INTERNATIONAL
BACCALAUREATE EXAMINATION
YEAR
Psychology Higher Level
Internal Assessment
An experiment to investigate the effect of reading
incongruently coloured words on the time it takes to process
information
Word Count: 1944
Candidate Number:
Centre Name: Emirates International School – Jumeirah
Centre Number:
Submission Date: 7th February
Abstract
The aim of this experiment was to investigate whether visual interference affects the
cognitive processing speed (in seconds) in naming coloured words. The research hypothesis
states that the mean time to identify the series of coloured blocks will be significantly less
than the mean time required to read the list of incongruently coloured words.
The method used for this experiment involved a repeated measures design The independent
variable was the list of incongruently coloured words and the dependent variable was the
mean time taken to state the colour aloud in the experimental condition (in seconds). The
participants partook in two conditions. Condition 1 was the control where a series of coloured
blocks had to be identified. Condition 2 was the experimental condition where the ink colour
of a series of incongruently coloured words had to be stated. The time taken for each
participant to complete both tasks was recorded. The experiment was counterbalanced, with
the order in which Conditions 1 and 2 were performed being switched after each participant.
There were 34 participants (18 males, 16 females), aged between 16 and 17 years, who were
taken from an opportunity sample of Grade 12 Psychology students and after school CAS
students in Emirates International School Jumeirah.
The results supported the research hypothesis, which depicts that the mean time to identify
the series of coloured blocks is significantly less than the mean time to process incongruently
2
coloured words (visual interference has a significant effect on information processing). The
results support Schneider and Shiffrin’s (1977) automaticity model.
Word Count: 254
3
Contents Page
Title
Page(s)
5-7
Introduction
Method
Design
Participants
Materials
Procedure
Results
Bar Graph (Figure 1)
Description of Results
Analysis of Results
8-10
8
8-9
9
9-10
11-12
11
12
12
Discussion
13-15
References
16-17
Appendices
Appendix 1: Standardised Instructions
Appendix 2: Condition 1
Appendix 3: Condition 2
Appendix 4: Results Recording Sheet
Appendix 5: Debriefing Note
Appendix 6: Parents Informed Consent
Appendix 7: Participant Informed Consent
Appendix 8: Table of Results (1 and 2)
18-27
18
19
20
21
22
23
24
25-26
4
Introduction
Reading is a very easy task for most people. However, at a closer look, there are many
perceptual and cognitive factors involved in this task, 1 which when interrupted with visual
interference, can have an effect on the task being undertaken. This study on interference in
perceptual cognition lies in cognitive psychology, which is the study of mental processes.
The aim of this is experiment was to investigate whether visual interference affects the
cognitive processing speed (in seconds) in naming incongruently coloured words.
The Stroop effect is based on the study J. Ridley Stroop (1935) created. Stroop observed that
it takes longer to name the colour of the ink in an incongruently coloured word (the name of
the colour conflicts with its ink colour) than a congruently coloured word (the name and ink
of the colour are the same). Stroop carried out a variety of experiments, recording the time
taken and errors made in each. The different control conditions involved a list of colours in
black ink, a series of coloured blocks, and a list of swastika coloured symbols followed by
incongruent coloured words (the experimental).2 The independent variable was the list of
words he presented as a stimulus to the participants. The dependent variable was the response
time of the participants. Stroop found that participants were slower to perform a task and
made more errors when they were required to visually process incongruent information. In
this study, Stroop’s later experiment (series of coloured blocks) has been used with only the
time recorded.
Eyesenck, Michael W.; Keane, Mark T. Cognitive Psychology: A Student’s Handbook. (Psychology Press
Limited) pg. 322
2
Grivas, John et al. Psychology, VCE. (National Library of Australia) pg. 267
1
5
In the automaticity model, Schneider and Shiffrin (1977) distinguish between controlled and
automatic attentional processing. A controlled process is a task which is new or unique to the
person. It is serial (one activity performed at a time), takes heavy demands on attention,
requires conscious efforts to direct attention towards the task and is slow. An automatic
process is a task which is already learnt. It can be parallel (many activities performed at a
time), makes no demands on attention, does not need conscious direction of attention towards
the task and is fast.3 This implies that when we are presented with a word, the action of
stating its colour is a relatively new task compared to the already learnt behaviour to read just
words. Therefore, reading is seen as the automatic process which interferes with the slower
controlled process of stating the colour.
Norman and Shallice’s (1986) Attention to Action model (ATA) is a theory on executive
control processes and consists of three parts: action schemas, contention scheduling and
supervisory attentional system (SAS). Each action has a schema which is triggered by
different stimuli. In the case of conflicting tasks (reading the word and naming the colour),
reading is a high activation schema which suppresses the action of colour-naming. Due to this
conflict, the same stimulus elicits different responses which can produce errors. The SAS
consciously diverts behaviour to organise and perform this new task in a top-down method,
and inhibits the interfering action schema by actively selecting another. This allows better
capacity for the person to complete the task at hand, but the result is a lag in response time in
3
Grivas, John et al. Psychology, VCE. (National Library of Australia) pg. 266
6
order to switch behaviour from the high activation schema (reading) to the new task (colour
name).4
H0 – Null Hypothesis
There will be no significant difference in the mean time to read the series of incongruently
coloured words and coloured blocks, or any difference that occurs may be due to chance.
H1 – Alternative Hypothesis
The mean time to identify the series of coloured blocks will be significantly less than the
mean time required to read the list of incongruently coloured words.
Word Count: 604
Joshua S. Rubenstein et al. “Executive Control of Cognitive Processes in Task Switching”. Journal of
Experimental Psychology: Human Perception and Performance 2001 (Vol. 27, No. 4, pg 764). American
Psychological Association (2001)
4
7
Method
Design
A pilot study was carried out before the actual experiment. A repeated measures design was
used as participants took part in both the conditions. This way, all differences between
participants become irrelevant and the results were based solely on the individual’s
performance.5 It was also counter-balanced by half performing the experimental condition
first and half performing the control condition first. This was done to ensure that the
confounding variable of practice improving performance in the task was removed and also to
prevent fatigue from affecting the results. The independent variable was the list of
incongruently coloured words and the dependent variable was the mean time taken to state
the colour aloud in the experimental condition (in seconds). Informed consent was taken from
the participants and parents, and the participants also had the right to withdraw from the
experiment whenever they wanted. Their identities were kept confidential and not noted. All
participants were debriefed after they took part in the experiment and they were told they
could be informed about the results at a later date.
Participants
There were a total of 34 participants, 18 of which were male and 16 were female (roughly an
