The Effect of Reaction Time Using Stroop Effect

Correspondence concerning this article should be addressed to Cassandra Porto,

Department of   Psychology, CUNY, Queens College, Flushing, NY, 11367.

Abstract

Based on the literature of the original Stroop experiment , J.R Stroops main focus was the general inhibition of automatic mental processes. Eighteen undergraduate students whom were assigned to three different condition groups (control, congruent, interference) performed a replicated Stroop task to indicate whether the color word combinations effected reaction time. The results obtained through a between groups t-test showed there was no significant effect of congruent and confusion stimuli on reaction time. More studies on the Stroop task will increased a better understanding, and application on future psychological tests.

Keywords: Stroop task, stimuli, and color.

Introduction

In 1935 J.R. Stroop conducted an experiment on the understanding of automatic mental process. This experiment was known as the Stroop effect and today has many replication in different types of areas. The Stroop experiment can be used to study the effect of different behavioral situations or disorders in both children and adults.

One study that was conducted by Faccioli (2008) studies was whether the Stroop effect has any significance on children with developmental dyslexia when compared to standardized readers.  A total of 24 particpants being children diagnosed with developmental dyslexia in second to fifth grade. The children with dyslexia performed slower in reaction time on incongruent stimulus than standardized readers. The results showed children with dyslexia performed the same as standardized readers on congruent stimulus. This allowed Faccioli to determine that the Stroop task had a greater effect on children with dyslexia, we can see that the children were still able to process the colored words automatically like standardized readers.

In another study, in 2006 Young replicated Stroops experiment to distinguish whether adults with Attention Deficit Hyperactivity Disorder had impaired performance performing this task. The experiment focused on whether impaired performance was attributed to response time or verbal information processing impairments. The study obtained 26 adults that were diagnosed with ADHD  who weren’t on their medication. A control group of 27 people went through a neuropsychological screen test. The test required all of the partcipants to read off a list of 112 incongruent and congruent color words as quickly as possible based on their mental procces. The results showed that adults with ADHD completed the test with significantly lower scores than the control group.

Lastly, Westerhausen conducted his experiments testing schizophrenic patients to observe impairment in executive functioning. His main focus was the sub-component of cognitive inhibition schizophrenic patients had on Stroop effect. The experiment consisted of 32 studies testing 1081 schizophrenia patients and 1026 healthy control participants. He used a classical card and computerized version to replicate the Stroop effect. The results showed that schizophrenic patients had a slower reaction time in comparison to the participants of the control group. Schizophrenic patients were more likely to encounter more errors in the inhibitory control task. The findings support the issues of cognitive inhibition, resulting in higher in schizophrenic patients. Thus, these findings allow researchers to find or reevaluate different treatments available for schizophrenia patients dealing with deficits in executive functioning.

The purpose of our experiment was to test the reaction time of congruent and incongruent  words on a Stroop task on undergraduate students. Undergraduate students were to participate in a between-group experiment by looking at congruent and confused word combination. Each participant was presented with a confused and congruent stimulus. All participants had to process the different stimuli by saying the right color. Based on previous studies we hypothesized that there would be no significant difference between the reaction time of all three stimuli.

Method

Participants

A total of eighteen undergraduate students (10 women ,9 men) ranging in age from 19 to 32 participated in this experiment. Majority of the students were Psychology majors. These students attended Queens College located in Flushing, New York. The participants were randomly assigned into pairs of two in the beginning to perform the controlled condition.Further in the experiment the participants were randomly assigned to three different condition groups (control, congruent, confusion. These participants were given a specific role based on their condition group.

Materials

The participants were distributed a stopwatch and three 8.5×11 standardized white printing paper consisting of three different stimuli. One being the control condition which was assorted colors in black ink. Another being the congruent stimulus which consisted of the color names corresponding to their original color. Lastly the confused stimulus, was the color names in different colored ink.

 

Design

This experiment was conducted by using a between groups design.

Procedures

            The participants were responsible to test the reaction time of how fast the test subject could pronounce the color of each assortment of words dealing with interference. The experiment consisted of three different conditioned grid sheets (control, congruent, and confusion) as the independent variable and the dependent variable was reaction of time. On day one of the experiment, all participants were randomly assigned into groups of twos and threes. Each group was distributed two control sheets listing assorted colors in black ink (control condition) and a stopwatch that measured hundredths of a second. The participants began with the control sheet faced down on the table. Once the participant turned the sheet over the experimenter begun the stopwatch. The participants were told to read each named color on the grid as fast as they could. If any mistake was made in naming the correct color, the experimenter had to say “mistake”, causing the participant to restate the color until correct. Once the participant read the entire grid, the experimenter stopped the timer and recorded the results. The participant and experimenter switched roles. The entire class performed the controlled condition. On the second day of the experiment, the participants were randomly assigned to a condition (control, congruent, or confusion). Each group obtained 6 participants. If a participant was assigned to the control condition they were not retested. The participants who were assigned to the congruent condition were responsible to test the participants assigned to the confusion group. Control participants tested those in the congruent group. Each group completed the Stroop task as performed on day one with the exception of being distributed either a congruent or confused sheet based on their group.

