RESUMO
Behavioral and cognitive flexibility allow adaptation to a changing environment. Most tasks used to investigate flexibility require switching reactively in response to deterministic task-response rules. In daily life, flexibility often involves a volitional decision to change behavior. This can be instigated by environmental signals, but these are frequently unreliable. We report results from a novel "change your mind" task, which assesses volitional switching under uncertainty without the need for rule-based learning. Participants completed a two-alternative choice task, and following spurious feedback, were presented with the same stimulus again. Subjects had the opportunity to repeat or change their response. Forty healthy participants completed the task while undergoing a functional magnetic resonance imaging scan. Participants predominantly repeated their choice but changed more when their first response was incorrect or when the feedback was negative. Greater activations for changing were found in the inferior frontal junction, anterior insula (AI), anterior cingulate, and dorsolateral prefrontal cortex. Changing responses were also accompanied by reduced connectivity from the AI and orbitofrontal cortices to the occipital cortex. Using multivariate pattern analysis of brain activity, we predicted with 77% reliability whether participants would change their mind. These findings extend our understanding of cognitive flexibility in daily life by assessing volitional decision-making.
Assuntos
Encéfalo , Comportamento de Escolha , Cognição , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem , Algoritmos , Encéfalo/citologia , Encéfalo/fisiologia , Mapeamento Encefálico , Comportamento de Escolha/fisiologia , Cognição/fisiologia , Voluntários Saudáveis , Imageamento por Ressonância Magnética , Vias NeuraisRESUMO
In the last 20 years, technology is increasingly integrated into daily life. Daily interactions with smart devices have become routine with much of our lives taking place in a digital environment. It is therefore not surprising that the manifestations of psychiatric disorders including Obsessive-Compulsive Disorder have changed in recent years reflecting this reality. Clinicians should be aware of the potential impact of such changes when considering symptom presentation and diagnosis.
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Transtorno de Adição à Internet/psicologia , Transtorno Obsessivo-Compulsivo/psicologia , HumanosRESUMO
Adequate control of impulsive urges to act is demanded in everyday life but is impaired in neuropsychiatric conditions such as stimulant use disorder. Despite intensive research it remains unclear whether failures in impulse control are caused by impaired suppression of behavior or by the over invigoration of behavior by stimuli associated with salient incentives such as drugs, food, and money. We investigated failures in impulse control using functional magnetic resonance imaging (fMRI) to map the neural correlates of premature (impulsive) responses during the anticipation phase of the Monetary Incentive Delay (MID) task in healthy controls (HC), stimulant-dependent individuals (SDIs), and their unaffected first-degree siblings (SIB). We combined task-based fMRI analyses with dynamic causal modeling to show that failures of impulse control were associated with interactions between cingulo-opercular and dorsal striatal networks regardless of group status and incentive type. We further report that group-specific incentive salience plays a critical role in modulating impulsivity in SDIs since drug-related incentives specifically increased premature responding and shifted task modulation away from the dorsal striatal network to the cingulo-opercular network. Our findings thus indicate that impulsive actions are elicited by salient personally-relevant incentive stimuli and those such slips of action recruit a distinct fronto-striatal network.
