4 – Divided Attention divided attention trying to do two things at the same time Some dual tasks cause no interferenc

1. 4 – Divided Attention divided attentiontrying to do two things at the same time Some dual tasks cause no interference. Example Walk and chew gum Some dual tasks cause interference. Example Drive and talk on cell phone. Question What kinds of tasks can be done concurrently without interference?

2. Demo Task A = Rotate right arm clockwise. Task B = Rotate left arm counterclockwise A & B  no interference Demo Task A = Rotate right arm clockwise. Task B = Rotate right leg counterclockwise A & B  interference Typical Divided Attention Experiment 3 conditions: A only B only dual-task (A and B at the same time) dual task interference occurs if Performance on A is better during A-only condition than during dual-task. or Performance on B is better during B-only condition than in dual-task.

3. Laws prohibiting cell phone use while driving (as of 2013) For experienced drivers, hands-free phone banned in 0 states. Handheld phones banned in 10 states (but not Florida). Texting while driving is banned in 41 states, including Florida. In Florida, texting is “secondary offense” (Source - Insurance Institute for Highway Safety) www.iihs.org/laws/cellphonelaws.aspx

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5. Driver Distraction Common belief: Driving is unaffected by driver’s use of hands-free phone Typical explanation. The two tasks are very dissimilar. driving car  visual, spatial, manual talking on hands-free phone  oral, verbal, auditory Laws conform to this belief. Use of handheld phones prohibited in many states. Use of hands-free phones allowed in every state (as of 2011). Does this make sense? Or do hands-free phones also cause interference?

6. Driver Distraction experiments Task Ss drive in simulators Ss must avoid cars, pedestrians. Typical Measures Braking time Number of collisions Common Conditions driving while talking on handheld phone driving while talking on hands-free phone driving while talking to passenger driving while reading text driving while composing text driving intoxicated

7. Experiment: Effect of hands-free phone Ss drove in simulator. During dense traffic, car in front stopped unexpectedly. Sample result Brake Time (ms) no distraction 933 talking on hands-free phone 1112 Conclusion Interference is attentional – not just manual. (Strayer et al., 2003)

8. Experiment: Hands-free phone vs. Intoxication Ss drove in simulator. Car in front suddenly stopped. One result: Brake time (ms) intoxicated (BAC 0.08%) 779 hands-free phone 849 (Strayer et al., 2011)

9. Experiment: Is hands-free phone worse than talking to passenger? “… Passengers tend to adjust their conversation based on driving difficulty; often helping the driver to navigate and identify hazards on the roadway and pausing the conversations during difficult sections of the drive. By contrast, this real-time adjustment based upon traffic demands is not possible with cell phone conversations.” Strayer and Drews (2006, p. 130) Experiment S drove in simulator; was asked to exit the highway at rest stop “about 8 miles away” S listened to friend tell story Result: Drivers who Missed the Exit driving alone 4% passenger conversation 12% hands-free cell phone conversation 50% (Drews et al., 2008)

10. Other findings from driver distraction studies: Most Ss overestimate their ability to drive while using a hands-free phone. Hands-free phone as bad as handheld phone Four 1-minute videos (bottom of webpage) www.psych.utah.edu/lab/appliedcognition/news.html Strayer and his colleagues (2001, 2003, 2006, 2009)

11. Bottleneck Experiments Driving and talking are hard tasks. Can interference occur if tasks are dissimilar and easy? Procedure Task 1 S1 Hear high or low tone R1 say “high” or “low” Task 2 S2 See “A” or “B” R2 press left or right key RT1 RT2

12. Ss practiced task 1 alone, task 2 alone, and dual task. Practice trial data were excluded from final analysis. Results: RT2 Task 2 alone ~ 500 ms Task 2 in dual task ~ 700 ms Conclusion Even two easy, dissimilar tasks can yield massive dual-task interference. (Pashler, 1984; Welford, 1941)

13. Why does Task 2 take so long? That is, in which stage does interference arise? PerceptionResponse SelectionResponse Production Perceive high toneSince tone is high, say “high” Say “high” Perceive “A” Since letter is A, press left key Press left key. Hypothesis: The mind can perform only one “response selection” at a time.

