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(1) Background: 1–2% of children and adolescents are affected by Obsessive-Compulsive Disorder (OCD). The rigid, repetitive features of OCD and an assumed disability to inhibit recent mental representations are assumed to have led to a paradoxical advantage in that the Backward Inhibition (BI) effect was recently found to be lower in adolescents with OCD as compared to healthy controls. It was hypothesized that app-based mindfulness meditation training could reduce the disability to inhibit recent mental representations and thus increase the BI-effect by adapting cognitive flexibility and inhibition abilities according to healthy controls. (2) Methods: 58 adolescents (10–19 years) with OCD were included in the final sample of this interviewer-blind, randomized controlled study. Participants were allocated to an intervention group (app-based mindfulness meditation training) or an (active) control group (app-based audiobook) for eight weeks. Symptom (CY-BOCS), behavioral (reaction times and mean accuracy), and neurophysiological changes (in EEG) of the BI-effect were analyzed in a pre-post design. (3) Results: The intervention and the control group showed an intervention effect (Reliable Change Index: 67%) with a significant symptom reduction. Contrary to the hypothesis, the BI-effect did not differ between pre vs. post app-based mindfulness meditation training. In addition, as expected the audiobook application showed no effects. Thus, we observed no intervention-specific differences with respect to behavioral (reaction times and mean accuracy) or with respect to neurophysiological (perceptual [P1], attentional [N1], conflict monitoring [N2] or updating and response selection [P3]) processes. However, in an exploratory approach, we revealed that the BI-effect decreased in participants who did not benefit from using an app, regardless of group. (4) Conclusions: Both listening to an app-based mindfulness meditation training and to an audiobook reduce symptom severity in adolescent OCD as measured by the CY-BOCS; however, they have no specific effect on BI. The extent of the baseline BI-effect might be considered as an intra-individual component to predict the benefit of both mindfulness meditation training and listening to an audiobook. [ABSTRACT FROM AUTHOR]

Task switching is one of the typical paradigms to study cognitive control. When switching back to a recently inhibited task (e.g., "A" in an ABA sequence), the performance is often worse compared to a task without N-2 task repetitions (e.g., CBA). This difference is called the backward inhibitory effect (BI effect), which reflects the process of overcoming residual inhibition from a recently performed task (i.e., deinhibition). The neural mechanism of backward inhibition and deinhibition has received a lot of attention in the past decade. Multiple brain regions, including the frontal lobe, parietal, basal ganglia, and cerebellum, are activated during deinhibition. The event-related potentials (ERP) studies have shown that deinhibition process is reflected in the P1/N1 and P3 components, which might be related to early attention control, context updating, and response selection, respectively. Future research can use a variety of new paradigms to separate the neural mechanisms of BI and deinhibition. [ABSTRACT FROM AUTHOR]

Task switching is one of the typical paradigms to study cognitive control. When switching back to a recently inhibited task (e.g., “A” in an ABA sequence), the performance is often worse compared to a task without N-2 task repetitions (e.g., CBA). This difference is called the backward inhibitory effect (BI effect), which reflects the process of overcoming residual inhibition from a recently performed task (i.e., deinhibition). The neural mechanism of backward inhibition and deinhibition has received a lot of attention in the past decade. Multiple brain regions, including the frontal lobe, parietal, basal ganglia, and cerebellum, are activated during deinhibition. The event-related potentials (ERP) studies have shown that deinhibition process is reflected in the P1/N1 and P3 components, which might be related to early attention control, context updating, and response selection, respectively. Future research can use a variety of new paradigms to separate the neural mechanisms of BI and deinhibition.

