Stroop(2)

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  • John Ridley Stroop March 21 1897 Tennessee farm 2 nd youngest of 6 Poorly didn’t do heavy work on farm Top of class @ school Kitrell County school David Lipscomb College in Nashville Initial financial support: father sold 2 cows & a horse Stroop helped finance self by growing and selling a crop of potatoes the summer before college. Dec 23 1921, 2 nd yr @ college married Zelma Dunn Over 7 yrs whilst he at Uni, 3 sons. To support family, Stroop taught @ David Lipscomb college, worked as janitor & as librarian, taught high school, & built his own house. B.S. In 1924, M.A. 1925, PhD in Exptal Psych 1933 (supervisor Joseph Peterson) Continued to work @ David Lipscomb College – taught, Registrar, Chair of Psych for 16 yrs (1948-1964) 1 st to combine word & object property dimensions -> response conflict. !935 paper little impact at the time – behaviourism prevalent; 1960’s info processing & cog psych Stroop’s work rediscovered. Used to highlight goal of examining stages of mental processing thro analysis of response time. Still widely studied today
  • Stroop(2)

    1. 1. METHODS IN PSYCHOLOGY PRACTICALS 1 THE STROOP EFFECT
    2. 2. 2 Session Aims  To give an introduction to a classic experiment: Stroop (1935)  To briefly describe Klein’s (1964) experiment  To run a partial replication of Klein’s experiment  To give some possible explanations of Stroop and Klein  To give some examples of other Stroop-like experiments
    3. 3. 3 The Stroop effect (1935) Named after 1st person to systematically demonstrate the effect Jaensch (1929) also described effect …but not well written up…a lesson to us all! J. Ridley Stroop (1897-1973 ) c.1933
    4. 4. 4 Why study Stroop? Reason 1: Example for use of mental chronometry Most common form is the measurement of RTs Response to single trials is measured repeatedly Time to complete a task consisting of many trials is measured or
    5. 5. 5 Why study Stroop? Reason 2: To investigate the nature of attention & semantic representations -> more about this later !
    6. 6. 6 Stroop (1935) Part 1: Read 100 colour words Condition 1 red, blue Condition 2 red, blue Part 2: Name ink colour for 100 items Condition 1 red, blue Condition 2 ■■■, ■■■■ 43s 41s 110s 63s
    7. 7. 7 Stroop’s conclusions:  Participants could largely ignore the ink colour when reading colour words  BUT: Incongruent colour words interfered with the task of colour naming
    8. 8. 8 Today’s experiment:  Klein (1964) – partial replication  Klein used 6 different classes of words  Task: name ink colour  Klein showed not only incongruent colour words produce interference
    9. 9. 9 Klein (1964) – 6 cond typed in red, blue, green & yellow ink 1. Colour words (Classic Stroop) redred,, blueblue,, greengreen,, yellowyellow 2. Other colour words (not required as naming responses) tantan,, greygrey,, blackblack,, purplepurple 3. High frequency colour-related words skysky,, firefire,, grassgrass,, lemonlemon 4. High frequency ‘neutral’ words putput,, taketake,, heartheart,, friendfriend 5. Low frequency ‘neutral’ words solsol,, efteft,, helothelot,, abjureabjure 6. Nonsense syllables (really letter strings) hjhhjh,, bhdrbhdr,, gsxrqgsxrq,, evgjcevgjc
    10. 10. 10 Klein’s results:  Klein measured the time taken to name ink colour in each of the 6 conditions  Compared with a control condition (name colour of rows of asterisks)  Result: a graded interference effect  Explanations later…
    11. 11. 11 Klein’s results: 0 5 10 15 20 25 30 35 40 Colour names Other colour words High freq colour- related High freq neutral Low freq neutral Letter strings Colour-naming condition Meancolournamingtime increment(secs)
    12. 12. 12 Klein - faults:  Return to Klein’s materials…  What might be improved on them?
