Abstract:

Sequential congruency effects (CSEs) or conflict adaptation effects refer to the ability to flexibly and rapidly adapt interference control. The Gratton effect, as demonstrated using a standard Stroop or flanker task, can be explained in at least three ways. The first explanation is the conflict-monitoring account. A second theory is the repetition-expectancy account. A third explanation rests on the notion of low-level repetition effects and has been incorporated in the feature-integration or feature-priming account. Concerning age differences in CSEs, the great majority of studies examined adult populations. The relatively few studies that (also) examined children and adolescents, using one of the standard interference control tasks. Previous studies examining age differences in cognitive control adaptations, as reflected in congruency sequence effects (CSEs) in tasks inducing stimulus or response conflict, did not consistently control for priming confounds. Hence, answering the question whether or not children have an equal ability and pattern of cognitive control adaptations, relative to adults, still requires more research.

The participants were 33 adults with a mean age of 20.6 years and 34 children with a mean age of 9.5 years. The experiment consists of two tasks: Task 1 is a Stroop task; Task 2 consisted of a mix of trials from the Stroop and flanker tasks. The stimuli used for the Stroop task (Task 1) consisted of the Hanzi representing the word “RED” printed in red (congruent trial) or green (incongruent trial), and the Hanzi representing the word “GREEN”, also printed in red (incongruent trial) or green (congruent trial). These stimuli were also used in Task 2, which also incorporated a flanker task. The stimuli of the flanker task were five arrows that all pointed to the right or left (congruent trials), or with the middle arrow pointing in one direction and the surrounding arrows in the other (incongruent trials). The experiment was performed on two consecutive days. On the first day, participants performed the Stroop task (Task 1), the next day participants performed the Task 2. An analysis of variance (ANOVA) was used to analyze the RTs and accuracy in the two tasks.

For Task 1, of primary interest, the Trial n-1 congruency × Trial n congruency interaction was significant. Follow-up analyses revealed that the congruency effect was significant after congruent trials (cC vs. cI trials). The congruency effect was also significant after incongruent trials (iC vs. iI trials). Responding on cC trials was faster than on iC trials and responding on cI trials was slower than on iI trials, reflecting a clear CSEs. The two groups did not differ in the size of the conflict adaptation effect. The accuracy data, also suggest a clear reduction of the congruency effect in both age groups, which seemed to be mainly caused by more accurate responding on iI relative to cI trials. For Task 2, the Trial n-1 congruency × Trial n congruency interaction revealed that, although the congruency effect was significant both after congruent (cC vs. cI), and incongruent trials (iC vs. iI), cC trial pairs were associated with faster responses compared to iC trial pairs. However, RTs on iI trials did not differ from those on cI trials. There was no difference between the groups in mean CSE magnitude for both the Stroop→Flanker and Flanker→Stroop transition trials. The accuracy data suggest a similar pattern.

The strong resemblance between CSEs observed for 9~10-year-old children and adult participants under both single- and two-task conditions adds to the behavioral evidence of cognitive control adaptation capacities in children of this age, which seem to reach adult-like levels despite a relative immaturity of brain areas that subserve those capacities in adults. Hence, the observed CSE reflected higher-order, cognitive adaptation rather than the lower-level effects potentially induced by response repetition.

Key words: cognitive adaptation, congruency sequence effect, colour-word Stroop task, Flanker task