关键词: 认知控制, 一致性序列效应, 调节, flanker任务, 背景颜色

Abstract: Cognitive control is essential for human to adapt to rapidly changing environment. Performance on congruency tasks has long been considered a useful model for probing cognitive control processing. In particular, the congruency sequence effects provide a direct window onto online adjustments in cognitive control. The congruency sequence effects refer to that the interference effect is smaller after incongruent trials than after congruent trials in the congruency tasks. Previous studies have indicated that the congruency sequence effects are influenced by subject factors (e.g., motivation and emotion). However, there is little research on the effect of the direct environmental variables (e.g., the environmental color) on the congruency sequence effects. And lines of research have suggested that color can exert influence on cognition and behavioral performance. Therefore, we speculated that the effect of background color on the on-going adjustment of cognitive control is a critical but ignored issue. The present study employed the four-letter flanker task, which was presented by E-Prime software (Psychological Software Tools, Pittsburgh, PA, USA) and investigated whether the congruency sequence effects were influenced by the gray, blue, and red backgrounds. In each trial, a line of five letters was presented: the central one was the target, and the remaining letters were the flankers. Four letters (i.e., S, H, N, and P) were employed in the task, and each letter could be a target or a flanker. In the congruent trials, the flankers were identical to the target (e.g., NNNNN), and in the incongruent trials, the flankers were mapped onto a different response hand to the target stimulus (e.g., SSNSS). Participants were instructed to press the key corresponding to the central letter. Responses were made using one of four different fingers (i.e., left middle finger, left index finger, right index finger and right middle finger). The four responses corresponded to four keys (i.e., 1 key, 2 key, 9 key, and 0 key). The flanker task consisted of three blocks, and each block was set as one color and comprised 192 trials. Stimuli were presented in a pseudorandom order in which the numbers of CC, CI, IC, and II trial sequences were counterbalanced. In order to control for repetition priming and feature integration effects, target and flanker stimuli were always alternated across trials. The order of a trial was as follows. After a 300 ms fixation displayed, followed by a random blank presented for 300-500 ms, and the letter array was presented in the center of screen for 200 ms. Then, a blank screen was presented for 1, 500 ms, during which period participants were instructed to press the corresponding key as quickly and as accurately as possible. After another random blank screen, lasting for 800-1, 200 ms, the next trial started. The results showed that the background color type × previous trial × current trial congruency repeated-measures ANOVA on RT data revealed a significant three-way interaction effect (p < .05). The congruency sequence effects were significant on gray and red backgrounds (p < .01; p < .01), however the congruency sequence effect was absent within blue background (p > .05). Additionally, we found that there were significant flanker interference effects across the three backgrounds (p < .001; p < .001; p < .001), but there is no significant difference between them (p > .05). These results suggested that the blue background affected the congruency sequence effect; however, the interference effect was not be modulated by the background color. The present study, for the first time, reveals the impact of the background colors on the on-going adjustment of cognitive control and furthers our understanding of the congruency sequence effect.

Key words: cognitive control, congruency sequence effect, modulation, flanker task, background color