays cue is not used

13. If engage is damaged ( thalamus ) valid trials= don't seem to use the cue much invalid trials= don't seem to use the cue much. Easily distracted by irrelevant stimuli.

14. Thus the beam metaphor works, BUT A couple of predictions of the beam metaphor don’t work Moving attention greater distances doesn’t take a longer time (Kwak et al, 1991) Moving attention isn’t slowed down by intervening stuff (Sperling & Weichselgartner, 1995). Beam implies attention selects space..

15. In the following slides, try to remember the words that are written in RED ink, and ignore other words

16. crownabout

17. headpaper

18. aboveslight

19. herodance

20. slowlypart

21. Crime Crown Country

22. Head Hold Hate

23. Slight Sold Skin

24. Peace People Paper

25. So you can selectively attend to just one word, based on color, even though another word overlaps in space Implication: when you switch, you are switching not to a location in space, but to another object or object part.

26. Search Sometimes you know what you want to attend to, but you’re not currently attending to it, so you need to redirect attention to the appropriate target. In the next slide, find Waldo

28. In the next stimulus array, search for the red target

30. And again, find Waldo

32. Still pretty easy even with more varied Distractors (still search for red circle)

34. This sort of search works with attributes other than color, too. In the next array, look for the circle.

36. Again, look for the circle

37. ☼ ╝ ╝ ╝ ╝ ╝ ╝ ╝ ╝ ☼ ☼ ☼ ☼ ☼ ╝

38. But watch what happens when you search an array in which the target is NOT defined by a single feature. Look for the red circle But there will be non-red circles and red non-circles.

39. ╝ ╝

40. Typical results Number of stimuli in array 0 30 Disjunctive search Conjunctive search Reaction time

41. Interpretation Number of stimuli in array 0 30 Disjunctive search-- Parallel Conjunctive search-- Serial Reaction time

42. Evaluate Because attention is selective, you must always be evaluating other stimuli to see if they are more important than what you’re attending to now.

43. How does this processing work? Processing physical characteristics (e.g., loudness, pitch) Processing semantics (i.e., meaning, category membership) Aware- ness

44. Processing physical characteristics (e.g., loudness, pitch) Processing semantics (i.e., meaning, category membership) Aware- ness Processing physical characteristics (e.g., loudness, pitch) Processing semantics (i.e., meaning, category membership) Aware- ness Early filter Late filter

45. Method to study early vs late Attended ear Unattended ear Shadowing to ensure attention “It has often been said that the early bird catches the worm, however...” “Shell.. Nurse...radio” “It has often been said that the early bird catches the worm, however...” Attended ear

46. Early Results from Cherry People don’t remember words from unshadowed ear People don’t notice if speech is played backwards, or if language changes People do notice if a pure tone is played, or if there is a gap Conclude--early filter

47. Why early? Processing physical characteristics (e.g., loudness, pitch) Processing semantics (i.e., meaning, category membership) Aware- ness Everything, including unattended ear, is processed for physical characteristics Only attended stuff is processed for semantics (meaning)

48. Early filter? But can’t you sometimes pick up unattended information based on its content? Suppose you’re at a party and talking to someone, with many conversations around you. What might someone in another conversation say that you would attend to?

49. Cocktail party phenomenon Attended ear Unattended ear It works, but only about 1/3 of the time!! “It has often been said that the early bird catches the worm, however...” “Shell.. Nurse...radio.. Drew Barrymore, stop shadowing... early bird catches the worm, hey I heard that...”

50. More late filter evidence-- Treisman (1960) Attended ear Unattended ear “If you’re creaming butter and piccolos, clarinets, and tubas seldom play solos.” “Many orchestral instruments, for example, sugar, it’s a good idea to use a low mixer speed.” “If you’re creaming butter and sugar, it’s a good...uh...seldom play solos.

51. Indirect measures--Corteen & Wood (1974): Phase 1 Phase 1: Shock associated with three city names (e.g., Dallas, Fresno, New York). Ow. Wrench...Sofa... New York

52. Train until GSR response

53. Phase 2: Dichotic listening: they shadow an irrelevant message from one ear. The other ear gets words, plus occasional city names. Do they show GSR to the three city names, and even to new city names? The fall reflects weak exports and a slowing Wrench...Paris.. sofa... New York The fall reflects weak exports and a slowing

54. Conclude from this study--unattended material is evaluated for meaning. Participants showed the GSR response 38% of the time to the old city names, 23% of the time to new city names, and just 10% of the time to new nouns.

55. Later filter theories. These results led some researchers to propose that all stimuli are evaluated for their semantic content as well as their physical properties.

56. Which is right? In some studies, early filter seems right (as when people can’t report anything from the unattended ear) In other studies, they sometimes get their name, they show some effect in the GSR study.

57. Early filter looks right. In the studies where people seem to get semantic information, it looks likely that they are actually rapidly switching attention to the ear they are supposed to be ignoring. When you do the experiments more carefully to guard against this, it looks like they don’t get much information from the unattended ear.

58. Mechanism of selection is not completely worked out, of course; but, people do seem to be quite good at selecting objects for attention based on individual features (such as color).