In task switching, the n-2 repetition cost (informally, the elevationin RT associated with performing a recently abandonedtask) is an indicator of residual task-set inhibition. One suggestionis that such inhibition is triggered by conflict betweentask-set elements. We present a novel computational modelinstantiating this proposal, by adding task-conflict monitoringunits to an existing, interactive activation model of task switching.The model produces the empirical pattern, n-1 switchcosts and n-2 repetition costs, as an intrinsic property of itsarchitecture, but dependent on the inhibition of task demandunits by the conflict detection mechanism. In a further simulation,we make predictions about n-2 repetition costs for asymmetrictasks, and show that one functional benefit of such aconflict-based, task inhibition mechanism is to facilitate topdowncontrol of tasks by automatically reducing cross-task interference

Abstract It is well-known that alcohol impairs behavioral control and motor response inhibition, but it has remained rather unclear whether it also impairs cognitive inhibition. As automatized behavior is less vulnerable towards the detrimental effects of alcohol than cognitive control processes, potential cognitive inhibition deficits might however improve with training. We investigated the effect of an acute, binge-like alcohol intoxication in a balanced within-subjects design, asking n=32 healthy young males to perform a backward inhibition paradigm once sober and once while intoxicated (~1.1 ‰). To identify the underlying neurophysiological mechanisms, we analyzed stimulus- and response selection-related processes in neurophysiological data after Residue Iteration Decomposition (RIDE). Alcohol generally impaired behavioral task performance (accuracy and response times) during task switching. This was associated with impaired attentional processing of the task-relevant cue (reflected by reduced P1 and N1 amplitudes), which likely resulted in a larger need for reactive control at the later stage of response selection and control (reflected by increased fronto-central theta power). Without prior practice (~30 minutes), the intoxicated participants further struggled to overcome the cognitive inhibition of a previously relevant task set (reflected by a larger backward inhibition effect). This was linked to reduced posterior theta power, which reflects alcohol-induced impairments in working memory capacity and task set-relevant memory retrieval. As individuals with ~30 min task practice did not show the same alcohol-related deficit, it may be deduced that (partial) task set automatization via stimulus-response associations may help to reduce the detrimental effects of alcohol on cognitive inhibition during task switching. Highlights • We investigated the effects of alcohol and task training on cognitive inhibition • Alcohol intoxication generally impaired cognitive flexibility/task switching • This was linked to reduced attentional processing and larger control requirements • Effects of alcohol on cognitive inhibition were attenuated by task training • The effect of task automatization was linked to proactive task preparation capacity [ABSTRACT FROM AUTHOR]

Cognitive flexibility is a major facet of executive functions and often refers to sequential task control; that is, it is very likely that one may re‐encounter a task that has previously been abandoned to carry out a different task. In the context of sequential cognitive flexibility, the "backward inhibition (BI) effect" has been studied quite extensively. Here we ask whether there are age‐related differences between adolescents and adults to overcome BI and what system‐neurophysiological mechanisms underlie these modulations. This was examined using a system neurophysiological study procedure combining event‐related potentials data with source localization and EEG signal decomposition methods. We show that sequential cognitive flexibility, and the ability overcome backward inhibition, is inferior in adolescents compared with adults. Accounting for intra‐individual variability in the neurophysiological data, this data suggest that two partly inter‐related processes underlie the differences between adolescents than adults to overcome backward inhibition: One process refers to the suppression of the inhibitory effect of the n‐1 trial on the n‐2 trial during perceptual categorization of incoming information that is associated with right inferior frontal regions. The other process refers to immature response selection and conflict monitoring mechanisms associated with regions in the medial frontal cortex. [ABSTRACT FROM AUTHOR]

The n − 2 repetition cost seen in task switching is the effect of slower response times performing a recently completed task (e.g. an ABA sequence) compared to performing a task that was not recently completed (e.g. a CBA sequence). This cost is thought to reflect cognitive inhibition of task representations and as such, the n − 2 repetition cost has begun to be used as an assessment of individual differences in inhibitory control; however, the reliability of this measure has not been investigated in a systematic manner. The current study addressed this important issue. Seventy-two participants performed three task switching paradigms; participants were also assessed on rumination traits and processing speed—measures of individual differences potentially modulating the n − 2 repetition cost. We found significant n − 2 repetition costs for each paradigm. However, split-half reliability tests revealed that this cost was not reliable at the individual-difference level. Neither rumination tendencies nor processing speed predicted this cost. We conclude that the n − 2 repetition cost is not reliable as a measure of individual differences in inhibitory control. [ABSTRACT FROM PUBLISHER]