14. Two findings showing bottleneck during Response Selection Manipulation Effect on RT1 Effect on RT2 ----------------- ------------------------------------ Task 2 Perception made harder none none (e.g., “A” appeared blurry) Task 2 Response-Selection made harder none increased (e.g., if “A” then press B key) (Pashler, 1984) RT1 lag wait RT2

15. Bottleneck Practice Questions Predict the effect of each manipulation on RT1 and RT2 Manipulation RT1 RT2 Harder P1 increase increase Harder P2 none none Harder RS1 increase increase Harder RS2 none increase Harder RP1 increase none Harder RP2 none increase RT1 lag wait RT2

16. Another Prediction: Increasing lag by 1 ms should shorten RT2 by 1 ms (up to a point) lag wait 50 150 RT2 = 600 lag wait 100 100 RT2 = 550

17. Another Bottleneck Experiment Same Basic Procedure Task 1 S1 Hear high or low tone R1 say “high” or “low” Task 2 S2 See “A” or “B” R2 press left or right key Lag between S1 and S2varied from 50 to 900 ms (continued) RT1 RT2

18. Prediction of bottleneck theory Actual data (Pashler, 1984) RT2 RT2 RT2 Lag between S1 and S2 Lag between S1 and S2 Lag between S1 and S2 Slope = -1 RT2 Lag between S1 and S2

19. What dual-tasks can be done without interference? • Distinction • choice-RT task • Examples Tasks used in bottleneck studies • simple-RT task • Examples • hit key as soon as light appears • catch ruler dropped between your fingers • Two choice tasks  interference • Two simple tasks  no interference • One simple, one choice  no interference Perception Response Selection Response Production Perception Response Production

20. Summary of Bottleneck Studies Many easy tasks require “response selection.” If people try to do two such tasks concurrently, one task must wait (bottleneck). The bottleneck occurs if both tasks need “response selection”

21. Task Switching If we cannot do two things at once, can we at least switch back and forth? Yes, but switch is costly task 1 alone -------------------------- task 2 alone -------------------------- Switch without cost 1 -------- --------- --------- 2 --------- --------- -------- Switch with cost 1 --------- --------- --------- 2 --------- --------- -------- Data show that switch cost is high.

22. Experiment Ss shown two category names (e.g., Insect, Vegetable) Ss immediately say 4 examples of each category as quickly as possible Ss told in advance that responses should be: blocked A AAA B BBB ant gnat moth fly bean corn pea yam or alternating A B A B A B A B ant bean gnat corn moth pea fly yam Result Alternating is almost twice as slow! Conclusion Switching is costly.

23. demo Reversed Normal

24. Mental Rotation demo Indicate whether F is mirror-reversed or normal

25. Mental Rotation Letter Rotation Experiment Indicate whether letter can be rotated so that it looks normal. no yes IV = amount of rotation 135° 30°

26. Results Interpretation Ss “mentally rotated” object at constant rate 800 RT(ms) 500 0 180 rotation (degrees)

27. Demo: For each pair, indicate whether two images depict same object. yes yes no

28. More examples yes yes no

29. 3D mental rotation experiment Ss saw pairs of images depicting 3D objects. For each pair, Ss indicated whether two images depict same object or different objects. When images depicted the same object, it was rotated. within the plane or in depth (continued)

30. Results Interpretation Object is mentally rotated (Shepard & Meltzer, 1971)

31. Demo –digit span forward • 8 7 2 • 6 1 9 4 • 3 7 8 6 9 • 6 9 4 5 2 8 •  7 4 2 6 9 8 5 7 •  8 8 1 6 3 7 2 4 9 •  9 6 2 5 7 3 4 9 8 1 •  10 9 3 8 2 4 7 1 5 3 6 •  11 5 8 1 4 7 9 3 2 6 1 7 •  12 6 9 5 1 7 2 8 5 3 7 2 4

32. Demo –digit span backward • 2 7 3 • 3 6 9 4 • 4 3 8 5 2 • 5 5 3 9 8 1 • 6 7 5 9 8 3 4 • 7 9 8 4 1 3 6 8 • 8 5 1 7 3 6 7 9 2

