Proportion congruent effects in the absence of sequential congruent effects

A debated question in the cognitive control field is whether cognitive control is best conceptualized as a collection of distinct control mechanisms or a single general purpose mechanism. In an attempt to answer this question, previous studies have dissociated two well-known effects related to cognitive control: sequential congruence and proportion congruent effects. In the present experiment, we pursued a similar goal by using a different strategy: to test whether proportion congruent effects can be present in conditions where sequential congruence effects are absent. We used a paradigm in which two conflict types are randomly intermixed (Simon and Spatial Stroop) and the proportion of congruency is manipulated for one conflict type and kept neutral for the other conflict type. Our results showed that in conflict type alternation trials, where sequential congruence effects were absent, proportion congruent effects were still present. It can be concluded that, at least under certain circumstances, sequential congruence and proportion congruent effects can be independent of each other and specific to the conflict type.