A computational theory of executive cognitive processes and multiple-task performance: Part I. Basic mechanisms.

A new theoretical framework, executive-process interactive control (EPIC), is introduced for characterizing human performance of concurrent perceptual-motor and cognitive tasks. On the basis of EPIC, computational models may be formulated to simulate multiple-task performance under a variety of circumstances. These models account well for reaction time (RT) data from representative situations such as the psychological refractory-period procedure. EPlC's goodness of fit supports several key conclusions: (a) At a cognitive level, people can apply distinct sets of production rules simultaneously for executing the procedures of multiple tasks; (b) people's capacity to process information at "peripheral" perceptual-motor levels is limited; (c) to cope with such limits and to satisfy task priorities, flexible scheduling strategies are used; and (d) these strategies are mediated by executive cognitive processes that coordinate concurrent tasks adaptively. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The restless mind.

This article reviews the hypothesis that mind wandering can be integrated into executive models of attention. Evidence suggests that mind wandering shares many similarities with traditional notions of executive control. When mind wandering occurs, the executive components of attention appear to shift away from the primary task, leading to failures in task performance and superficial representations of the external environment. One challenge for incorporating mind wandering into standard executive models is that it often occurs in the absence of explicit intention--a hallmark of controlled processing. However, mind wandering, like other goal-related processes, can be engaged without explicit awareness; thus, mind wandering can be seen as a goal-driven process, albeit one that is not directed toward the primary task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alcohol and cognitive control: Implications for regulation of behavior during response conflict.

Alcohol intoxication often leads to dysregulated behavior in contexts characterized by conflict between prepotent response tendencies and incompatible alternative responses. Recent research has identified 2 components of an anterior executive attention system that are essential for adaptive behavior when response conflict exists. Event-related potential (ERP) measures of evaluative and regulative cognitive control were collected to determine if impaired executive attention was responsible for observed behavior deficits when intoxicated. Intoxicated participants displayed task performance deficits on incongruent color-naming trials relative to sober controls. Alcohol did not affect P3 magnitude/latency, indicating that timing and integrity of stimulus evaluation remained intact. In contrast, alcohol did reduce frontal components of ERP that index evaluative and regulative cognitive control processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aerobic fitness and cognitive development: Event-related brain potential and task performance indices of executive control in preadolescent children.

The relationship between aerobic fitness and executive control was assessed in 38 higher- and lower-fit children (Mage = 9.4 years), grouped according to their performance on a field test of aerobic capacity. Participants performed a flanker task requiring variable amounts of executive control while event-related brain potential responses and task performance were assessed. Results indicated that higher-fit children performed more accurately across conditions of the flanker task and following commission errors when compared to lower-fit children, whereas no group differences were observed for reaction time. Neuroelectric data indicated that P3 amplitude was larger for higher- compared to lower-fit children across conditions of the flanker task, and higher-fit children exhibited reduced error-related negativity amplitude and increased error positivity amplitude compared to lower-fit children. The data suggest that fitness is associated with better cognitive performance on an executive control task through increased cognitive control, resulting in greater allocation of attentional resources during stimulus encoding and a subsequent reduction in conflict during response selection. The findings differ from those observed in adult populations by indicating a general rather than a selective relationship between aerobic fitness and cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serial modules in parallel: The psychological refractory period and perfect time-sharing.

The authors describe ACT-R/perceptual-motor (ACT-R/PM), an integrated theory of cognition, perception, and action that consists of the ACT-R production system and a set of perceptual-motor modules. Each module (including cognition) is essentially serial, but modules run in parallel with one another. ACT-R/PM can model simple dual tasks such as the psychological refractory period (PRP), including subtle results previously explained with executive process interactive control (EPIC, D. E. Meyer & D. E. Kieras, 1997a). The central difference between the theories is that EPIC's productions can fire in parallel, whereas in ACT-R/PM, they are serial. Results from three PRP-like experiments with more demanding cognitive requirements indicate that cognitive processing for the 2 tasks need not overlap. ACT-R's activation-based retrieval processes are critical in accounting for the timing of these tasks and for explaining the dual-task performance decrement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The use of biological markers for the study and prevention of chronic degenerative diseases. 1. Definitions, scope of the study and classification