    13. 13. 13 Errors in Klein’s materials  Not all ‘neutral’ words i.e. heart, sol  Word length not controlled (3, 4, 5, 6 letters) – see Klein’s condition 3 We’ll correct for these and  We’ll use Orange ink not Yellow ink
    14. 14. 14 Our stimuli: 1. Colour words redred,, blueblue,, greengreen ,, orangeorange 2. Other colour words (non naming responses) tantan,, greygrey,, brownbrown,, yellowyellow 3. Hi freq colour-related words skysky,, firefire,, grassgrass,, carrotcarrot 4. Hi freq ‘neutral’ words putput,, taketake,, grantgrant,, friendfriend 5. Low freq ‘neutral’ words sotsot,, groggrog,, tapirtapir,, piquetpiquet 6. Letter strings hjhhjh,, bhdrbhdr,, evgjcevgjc,, gsxrqzgsxrqz
    15. 15. 15 Experimental Design Between – participants (independent groups) design: Separate groups of participants are tested for every condition Advantage: results in one condition not influenced by participants prior experience with other conditions Disadvantage: Random differences between groups might mask experimental effects
    16. 16. 16 Experimental Design Within – participants (repeated measures) design: Every participant is tested in every condition Advantage: Results not influenced by random differences between participants Disadvantage: results in one condition influenced by participants prior experience with other conditions
    17. 17. 17 Experimental Design Mixed design: One (or more) within-subjects variable One (or more) between-subjects variable -> That’s what we will do here !
    18. 18. 18 Procedure – Part 1  Form groups of four  Refer to Instructions for procedure on Duo (Stroop ‘handout’)  Do Condition A (read) and Condition B (name ink colour of x’s) for each participant; record times  Timer: use your mobile!  Write time for A and B on results sheet
    19. 19. 19 Procedure: Important Notes  Do not deliberately distort your vision (e.g. don’t squint)  Do not use finger to point to words  Do not cover up words/parts of words  Do correct mistakes  Anyone colour blind?!
    20. 20. 20 Procedure – Part 2  Between-Subjects design: assigning Participants to conditions  Class compares RTs for Conditon B  Each participant given 1 experimental condition on basis of control condition (B = colour naming of ‘x’s)  Each participant does their own experimental condition only
    21. 21. 21 Results When finished, bring your results to the front please: 1. Reading time for Condition A 2. Colour naming time for Condition B 3. Name of your experimental condition 4. Naming time for experimental conditon 5. Naming time difference (Experimental condition – Condition B) 6. Age / Sex
    22. 22. 22 Explanations & Presentations:  Interference  Examples of other Stroop-like experiments  Why you might get graded interference  What to do with your results ....
    23. 23. 23 Interference:  Incongruent colour words interfered with the task of colour naming => interference  “Automatic reading” when attention paid to words (Posner & Snyder, 1973)  Note: Reading words (which is the normal response) is faster than colour-naming
    24. 24. 24 Interference: Competition – how? Word read could interfere with 1.IDENTIFICATION of ink colour 2. SAYING ink colour (i.e. response) Both occur - response competition more important
    25. 25. 25 Other Stroop-like experiments Henderson (1973) – Find a letter Find “A” oeDcinAoieNie easier oeDcanAoaeNae harder (because other ‘a’s interfere)
    26. 26. 26 Other Stroop-like experiments Navon (1977) – Name global letter FFFF E F E FFF easier than E F E F EEEEE
    27. 27. 27 Other Stroop-like experiments Morton (1979) – how many digits on line? 4444 44 333 faster than 3333 55555 555
    28. 28. 28 Other Stroop-like experiments Spatial task – where is word written: top or bottom of square easier than TOP TOP BOTTOM BOTTOM
    29. 29. 29 Other Stroop-like experiments Verbal task: what is the pitch of the voice? Say words “High” and “Low” in a high/low tone “High” in high tone & “Low” in low tone easier than “High” in low tone & “Low” in high tone
    30. 30. 30 Graded interference - Explanation based on: SEMANTIC MEMORY Words stored in SEMANTIC NETWORK Attend to word -> spreading activation through network One word PRIMES another -> words more available as response SKY might activate response “blue” GROG unlikely to activate “blue”
    31. 31. 31 …but “semantic memory” may not be the whole story… GROG unlikely to activate “blue” it might activate “ green” ? because of the GR …so orthography or other things may also affect results
    32. 32. 32 Presentations:  In groups of about 4 people prepare a ppt- Presentation on the Stroop experiment  About 10 minutes of presentation / 5 min of questions / comments  Form groups now, write down names!
