Stroop(2)

METHODS IN PSYCHOLOGY PRACTICALS
1
THE
STROOP
EFFECT

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
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
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
Why study Stroop?
Reason 2:
To investigate the nature
of attention & semantic
representations
-> more about this later !

6
Stroop (1935)
Part 1: Read 100 colour words
Condition 1 red, blue
Part 2: Name ink colour for 100 items
Condition 2 ■■■, ■■■■
43s
41s
110s
63s

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
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
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
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
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
Klein - faults:
 Return to Klein’s materials…
 What might be improved on them?

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
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
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
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
Experimental Design
Mixed design:
One (or more) within-subjects variable
One (or more) between-subjects variable
-> That’s what we will do here !

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
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
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
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
Explanations & Presentations:
 Interference
 Examples of other Stroop-like experiments
 Why you might get graded interference
 What to do with your results ....

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
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
Other Stroop-like experiments
Henderson (1973) – Find a letter
Find “A”
oeDcinAoieNie easier
oeDcanAoaeNae harder
(because other ‘a’s interfere)

26
Navon (1977) – Name global letter
FFFF E
F E
FFF easier than E
F E
F EEEEE

27
Morton (1979) – how many digits on line?
4444 44
333 faster than 3333
55555 555

28
Spatial task – where is word written: top or
bottom of square
easier
than
TOP
TOP
BOTTOM
BOTTOM

29
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
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
…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
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
Presentations:
 Find data on DUO:
 Methods In Psychology -> 07_Stroop ->
Stroop_Results.xls

35
Title
 Should describe experiment completely &
appropriately
 Try and include Independent Variable (IV)
and Dependent Variable (DV) in title

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
Introduction
Experimental hypotheses:
1. Reading faster than Colour-Naming
(comparison of Conditions A & B)
2. Graded Interference effect (spell out
expected findings)

38
Method
 Should enable others to repeat your
study
 For presentation: not as detailed as for
your research reports

39
Participants
 Number, age (mean & sd), sex
 any other relevant info (e.g. vision
normal or corrected to normal; reading
problems; colour blindness?)

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
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
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
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?

Giving
Research Presentations
44

Outline
 Structuring your story
 Preparing your data/information
 Preparing and giving the presentation
 Concluding your presentation
 Questions and answers
45

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

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

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

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

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

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

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)

Preparing Your Data, continued
 Figures
‘1 figure ≈ 1000 words’
Figures should be readable, understandable,
uncluttered
Keep figures simple, use color logically for
clarification
53

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

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

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

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

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

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

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

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

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

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

Experienced speakers:
Speak freely and look
directly at audience
64

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

 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

 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

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

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

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

What Can Go Wrong?
 Uncertainty about material
 Interruptions
 Running out of slides
 Running out of time
71

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

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

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

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

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

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

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

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

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

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

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

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
ANY QUESTIONS?
IMPORTANT:
In two weeks !
Bring you presentation on a memory
stick
Or email it to me by Dec. 3rd
!

Stroop(2)

More Related Content

What's hot (20)

Viewers also liked (20)

Similar to Stroop(2) (20)

Recently uploaded (20)

Stroop(2)

Editor's Notes