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
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
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
Why study Stroop?
Reason 2:
To investigate the nature
of attention & semantic
representations
-> more about this later !
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
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
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
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
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…
12. 12
Klein - faults:
Return to Klein’s materials…
What might be improved on them?
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
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
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
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
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
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
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
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
Explanations & Presentations:
Interference
Examples of other Stroop-like experiments
Why you might get graded interference
What to do with your results ....
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
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
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
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
…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
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!
35. 35
Title
Should describe experiment completely &
appropriately
Try and include Independent Variable (IV)
and Dependent Variable (DV) in title
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
38. 38
Method
Should enable others to repeat your
study
For presentation: not as detailed as for
your research reports
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
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
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
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
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?
45. Outline
Structuring your story
Preparing your data/information
Preparing and giving the presentation
Concluding your presentation
Questions and answers
45
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. 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. 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. 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. 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
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
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Precipitation(in/day)
discharge (cf/s)
precipitation (in/day)
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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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
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. 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. 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. 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. 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. 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. What Can Go Wrong?
Uncertainty about material
Interruptions
Running out of slides
Running out of time
71
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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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
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
