Correlational cuing as a function of target complexity and target-flanker similarity

In Support of a Distinction between Voluntary and Stimulus-Driven Control: A Review of the Literature on Proportion Congruent Effects

Cognitive control is by now a large umbrella term referring collectively to multiple processes that plan and coordinate actions to meet task goals. A common feature of paradigms that engage cognitive control is the task requirement to select relevant information despite a habitual tendency (or bias) to select goal-irrelevant information. At least since the 1970s, researchers have employed proportion congruent (PC) manipulations to experimentally establish selection biases and evaluate the mechanisms used to control attention. PC manipulations vary the frequency with which irrelevant information conflicts (i.e., is incongruent) with relevant information. The purpose of this review is to summarize the growing body of literature on PC effects across selective attention paradigms, beginning first with Stroop, and then describing parallel effects in flanker and task-switching paradigms. The review chronologically tracks the expansion of the PC manipulation from its initial implementation at the list-wide level, to more recent implementations at the item-specific and context-specific levels. An important theoretical aim is demonstrating that PC effects at different levels (e.g., list-wide vs. item or context-specific) support a distinction between voluntary forms of cognitive control, which operate based on anticipatory information, and relatively automatic or reflexive forms of cognitive control, which are rapidly triggered by the processing of particular stimuli or stimulus features. A further aim is to highlight those PC manipulations that allow researchers to dissociate stimulus-driven control from other stimulus-driven processes (e.g., S-R responding; episodic retrieval). We conclude by discussing the utility of PC manipulations for exploring the distinction between voluntary control and stimulus-driven control in other relevant paradigms.

Conflict-Frequency Affects Flanker Interference

Performance in choice reaction time tasks deteriorates when an irrelevant stimulus feature is associated with an incorrect response (conflict condition). Such interference effects are reduced under conditions of increased conflict-frequency. Although models of cognitive control account for this modulation in terms of conflict-related attentional focusing on the target stimulus dimension, it is possible that the effect reflects practice with specific stimulus ensembles or stimulus feature-response contingencies. Using an Eriksen flanker task, we deconfounded the frequency of conflict trials and the frequency of specific stimulus ensembles (i.e., target-flanker conjunctions). In Experiments 1 and 2, flanker interference varied inversely with the frequency of conflict trials, irrespective of practice with specific target-flanker conjunctions, thereby disputing a stimulus ensemble learning account. In Experiment 3, however, flanker interference was reduced for specific flanker stimuli which occurred predominantly in conflict trials. Taken together, the findings are consistent with flanker-specific attentional adjustment or associative flanker-response priming.

Context-specific learning and control: the roles of awareness, task relevance, and relative salience

The processes mediating dynamic and flexible responding to rapidly changing task-environments are not well understood. In the present research we employ a Stroop procedure to clarify the contribution of context-sensitive control processes to online performance. In prior work Stroop interference varied as a function of probe location context, with larger Stroop interference occurring for contexts associated with a high proportion of congruent items [Crump, M. J., Gong, Z., & Milliken, B. (2006). The context-specific proportion congruent stroop effect: location as a contextual cue. Psychonomic Bulletin &Review, 13, 316-321.] Here, we demonstrate that this effect does not depend on awareness of the context manipulation, but that it can depend on attention to the predictive context dimension, and on the relative salience of the target and predictive context dimensions. We discuss the implications of our results for current theories of cognitive control.