Proactive adjustments of response strategies in the stop-signal paradigm.

In the stop-signal paradigm, fast responses are harder to inhibit than slow responses, so subjects must balance speed in the go task with successful stopping in the stop task. In theory, subjects achieve this balance by adjusting response thresholds for the go task, making proactive adjustments in response to instructions that indicate that relevant stop signals are likely to occur. The 5 experiments reported here tested this theoretical claim, presenting cues that indicated whether or not stop signals were relevant for the next few trials. Subjects made proactive response-strategy adjustments in each experiment: Diffusion-model fits showed that response threshold increased when participants expected stop signals to occur, slowing go responses and increasing accuracy. Furthermore, the results show that subjects can make proactive response-strategy adjustments on a trial-by-trial basis, suggesting a flexible cognitive system that can proactively adjust itself in changing environments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic and controlled response inhibition: Associative learning in the go/no-go and stop-signal paradigms.

In 5 experiments, the authors examined the development of automatic response inhibition in the go/no-go paradigm and a modified version of the stop-signal paradigm. They hypothesized that automatic response inhibition may develop over practice when stimuli are consistently associated with stopping. All 5 experiments consisted of a training phase and a test phase in which the stimulus mapping was reversed for a subset of the stimuli. Consistent with the automatic-inhibition hypothesis, the authors found that responding in the test phase was slowed when the stimulus had been consistently associated with stopping in the training phase. In addition, they found that response inhibition benefited from consistent stimulus-stop associations. These findings suggest that response inhibition may rely on the retrieval of stimulus-stop associations after practice with consistent stimulus-stop mappings. Stimulus-stop mapping is typically consistent in the go/no-go paradigm, so automatic inhibition is likely to occur. However, stimulus-stop mapping is typically inconsistent in the stop-signal paradigm, so automatic inhibition is unlikely to occur. Thus, the results suggest that the two paradigms are not equivalent because they allow different kinds of response inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociating interference-control processes between memory and response.

The ability to mitigate interference is of central importance to cognition. Previous research has provided conflicting accounts about whether operations that resolve interference are singular in character or form a family of functions. Here, the authors examined the relationship between interference-resolution processes acting on working memory representations versus responses. The authors combined multiple forms of interference into a single paradigm by merging a directed-forgetting task, which induces proactive interference, with a stop-signal task, which taps response inhibition processes. The results demonstrated that proactive interference and response inhibition produced distinct behavioral signatures that did not interact. By contrast, combining two different measures of response inhibition by merging a go/no-go task variant and a stop signal produced overadditive behavioral interference, demonstrating that different forms of response inhibition tap the same processes. However, not all forms of response conflict interacted, suggesting that inhibition-related functions acting on response selection are dissociable from those acting on response inhibition. These results suggest that inhibition-related functions for memory and responses are dissociable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working-memory-triggered dynamic adjustments in cognitive control.

Dynamic adjustments in cognitive control are well documented in conflict tasks, wherein competition from irrelevant stimulus attributes intensifies selection demands and leads to subsequent performance benefits. The current study investigated whether mnemonic demands, in a working memory (WM) task, can drive similar online control modifications. Demand levels (high vs. low) of WM maintenance (memory load of 2 items vs. 1 item) and delay-spanning distractor interference (confusable vs. not confusable with memoranda) were manipulated using a factorial design during a WM delayed-recognition task. Performance was best subsequent to trials in which both maintenance and distractor interference demands were high, followed by trials with high demand in either of these 2 control domains, and worst following trials with low demand in both domains. These results suggest that dynamic adjustments in cognitive control are not triggered exclusively by conflict-specific contexts but are also triggered by WM demands, revealing a putative mechanism by which this system configures itself for successful task performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term aftereffects of response inhibition: Repetition priming or between-trial control adjustments?

Repetition priming and between-trial control adjustments after successful and unsuccessful response inhibition were studied in the stop-signal paradigm. In 5 experiments, the authors demonstrated that response latencies increased after successful inhibition compared with trials that followed no-signal trials. However, this effect was found only when the stimulus (Experiments 1A-4) or stimulus category (Experiment 3) was repeated. Slightly different results were found after trials on which the response inhibition failed. In Experiments 1A, 2, and 4, response latencies increased after unsuccessful inhibition trials compared with after no-inhibition trials, and this happened whether or not the stimulus repeated. Based on these results, we suggest that the aftereffects of successful response inhibition are primarily due to repetition priming, although there was evidence for between-trial control adjustments when inhibition failed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context-sensitive adjustments of cognitive control: Conflict-adaptation effects are modulated by processing demands of the ongoing task.

Dynamic adjustments of cognitive control in response to interference from irrelevant stimulus attributes have repeatedly been shown. The purpose of the current research was to investigate how these control adjustments are modulated by the processing demands of a primary task. To this end, the authors combined a primary task (a number comparison task: classifying digits as smaller or larger than 5) with a Simon task. Control adjustments were observed in the form of typical sequential modulations of the Simon effect. In addition, the authors found sequential modulations of the numerical distance effect and an interaction of both effects. Results suggest that not only response conflict due to interference from task-irrelevant features but also processing demands of task-relevant features determine the level of control adjustment in the subsequent trial. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How to stop and change a response: The role of goal activation in multitasking.

