Attention

1. تهیه و تنظیم: دکتر مهدی علیزاده Attention ارائه شده در کارگاه تخصصیتوانبخشی توجهاز سری کارگاه های آخر هفته های شناختی تابستان 1396

2. What is attention? • "Everyone knows what attention is. It is the taking possession by the mind in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought...It implies withdrawal from some things in order to deal effectively with others." • William James

3. What is attention? • Though we may talk about it in the following ways… • “I can only do so much at once!” • “I missed the play on the field, I wasn’t paying attention.” • “Pay attention to me!” • “I need to focus.” • “She has attention deficit disorder.” • Are they all referring to the same thing?

4. What is attention? • What was first viewed as simple bottlenecks is really much more complex • Attention determines how information is processed by the cognitive system… • …and vice versa • Cognitive Control of Attention • Limits to attention may be processing limits • In some ways however we really don’t know much more about it than folk theories. • So what do we know?

5. Attention • What is Attention? • Attention is the control of sensory input and cognitive resources • Input = how much/ what gets in • Control = what guides attention • Internal • External

6. Other distinctions • Task-defined and Maintenance of activity • Descriptive notion of attention defined by the task used in the study (e.g. if they answer a certain way they are attending to that stimulus), or continued action • Doesn’t speak to underlying mechanisms • Process-oriented • Attention as a psychological process • Involves selection among alternatives and improving the effectiveness of mental processes

7. Other distinctions • Perceptual Attention vs. Attention in Complex Tasks • Perceptual • Attention involved in the enhancement and selection of stimulus input from the environment • Complex Tasks • Attention used for non-automatic tasks and task selection

8. Five functions of attention (from Medin) • Perceptual 1. Focusing 2. Perceptual enhancement 3. Binding • Complex Tasks 4. Automaticity (sustaining behavior) 5. Task Selection

9. Paradigms of Attention Research • Cuing • Analyze the orienting process and comparison of processing attended vs unattended stimuli • Search • Analyze how attention eliminates interference from irrelevant stimuli • Filtering • Analyze how attention eliminates interference from irrelevant stimuli and the stages at which such stimuli are suppressed • Dual-Task • Analyze how attention is involved in the coordination of multiple tasks

10. Cuing • Participants are led to expect a specific stimulus to be presented in a particular manner • Example: Spatial cuing • Types of cues • Valid vs. Invalid • Does the target appear at the cues location or not • Peripheral (exogenous) vs. Central (endogenous or symbolic) • Predictive (target is more often than not consistent with cue) vs. Non-Predictive (target is as likely to appear anywhere else same as the cued location) • Ex. 80% predictive or 50-50% chance at being valid or not

11. Inhibition of return: bias against previously attended to areas

12. Cuing • Predictive/Symbolic • Elicits long-lasting orienting of attention but takes a bit (100-200ms) for attention to shift due to being a symbolic cue • Predictive/Peripheral • Rapid (50-100ms after cue onset) and long-lasting • Non-predictive/Symbolic • No real orienting effect as there is no real motivation to shift attention • Non-predictive/Peripheral • Rapid orientation but doesn’t last long • If cue does appear at location (valid) this will be detected much more quickly with shorter cue-target onset • With more delay, attention shifts elsewhere and actually RT is slowed for valid trials • Inhibition of return

13. Search • Look for stimuli embedded among non-target stimuli • Slopes and set size • Flat slopes indicate stimuli are processed independently (parallel search or automatic), no interference from non-targets • Steep slopes • Serial search: attention shifted from one item to the next until the target is found. Or… • Limited-capacity parallel search (parallel but slower due to set size increase)

14. Filtering • Dichotic Listening Task • See how well we attend to message or how much of ignored gets through • Stroop task • Blue Red • Word processing ok in general, but if reporting color, word can interfere • Global/Local • Navon letters: slower to report local features if global does not match • However size can affect

15. Filtering • Flankers • H T H T T T • Respond what middle is (one response for T, a different one for H) • RT is slowed when flankers have a different response associated with them (HTH), unless far enough apart • Can show the spread of attention to nearby areas • Negative Priming • B • Particular letter requires a response • RT slowed when unattended letter later is the to-be-attended letter • Previous inhibition affects later processing A

16. Dual-Task • How much interference? • If involve the same cognitive processes, paying attention to one will lead to a decrease in performance on the other • If independent, no interference • However, in some cases increased difficulty in one task will result in the other beginning to interfere • So not necessarily same resources involved, but a reflection of cognitive ‘load’

17. Focusing • Perceptual Enhancement • Lu & Dosher (1998) • Attention acts as sensory amplifier in general, not just signal amplifier • Performance should improve in low noise situations • If lots of noise, attention will amplify that as well and so performance will not improve with focus of attention • What gets in? • Early Selection • Attention operates to help prevent sensory/perceptual overload • Late Selection • Attention serves to protect higher level cognitive processes (e.g. working memory)

18. Sensory Memory (Sperling 1960) • Participants view a briefly presented array of letters. • Change the duration between presentation of array and the recall tone. • Report as many characters as possible.