    33. 33. 33 Presentations:  Find data on DUO:  Methods In Psychology -> 07_Stroop -> Stroop_Results.xls
    34. 34. 34 Presentations:
    35. 35. 35 Title  Should describe experiment completely & appropriately  Try and include Independent Variable (IV) and Dependent Variable (DV) in title
    36. 36. 36 Introduction  Provides rationale for research  Good idea to start broad and end narrow:  Briefly discuss general issue  Review relevant literature; theoretical / experimental background; relate to your experiment (i.e. What is the Stroop effect? Explanations of Stroop; Klein’s experiment; explanations linked to semantic memory & attention)  General description of your experiment (i.e. Partial replication of Klein (1964); how same? how different?)  End with experimental hypotheses/specific predictions  Important to be selective about what material you include
    37. 37. 37 Introduction Experimental hypotheses: 1. Reading faster than Colour-Naming (comparison of Conditions A & B) 2. Graded Interference effect (spell out expected findings)
    38. 38. 38 Method  Should enable others to repeat your study  For presentation: not as detailed as for your research reports
    39. 39. 39 Participants  Number, age (mean & sd), sex  any other relevant info (e.g. vision normal or corrected to normal; reading problems; colour blindness?)
    40. 40. 40 Design  Design of experiment: MIXED 1 within-participant : Reading vs Naming; 1 between-participant: Colour relatedness  Independent variables IV1: Task type – 2 levels: Reading, Naming IV2: Colour relatedness – 6 levels (describe 6 experimental conditions)  Dependent variables DV1: Time to complete task DV2: Colour naming time increment (Experimental condition – Control Condition B)
    41. 41. 41 Results – Stroop  (Hypothesis 1)  summary of related t-test comparing Reading time (condition A) with Colour Naming time (condition B)  DO NOT include all the SPSS output!  Some graphical representation of Reading time (condition A) vs Colour Naming time (condition B)  (Hypothesis 2) Colour Naming time increment:  Mean value for 6 experimental conditions  Bar chart of 6 mean scores (like Klein’s)
    42. 42. 42 Discussion - General  Assess the results in terms of the original aims of the study.  Do results support the hypotheses? What does this mean regardingd theory? If more than one possible interpretation of results, what other studies might need to be done to find out which interpretation correct? Problems with theory?  Discuss unusual results  Experimental faults and improvements  What directions for future research does your study indicate?
    43. 43. 43 Discussion – Stroop Discuss results:  Is reading faster than colour naming?  Explanations of the Stroop effect (semantic network; attention)  Is there a graded interference effect – what accounts for this?  Comparison of our results with Klein’s – if differences, what accounts for them?  Any other unexpected results?
    44. 44. Giving Research Presentations 44
    45. 45. Outline  Structuring your story  Preparing your data/information  Preparing and giving the presentation  Concluding your presentation  Questions and answers 45
    46. 46. How to Give an Effective Presentation: Structure  Basic rule Say what you are going to say  1-3 main points in the introduction Say it  Give the talk Then say what you said  Summarize main points in the conclusion Don’t try to build suspense and then unveil a surprise ending 46
    47. 47. Tell a Story  Prepare your material so that it tells a story logically Subject: title, authors, acknowledgements Introduction/overview Method/approach Results/information/analysis Conclusion/summary 47
    48. 48. Tell a Story  Use examples, anecdotes, and significant details  Create continuity so that your slides flow smoothly Guide the audience through your story Your last point on one slide can anticipate the next slide 48
    49. 49. Audience  Why and to whom are you giving this presentation?  What do you want the audience to learn? Think about this as you construct your talk Edit your slides -- delete what is unnecessary, distracting, confusing, off point 49
    50. 50. Presenting Your Methods, Data, and Results  Methods, Instrumentation For most talks, only present the minimum  Data Tables Tables are useful for a small amount of data Include units Indicate data source if they are not your own But tables are often used badly … 50