Visual event-related brain potentials (ERPs) were recorded during a running memory task, in which subjects dynamically revised (updated) memory stores, and a control task not requiring maintenance of a changing memory set but utilising identical stimulus sequences and response patterns. In three experiments, ERPs associated with cognitive processes were isolated through subtraction of control potentials from ERPs acquired during updating. We provide evidence that resultant difference ERPs primarily reflected processing or processing control, as opposed to storage. These findings are consistent both with Baddeley's working memory model, which postulates separate storage and control modules, and Morris and Jones' behavioral evidence for specific involvement of Baddeley's central executive in memory updating. In addition, our ERP data indicate that updating requires processes not suggested by Morris and Jones' behavioural studies; possibly control processes engaged to reduce the effects of proactive interference. Overall the data are consistent with the discovery of an ERP correlate of central executive activity.     

Mood, reasoning, and central executive processes.

How positive induced mood states affect reasoning was investigated in three experiments. In Experiment 1, consistent with resource allocation theory (H. C. Ellis & P. W. Ashbrook, 1987), both positive and negative mood suppressed performance on a deontic version of Wason's selection task (P. W. Cheng & K. J. Holyoak, 1985)—participants confirmed where they normally falsify. Experiment 2 revealed the same confirmatory responses for participants performing a concurrent distracter task, indicating that induced mood states suppress reasoning by depleting central executive resources. This hypothesis was directly tested in Experiment 3. Participants in a positive, but not in a negative, mood state showed suppressed performance on the Tower of London task (T. Shallice, 1982)—the classical central executive task. The robust positive mood effects and the confirmation effects are discussed in terms of the D. A. Norman and T. Shallice (1986) model of central executive function and recent accounts of selection task performance (L. Cosmides, 1989; K. I. Manktelow & D. E. Over, 1991; M. Oaksford & N. Chater, 1994). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automaticity of cognitive control: Goal priming in response-inhibition paradigms.

Response inhibition is a hallmark of cognitive control. An executive system inhibits responses by activating a stop goal when a stop signal is presented. The authors asked whether the stop goal could be primed by task-irrelevant information in stop-signal and go/no-go paradigms. In Experiment 1, the task-irrelevant primes GO, ###, or STOP were presented in the go stimulus. Go performance was slower for STOP than for ### or GO. This suggests that the stop goal was primed by task-irrelevant information. In Experiment 2, STOP primed the stop goal only in conditions in which the goal was relevant to the task context. In Experiment 3, GO, ###, or STOP were presented as stop signals. Stop performance was slower for GO than for ### or STOP. These findings suggest that task goals can be primed and that response inhibition and executive control can be influenced by automatic processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correction to Kornblum et al.

Reports an error in "Dimensional overlap: Cognitive basis for stimulus-response compatibility--A model and taxonomy" by Sylvan Kornblum, Thierry Hasbroucq and Allen Osman (Psychological Review, 1990[Apr], Vol 97[2], 253-270). In this article, erroneous data were included in Figure 2. The figure and original caption are corrected in the erratum. (The following abstract of the original article appeared in record 1990-18942-001.) The classic problem of stimulus–response (S-R) compatibility (SRC) is addressed. A cognitive model is proposed that views the stimulus and response sets in S-R ensembles as categories with dimensions that may or may not overlap. If they do overlap, the task may be compatible or incompatible, depending on the assigned S-R mapping. If they do not overlap, the task is noncompatible regardless of the assigned mapping. The overlapping dimensions may be relevant or not. The model provides a systematic account of SRC effects, a taxonomy of simple performance tasks that were hitherto thought to be unrelated, and suggestive parallels between these tasks and the experimental paradigms that have traditionally been used to study attentional, controlled, and automatic processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dimensional overlap: Cognitive basis for stimulus-response compatibility--A model and taxonomy.