Performing an act of self-regulation such as making decisions has been suggested to deplete a common limited resource, which impairs all subsequent self-regulatory actions (ego depletion theory). It has however remained unclear whether self-referred decisions truly impair behavioral control even in seemingly unrelated cognitive domains, and which neurophysiological mechanisms are affected by these potential depletion effects. In the current study, we therefore used an inter-individual design to compare two kinds of depletion, namely a self-referred choice-based depletion and a categorization-based switching depletion, to a non-depleted control group. We used a backward inhibition (BI) paradigm to assess the effects of depletion on task switching and associated inhibition processes. It was combined with EEG and source localization techniques to assess both behavioral and neurophysiological depletion effects. The results challenge the ego depletion theory in its current form: Opposing the theory’s prediction of a general limited resource, which should have yielded comparable effects in both depletion groups, or maybe even a larger depletion in the self-referred choice group, there were stronger performance impairments following a task domain-specific depletion (i.e., the switching-based depletion) than following a depletion based on self-referred choices. This suggests at least partly separate and independent resources for various cognitive control processes rather than just one joint resource for all self-regulation activities. The implications are crucial to consider for people making frequent far-reaching decisions e.g., in law or economy.

Switching between tasks is assumed to be accompanied by inhibiting currently irrelevant, but competing tasks. A dominant task that strongly interferes with performing a weaker task may receive especially strong inhibition. We tested this prediction by letting participants switch among three tasks that differ in dominance: a location discrimination task with strong stimulus–response bindings (responding with left-hand and right-hand button presses to stimuli presented left or right to the fixation cross) was combined with a color/pattern and a shape discrimination task, for which stimulus–response mappings were arbitrary (e.g., left-hand button press mapped to a red stimulus). Across three experiments, the dominance of the location task was documented by faster and more accurate responses than in the other tasks. This even held for incompatible stimulus–response mappings (i.e., right-hand response to a left-presented stimulus and vice versa), indicating that set-level compatibility (i.e., “dimension overlap”) was sufficient for making this location task dominant. As a behavioral marker for backward inhibition, we utilized n-2 repetition costs that are defined by higher reaction times for a switch back to a just abandoned and thus just inhibited task (ABA sequence) than for a switch to a less recently inhibited task (CBA, n-2 non-repetition). Reliable n-2 task repetition costs were obtained for all three tasks. Importantly, these costs were largest for the location task, suggesting that inhibition indeed was stronger for the dominant task. This finding adds to other evidence that the amount of inhibition is adjusted in a context-sensitive way.

Task switching is regularly required in our everyday life. To succeed in switching, it is important to inhibit the most recently performed task and instead activate the currently relevant task. The process that inhibits a recently performed task when a new task is to be performed is referred to as 'backward inhibition' (BI). While the BI effect has been subject to intense research in cognitive psychology, little is known about the neuronal mechanisms that are related to the BI effect and those that relate to differences in the magnitude of the BI effect. In the current study, we examined the system neurophysiological basis of BI processes using event-related potentials (ERPs) and sLORETA by also taking inter-individual differences in the magnitude of the BI into account. The results suggest that BI processes and inter-individual differences in them strongly depend upon attentional selection mechanisms (reflected by N1-ERP modulations in the current task/trial) mediated via networks consisting of extrastriate occipital areas, the temporo-parietal junction and the inferior frontal gyrus. Other processes and mechanisms related to conflict monitoring, response selection, or the updating, organization and implementation of a new task-set (i.e. N2 and P3 processes) were not shown to be modulated by BI processes and differences in their magnitude, as evoked with a common BI paradigm. [ABSTRACT FROM AUTHOR]