Multitasking was studied in the stop-change paradigm, in which the response for a primary GO1 task had to be stopped and replaced by a response for a secondary GO2 task on some trials. In 2 experiments, the delay between the stop signal and the change signal was manipulated to determine which task goals (GO1, GO2, or STOP) were involved in performance and to determine whether the goals were activated in series or in parallel. As the delay increased, the probability of responding on stop trials changed very little, but GO2 task reaction times decreased substantially. Such effects are consistent with both a nondeterministic serial model (in which the GO1 goal is replaced by the STOP goal, which is subsequently replaced by the GO2 goal) and a limited-capacity parallel model (in which stopping and GO2 processing occur concurrently) with a capacity-sharing proportion that resembles serial processing. (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)     

Dissociating consciousness from inhibitory control: Evidence for unconsciously triggered response inhibition in the stop-signal task.

Theories about the functional relevance of consciousness commonly posit that higher order cognitive control functions, such as response inhibition, require consciousness. To test this assertion, the authors designed a masked stop-signal paradigm to examine whether response inhibition could be triggered and initiated by masked stop signals, which inform participants to stop an action they have begun. In 2 experiments, masked stop signals were observed to occasionally result in full response inhibition as well as to yield a slow down in the speed of responses that were not inhibited. The magnitude of this subliminally triggered response time slowing effect correlated with the efficiency measure (stop signal reaction time) of response inhibition across participants. Thus, response inhibition can be triggered unconsciously—more so in individuals who are good inhibitors and under conditions that are associated with efficient response inhibition. These results indicate that in contradiction to common theorizing, inhibitory control processes can operate outside awareness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the regulation of cognitive control: Action orientation moderates the impact of high demands in Stroop interference tasks.

Previous research has established that people vary in action orientation, a tendency toward decisiveness and initiative, versus state orientation, a tendency toward indecisiveness and hesitation (J. Kuhl & J. Beckmann, 1994b). In the present 3 studies, the authors examined whether action orientation versus state orientation regulates cognitive control under demanding conditions. Under high demands, action-oriented participants displayed better cognitive control than did state-oriented participants in a Stroop color naming task (Studies 1-3). No similar effects were found under low demands (Studies 2-3). Functional differences between action- and state-oriented participants emerged especially when the task included a high proportion of congruent Stroop trials (Study 3). These findings suggest that action-oriented individuals are better protected against goal neglect than are state-oriented individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Redundancy gain in the stop-signal paradigm: Implications for the locus of coactivation in simple reaction time.

The authors carried out 2 experiments designed to cast light on the locus of redundancy gain in simple visual reaction time by using a stop-signal paradigm. In Experiment 1, the authors found that single visual stimuli were more easily inhibited than double visual stimuli by an acoustic stop signal. This result is in keeping with the idea that redundancy gain occurs prior to the ballistic stage of the stop-signal task. In Experiment 2, the authors found that the response to an acoustic go signal was more easily inhibited by a double than by a single visual stop signal. This result provides conclusive evidence for a redundancy gain in the stop process—in a process that does not involve a motor response but rather its inhibition. (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)     

Rat prefrontal dopamine and cognitive control: Impaired and enhanced conflict performance.

It has been proposed that the cognitive dysfunction observed in patients with schizophrenia reflects a failure in cognitive control, in particular an inability to use task-relevant information to guide behavior. Using a prefrontal-dependent task designed to reflect aspects of cue and response conflict seen in human cognitive paradigms, we examined the influence of prefrontal dopamine receptor manipulation on the contextual control of response conflict. Rats were trained on two biconditional discrimination tasks, one auditory and one visual, in two discriminably different contexts. At test, audiovisual compounds of these training stimuli were presented, in extinction, in each of the training contexts. These compounds were formed in such a way that the individual elements previously dictated different responses during training, termed incongruent trials. Studies have shown that rats use contextual information to disambiguate the conflicting information provided by incongruent compounds, responding in manner that is appropriate to the stimulus element that was trained in the test context. Direct infusion of the D1 receptor agonist SKF-38393 into the prelimbic cortex was found to modulate incongruent trial performance in a manner that was dependent upon baseline performance: animals in the low baseline group demonstrated improved incongruent performance following infusion of SKF-38393 into the prelimbic cortex. In contrast, high performers showed a reduction in accuracy during incongruent compounds. This paradigm provides a reliable framework for assessing the efficacy of preclinical agents in treating the cognitive impairments seen in frontal-related disorders such as schizophrenia. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Inhibitory Control in Rats Performing a Stop-Signal Reaction-Time Task: Effects of Lesions of the Medial Striatum and d-Amphetamine.