    51. 51. Esopus Creek  Discharge of the Esopus Creek (Coldbrook, NY) and precipitation at Slide Mountain, NY (source: USGS/NCDC) 51 date discharge precipitation date discharge precipitation (cf/s) (in/day) (cf/s) (in/day) 1-Nov 631 0 1-Dec 1480 0.07 2-Nov 808 0 2-Dec 2920 0.96 3-Nov 794 0.08 3-Dec 2380 0 4-Nov 826 0 4-Dec 1990 0 5-Nov 1060 1.09 5-Dec 1770 0 6-Nov 1080 0.48 6-Dec 1620 0.1 7-Nov 1040 0.28 7-Dec 1500 0 8-Nov 779 0 8-Dec 1420 0 9-Nov 686 0 9-Dec 1350 0 10-Nov 670 0 10-Dec 1290 0 11-Nov 696 0.53 11-Dec 1280 0.1 12-Nov 831 0.23 12-Dec 1330 0.47 13-Nov 985 0.45 13-Dec 1280 0 14-Nov 1080 0.14 14-Dec 1250 0.57 15-Nov 1350 0.65 15-Dec 1190 0.04 16-Nov 1430 0 16-Dec 1180 0 17-Nov 2440 1.6 17-Dec 1160 0.17 18-Nov 2280 0 18-Dec 1120 0.01 19-Nov 2040 0 19-Dec 1080 0 20-Nov 1830 0.55 20-Dec 1070 0 21-Nov 1650 0 21-Dec 1080 0 22-Nov 1560 0 22-Dec 1060 0 23-Nov 1520 0.39 23-Dec 1060 0.18 24-Nov 1410 0 24-Dec 1050 0 25-Nov 1320 0 25-Dec 1050 0.5 26-Nov 1310 0.11 26-Dec 986 0 27-Nov 1450 0.78 27-Dec 1010 0 28-Nov 1560 0.22 28-Dec 1010 0.07 29-Nov 1550 0.45 29-Dec 977 0 30-Nov 1480 0 30-Dec 972 0 31-Dec 957 0
    52. 52. Esopus Creek Discharge of the Esopus Creek (Coldbrook, NY) and precipitation at Slide Mountain, NY (source: USGS/NCDC) 52 0 500 1000 1500 2000 2500 3000 3500 1-Nov 8-Nov 15-Nov 22-Nov 29-Nov 6-Dec 13-Dec 20-Dec 27-Dec Date in 1992 Dischargerate(cf/s) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Precipitation(in/day) discharge (cf/s) precipitation (in/day)
    53. 53. Preparing Your Data, continued  Figures ‘1 figure ≈ 1000 words’ Figures should be readable, understandable, uncluttered Keep figures simple, use color logically for clarification 53
    54. 54. Preparing the Presentation  Average not more than 1 slide per minute  MS Powerpoint is standard If you use something else, be careful to check it in advance  No sounds! Some logical animations good 54
    55. 55. Preparing the Presentation  Use 3-7 bullets per page Avoid writing out, and especially reading, long and complete sentences on slides because it is really boring to the audience  Slide appearance (font, colors) should be consistent  Spellcheck 55
    56. 56. What Font to Use  20 point  24 point  28 point  36 point 56 AVOID USING ALL CAPITAL LETTERS BECAUSE IT’S MUCH HARDER TO READ
    57. 57. Color 57 Dark letters against a light background work Dark letters against a light background are best for smaller rooms, especially when the lights are on for teaching
    58. 58. Color 58 Light letters against a dark background also work Many experts feel that a dark blue or black background works best for talks in a large room, especially when the lights are low
    59. 59. Preparing Yourself...  Immerse yourself in what you are going to say Web of Science/Google it: use the latest news  Make sure you are familiar with the projection equipment, remote control and Powerpoint Bring your presentation on a memory stick AND a laptop with power supply AND an extension cord … 59
    60. 60. Print Your Slides  Don’t read the presentation  Print out copies of your slides You can annotate them and use them as notes You can review them as you’re waiting If everything crashes – the bulb blows, you can still make your main points in a logical way 60
    61. 61. Rehearsing Practice – actually stand up and say the words out loud You discover what you don’t understand You develop a natural flow You come up with better phrasings and ways to describe things  It is harder to explain things than you think, practicing helps you find the words Stay within the time limit 61
    62. 62. Rehearsing Don’t over rehearse or memorize the talk The first practice things will improve at least 10 fold -- the second will make things twice as good -- the third may add a bit of polish, but from there it can easily get worse 62
    63. 63. Giving the Presentation  Starting out is the hardest part of the talk To get going, memorize the first few lines “Hello, I’m Stephanie Pfirman. The title of my presentation is, ‘The Arctic Marginal Ice Zone.’ … 63
    64. 64. Giving the Presentation Experienced speakers: Speak freely and look directly at audience 64
    65. 65. Giving the Presentation Inexperienced speakers: Put outline and key points of your presentation on your slides  You don’t have to remember what to say  Eyes are on the slide not on you  Key points are there for people who weren’t listening or who are visual learners 65
    66. 66. Giving the Presentation  Stand where the figures can be seen  Look at people during presentation  Be enthusiastic  Don’t worry about stopping to think  Don’t rush Figure out which slide is your half-way mark and use that to check your time 66
    67. 67. Giving the Presentation  Don’t apologize or make comments about yourself “I hope you’re not bored” “I was working on this ‘til 3 am”  Don’t overuse the pointer  Don’t force being funny  Don’t forget acknowledgements, always give proper credit 67
