The Stroop Phenomenon

Introduction
The stroop phenomenon is a way of measuring how automatic or
intentional some well practised tasks are and how we respond in conflict
situations. This phenomenon also measures individual distinctions,
originality and cognitive flexibility. The two aspects of cognitive
development that are demonstrated by the stroop task are naming response
and counting response. When two responses compete or are in conflict, the
time required to make the correct decision is dependent on speed and
accuracy.


In the article “Tracing The Time Course of Picture Word Processing”,
by M.C. Smith and L.E. Magee; these two researchers found that picture
naming was affected by the presence of incongruent words (Experiment 1).

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Also naming a picture was faster than when a congruent word was present.

Therefore pictures activate the name code. Another experiment (Experiment
2) indicated that memory for pictures and words, whether they were
initially named or categorized had an effect on memory. Memory was better
for words if they have been categorized and for pictures if they have been
named. Experiment 3 showed the same results as the previous two
experiments. The fourth experiment, with the introduction of less common
objects, subjects could name the words faster than generating a category
name for the words. Naming pictures are prone to interference when
incongruent words are presented simultaneously. Word naming is not as much
influenced by distracting pictures. Pictures and words differ in the
amount of information to be filtered out, to get the correct response.


The design of this experiment is a within subject experiment as the
number of choices to be made after viewing the stimulus on the screen are
same for everybody (2,3,4). Also the meaning versus number choices (same,
different, conflicting) are used by everyone. The dependent variables in
this experiment are average accuracy (%) and average time/response (msec).

the independent variable is the random stimulus which appeared on the
screen, whether it was the same, different or conflicting. In this
experiment we were shown 2, 3, or 4 items on the screen in a randomized
form and had to select the right number of items using 2,3,4 on the
keyboard as quickly and accurately as possible.


In this experiment, the stroop task will be demonstrated. When there
is no conflict between the stimulus and response to be chosen, responses
will be quick and accurate. When there is a conflict between the stimulus
and response to be made, interference will exist and responding will be
slower and less accurate.


Results & Discussion Figure 1
The average accuracy in percent for subject 1, was good for the ‘same’
condition. Then they started to decrease when the stimulus was
‘different’. This score for subject 1 at the ‘different’ condition was the
lowest among all 3 conditions. When the stimulus was ‘conflicting’, subject
1 was losing accuracy again and so was not as high as in the ‘same’
condition. Subject 1 was less accurate in the ‘different’ and
‘conflicting’ situations.


The average accuracy in percent for subject 2, was quite consistent,
being one hundred percent in all conditions. So this subject had a higher
accuracy rate than subject 1. Figure 2
In relation to average time/response in milliseconds, subject 1 was
quicker than subject 2. Then condition where subject 1 slowed down the
most was in the ‘different’ condition. In the ‘conflicting’ condition,
subject 1 increased their speed more than in any other condition.


Subject 2 was quite consistent in all 3 conditions in relation to
average time/response, with the milliseconds being only 3 or 4 different
from the other conditions. For subject 2 the highest responding rate was
in the ‘conflicting’ condition, followed by ‘same’, then the ‘different’
condition.


This shows that in the ‘conflicting’ condition, the subjects response
rate increased. In the ‘different’ condition the response decreased. Also
if one subject has a higher accuracy rate than another subject, then the
average time/response will be lower.


The stroop task demonstrates that the naming response (same) is faster
than the response used while counting (different) and that when 2 responses
conflict (conflicting), the time to make a correct decision increases.


Since people find the ‘conflict’ condition difficult, they will make
more errors and take more time to determine the correct response. So the
accuracy and response rate decreases in the ‘conflict’ situation.


The difference in speed and accuracy in the 3 conditions (same,
different, and conflicting) was the result of the experience with each
specific condition. The more practice with each condition, the smaller the
differences in speed and accuracy among the three conditions.


When there is no conflict, people are accurate and quick in responding
to the stimulus. So in the situations of ‘same’ and ‘different’ (22 and
**), people will respond by pressing 3 and do well. Subject 1 was least
accurate in the ‘different’ condition, but was still quicker compared to
subject 2; who was very accurate but not as quick as subject 1.


In the ‘conflict’ situation, where an example of 222 showed up on the
screen and the response was to be 3. In this incident most people have
trouble responding due to interference, which leads to slower responding
and less accuracy. When subject 1 was presented with the ‘conflicting’
situation, response was faster than in non- conflicting situations; but
accuracy suffered. Subject 2 was more accurate (100%) but was slower in
responding.


Just as in the research done by Smith and Magee, there was an effect
by the presence of an incongruent (conflicting) stimuli. Also when there is
a congruent (same) stimuli present, response becomes quick, as there is a
much faster processing rate which occurs. There is also support that
memory is better for words, in our case numbers and for pictures that are
given consistent symbols (eg. ***). When responding to the stimulus on the
screen, in ‘different’ conditions, if incongruent stimuli are presented
simultaneously, there is a chance of disruption. Recognizing the correct
number of items on the screen is not influenced much by distracting
pictures (symbols). In our case this was a problem that Subject 1 was
having, so it is not fully supported.


Reference
Magee, L.E. & Smith, M.C. Tracing The Time Course of Picture Word
Processing. Methods & Strategies : In Psychological Research, 1991,
8, 361-388.