The ability to flexibly switch between tasks is an important faculty in daily life. One process that has been suggested to be an important aspect of flexible task switching is the inhibition of a recently performed task. This is called backward inhibition. Several studies suggest that task switching performance can be enhanced by rewards. However, it is less clear in how far backward inhibition mechanisms are also affected by rewards, especially when it comes to the neuronal mechanisms underlying reward-related modulations of backward inhibition. We therefore investigated this using a system neurophysiological approach combining EEG recordings with source localization techniques. We demonstrate that rewards reduce the strength of backward inhibition processes. The neurophysiological data shows that these reward-related effects emerge from response and/or conflict monitoring processes within medial frontal cortical structures. Upstream processes of perceptual gating and attentional selection, as well as downstream processes of context updating and stimulus-response mapping are not modulated by reward, even though they also play a role in backward inhibition effects. [ABSTRACT FROM AUTHOR]

Background Inhibitory control processes are a central executive function. Several lines of evidence suggest that the GABAergic and the norepinephrine (NE) system modulate inhibitory control processes. Yet, the effects of conjoint increases in the GABAergic and NE system activity on inhibitory control have not been examined. Objective/hypothesis We examine the conjoint effects of the GABA and NE system for inhibitory control. Methods We used transcutaneous vagus nerve stimulation (tVNS), which has been shown to modulate both the GABAergic and NE system. We examine the effects of tVNS in two experimental paradigms examining different aspect of inhibitory control; i.e. a backward inhibition paradigm and a response inhibition paradigm modulating working memory load. Results There were no effects of tVNS on backward inhibition processes, but on response inhibition processes. Yet, these only emerged when working memory processes were needed to control response inhibition. Compared to a sham stimulation, tVNS induced better response inhibition performance (i.e. fewer false alarms). Conclusions A concomitant modulation of the GABAergic and NE system, as induced by tVNS, affects inhibitory control processes, but only when working memory processes play an important role for inhibitory control. Even though both the GABAergic and the NE system are modulated by tVNS, the results suggest that the modulation of the NE system is most important for the emerging effects. [ABSTRACT FROM AUTHOR]

Attention switching is a crucial ability required in everyday life, from toddlerhood to adulthood. In adults, shifting attention from one word (e.g., dog) to another (e.g., sea) results in backward semantic inhibition, that is, the inhibition of the initial word (dog). In this study, we used the preferential-looking paradigm to examine whether attention switching is accompanied by backward semantic inhibition in toddlers. We found that 24-month-olds can indeed refocus their attention to a new item by selectively inhibiting attention to the old item. The consequence of backward inhibition is that subsequent attention to a word semantically related to the old item is impaired. These findings have important implications for understanding the underlying mechanism of backward semantic inhibition and the development of lexical-semantic inhibition in early childhood. [ABSTRACT FROM AUTHOR]

N-2 task repetition cost is a response time and error cost returning to a task recently performed after one intervening trial (i.e., an ABA task sequence) compared with returning to a task not recently performed (i.e., a CBA task sequence). This cost is considered a robust measure of inhibitory control during task switching. The present article reports a novel sequential effect of n-2 task repetitions when trial n-3 is taken into consideration. In particular, performance is better in trials preceded by an n-2 repetition than in trials preceded by an n-2 switch. That is, performance is better in BABA sequences (where trial n-1 was an n-2 repetition) than in CABA sequences (where trial n-1 was an n-2 switch). Likewise, performance is better in BCBA (where trial n-1 was an n-2 repetition) than in ACBA or DCBA sequences (where trial n-1 was an n-2 switch). Evidence for this new n-3 effect is provided by a mini meta-analysis of a set of published data, as well as 2 new experiments applying a different paradigm. We suggest that this new effect reflects trial-by-trial modulation of cognitive control: Task conflict is higher in n-2 repetitions than in n-2 switches; therefore, cognitive control is increased in trials following n-2 repetitions, leading to improved performance. This facilitating effect of previous task conflict is discussed with respect to current theories on cognitive control. [ABSTRACT FROM AUTHOR]