    68. 68. Concluding Your Content  Announce the ending so that people are prepared For example, with a slide titled “Conclusions” Or by saying, “In my final slide …” or “My final point is …”  Have only a few concluding statements 68
    69. 69. Concluding Your Content  Come back to the big picture and summarize the significance of your work in that context Extend logically beyond your limited study – but don’t overreach  Open up new perspective Describe future work, raise questions, potential implications 69
    70. 70. Finishing Your Presentation  Think carefully about your final words and how to finish your presentation strongly Don’t just drift off … “I guess that’s all I have to say …” You may want to actually memorize your ending lines, just as you do your starting points Say: “Any questions?” 70
    71. 71. What Can Go Wrong?  Uncertainty about material  Interruptions  Running out of slides  Running out of time 71
    72. 72. Uncertainty About the Material  Try to structure your talk so that you are sure about the material you present  If you have to address something important that you are unsure of  Acknowledge the gap in your understanding  “I’m working on it” or “I’m looking into it”  This is better than being pressed to admit something  Also it may very well be an open question  Another way to handle this is to raise it as a question yourself 72
    73. 73. Minor Interruptions During Your Presentation  Don’t look irritated or rushed  Answer – briefly – just enough to straighten it out  Then carry on with your presentation without checking back  A question that you will answer later in your talk?  Say “Good point; just wait two slides”  Requires a long answer and is not critical understanding?  Say “Good point; I’ll come back to it at the end of the talk.” 73
    74. 74. Major Interruptions During Your Presentation  If most in the audience are non-specialists  Explain the issue to the audience  Delay discussion until after the talk  If most of the audience is knowledgeable  Make your point as clearly as you can  Discuss it out – don’t try to diminish or avoid it 74
    75. 75. Running Out of Slides  Short talks are better than ones that are too long  What to do: Don’t make a personal comment  “hum, I’m running out of slides …” Stretch it a little -- see if you can think of an example, or story, to bolster your points Conclude unhurriedly, summarizing your main points, but don’t be repetitious 75
    76. 76. Running Out of Time  Avoid this – impolite to other speakers and the audience: if it happens … Do not assume that you can carry on past your time Do not skip all of your slides looking for the right one to put on next Conclude – on time wherever you are in your talk -- by making your main points 76
    77. 77. Questions and Answers  Questions after your talk can be difficult but they definitely help you in writing up your research Identifies parts the audience did not understand Focuses and adds dimension to your analysis 77
    78. 78. Questions and Answers  You can repeat the question This gives you time to think The rest of the audience may not have heard the question Also if you heard the question incorrectly, it presents an opportunity for clarification 78
    79. 79. Questions and Answers, continued  Keep your answers short and to the point – don’t respond with another lecture  Don’t say that a question is bad, or that you addressed it already Rephrase it into something that you want to talk about The research world is smaller than you think and you will continue to encounter people throughout your career 79
    80. 80. Difficult Questions  First of all:  Usually you have thought more about the material than anyone else -- this puts you in a stronger position than you may think 80
    81. 81. Difficult Questions  Anticipate typical questions and prepare for them Generalizability of your findings to other times? Other places? Other conditions? Methodological bias? Uncertainties? Exceptions? Priorities?  Still concerned about questions? Make extra slides – perhaps on details of instrumentation or methodology 81
    82. 82. Difficult Questions, continued  If you really don't know the answer Say "Interesting, I will look into that" or “That’s a good point, let’s discuss it afterwards” Don't feel that you have to invent an answer on the fly -- you are only human and you can't have thought of everything 82
    83. 83. Conclusions  Structure your content in a way that is comfortable for you  Use your own style to your advantage  Think ahead about where you might encounter difficulties and figure out ways to overcome them 83
    84. 84. 84 ANY QUESTIONS? IMPORTANT: In two weeks ! Bring you presentation on a memory stick Or email it to me by Dec. 3rd !

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