A Replication of the Stroop Effect

A Replication of the Stroop Effect

Kimber-Ann Cook

Broughton High School

3/26/08

Ms. Greene

IB Psychology SL

1, 738

Abstract

The Stroop (1935) effect is the inability to ignore a color word when the task is to report the ink color of that word (i.e., to say "green" to the word RED in green ink). The present study investigated whether object-based processing contributes to the Stroop effect. According to this view, observers are unable to ignore irrelevant features of an attended object (Kahneman & Henik, 1981). In three experiments, participants had to name the color of one of two superimposed rectangles and to ignore words that appeared in the relevant object, in the irrelevant object, or in the background. The words were congruent, neutral, or incongruent with respect to the correct color response. Words in the irrelevant object and in the background produced significant Stroop effects, consistent with earlier findings. Importantly, however, words in the relevant object produced larger Stroop effects than did the other conditions, suggesting amplified processing of all the features of an attended object. Thus, object-based processing can modulate the Stroop effect.

Early “bottleneck” theories of selective attention allowed for only one channel of input to be semantically analyzed, other information being discarded. Later modifications to the attention theory proposed that all inputs were analyzed but that much of this is unconscious and automatic. However, automatic processes are difficult to unlearn and control. This paper reports a study of the Stroop effect that these over learned, automatic processing could intrude on a color identification tasks.

Introduction

The psychological occurrence we now call “the Stroop effect” was first described in 1935 by John Ridley Stroop. The Stroop effect was used in cognitive psychology to understand how behaviors interact. Stroop’s work was originated in the work done by J. M. Cattell (1885), who theorized objects and colors took longer to name than corresponding words. The psychologists were amazed at the experiment, because the Stroop effect appeared to have tap into the essential levels of cognition, offering more clues to the cognitive process of the brain.

Interested in the interference between conflicting processes, Stroop wanted to explain interference. His interests in the phenomenon lead him to ask two major questions:

• What effect of each dimension of the compound stimulus would have trying to name the other dimension

• What effect practice would have on the observed interference

To support his questions he constructed three experiments. In his first experiment, he studied the effect of incompatible ink color on reading words aloud. His results showed that subjects averaged 2.3 seconds longer to read words on experimental cards. The second experiment’s task was switched to naming colors aloud, with the control cards in the same order as experimental cards, except solid color squares were substituted for words. Results showed that subjects averaged forty-seven seconds longer to name the ink color of an incongruent word than a solid-color square. The last experiment had thirty-two subjects to name the ink colors of incompatible words for eight days. The results showed that the time, in seconds, on incompatible words decreased with practice. Stroop concluded that differential practice offered a reasonable account of the asymmetrical interference pattern he obtained. He also found that words evoked a single reading response, whereas colors evoked multiple responses and naming colors was much slower than reading them.

In the “Speed of Processing” hypothesis, it is suggested that word processing is much faster than color processing. Therefore, in a situation of incongruence between words and colors, when the task is to report the color, the word information arrives at the decision processing stage earlier than the color information and results in processing confusion. The discussion focused on two cognitive processes: automatic versus controlled processing. An interesting challenge arises when a task such as color naming is identified as both controlled and automatic, by varying the other task involved. Color naming is identified as a controlled process when the other task is word reading, but as an automatic process when the other task is shape naming. Cohen, Dunbar and McClelland (1990) proposed an alternative explanation of the Stroop effect, which does not distinguish between automatic and controlled processing. Instead, they proposed that automaticity is a range, and that Stroop interference depends on the relative degree of learning the particular tasks, not on processing speed.

Attention is thought to be selective-focused on one subject at a time. Traditionally, it has been assumed that automatic processing is involuntary, it does not require attention, and is relatively fast; whereas, controlled processing is voluntary, does require attention, and is relatively slow. We can conclude from this that the more we repeat a certain material or tasks the more it becomes automatic and effortless to us.

Methods

Design

The independent variable was represented by three conditions; three word lists printed in a variety of color inks. Two of the lists consisted of word colors; one in black ink and the other in incongruent colors. The third list consisted of square blocks in contrasting colors. The dependent variable was the time taken to name the black ink words, the square block colors, and the color names in incongruent color inks. The number of errors in identification was not recorded only the time.

Participants

Forty students volunteered to participate in the study. The volunteers consisted of both males and females between the ages of sixteen and nineteen. All were mentally capable, and all were fluent speakers of English. To the best of my knowledge, none suffered from any visual impairment or color interpretation