Assuntos
Mapeamento Encefálico , Giro do Cíngulo/fisiologia , Comportamento Impulsivo/fisiologia , Motivação/fisiologia , Neostriado/fisiologia , Rede Nervosa/fisiologia , Personalidade/fisiologia , Córtex Pré-Frontal/fisiologia , Adulto , Antecipação Psicológica/fisiologia , Estimulantes do Sistema Nervoso Central , Feminino , Giro do Cíngulo/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Masculino , Neostriado/diagnóstico por imagem , Rede Nervosa/diagnóstico por imagem , Córtex Pré-Frontal/diagnóstico por imagem , Irmãos , Transtornos Relacionados ao Uso de Substâncias/diagnóstico por imagem , Transtornos Relacionados ao Uso de Substâncias/fisiopatologia , Adulto JovemRESUMO
BACKGROUND: The Research Domain Criteria seeks to bridge knowledge from neuroscience with clinical practice by promoting research into valid neurocognitive phenotypes and dimensions, irrespective of symptoms and diagnoses as currently conceptualized. While the Research Domain Criteria offers a vision of future research and practice, its 39 functional constructs need refinement to better target new phenotyping efforts. This study aimed to determine which Research Domain Criteria constructs are most relevant to understanding obsessive-compulsive and related disorders, based on a consensus between experts in the field of obsessive-compulsive and related disorders. METHODS: Based on a modified Delphi method, 46 experts were recruited from Australia, Africa, Asia, Europe and the Americas. Over three rounds, experts had the opportunity to review their opinion in light of feedback from the previous round, which included how their response compared to other experts and a summary of comments given. RESULTS: Thirty-four experts completed round one, of whom 28 (82%) completed round two and 24 (71%) completed round three. At the final round, four constructs were endorsed by ⩾75% of experts as 'primary constructs' and therefore central to understanding obsessive-compulsive and related disorders. Of these constructs, one came from the Positive Valence System (Habit), two from the Cognitive Control System (Response Selection/Inhibition and Performance Monitoring) and the final construct was an additional item suggested by experts (Compulsivity). CONCLUSION: This study identified four Research Domain Criteria constructs that, according to experts, cut across different obsessive-compulsive and related disorders. These constructs represent key areas for future investigation, and may have potential implications for clinical practice in terms of diagnostic processes and therapeutic management of obsessive-compulsive and related disorders.
Assuntos
Consenso , Técnica Delphi , Internacionalidade , Transtorno Obsessivo-Compulsivo/diagnóstico , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: Youths with obsessive-compulsive disorder (OCD) experience severe distress and impaired functioning at school and at home. Critical cognitive domains for daily functioning and academic success are learning, memory, cognitive flexibility and goal-directed behavioural control. Performance in these important domains among teenagers with OCD was therefore investigated in this study. METHODS: A total of 36 youths with OCD and 36 healthy comparison subjects completed two memory tasks: Pattern Recognition Memory (PRM) and Paired Associates Learning (PAL); as well as the Intra-Extra Dimensional Set Shift (IED) task to quantitatively gauge learning as well as cognitive flexibility. A subset of 30 participants of each group also completed a Differential-Outcome Effect (DOE) task followed by a Slips-of-Action Task, designed to assess the balance of goal-directed and habitual behavioural control. RESULTS: Adolescent OCD patients showed a significant learning and memory impairment. Compared with healthy comparison subjects, they made more errors on PRM and PAL and in the first stages of IED involving discrimination and reversal learning. Patients were also slower to learn about contingencies in the DOE task and were less sensitive to outcome devaluation, suggesting an impairment in goal-directed control. CONCLUSIONS: This study advances the characterization of juvenile OCD. Patients demonstrated impairments in all learning and memory tasks. We also provide the first experimental evidence of impaired goal-directed control and lack of cognitive plasticity early in the development of OCD. The extent to which the impairments in these cognitive domains impact academic performance and symptom development warrants further investigation.
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Disfunção Cognitiva/fisiopatologia , Função Executiva/fisiologia , Aprendizagem/fisiologia , Transtorno Obsessivo-Compulsivo/fisiopatologia , Adolescente , Adulto , Aprendizagem por Associação/fisiologia , Criança , Feminino , Humanos , Masculino , Reconhecimento Visual de Modelos/fisiologia , Reconhecimento Psicológico/fisiologia , Reversão de Aprendizagem/fisiologia , Adulto JovemRESUMO
Adult ADHD has been linked to impaired motor response inhibition and reduced associated activation in the right inferior frontal cortex (IFC). However, it is unclear whether abnormal inferior frontal activation in adult ADHD is specifically related to a response inhibition deficit or reflects a more general deficit in attentional processing. Using functional magnetic resonance imaging, we tested a group of 19 ADHD patients with no comorbidities and a group of 19 healthy control volunteers on a modified go/no-go task that has been shown previously to distinguish between cortical responses related to response inhibition and attentional shifting. Relative to the healthy controls, ADHD patients showed increased commission errors and reduced activation in inferior frontal cortex during response inhibition. Crucially, this reduced activation was observed when controlling for attentional processing, suggesting that hypoactivation in right IFC in ADHD is specifically related to impaired response inhibition. The results are consistent with the notion of a selective neurocognitive deficit in response inhibition in adult ADHD associated with abnormal functional activation in the prefrontal cortex, whilst ruling out likely group differences in attentional orienting, arousal and motivation.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/patologia , Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Lobo Frontal/fisiopatologia , Lateralidade Funcional/fisiologia , Inibição Psicológica , Adulto , Análise de Variância , Mapeamento Encefálico , Tomada de Decisões , Imagem Ecoplanar , Feminino , Lobo Frontal/irrigação sanguínea , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Oxigênio/sangue , Fatores Sexuais , Adulto JovemRESUMO
Impulsivity and compulsivity represent useful conceptualizations that involve dissociable cognitive functions, which are mediated by neuroanatomically and neurochemically distinct components of cortico-subcortical circuitry. The constructs were historically viewed as diametrically opposed, with impulsivity being associated with risk-seeking and compulsivity with harm-avoidance. However, they are increasingly recognized to be linked by shared neuropsychological mechanisms involving dysfunctional inhibition of thoughts and behaviors. In this article, we selectively review new developments in the investigation of the neurocognition of impulsivity and compulsivity in humans, in order to advance our understanding of the pathophysiology of impulsive, compulsive, and addictive disorders and indicate new directions for research.