[Correction Notice: An erratum for this article was reported in Vol 99(1) of Psychological Review (see record 2008-10517-001). In this article, erroneous data were included in Figure 2. The figure and original caption are corrected in the erratum.] The classic problem of stimulus–response (S–R) compatibility (SRC) is addressed. A cognitive model is proposed that views the stimulus and response sets in S–R ensembles as categories with dimensions that may or may not overlap. If they do overlap, the task may be compatible or incompatible, depending on the assigned S–R mapping. If they do not overlap, the task is noncompatible regardless of the assigned mapping. The overlapping dimensions may be relevant or not. The model provides a systematic account of SRC effects, a taxonomy of simple performance tasks that were hitherto thought to be unrelated, and suggestive parallels between these tasks and the experimental paradigms that have traditionally been used to study attentional, controlled, and automatic processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Timing is affected by demands in memory search but not by task switching.

Recent studies suggest that timing and tasks involving executive control processes might require the same attentional resources. This should lead to interference when timing and executive tasks are executed concurrently. This study examined the interference between timing and task switching, an executive function. In 4 experiments, memory search and digit classification were performed successively in 4 conditions: search–search (search followed by search), search–digit, digit–search, and digit–digit. In a control reaction time (RT) condition, participants provided RT responses in each of the 2 tasks. In a time production condition, an RT response was provided to the first stimulus, but the response to the second stimulus, S2, was given only when participants judged that a previously presented target duration had elapsed. When responding to S2 required a switch, RTs to S2 were longer, but produced intervals were unaffected. These results show that memory search affects concurrent timing, but not task switching. Task switching seems therefore to be 1 executive function that does not interfer with timing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bilingualism, Aging, and Cognitive Control: Evidence From the Simon Task.

Previous work has shown that bilingualism is associated with more effective controlled processing in children; the assumption is that the constant management of 2 competing languages enhances executive functions (E. Bialystok, 2001). The present research attempted to determine whether this bilingual advantage persists for adults and whether bilingualism attenuates the negative effects of aging on cognitive control in older adults. Three studies are reported that compared the performance of monolingual and bilingual middle-aged and older adults on the Simon task. Bilingualism was associated with smaller Simon effect costs for both age groups; bilingual participants also responded more rapidly to conditions that placed greater demands on working memory. In all cases the bilingual advantage was greater for older participants. It appears, therefore, that controlled processing is carried out more effectively by bilinguals and that bilingualism helps to offset age-related losses in certain executive processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention control, memory updating, and emotion regulation temporarily reduce the capacity for executive control.

This research tested the hypothesis that initial efforts at executive control temporarily undermine subsequent efforts at executive control. Four experiments revealed that controlling the focus of visual attention (Experiment 1), inhibiting predominant writing tendencies (Experiment 2), taking a working memory test (Experiment 3), or exaggerating emotional expressions (Experiment 4) undermined performance on subsequent tests of working memory span, reverse digit span, and response inhibition, respectively. The results supported a limited resource model of executive control and cast doubt on competing accounts based on mood, motivation, or task difficulty. Prior efforts at executive control are a significant contextual determinant of the operation of executive processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the control of automatic processes: A parallel distributed processing account of the Stroop effect.

Traditional views of automaticity are in need of revision. Recent empirical data suggest that automatic processes are continuous and subject to attentional control. A model of attention is presented. Within a parallel distributed processing framework, it is proposed that the attributes of automaticity depend on the strength of a processing pathway that strength increases with training. With the Stroop effect as an example, automatic processes are shown to be continuous and to emerge gradually with practice. Specifically, a computational model of the Stroop task simulates the time course of processing as well as the effects of learning. This was accomplished by combining the cascade mechanism described by J. L. McClelland (see record 1979-32860-001) with the backpropagation learning algorithm (D. E. Rumelhart et al, 1986). The model can simulate performance in the standard Stroop task, as well as aspects of performance in variants of this task that manipulate stimulus-onset asynchrony, response set, and degree of practice. This model is contrasted against other models, and its relation to many of the central issues in the literature on attention, automaticity, and inference is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term aftereffects of response inhibition: Memory retrieval, task goals, and cognitive control.