19. Sperling • Array of 12 letters • 50 msec. presentation 7 I V F X L 5 3 B 4 W 7

20. Sperling • Full-report • Report as many items as possible • Recall (no delay) = ~4 items • Recall decreased dramatically with tone delay • Suggests a limit (‘span of apprehension’) to what can be perceived.

21. Sperling • Partial-report paradigm • Tone cued which line of the array to recall • High = top line • Medium = middle line • Low = bottom line • Compare recall across rows 7 I V F X L 5 3 B 4 W 7

22. Sperling • Recall with no delay • Regardless of row asked to recall, about 3/4 of the items would be, or 9 on average for 12 item presentation • Conclusions: • Lots of information gets in and receives some initial processing • Lasts a short time • Same pattern of results as full report with tone delay • Sensory memory is rather large but has a short duration.

23. Focusing: Selecting Channels • Early Selection • Attention operates early on to protect low level processes from being overloaded • Late(r) Selection • Operates after meaning has been extracted from incoming stimuli • Working memory • If we don’t use the information…it is lost • Cocktail Party Paradigm • Dichotic listening • If early sensory systems do not limit the information that is processed, when does selection take place?

24. What Gets In? • Early idea: Only what is specifically attended to gets in • Broadbent’s bottleneck (1958) • One sensory input at a time processing • Dichotic listening • Filter is flexible and can shift, but only what is focused on gets to later processing

25. R E S P O N S E I N P U T Sensory register Selective filter Detection device Short-term memory • Filter acts early after sensory stage • Problem • Some ‘unattended’ info gets through • Moray 1959 (can still hear our name in unattended channel)

26. Based on current goals Danger signals, one’s name Determine who is speaking Revised conceptualization: some stable high priority info is checked without attention

27. Attended Unattended In Cat The Large Picnic Day Basket Apple She Friend Had House Peanut Spoon Butter Cap Book Sandwiches Wood And Live Chocolate At Cake On Crab Early/Late Selection • Such a model comes from Triesman (1960) • All in but some in attenuated form • More relevant, less attenuated • In the example here, Ss report hearing the whole sentence • Cocktail Party effect: • If meets certain criteria, will be attended (flexible bottleneck) • Capacity • Limit for the amount of information (and the amount of resources) available at any one time. • Although ‘early’ selection, key differences compared to Broadbent’s include: • All info gets in initially for at least some basic low level processing • Possibility for flexible or multiple filtering

28. Treisman • Suggests that the filter/attenuator is occurring somewhat later but still before information reaches short-term/working memory

29. Late Selection • Deutsch & Deutsch (1963), Norman (1968) • Proposed ideas for a late selection of attended information • Essentially a different interpretation/version of Treisman • Both channels of information (in dichotic listening task) are recognized but are quickly forgotten unless they are relevant (or strong) • Info makes it to short-term memory • Not really all that different from Treisman’s except the filter comes after meaning is fully processed for both channels

30. Subject shadows this Unattended ear More on Late selection • Mackay (1973). • Sophisticated meaning analysis of unattended channel They threw stones towards the bank … … … … … money or … … … … … river

31. Late selection Post-Shadowing Test • Heard 26 ambiguous sentences. • 26 “recognition trials” pick sentence that best matches meaning of the sentences on the attended channel: • “They threw stones toward the side of the river yesterday.” vs. • “They threw stones toward the savings and loan association yesterday.”

32. Late Selection • Result • Choice of sentence influenced by word in unattended ear • Hear: money → More likely to pick “financial institution” • Hear: river → More likely to pick “river bank” • When asked about the word in the unattended ear, participants entirely unaware of unattended word • Conclusion • Unattended information was fully processed for meaning • No attenuation early on, but rather is it relevant to the required response?