equal mix of genders). The participants were Grade 12 Psychology students and after school
CAS students from Grade 12 as well. The target population was students from Emirates
International School Jumeirah, averaging between the ages of 16 and 17 years. They were
5
Research Methods and Statistics in Psychology - Coolican, Hugh
8
from a range of different international backgrounds. The sampling used was an opportunity
and invitational sampling, which was convenient and saved time. Participants with informed
consent were taken from their class right before the study instead of keeping them all in one
room to avoid discussion and restlessness from influencing the results.
Materials
Standardised Instructions [Appendix 1]
Stimulus sheets (series of coloured blocks and series of incongruently coloured words)
[Appendix 2 and 3]
Stop watch
Results recording sheet [Appendix 4]
Debriefing note [Appendix 5]
Informed consent forms [Appendix 6]
Participant informed consent forms [Appendix 7]
Procedure
Prepare multiple places for the experiment to take place in, which are distant from one
another (as each pair of researchers took one participant at a time to perform the task).
Organise a desk with two chairs on one side (for experimenters) and one chair facing
opposite (for the participant). One experimenter gives instructions and debriefs the
participant. The other times and records responses.
9
1. From the group of participants, choose at random a participant one at a time to take
part in the study. Participants were experimented upon one by one, while the others
waited.
2. The participant was invited to take a seat and handed the “informed consent form”.
They were informed of their right to withdraw and assured confidentiality.
3. Keep control condition stimulus sheet [“Condition 1”] (Appendix 2) face down in
front of participant.
4. Follow instruction sheet 1.
5. Collect results.
6. Take back the stimulus sheet.
7. Put experimental condition stimulus sheet [“Condition 2”] (Appendix 3) face down in
front of participant.
8. Follow instruction sheet 2.
9. Collect results.
10. Present participant with debriefing sheet after reading it to them.
11. Allow participant to leave the room and return back to their class
12. Repeat experiment, except with Condition 2 first then Condition 1 (i.e. steps 7-9
before steps 3-5), to counter-balance the study.
Word Count: 550
10
Figure 1: Bar Graph to Show Mean Response Time and Standard
Deviation for Control and Experimental Conditions
12
10
8
Control (Condition 1: Series of
coloured blocks)
6
Experimental (Condition 2:
Incongruent colour words)
4
2
0
Mean Response Time
Standard Deviation
11
Results
Description of Results
A bar graph (Figure 1) shows the mean time and standard deviation for participants in the
control and experimental conditions (Appendix 8, Table 1). The results show the mean time
taken in Condition 1 was 8 seconds, compared to Condition 2 which was 3 seconds longer, 11
seconds. The standard deviation for both conditions was found to be 2, which reflects an
equal dispersal in both conditions.
Analysis of Results
A Wilcoxon T (non parametric) test was conducted to determine if the difference obtained
was significant at the 0.05 level of significance (Appendix 8, Table 2). This test was used
because it is at an ordinal level for a related design. The sum of the ranks of the negative
differences is D = 9. The number of participants is 32 (N = 32) because participants F and L
are excluded due to no difference in performance in the two conditions. Using a two-tailed
test, it was found that p<0.002, therefore, the results were found to be better than p<0.05. The
T value is less than the critical level, therefore H0 was rejected and H1 was accepted.
12
Discussion
The results show that the mean time to say the colour of the blocks (8 seconds) was less than
the mean time to say the colour of incongruent colour words (11 seconds). The standard
deviation for both was 2, showing that most results were close to the average and there was
equal dispersion in both conditions. There was a significant difference in the time taken to
state the colour as is shown by the Wilcoxon T test (p<0.002) and therefore the null
hypothesis was rejected and the research hypothesis was accepted.
Although Norman and Shallice’s model effectively explains the time difference between the
two tasks through the focus on conflicting schemas, Schneider and Shiffrin’s model better
suits the study. Reading can be seen as an automatic process which interferes with the
controlled process of naming the colour of the incongruently coloured word. Naming the
incongruent ink colour draws more heavily on attentional resources than naming the words,
therefore the response time for participants in the experimental condition was longer.6 The
desired response is the identification of the ink colour which, it is assumed, is a unique and
new task for participants as words are usually automatically read. The conscious effort
required to do the new task rather than read the word automatically, requires mental effort
and awareness, which results in a longer response time. This emphasises the importance of
inhibiting the automatic response in order to carry out the controlled one.7
“Stroop Effect” <http://psychlops.psy.uconn.edu/psych132/manual/stroop.html>.
Colin M. Macleod. “John Ridley Stroop: Creator of a Landmark Cognitive Task”.
<http://arts.uwaterloo.ca/~cmacleod/Research/Stroopbiog.htm>
6
7
13
One of the strengths of this study is the controlled environment used which was prepared
beforehand. This prevented extraneous variables such as noise, weather or intrusions from
affecting the results. However, this ‘artificially created’ environment lacks ecological
validity.
Some of the limitations in this study were that only the time taken to respond was recorded
and not the mistakes made by participants, like in Stroop’s experiment. Taking mistakes into
account would have been ideal in this study, as for two of the participants; there was no
difference in the time taken to complete both conditions. There may have been mistakes in
the experimental condition in an attempt to finish the task as fast as possible (reading the
word instead of stating the colour), which still shows how the automatic response of reading
interferes with the task at hand. Other factors could have influenced participants’
performance on the task such as their intelligence and the amount of effort applied, which
could not have been controlled.
The experiment was restricted in the type of sample taken. An opportunity sample from
within the school makes the results valid only for the target population, and therefore it may
be difficult to generalise to the greater population.
To elaborate on the study and results, the experiment could be carried out by using one word
from each condition successively one after the other (one control, then one experimental
instead of two separate lists) to investigate whether it is the shift of attention to different
14
schemas or the difference in the nature of the task (automatic or controlled) which results in
the time difference between the two conditions.
The Stroop effect has been used as a medical diagnostic tool for schizophrenic patients, who
display greater interference problems and so a longer response time in contrast with others, as
deficits in attention characterises this condition,8 and for ADHD patients to assess response
conflicts.9
In conclusion, the research hypothesis was supported which shows that the mean time to
identify the series of coloured blocks is significantly less than the mean time to process
incongruently coloured words (visual interference has a significant effect on information
processing) and the results support Schneider and Shiffrin’s (1977) automaticity model.
Word Count: 607
Avishai Henik and Ruth Salo. “Schizophrenia and the Stroop Effect”.
<http://ucdirc.ucdavis.edu/people/papers/henik_salo_BCNR2004.pdf>
9
Stins et al. “Heritability of Stroop and Flanker Performance in 12-Year Old Children”. 03/12/04.
<http://www.biomedcentral.com/1471-2202/5/49>.
8
15
References
Books

