The Stroop task presents subjects with a set of color naming words ("red", "green", "blue", or "yellow") written in various incongruent colors (e.g. "red" printed in the color blue) along with neutral symbols such as "XXX" presented in the same colors. The task of the subject is to respond as quickly as possible to the color the word or symbol is printed in regardless of what the word reads. The Stroop effect is defined as the longer reaction times needed to name the color in which incongruent words are printed compared to neutral stimuli. The traditional argument is that this occurs because the easier, well-learned task (often called the "dominant response") is word reading (Baron, 1986).
The present experiment was a follow up to a French study by Huguet, Monteil, and Galvaing (1998). They looked at the effect of an attentive audience on Stroop performance. This study of "social facilitation" found that an audience did facilitate performance, which the authors interpreted as support for an "attention focusing" explanation. This contrasts with Zajoncıs (1965) popular explanation for social facilitation which states that dominant responses (such as word reading in the Stroop situation) should be facilitated by an audience since the increased motivation created by an audience primarily affects such responses. Other competing responses (such as color naming) should therefore be inhibited. The attention focusing hypothesis, on the other hand, actually suggests that any task that can be performed well by focusing attention (such as both word reading [attending to the wordıs meaning] and color naming [attending to the wordıs color]) should be facilitated.
The purpose of the present study was to compare both the dominant response and attention focusing hypotheses in a Stroop situation. Huguet et al., in using only the color naming task, left open the possibility that this task is the dominant response in the Stroop situation. Increased performance in the audience condition might therefore be explained by Zajoncıs theory. We elected to have some subjects perform the color naming task while other subjects were asked to read the wordsı meanings (what we called a reverse Stroop condition). Half of the subjects with each task were observed and half performed their task alone.
The attention focusing hypothesis would predict increased performance in the observed condition, regardless of task type. The dominant response hypothesis would indicate increased performance of observed subjects in the Stroop condition, but inhibition of performance of observed subjects in the reverse Stroop condition.
The subject pool consisted of Introduction to Psychology, and Social Psychology students from State University of New York College at Fredonia. Each subject was randomly assigned to one of three experimenters, one of the two social conditions (observed vs. alone) and one of the two task conditions (Stroop color naming vs. reverse Stroop word reading). Thirty nine subjects were individually tested by computer, with a scripted introduction by the experimenter. Each subject was instructed by the computer and allowed practice trials. Each subject was taught that one of four keys on the keyboard represented a color. When a color word was flashed on the screen, the subject had to press the key that corresponded to the color the word was printed in (Stroop), or to the color the word read (reverse Stroop). After the key was pressed, the subject was instructed to press the Enter key and another word would flash on the screen. Each subject responded to forty eight color words. The reaction times to incongruently colored words and to control stimuli ("XXX"ıs in the Stroop task, congruently colored color words in the reverse Stroop task) were recorded separately on the computer.
The results of the experiment suggest interesting possibilities for future experiments. First of all, as indicated by the solid bars in the attached graph, word reading of incongruent words was significantly easier than color naming of those words. This supports the idea that word reading is the dominant response. According to the dominant response hypothesis for social facilitation, being observed (striped bars) should have further facilitated performance on this task, which it did not. Also, the observed condition significantly reduced Stroop interference in the color naming task, which again argues against the dominant response interpretation and supports the attention focusing hypothesis. It is interesting that although both theories predict a social facilitation of performance on the word reading task, no such effect was obtained. Perhaps there just was not room for improvement.
References
Huguet, P., Monteil, J., &Galvaing, M. Social presence reduces stroop interference: Empirical evidence for an attentional view of social facilitation. Submitted to Psychological Science.
Zajonc, R. B. (1965). Social facilitation. Science, 149, 269-274.
Baron, R. S. (1986). Distraction-conflict theory: Progress and problems. In L. Berkowtiz (Ed.), Advances in Experimental Social Psychology (pp. 1-40). New York: Academic Press.