Chris Blais

Item-specific adaptation and the conflict-monitoring hypothesis: a computational model.

M. M. Botvinick, T. S. Braver, D. M. Barch, C. S. Carter, and J. D. Cohen (2001) implemented their conflict-monitoring hypothesis of cognitive control in a series of computational models. The authors of the current article first demonstrate that M. M. Botvinick et al.s (2001) conflict-monitoring Stroop model fails to simulate L. L. Jacoby, D. S. Lindsay, and S. Hesselss (2003) report of an item-specific proportion-congruent (ISPC) effect in the Stroop task. The authors then implement a variant of M. M. Botvinick et al.s model based on the assumption that control must be able to operate at the item level. This model successfully simulates the ISPC effect. In addition, the model provides an alternative to M. M. Botvinick et al.s explanation of the list-level proportion-congruent effect in terms of an ISPC effect. Implications of the present modeling effort are discussed.

Behavioral and neural evidence for item-specific performance monitoring

How cognitive control is recruited and implemented has become a major focus of researchers in cognitive psychology and neuroscience. Current theories posit that cognitive control operates at the level of general rules—for example, in a Stroop task, “attend to the color of the stimulus.” Here we report behavioral evidence suggesting that cognitive control is implemented much more locally, operating at the level of specific stimuli appearing in a task block. In addition, we report neural evidence that many of the regions implicated in cognitive control on the Stroop task, including anterior cingulate cortex and dorsolateral prefrontal cortex, operate at a local level.

Rethinking the role of automaticity in cognitive control

Behaviour that is assumed to be guided by strategy can, in fact, be based on the implicit learning of regularities in the environment. We demonstrate this point in the context of a Stroop experiment. It has been shown previously that performance on this measure of cognitive control varies as a function of the relative proportions of congruent and incongruent trials in a block. Here we provide evidence that this modulation of performance is largely based on implicit, rather than explicit, knowledge of these proportions. This result has important implications for our understanding of cognitive control.

Increasing set size breaks down sequential congruency: Evidence for an associative locus of cognitive control ☆

In recent years, a number of studies have revealed that cognitive control is strongly context-dependent (e.g., Crump et al., 2006). Inspired by this, computational models have been formulated based on the idea that cognitive control processes are based on associative learning (Blais et al., 2007; Verguts & Notebaert, 2008). Here, we test a natural consequence of this idea, namely, that sequential congruency effects (Gratton et al., 1992) should gradually decrease with an increasing number of task-relevant features (e.g., stimuli). The effect is empirically observed and simulated in a computational model. Implications of our findings are discussed.

Reverse stroop effects with untranslated responses

Translation accounts have argued that the presence of a Stroop effect in the context of a nonvocal untranslated response is caused by verbal mediation. In its simplest form, color-labeled buttons are translated into a verbal code that interferes with color responses. On this logic, in the reverse Stroop task (identify the word; ignore the color), responses made via word-labeled buttons should also be verbally mediated. Thus, no reverse Stroop effect (RSE) should be seen. The authors tested this verbal mediation hypothesis in 4 reverse Stroop task experiments. An RSE was observed across 4 experiments. The results of Experiments 3 and 4 suggest that this RSE is driven by response competition. It is argued that the data from these 4 experiments are inconsistent with unadorned translation accounts of the RSE but consistent with an account in which the strength of association between a stimulus and a specific response plays a major role.

The Gratton effect remains after controlling for contingencies and stimulus repetitions

Highlights: The conflict monitoring hypothesis signals the need for cognitive control The Gratton effect is a key result attributed to the conflict monitoring hypothesis Some argue that controlling binding confounds eliminates the Gratton effect A Gratton effect remains in a vocal Stroop task after eliminating confounds The Gratton effect, the observation that the size of the Stroop effect is larger following a congruent trial compared to an incongruent trial, is one pivotal observation in support of the conflict-monitoring hypothesis. Previous reports have demonstrated that non-conflict components, such as feature binding, also contribute to this effect. Critically, Schmidt and De Houwer (2011) report a flanker task and a button-press Stroop task suggesting that there is no conflict adaptation in the Gratton effect; it is entirely caused by feature binding. The current investigation attempts to replicate and extend this important finding across two experiments using a canonical four-choice Stroop task with vocal responses. In contrast to Schmidt and De Houwer, we observe reliable conflict adaptation after controlling for feature binding. We argue that the overall strength of conflict is critical for determining whether a conflict adaptation component will remain in the Gratton effect after explaining binding components.

A reverse Stroop effect without translation or reading difficulty.

It is well known that irrelevant color words affect the time needed to identify the color they are displayed in (the Stroop effect). One major view is that a reverse Stroop effect (RSE)—in which the irrelevant color affects the time needed to identify the word—does not occur unless a translation is needed between domain-specific memory codes. In the present article, we report an experiment in which the reverse Stroop effect was investigated by having subjects identify a colored word at fixation by pointing to a location on the screen containing that word. Although the response was untranslated, an RSE was observed. An account is provided in which the strength of association between a stimulus and a specific response plays a central role.

Nonstrategic Contributions to Putatively Strategic Effects in Selective Attention Tasks

Proportion compatible manipulations are often used to index strategic processes in selective attention tasks. Here, a subtle confound in proportion compatible manipulations is considered. Specifically, as the proportion of compatible trials increases, the ratio of complete repetitions and complete alternations to partial repetitions increases on compatible trials but decreases on incompatible trials. This confound is demonstrated to lead to an overestimation in the magnitude of the proportion compatible effect in the context of both a Stroop and a Simon task. Implications for previous research and directions for future research using proportion compatible manipulations are discussed.

Social class affects Mu-suppression during action observation

Socioeconomic status (SES) has been linked to differences in the degree to which people are attuned to others. Those who are lower in SES also tend to be more interpersonally attuned. However, to date, this work has not been demonstrated using neural measures. In the present electroencephalogram study, we found evidence that lower SES was linked to stronger Mu-suppression during action observation. This finding adds to the growing literature on factors that affect Mu-suppression and suggests that the mirror neuron system may be influenced by one’s social class.

Covert orienting: A compound-cue account of the proportion cued effect

An increase in the proportion of spatially cued trials in the context of the covert orienting paradigm increases the magnitude of the cuing effect. This proportion cued effect is widely interpreted to reflect a form of control. Specifically, it is argued that participants strategically allocate attention as a function of the utility of the spatial cue. Here, an alternative explanation of the proportion cued effect is proposed that does not require control. According to this account, the cue-target event forms a compound cue and the proportion cued manipulation produces a relative disparity in the frequency with which particular compound cues occur. Specifically, when the proportion of spatially cued trials is increased, the frequency of spatially cued cue-target events increases and the frequency of spatially miscued cue-target events decreases, thus increasing the magnitude of the cuing effect. The results of two experiments support this account.