33. Sensory register Detection device Working memory Late selection • Information makes it to the detection/processing of meaning stage and passed on to STM for further processing and perhaps eventually to LTM • Both channels are processed fully for meaning, but only one of those reaches conscious awareness

34. The end of early selection? • Not so fast • Evidence from neurophysiological studies studies show the workings of attention very early on, before sensory/ perceptual processing is complete

35. Recap: Comparison of early/late selection • So there is evidence for both early and late • May be that how attention is utilized depends on the task and the current perceptual load, and instead be related to ‘attentional resources’ available rather than bottlenecks.

36. Other ideas • Lavie (1995) suggested that it may have to do with perceptual load • If low load all information will be initially processed and selection for further processing will take place after all relevant information has been analyzed • E.g. flankers task • In high load conditions, attention acts as a perceptual filter • Adding more stimuli to the flankers task suppresses the effect of the flankers (i.e. they are not making it through the initial perceptual filter)

37. Capacity Model • Kahneman (1973) • What gets in depends • Attention is a resource to be allocated across tasks • Practiced tasks require less resources • Automaticity

38. Attentional Control • Dual-Task Paradigm • Participant must perform more than one task at a time • In general, two tasks can be performed at once.. • … with a detriment to one task … • … depending on the type of tasks. • Driving and talking on the phone- which suffers?

39. Dual-Task • Psychological Refractory Period and Attentional Blink • Refer to the same thing only usually in terms of RT in the former and accuracy in the latter • How long does it take a process to “prepare” for additional work?

40. PRP • Present two stimuli at about the same time. • Each stimulus varies on some distinct psychological dimension • Example • Tone (high or Low) • Letter (‘T’ or ‘Q’) • Make a forced-choice response to both stimuli • Instructed to give one response first

41. PRP • Measure the RT to the Second Response and compare it with RT in a control situation (respond to second target alone) • RT typically is longer in the dual task situation even for much different stimuli • Differences in RT patterns indicate the presence of central processes that must be completed before response selection for the second stimulus can occur • RT varies as a function of a number of factors such as: • Perceptual ambiguity of stimuli • The nature of the response required • Difficulty of tasks

42. Attentional blink • Rapid serial visual presentation of stimuli • E.g. letters • Two tasks required of participant • Name the white letter • Target • Was there an X? • Probe • When the time between target and probe is short, participants are more likely to miss the probe

43. 1.0 .9 .8 .7 .6 Control Experimental .5 .4 0 200 400 600 800 1000 Stimulus Onset Asynchrony PRP and Attentional Blink summary of results % Correct Probe Detection As one can see, with more time between stimulus and probe, attention has ‘returned’ and the probe is more readily identified.

44. PRP and Attentional Blink • Suggests appears to be a bottleneck in response selection and consolidating the perception into a reportable memory • Both tasks use the process before response can be made • Can’t be used at the same time • However… • Shapiro notes in the article there are cases in which no AB is seen • May be related to stimulus similarity • Awh et al. (2004) • Digit response (target) Face response (probe) • Faces unaffected • Perhaps competition among multiple limited-capacity resources rather than (dis)similarity • Dual task costs can be predicted based on the degree to which each task calls upon overlapping components of a broad range of resources • Target hits on resources required for probe processing

45. Multiple Resource Theories • Pashler (1998) • Attention • Perceptual component that acts as both a filter and has resource limitations • Bottleneck component corresponding to response selection • Some information may be blocked early on, but even that which is not filtered is subject to available resources • Complex Tasks • Capacities can be coordinated • Response selection must occur for one task before next can be completed • Coordinated by the Central Executive

46. Resource Theories • Limitations • Nature of the limitation is unspecified • Not really testable • If two tasks can’t be performed without some impairment  shared resource which is limited • If no impairment  they don’t require same resource • Ambiguous results  multiple resources • By explaining everything it may not really be able to provide a true understanding

47. Decision Noise • An alternative explanation of such results is that, in tasks that require multiple decisions, accuracy will decline just because there is more opportunity to make errors (Shiu & Pashler, 1994) • I.e. more noise in terms of signal detection • Evidence from • Visual Search • Spatial Cuing

48. Decision Noise • Looking for a red T • Resource perspective: • If accuracy decreases with increase in red items but not with increase in green, we might conclude… • Some resource allocated to red but not green • Each red item receives fewer available resources with increase in red items

49. Decision Noise • Decision noise perspective • More noise with additional red items  • More opportunity for decision error • Decisions are not made for green letters, so no performance detriment with increase in green items

50. Decision Noise • We accumulate evidence over time until criterion reached • More time (longer RT)  more accurate • Less time (quicker), less accurate • Changes in criterion, sensitivity will influence speed and accuracy (no need to refer to resources)