33. Span Task S hears 3 – 10 items (digits or words), typically at a rate of item per second Immediately afterwards, S tries to repeats items aloud in same order DV = span = number of items S can report in the correct order Digit span task used on many IQ tests. (e.g., Baddeley, 2003; Cowan, 2005)

34. How do people perform the span task? rehearsal loop Mental mechanism that is used to rehearse verbal info (silently or aloud) Examples Rehearsing a phone number until you have a chance to jot it down Rehearsing someone’s name so you’ll remember it later. Mental arithmetic 23 x 15 = (20 x 15) + (3 x 15) = 300 + 45 = 345

35. Does span increase if items rhyme? book love trap wait bird head wall who blue view do coup you true rope dark hand moon soft fear edge rake bake make lake take cake fake

36. Word Span Experiment Each list included 7 words. Two kinds of lists: rhyme and non-rhyme Results rhyme span < non-rhyme span This is the phonological similarity effect Effect occurs even if rhyming words are spelled very differently crew, who, moo, through Thus, when using rehearsal loop, information is stored as sound, not image. (e.g., Baddeley, 1986)

37. How many items can you hold in your rehearsal loop? 7 ± 2 ? Demo 6 words on each list association opportunity representative organization considerable immediately sum hate wit bond yield twice

38. Another Word Span Experiment Ss perform word span task Each list included 6 words. Two kinds of lists: short words (1 syllable each) and long words (5 syllables each) Results long-word span < short-word span This is the word length effect Conclusion span = amount of info that can be said in about 2 s The magic number 7 is wrong  (Baddeley et al., 1975)

39. If magic number is wrong, why does digit span equal about 7? Observation IQ tests reveal that English kids had greater digit span than Welsh kids Experiment Welsh-English bilinguals tested in both languages Results: English digit span > Welsh digit span Why? English digit words are shorter than Welsh digit words (Ellis & Hennelly, 1980)

40. Prediction If digit span = 2 sec, then digit span should vary by language so that digit span = number of digits that can be said in 2 s Cantonese Digits 1. yat 2. yih 3. saam 4. sei 5. ngh 6. luhk 7. chat 8. baat 9. gau 10. sahp Arabic Digits 1. wahed 2. ithnan 3. thalatha 4. arba 5. khamse 6. sitta 7. seba 8. thamanya 9. tesa 10. ashara

41. Cross-Language Digit Span Experiment E measured how fast Ss could read digits in their native language E measured Ss’ digit span in their native language Results Languagesyllables per digit words read in 2 sdigit span Arabic 2.3 5.4 5.8 Spanish 1.6 7.0 6.4 English 1.2 7.6 7.2 Thus, digit span = number of digits that can be said in about 2 seconds. Conclusion Magic number 7 is merely an artifact of the English language. (Naveh-Benjamin & Ayres, 1986; see also Stigler, Lee, & Stevenson, 1986)

42. Sign Language In ASL, some words take longer to sign Long signs include PIANO, BICYCLE, CROSS Short signs include TYPEWRITER, MILK, CHURCH Word span is shorter if signs are long. (Wilson & Emmorey, 1998)

43. The End

44. Sometimes, we need to “work with” or “hold information” that is visual Questions How many windows are on the front of your house?  If you’re traveling south, and you must turn east, do you turn left or right?

45. Demo 1 7 7 6 1 4 9 2 1 9 4 1 1 7 7 6 1 4 9 2 1 9 4 1 chunkingincreases span by reducing number of items

46. visuospatial scratchpad Used for temporary storage and manipulation of spatial and visual information Examples Visualizing the campus layout in order to give someone directions. If you’re traveling south, and you must turn east, do you turn left or right?

47. Sample Task

48. Are visual-spatial scratchpad and rehearsal loop truly different mechanisms? Experiment Dual-task Results Both verbal  hard Both visual  hard One of each  easier (Baddeley & Hitch, 1974; Brooks Cocchini et al., 2002; Fougnie & Marois, 2006)

49. Demo Verbal Task As the woman chased her poodle, her poodle chased a cat Spatial Task Spatial Response point to “yes” or “no” Verbal Response say “yes” or “no” (Brooks, 1968) W