Cardwell, Michael; Clark, Liz; Meldrum, Claire (2000). Psychology for A LEVEL.
(Pages 368-369). Harper Collins Publishers Limited.

Coolican, Hugh (2004). Research Methods and Statistics in Psychology (4th edition).
(Page 65). Hodder Arnold.

Eyesenck, Michael W.; Keane, Mark T (2005). Cognitive Psychology: A Student’s
Handbook. (Page 322). Psychology Press Limited.

Grivas, John; Down, Ross and Carter, Linda (2004). Psychology, VCE (3rd edition).
(Pages 265-268). National Library of Australia.
Online Journals

Henrik, Avishai and Salo, Ruth. “Schizophrenia and the Stroop Effect”.
<http://ucdirc.ucdavis.edu/people/papers/henik_salo_BCNR2004.pdf>. 02/02/10,
11:15 pm.

“Stroop Effect” <http://psychlops.psy.uconn.edu/psych132/manual/stroop.html>.
29/12/2009, 6:17 pm.
16
Online Websites

Macleod, Colin M. “John Ridley Stroop: Creator of a Landmark Cognitive Task”.
31/01/2010, 4:31 pm <http://arts.uwaterloo.ca/~cmacleod/Research/Stroopbiog.htm>

Stins, John F.; Baal, G Caroline M van; Polderman, Tinca JC; Verhulst, Frank C;
Boomsma, Dorret I. “Heritability of Stroop and Flanker Performance in 12-Year Old
Children”. BioMed Central Ltd. 03/12/04.
<http://www.biomedcentral.com/1471-2202/5/49>. 02/02/10, 11:22 pm
Magazines

Rubenstein, Joshua S.; Meyer, David E.; Evans, Jeffery E. “Executive Control of
Cognitive Processes in Task Switching”. Journal of Experimental Psychology: Human
Perception and Performance 2001 (Vol. 27, No. 4, pg 764). American Psychological
Association (2001)
17