Multiple levels of control in the Stroop task

Abstract

1484The Stroop color-naming task (Stroop, 1935) is well suited for evaluating flexibility in the control of cognitive processes and behavior. In the congruent condition of the task, stimulus word matches stimulus color (e.g., BLUE in blue ink) and participants may rely on well-learned reading processes to produce fast and accurate responding. In the incongruent condition, in contrast, accurate responding requires participants to use cognitive control mechanisms to dampen word reading and activate color-naming processes. The additional time that is taken to name the ink color in the incongruent relative to the congruent condition is referred to as Stroop interference. Although the task might seem relatively simple, the literature is replete with reports of robust Stroop interference effects (for a review, see MacLeod, 1991). Close to 1,000 articles have been published on the topic, yet the control mechanism(s) used to dampen word reading and activate color-naming processes remain to be fully explicated.A complicating (or revealing, as we will argue) factor is the different instantiations (e.g., blocked conditions vs. intermixed trials) of the Stroop color-naming task appearing in the literature. Different task contexts appear to elicit different forms of cognitive control, precluding a unitary account of control mechanisms. Proportion congruence is one prominent factor that influences the control mechanisms that are adopted within a given task. Traditionally, proportion congruence is manipulated at a list-wide level by disproportionately presenting congruent and incongruent trials within a list. Participants can use frequencies to predict what type of trial is most likely to occur next, and control processes can be biased toward (as in a mostly congruent list) or away from (as in a mostly incongruent list) word reading prior to stimulus onset on the basis of these expectancies. Such contexts seem to induce a preparatory, goal-driven control mechanism that is implemented in a sustained fashion across trials (i.e., the bias toward or away from word reading remains constant throughout a list), analogous to the proactive control mechanism recently posited in the dual-mechanisms-of-control account (Braver, Gray, & Burgess, 2007). In contrast, in other task contexts, congruent and incongruent trials occur equally often within a list, and one is unable to anticipate the upcoming trial type and prepare control processes accordingly. These contexts demand a more flexible control mechanism that is capable of modulating word-reading and color-naming processes in a transient fashion on a trial-by-trial basis. Because such modulation occurs after stimulus onset, such a control mechanism must operate rapidly.By this analysis, different cognitive control mechanisms underlie Stroop performance. One control mechanism appears to operate slowly and strategically at a list level, acting prior to stimulus onset. A second appears to operate rapidly at a trial or item-specific level, and acts after the stimulus has been presented. This...

Selective attention and recognition: effects of congruency on episodic learning

“…By this alternative view, the requirement to respond to the word BLUE in red could result in learning that favours processing of the colour dimension relative to the word dimension for that particular item, but not for other items. This idea gained initial support from findings of itemspecific proportion congruency effects in the Stroop task (Jacoby, Lindsay, & Hessels, 2003;see also Blais, Robidoux, Risko, & Besner, 2007;Bugg, Jacoby, & Toth, 2008; for a review see Bugg & Crump, 2012). Jacoby et al (2003) manipulated the relative proportions of congruent and incongruent items separately for different sets of Stroop items.…”

The Parallel Episodic Processing (PEP) model: Dissociating contingency and conflict adaptation in the item-specific proportion congruent paradigm

“…On a similar note, context-level conflict adaptation might also be possible in some situations (e.g., Bugg, Jacoby, & Toth, 2008;Crump, Gong, & Milliken, 2006). That is, a contextual cue such as stimulus font could serve as a cue to conflict.…”

Time-out for conflict monitoring theory: Preventing rhythmic biases eliminates the list-level proportion congruent effect.

“…An informed reader might note that this design makes use of a simple contingency matrix in which there are some strongly predictive inducers and some unpredictive diagnostic items. Such simple manipulations have often proved unsuccessful in the past (e.g., Blais & Bunge, 2010;Bugg et al, 2008). However, as noted earlier, the prime-probe task is particularly potent (e.g., , unlike the Stroop task.…”

“…Said differently, at the level of the items, diagnostic items have the same LIST-LEVEL PROPORTION CONGRUENT EFFECT 5 congruent:incongruent ratio in the mostly congruent and mostly incongruent lists, but fall within different PC list contexts. In many reports, the PC effect did not transfer to diagnostic items (e.g., Blais & Bunge, 2010;Bugg, Jacoby, & Toth, 2008). However, in some conditions a LLPC effect is observed (e.g., Bugg, 2014;Bugg, McDaniel, Scullin, & Braver, 2011;Hutchison, 2011;Wühr, Duthoo, & Notebaert, 2015).…”