The Stroop Effect

Commonly applied in cognitive psychology the Stroop effect indicates an illustration of how the mind reads colors and how the same colors are read using words written in different colors. The test is always performed in children and adults who have difficulty in reacting to different stimuli in color differentiation. Stroop effect test can be performed in numerical and alphabetical comparisons. In this paper focus will be on one numerical strop effect in children and two alphabetical researches conducted by different scientists. In their submissions, several methodologies were applied and different conclusions were arrived at in the end. But the main study participants will be children and how these effects alter their cognitive response to different stimuli in recognizing texts written in different colors and those that represent the name of the color they are written.

1. The Numerical Stroop effect in Primary School children: a comparison of low, normal and high achievers by Heine et al.

In this experiment numerical Stroop experiment was conducted on 66 school children and among them they were divided according to their scores in math test. There are those who scored low in the test (21), those who had average results (23) and the high achievers who were represented by 22 of the sixty six. The test was divided into two, first is the numerical comparison of digits and second was the physical size comparison of digits. Congruity and distance effects were measured and the physical comparison group indicated Stroop effect when the distance between the digits was large but showed no difference when the distance between the digits was made smaller. It was noted that the numerical distance effects were in relation with the congruent condition which indicated a typical effect of distance in the congruent and a negative effect in the incongruent condition.

Hypothesis: Primary school children of different math achievement levels show difference in measure of controlled and automatized processing of numerical magnitude information.

Method

Sixty six primary school children were selected from a poll of 1242 in which 21 of them scored low on standardizes match achievement test, 23 were average and the remaining 22 scored highly. The children were asked to make numerical and physical size comparisons on some of the digit pairs.

Procedure

A pair of digits were presented were presented to the participants with one on the left of a computer screen and the other on the right of the same display separated by 3 centimeters. The pairs of either digit differed in both numerical size and also physical size. The kids were asked to select the numerically large digit in one task and the physically bigger digger in the other task.

The stimulus for each condition included numbers 1 to 9 with number 5 excluded in the procedure. Each digit was allowed to occur only twice in either position left or right and this resulted in 16 digits. In other words, 1-2, 2-1: 3-4, 4-3;6-7, 7-6; 8-9, 9-8; 1-6, 6-1; 2-7, 7-2; 3-8, 8-3; 4-9 and 9-4. The numerical size differed by 1.2 cm for font 48pt or 0.6 for font 24 for the different digits. For each task the same digit never occurred in the same position in the successive trials, secondly the correct response was changed foe every trial. Third no two stimuli for same congruity condition appeared in succession. Finally numerical splits between the digits were displayed in no more than two successive trials.

Whether the hypothesis was supported

There were longer reaction times and higher error rates for the most demanding conditions. These conditions included numerical when compared with physical size comparisons, incongruent when related to congruent and those comparisons that linked smaller and larger numerical distances.

2. Word reading practice reduces Stroop interference in children

The research question in this case was about the influence of word reading on reduction of Stroop interference in children. Informed consent was sought for the participants before they were used in the study. That if kids are exposed to more word reading practices the likelihood of them having the Stroop interference being reduced increases tremendously. In this study color naming of incongruent and neutral stimuli and word reading of color names was conducted in children of grades 4-5. In both cases Stroop interference was reduced after practicing color reading of incongruent stimuli. In addition in word reading of color names the interference was also reduced considerably. But in all the cases the introduction of neutral stimuli never had any effect in the interference effect of the children. (Ziaka et al., nd)

Method

The study randomly selected adult and children from the general population in a school. Among the groups the adult population consisted of 92 volunteers who were in the bracket of 18-40 years of age. 25 of them were placed in the incongruent group, 23 were in the neutral color group, 22 in the word group and 22 in control. The control group never received any form of training before the experiment. In the school sample, 105 children were selected from grades 4-5. In the incongruent color group there were only 22 kids, the neutral color group were 26 children 31 in word cluster and 26 in the control.

Greek words were applied in each case to different colors red (/kocino/), yellow (/citrino/) and green (/Prasino/). These word structures was applied because the Greek words have same letters and syllables, comparable written frequency and also begin with voiceless stops, and these were essential in triggering response time triggers in the participants. The color condition comprised of three words in white font. Color stimuli ere made up 7 repetitions of letter X with no spaces in red, green and yellow colors. For the incongruent condition the Greek words for red, green and yellow appeared in non matching color. A black background was applied to all the stimuli in the study.