Mindfulness practice has been linked to reduced depressive rumination and described as involving inhibition of information that has been relevant in the past and is no longer relevant in the present moment. Backward inhibition (BI) is considered to be one of the purest measures of task set inhibition, and impaired BI has been linked to depressive rumination. BI was contrasted with Competitor Rule Suppression (CRS), which is another phenomenon observed in task switching, yet one which involves episodic memory tagging of information that is currently conflicting rather than active inhibition. Although similar at baseline level, a randomly assigned group (n=38) who underwent an eight session mindfulness training program exhibited improved BI but not CRS compared to a waiting list group (n=38). Findings indicate that mindfulness improves the specific component of task set inhibition, which has previously been linked to reduced rumination. Implications regarding the potential role of task set inhibition in mediating between mindfulness and reduced rumination, as well as the role of mindfulness in being in the present moment are discussed.

In task switching, a common result supporting the notion of inhibitory processes as a determinant of switch costs is the occurrence of n - 2 repetition costs. Evidence suggests that this effect is not affected by preparation. However, the role of preparation on preceding trials has been neglected so far. In this study, evidence for an influence of preparatory processes on n-2 repetition costs is provided by focusing . on the cue-target interval on trials n - 1 and n - 2. N- 2 repetition costs were affected by an interaction of both n - 1 and n - 2 preparation time, being more pronounced when both preparatory intervals were long. The results provide support for the notion of active preparation processes involved in backward inhibition. [ABSTRACT FROM AUTHOR]

In task switching studies, pre-cuing of the upcoming task improves performance, indicating preparatory activation of the upcoming task set and/or inhibition of the previous task set. To further investigate cue-based task preparation, the authors presented both valid and invalid task cues in a task switching experiment involving three tasks. Consistent with previous findings, a validity effect in terms of higher reaction times on invalidly compared to validly cued tasks was obtained. However, this validity effect was reduced following invalidly cued trials, suggesting dynamic adjustment in terms of decreased cue-based preparation after being misled. Performance was particularly impaired when the current task was the one that was invalidly cued on the preceding trial. This finding may reflect either particular reluctance to prepare or persisting inhibition of the erroneously prepared task set from the pre-trial.

Switching between tasks requires individuals to inhibit mental representations of the previous task demands and to activate representations of the new demands. To date, investigators have identified only one way to measure task set inhibition-that is, through a backward inhibition (BI) paradigm. In this paradigm, participants take more time to return to a task set that was recently abandoned (e.g., 'A' in an AB A task sequence) than to a nonrecently abandoned task set (e.g., CB A), and investigators have demonstrated that this time cost reflects time needed to overcome the inhibition of the recently abandoned task set. To date, however, investigators have not been able to use this paradigm, or any other, to isolate brain activity related to task set inhibition. For example, contrasting the brain activity elicited by AB A and CB A trials will not isolate activity related to task set inhibition, because inhibition occurs during the initial switch away from task A (i.e., A BA). Given that there is currently no way to directly isolate the brain activity related to task set inhibition, we decided instead to examine how brain activity during task switching varies in individuals who are better than others at inhibiting the previous task set. We found that participants who were good at inhibiting previous task sets, as measured with the BI paradigm, exhibited more activity in the basal ganglia and supplementary motor area/premotor area when task switching, as measured via functional magnetic resonance imaging. These findings suggest that activity in these regions plays a role in task set inhibition. [ABSTRACT FROM AUTHOR]

In their recent review article, Koch, Gade, Schuch, & Philipp, (Psychonomic Bulletin & Review, 17, 1-14, 2010) present compelling evidence for the role of inhibition in task switching, as measured by n-2 repetition costs. They promote the view that inhibition targets response-related processes of task performance rather than cue-based preparatory stages. In support of this distinction, they cite the finding in the literature that n-2 repetition costs are not reduced given longer preparation intervals. In this article, we advocate the analysis of whole reaction time distributions for investigating the influence of task preparation on task inhibition. We present such analyses from two of our published experiments that support the view that n-2 repetition costs can be reduced given sufficient preparation. The results suggest that cue-based processes do contribute to inhibition in task switching. [ABSTRACT FROM AUTHOR]