The stop-signal task measures the ability to inhibit a response that has already been initiated, that is, the ability to stop. Imaging studies have implicated frontostriatal circuitry in the mediation of this form of response control. The authors report inhibition functions of normal rats and those with medial striatal damage performing the stop-signal task. Excitotoxic lesions of the medial striatum produced significant deficits on task performance, including increased omissions on the go task and flattened inhibition function, possibly as a result of increased reaction-time mean and variability. Medial striatal lesions also significantly slowed stop-signal reaction time. Subsequent treatment with d-amphetamine removed (0.3 mg/kg) or exacerbated (1.0 mg/kg) this deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effective warnings in the Deese-Roediger-McDermott false-memory paradigm: The role of identifiability.

These experiments document that warnings can substantially reduce false memories in the Deese-Roediger-McDermott (DRM) paradigm when the critical items are easily identifiable. Participants in a norming study identified the critical item after hearing a list of words. The lists with critical items that could be identified by the largest proportion of participants (high identifiable [HI] lists) and the smallest proportion of participants (low identifiable [LI] lists) were used in the experiment. Participants heard lists of words (e.g., bed, rest, doze) related to a critical item (e.g., sleep) and were warned about the nature of the lists before the study phase. The results indicated that warnings reduced false recognition of critical items for HI lists but not LI lists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Relations Among Inhibition and Interference Control Functions: A Latent-Variable Analysis.

This study used data from 220 adults to examine the relations among 3 inhibition-related functions. Confirmatory factor analysis suggested that Prepotent Response Inhibition and Resistance to Distractor Interference were closely related, but both were unrelated to Resistance to Proactive Interference. Structural equation modeling, which combined Prepotent Response Inhibition and Resistance to Distractor Interference into a single latent variable, indicated that 1 aspect of random number generation performance, task-switching ability, and everyday cognitive failures were related to Response-Distractor Inhibition, whereas reading span recall and unwanted intrusive thoughts were related to Resistance to Proactive Interference. These results suggest that the term inhibition has been overextended and that researchers need to be more specific when discussing and measuring inhibition-related functions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Modeling behavioral measures of error detection in choice tasks: Response monitoring versus conflict monitoring.

The present study investigated the mechanisms underlying error detection in the error signaling response. The authors tested between a response monitoring account and a conflict monitoring account. By implementing each account within the neural network model of N. Yeung, M. M. Botvinick, and J. D. Cohen (2004), they demonstrated that both accounts make different predictions as to how error signaling performance is influenced by varying the participants' response criterion. These predictions were tested in an experiment using the Eriksen-flanker task. The qualitative pattern as well as a model fit favored the response monitoring account, which states that error detection is mediated by detecting internal error corrections. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deleterious effects of alcohol intoxication: Diminished cognitive control and its behavioral consequences.

The authors tested the hypothesis that impaired behavioral performance during intoxication results partly from alcohol's deleterious effects on cognitive control. The impact of alcohol on perseverative behavior was examined with an n-back working memory task that included manipulations of task complexity and prepotency of inclinations to respond or withhold responding. Thirty-two social drinkers (16 men) participated in either an alcohol (.075g/100ml) or a no-alcohol condition. Alcohol increased perseveration of prepotent, task-inappropriate response patterns only under cognitively demanding (heavy memory load) conditions. This effect was evident for both commission errors (response persistence despite contingencies altered to require restraint) and omission errors (failure to respond when contingencies were revised to encourage action). Findings suggested that alcohol-induced perseveration arises from impairments in cognitive control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The strategic nature of false recognition in the DRM paradigm.

The false memory effect produced by the Deese/Roediger & McDermott (DRM) paradigm is reportedly impervious to warnings to avoid false alarming to the critical lures (D. A. Gallo, H. L. Roediger III, & K. B. McDermott, 2001). This finding has been used as strong evidence against models that attribute the false alarms to a decision process (e.g., M. B. Miller & G. L. Wolford, 1999). In this report, the authors clarify their earlier article and suggest that subjects establish only 2 underlying criteria for a recognition judgment, a liberal criterion for items that seem to be related to 1 of the study list themes and a conservative criterion for items that do not seem to be related. They demonstrate that warnings designed on the basis of these underlying criteria are effective in significantly suppressing the false recognition effect, suggesting that strategic control of the retrieval response does play a role in the DRM paradigm. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Implicit false memory in the DRM paradigm: Effects of amnesia, encoding instructions, and encoding duration.

Recent studies with the Deese/Roediger–McDermott (Deese 1959; Roediger & McDermott, 1995) paradigm have revealed that amnesic patients do not only show impaired veridical memory, but also diminished false memory for semantically related lure words. Due to the typically used explicit retrieval instructions, however, this finding may reflect problems at encoding, at recollection, or both. Therefore, the present experiments examined implicit as well as explicit false memory in patients suffering from Korsakoff’s syndrome and controls. In Experiment 1, encoding instructions either focused on remembering individual list words, or on discovering semantic relationships among the words. In Experiment 2, different presentation durations were used. Results emphasize the distinction between automatic and intentional retrieval: Korsakoff patients’ veridical and false memory scores were diminished when explicit recollection was required, but not when memory was tested implicitly. Encoding manipulations only significantly affected veridical memory: Priming was reduced with thematic encoding, and explicit retrieval was facilitated when given more study time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)