Practice

The participants were taken into four groups randomly and asked to practice color reading and naming for three consecutive days. In the first group, color naming of incongruent stimuli say red was conducted. In the second group, B, color naming for the neutral stimuli was for instance, XXXXXXX while the third group performed word reading of neutral stimuli for example, red. Children were supposed to complete one block of 144 trials as adults were assigned a block of 192 trials in a day and this had to continue for three days. The other group was the control and they were not supposed to do any practice since they acted as the baseline.

Whether the hypothesis was supported

Responses were checked for accuracy using CheckVocal to determine the accuracy and placement of the timing marks. To examine the different effects of practice on interference between the groups the researchers tested the triple interaction between groups, time and condition using the 1mer of the 1mer4 in R.

For children as postulated the color naming for incongruent condition there was a reduction in color naming time interference as compared to the control group by -0.14, t=-3.83, X2=12.84, df=1,p<0.005. Group making color word reading, there was a significant reduction in time interference (t=-2.05; X=4.05, d.f =1, p=0.044). The neutral group showed no difference in time interference with the control.

For adults also color naming for the incongruent condition also reduced their interference in relation to no practice group (t=-3.44; X2=10.56, df= 1, p=0.001). But there was no change in the interference for both the neutral group and the color word reading group.

The finding in this research that word reading practice leads to reduction in Stroop interference is also consistent with the negative correlation between reading ability and Stroop interference.

3. Bub et al., Cognitive control in children: Stroop interference and suppression of word reading.

Introduction

Color naming trials and word reading trials were conducted in children of elementary school level. The number of participants was 65 in total and the colored Stroop items were either non color (incongruent condition) or asterisks rows (neutral condition). The younger children indicated higher degrees of Stroop interference and lapses in time of reading word in incongruent condition. Further analysis was conducted on response time distributions that assess the level of word reading suppression applied by both the young and older children. The results pointed to stronger suppression in younger children than older children.

Hypothesis: Cognitive control has an influence in overcoming Stroop interference in children.

Method and procedure

Participants of about 65 in number were randomly selected with boys being 35 and girls 30 in number. The participants were between ages 7 years 3 months to 11 years. The mean of their ages was 9 years 1 month and he standard deviation was 1 0 months. The group came from an elementary school. Five colors were used: blue, green, pink, red and yellow and five words: back, cold, face, home and look. Reading ability was measured using spelling and word decoding subsets of the Wide Range Achievement Test (WRAT3)

The scores on WRAT3 on spelling and word decoding were averagely at 69.9 (SD=24.1) for boys and 61.4 (SD=25.6) for the girls. To test for Stroop and modulation effect analysis of variance was used in either case for response time and error data. The response time data indicated that the participants had a large interference Stroop effect of 1267 ms vs. 1042 ms and F(1, 64) = 166.29 as well as a strong modulation of word reading of 943 ms vs. 861 ms. There were also longer latencies in the incongruent condition in all the cases.

Whether results reflect hypothesis

The results show that the children demonstrated a large Stroop interference effect and they also indicate a slowed word reading effect in the incongruent condition. Also age related differences in cognitive control that were assessed by Stroop interference and word reading modulation showed an increase in reading latency in the either case. But older children showed increase in Stroop effect across the response time distribution and vice versa for younger ones.

Conclusion

Stroop effect can be assessed in different ways but the most basic ones is by use of both congruent and incongruent comparisons as well as the application of neutral conditions which are inherent in both tests. The main address point is that all conditions indicate the same results in children of early stages of development.

References

Bub, D.N., Masson, EJ M, & Lalonde, C.E. (2005).Cognitive control in children: Stroop interference and suppression of word reading. Psychological Science, 1-7.

Heine, A., Tamm, S., Smedt, D.B. & Schneider, M. et al. (2010). The numerical Stroop effect in primary school children: A comparison of low, normal and high achievers. Child Neuropsychology, 16: 461-477.

Ziaka, L., Moirou, D., Vlahou, E.L. & Protopapas, A.(2013). Word reading practice reduces Stroop Interference in children.Mindmodelling.org. Retrieved from: https://mindmodeling.org/cogsci2013/papers/0308/paper0308.pdf