Cognitive control theories attribute control to executive processes that adjust and control behavior online. Theories of automaticity attribute control to memory retrieval. In the present study, online adjustments and memory retrieval were examined, and their roles in controlling performance in the stop-signal paradigm were elucidated. There was evidence of short-term response time adjustments after unsuccessful stopping. In addition, it was found that memory retrieval can slow responses for 1-20 trials after successful inhibition, which suggests the automatic retrieval of task goals. On the basis of these findings, the authors concluded that cognitive control can rely on both memory retrieval and executive processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Voluntary Task Switching: Chasing the Elusive Homunculus.

In the voluntary task switching procedure, subjects choose the task to perform on a series of bivalent stimuli, requiring top-down control of task switching. Experiments 1-3 contrasted voluntary task switching and explicit task cuing. Choice behavior showed small, inconsistent effects of external stimulus characteristics, supporting the assumption of top-down control of task choice. Switch costs were smaller when subjects chose to switch tasks than when instructed by an external cue. Experiments 4-6 separated choice costs from switch costs. These findings support models of task switching that incorporate top-down processes in accounts of switch costs. The degree to which task switching procedures capture top-down versus bottom-up processes may depend on the extent of environmental support provided by the procedure. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Process interference and code overlap in dual-task performance.

Perceptual encoding processes have recently been shown to interfere with response selection in dual tasks (P. Jolicoeur & R. Dell'Acqua, 1998). Spatial cross-task compatibility (CTC) was varied to additionally manipulate code overlap across tasks. A new response-cuing paradigm was devised, in which a stimulus movement was used for later report in a perceptual task and a finger movement was used as response in a logically independent reaction task. Three experiments were conducted showing dual-task process interference, but shorter reaction times with CTC than without were also observed. This CTC priming effect was largest with high temporal overlap between the perception and reaction stimuli. The CTC effect was interpreted as resulting from overlap of code activation across tasks, whereas process interference seems to occur to prevent temporal overlap on the level of perceptual encoding and response retrieval processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Positive mood and executive function: Evidence from Stroop and fluency tasks.

Contrasting predictions have been made about the effects of positive mood states on the performance of frontal lobe tests that tap executive functions such as inhibition, switching, and strategy use. It has been argued that positive mood is likely to improve some cognitive processes, particularly those dependent on the frontal cortex and anterior cingulate of the brain. However, there is some evidence that happy mood may impair executive functioning. The current experiments investigated the effects of positive mood on Stroop and fluency tests, which are frequently used to assess executive function. Positive mood impaired performance on a switching condition of the Stroop test, but improved performance on a creative uses test of fluency. The effect of positive mood on an executive task may therefore depend on whether a task is inherently motivating or is impaired by diffuse semantic activation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A queue-series model for reaction time, with discrete-stage and continuous-flow models as special cases.

Presents a new reaction time (RT) model that includes both sequential-stage (discrete) and overlapping-stage (continuous-flow) models as special cases. In the new model, task performance is carried out by a series of distinct processing stages, each of which functions as a queue. A stimulus conveys 1 or more distinct components of information (e.g., features), and each stage can begin processing as soon as it receives 1 component from its predecessor. If a stimulus activates only 1 component, successive stages operate in strict sequence; if it activates multiple components, successive stages operate with temporal overlap. Within this class of models, experimental factors affecting different processing stages always have additive effects on RT with sequential stages but rarely do so with overlapping stages. Within this class of models, then, observations of factor additivity support discrete-stage models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using confirmatory factor analysis to understand executive control in preschool children: I. Latent structure.

Although many tasks have been developed recently to study executive control in the preschool years, the constructs that underlie performance on these tasks are poorly understood. In particular, it is unclear whether executive control is composed of multiple, separable cognitive abilities (e.g., inhibition and working memory) or whether it is unitary in nature. A sample of 243 normally developing children between 2.3 and 6 years of age completed a battery of age-appropriate executive control tasks. Confirmatory factor analysis was used to compare multiple models of executive control empirically. A single-factor, general model was sufficient to account for the data. Furthermore, the fit of the unitary model was invariant across subgroups of children divided by socioeconomic status or sex. Girls displayed a higher level of latent executive control than boys, and children of higher and lower socioeconomic status did not differ in level. In typically developing preschool children, tasks conceptualized as indexes of working memory and inhibitory control in fact measured a single cognitive ability, despite surface differences between task characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)