Backward inhibition (BI) is a performance cost that occurs when an individual returns to a task after 1 (vs. more than 1) intervening trial, and it may reflect the inhibition of task-set components during switching. In 3 experiments, we support the theory that inhibition can target cue-based preparatory stages of a task. Participants performed a cued target-localization task that had been previously shown to produce BI. In Experiment 1, reassignment of arbitrary cue-target pairings midway through the experiment doubled the size of BI, though cue, target, and response sets remained unchanged. In Experiment 2, we controlled for effects of order of conditions or simple change of cue meaning. In Experiment 3, we demonstrated that the effect depends on re-pairing members of the same cue and target sets. The results are attributed to heightened conflict (and hence greater inhibition) during cue-target translation when a previously learned cue-target mapping is remapped. [ABSTRACT FROM AUTHOR]

Lag 2 repetition costs are a performance cost observed when participants return to a task after just one intervening trial of a different task, compared to returning after a longer interval (ABA vs. CBA sequences, where A, B, C are tasks). This effect is known as backward inhibition (BI) and is thought to reflect the need to overcome inhibition applied specifically to Task “A” during disengagement at trial n - 1. Druey and Hubner (2007) have suggested that employment of such a specific inhibitory mechanism relies upon the cue and the target of the task overlapping temporally. We provide evidence across three experiments (including a direct replication attempt) that this is not the case, and that the presence of task-specific BI relies to some extent on the need to translate the cue-target relationship into working memory. Additionally, we provide evidence that faster responses in no overlap conditions are driven by low-level perceptual differences between target displays across overlap conditions. We conclude that BI is an effective sequential control mechanism, employed equally in cases of temporally overlapping and temporally separated cues and targets. [ABSTRACT FROM AUTHOR]

When people switch between languages, inhibition of currently irrelevant languages is assumed to occur. The authors examined inhibition of irrelevant languages with a cued language-switching paradigm. A cue indicated in which of 3 languages (German, English. or French) a visual stimulus was to be named. In 2 experiments, the authors found that naming latencies were increased in n-2 language repetitions (e.g., German/English/German) compared with in n-2 language nonrepetitions (e.g., French/English/German). This difference (n-2 repetition costs) indicates persisting inhibition of abandoned languages. It is important to note that n-2 language-repetition costs also occurred in conditions in which the language but not the cue (Experiment I) or the stimulus/response set (Experiment 2) repeated from trial n-2 to trial n. These data demonstrate that inhibition is not restricted to a specific cue or stimulus/response set. Rather, the data suggest more global inhibitory processes that affect the mental representation of competing languages. [ABSTRACT FROM AUTHOR]

Backward inhibition (BI) refers to a reaction time cost incurred when returning to a recently abandoned task compared to returning to a task not recently performed. The effect has been proposed to reflect an inhibitory mechanism that aids transition from one task to another. The question arises as to precisely what aspects of a task may be inhibited and when the process takes place. Recent work has suggested a crucial role for response-related components of the task, which occur late in the typical trial structure (cue-target-response). In contrast to this suggestion, the authors present evidence that the way in which the task is cued can also modulate BI. Specifically, they find that the less transparent the cue-target relationship, the greater the level of BI. This also demonstrates that BI can be triggered at early stages of the trial structure, specifically during task preparation and prior to response processes. The authors conclude that BI is not tied to any particular component of the task structure but arises from whatever component generates the greatest intertrial conflict. [ABSTRACT FROM AUTHOR]