 

Results

A single factor ANOVA compared naming colors based on three different stimulus resulting in no significant difference, F (2,15) =3.68, p<.05. Based on our results we rejected the null hypothesis and accepted the alternative hypothesis. A Post-Hoc test found significant difference between congruent (M=39.42), and confusion (M=92.03). Control (M= 43.05) differed significantly from confusion (M=92.03), but there was no difference between congruent (M= 39.42) and control (M= 43.05) (p<.05).

Discussion

Based on our hypothesis we concluded that undergraduate students have a faster reaction time when presented with congruent words. However, the results obtained that there were no was no signifant difference of word types on reaction time. Even though, participants performed significantly faster when presented with congruent stimuli, the analysis showed no significant effect.  Our findings differ from prior research conducted by Faccioli, where children with developmental dyslexia performed a significant Stroop Task. These results differed significantly with our results due to the different methodology implicated in his experiment. In addition, the research conducted by Westerhausen (2011) on the Stroop paradigm in schizophrenic patients differed from our results. The results showed a significance performing Stroop effect in schizophrenic patients which was not relevant to our findings. This could have been due to sample size Westerhausen obtained.

One limitation our findings were only tested on undergraduate students not on participants with developmental disabilities as well as other variety of population. In addition, researchers should consider performing the Stroop experiment on participants with developmental disabilities such as dyslexia and ADHD. More studies on the performance of variety of population will help increase our understanding, and application on future psychological tests.

Table 1

ANOVA: single factor

SUMMARY
Groups	COUNT	SUM	AVERAGE	VARIANCE
Congruent	6	236.57	39.42833	29.7881
Confusion	6	552.22	92.03667	145.6334
Control	6	258.3	43.05	9.6028
ANOVA
Source of Variation	SS	df	MS	F	P-value	F-crit
Between Groups	10360.89	2	5180.447	83.99622	7.12E-09	3.68232
Within Groups	925.1214	15	61.67476
Total	11286.01	17

 

Table 2

 

T-Test: Two-Sample Assuming Unequal Variances
	Congruent	Control
Mean	39.42833	43.05
Variance	29.7881	9.6028
Observations	6	6
Hypothesized Mean Difference	0
df	8
t Stat	-1.41347
P(T<=t) one-tail	0.097613
t Critical one-tail	1.859548
P(T<=t) two-tail	0.195227
t Critical two-tail	2.306004

Table 3

 

T-Test: Two-Sample Assuming Unequal Variances
	Confusion	Control
Mean	92.03667	43.05
Variance	145.6334	9.6028
Observations	6	6
Hypothesized Mean Difference	0
df	6
t Stat	9.630682
P(T<=t) one-tail	3.59E-05
t Critical one-tail	1.94318
P(T<=t) two-tail	7.18E-05
t Critical two-tail	2.446912

 

     Table 4

 

T-Test: Two-Sample Assuming Unequal Variances
	Congruent	Confusion
Mean	39.42833	92.03667
Variance	29.7881	145.6334
Observations	6	6
Hypothesized Mean Difference	0
df	7
t Stat	-9.72946
P(T<=t) one-tail	1.28E-05
t Critical one-tail	1.894579
P(T<=t) two-tail	2.56E-05
t Critical two-tail	2.364624

References

Faccioli, C., Peru, A., Rubini, E., & Tassinari, G. (2008). Poor Readers but Compelled to Read: Stroop Effects in Developmental Dyslexia. Child Neuropsychology, 14, 277-283.

Stroop, J. (1935). Studies Of Interference In Serial Verbal Reactions. Journal of Experimental Psychology, 643-662.

Westerhausen, R., Kompus, K., & Hugdahl, K. (2011). Impaired cognitive inhibition in schizophrenia: A meta-analysis of the Stroop interference effect. Schizophrenia Research, 133, 172-181.

Young, S., Bramham, J., Tyson, C., & Morris, R. (2006.). Inhibitory dysfunction on the Stroop in adults diagnosed with attention deficit hyperactivity disorder. Personality and Individual Differences, 41.