1. Research Before Stroop’s Study
James McKeen Cattell
(1860 – 1944)
• James McKeen Cattell: did his doctoral research at the
University of Leipzig under the supervision of Wilhelm Wundt
(first American to get a PhD in psychology, first Professor of
Psychology in USA)
Wilhelm Wundt
1832 - 1920
• Studied, among other things, the time taken to name objects
and colours
• Reported that it took longer to name objects and
colors than it did to name the corresponding words
Blue
“blue” “blue”
>
2. “This is because, in the case of words
and letters, the association between the
idea and name has taken place so often
that the process has become automatic,
whereas in the case of colors and
pictures we must by a voluntary effort
choose the name”
Cattell, J. M. (1886). The time it takes to see and name objects. Mind, 11, 63-65.
3. Research Before Stroop’s Study
• Cattell’s idea, which we can call an automaticity, or differential-practice
hypothesis, was quite influential
• Many people supported this interpretation, including Stroop. There were
some alternative explanations, however
• Hollingworth (1912, 1915, 1923): word reading required only articulation,
but color naming demanded articulation plus association
• Peterson, Lanier, and Walker (1925): many responses might be
conditioned to a single color, but only one response is conditioned to a
single word (not inconsistent with practice hypothesis)
6. Stroop’s Classic Study
• Interested in source of interference between reading words and naming
colours
• Had an important insight: combine the two stimulus types into one
compound stimulus where the word is incongruent with the ink colour,
which permits a direct examination of the interference of one feature (e.g.,
the printed word) on the other (e.g., the ink colour), and vice versa
Red
Red Blue
Name the colour Read the word
Name the colour or read the word
Two tasks
conducted on
different stimuli
Two tasks
conducted on
same stimuli
7. Stroop’s Classic Study
• Three research questions:
1. Does the perception of the ink colour of the compound stimulus interfere
with naming the word (Experiment 1)?
2. Does the perception of the word interfere with naming the ink colour of
the compound stimulus (Experiment 2)?
3. What is the effect of practice/training on these interference effects
(Experiment 3)?
8. Experiment 1
• Research question: Does the colour of the ink interfere with reading the
name of the word aloud?
• Used 5 colour words (red, blue, green, brown, and purple), with each
word being presented in a different ink colour
red red red red
Each presented 5 times, giving 20 presentations for each colour word, and 100
presentations in total (5 colour words x 20 presentations/word)
• 100 words presented on a single stimulus card, in a 10 x 10 array
• Second stimulus card was created, with the reverse order
9. Experiment 1
• Experimental condition: Read colour names of words where the colour of
the ink and the name of the word are different (RCNd)
• Control condition: Read colour names of words printed in black ink (RCNb)
• Two stimulus cards were created for the control condition (each 100
words in a 10 x 10 array, with the order reversed across the two forms)
• All 70 participants first took part in 10 practice trials, and then half of the
participants were tested in the order Control 1, Experimental 2,
Experimental 1, Control 2, and half were tested in the reverse order
• In doing so Stroop controlled for practice, fatigue, and order effects
10. red blue green brown purple
red blue brown
brown purple
red
blue
green brown purple
red blue
green
green
purple
Task: Name the words out loud
RCNb
11. red blue green brown purple
red blue brown
brown purple
red
blue
green brown purple
red blue
green
green
purple
Task: Name the words out loud
RCNd