The compound-cue model of cognitive control in task switching explains switch cost in terms of a switch of task cues rather than of a switch of tasks. The present study asked whether the model generalizes to Lag 2 repetition cost (also known as backward inhibition), a related effect in which the switch from B to A in ABA task sequences is costlier than is the same switch in CBA task sequences. The model suggests that Lag 2 repetition cost should be absent from A′BA task sequences, in which A′ and A are different cues for the same task. The cost is robust on such sequences, which suggests that cue-independent, task-specific representations are necessary for explaining task-switching performance and that the compound-cue model has limited explanatory power. [ABSTRACT FROM AUTHOR]

A task set may need to be inhibited to facilitate the switch to another task. This event-related potential (ERP) study determined (1) whether backward inhibition (BI) is exerted preferentially in high interference environments, and (2) whether ERPs locked to critical time points reflect BI during cue preparation and/or response stages. High interference (HI) and low interference (LI) were created by manipulating task difficulty. A reaction time (RT) BI effect (i.e., BI>control trials) was shown only during HI tasks. Cue-locked ERPs on LI tasks suggest increased attentional resources were allocated during the reactivation of a recently inhibited task. For HI tasks, BI versus control trial differences were reflected in a response-locked ERP negativity only after response selection (indexed by the response-locked lateralized readiness potential), indicating that BI is a lateral inhibition mechanism exerted during response preparation. [ABSTRACT FROM AUTHOR]

Abstract: We report data from eight participants who made alignment judgements between a moving object and a stationary, continuously visible ‘landmark’. A reversing object had to overshoot the landmark by a significant amount in order to appear to reverse aligned with it. In addition, an adjacent flash irrelevant to the judgment task reliably increased this illusory ‘foreshortening’. This and other results are most simply explained by a model in which the flash causes attentional capture, complemented by processes of temporal integration, or backward inhibition, and object representation. A flash used to probe the perception of a moving object’s position disrupts that very perception. [Copyright &y& Elsevier]

Abstract: Parkinson's disease has been associated with executive dysfunction, especially task-switching deficits. One factor contributing to task-switching costs is backward inhibition, as measured by less efficient performance when switching back to a task from which one has recently switched away. This alternating-switch cost is considered to be due to persisting inhibition of elements of the previous task set after a switch. In this study, patients with mild to moderate Parkinson's disease and controls performed three tasks (A–C) in an intermixed fashion. Patients with mild to moderate Parkinson's disease and controls showed equivalent response times. However, the patients made significantly more errors during an alternating switch (i.e., AB A ) than did control participants. In contrast, there was no group difference in accuracy in the comparable condition of two consecutive switches between different tasks (i.e., CBA). In addition, accuracy for the two groups was similar for trials in which the task was repeated. These data suggest that Parkinson's disease is associated with either increased backward inhibition, or a reduced ability to overcome this inhibition when reactivating a recently abandoned task set. [Copyright &y& Elsevier]

Abstract: Three experiments were conducted to examine the backward inhibition effect in attention switching within verbal working memory. Experiment one showed significant backward inhibition effect in a “tri-count task”. Experiment two suggested that the effect was not due to a perceptual inhibition on the previously presented figure. Experiment three excluded the sequential expectancy explanation for this inhibition effect. Our results suggest that attention switching between working memory items is accompanied by inhibition of the previously attended working memory item. The findings are discussed in respect to the account of the executive function. [Copyright &y& Elsevier]

Backward inhibition is proposed as a process of lateral inhibition that operates during response selection in task switching, reducing interference caused by the most recently abandoned task set. The effect has been observed across a wide range of contexts but is eliminated by using spatial location to cue tasks (K. D. Arbuthnott & T. S. Woodward, 2002). The present studies replicated this finding, showing that spatial cues are also associated with greater response congruity than verbal cues, consistent with the lateral inhibition model. Spatial cues may introduce greater discriminability between competing category–response rules, reducing the need for lateral inhibition. However, when participants named the task before target presentation, backward inhibition was observed with spatial cues, suggesting that verbalization increased competition between sets, despite spatial localization. [ABSTRACT FROM AUTHOR]