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Ciência Cognitiva/tendências , Comportamento Compulsivo/genética , Comportamento Compulsivo/psicologia , Comportamento Impulsivo/genética , Comportamento Impulsivo/psicologia , Animais , Comportamento Aditivo/genética , Comportamento Aditivo/patologia , Comportamento Aditivo/psicologia , Comportamento Compulsivo/patologia , Humanos , Comportamento Impulsivo/patologia , Prognóstico , Transtornos Relacionados ao Uso de Substâncias/genética , Transtornos Relacionados ao Uso de Substâncias/patologia , Transtornos Relacionados ao Uso de Substâncias/psicologiaRESUMO
Female Phenotype Theory (FPT) suggests that autistic women often present with less obvious social impairments than autistic men. We examined the possibility of an exaggerated female phenotype among undiagnosed but probably autistic women. In two nationwide online surveys, we compared self-reported social functioning and mental health between diagnosed autistic women and women without diagnosis who scored ≥ 32 on the Autism Quotient. Compared to diagnosed autistic women, probably autistic women had higher empathy and general social functioning, and were more likely to have received a diagnosis of Borderline Personality Disorder. Autistic women had typically received more mental health diagnoses prior to their ASC diagnosis than autistic men. These findings shed light on the history of misdiagnosis experienced by many autistic women.
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Transtorno do Espectro Autista , Transtorno Autístico , Humanos , Feminino , Transtorno Autístico/diagnóstico , Transtorno Autístico/psicologia , Transtorno do Espectro Autista/diagnóstico , Transtorno do Espectro Autista/psicologia , Interação Social , Saúde Mental , EmpatiaRESUMO
BACKGROUND: The Autism Spectrum Quotient is a popular autism screening tool recommended for identifying potential cases of autism. However, many women with autism demonstrate a different presentation of traits to those currently captured by screening measures and assessment methods, such as the Autism Spectrum Quotient. AIMS: Different models of the Autism Spectrum Quotient have been proposed in the literature, utilising different items from the original 50-item scale. Within good-fitting models, the current study aimed to explore whether these items assess autistic traits similarly across men and women. METHOD: Seventeen Autism Spectrum Quotient models were identified from the literature. Using the responses of a large sample of adults from the UK general population (5246 women, 1830 men), confirmatory factor analysis was used to evaluate the fit of each model. Measurement invariance with respect to gender, adjusting for age, was explored in the 11 model frameworks that were found to have satisfactory fit to our data. RESULTS: It emerged that only two items were gender invariant (non-biased), whereas for the remaining items, the probability of endorsement was influenced by gender. In particular, women had a higher probability of endorsing items relating to social skills and communication. CONCLUSIONS: If the items of the Autism Spectrum Quotient indeed reflect autism-related traits, those items should be rephrased to ensure they do not present a gender-related bias. This is vital for ensuring more timely diagnoses and support for all people with autism.
RESUMO
A growing body of preclinical evidence indicates that addiction to cocaine is associated with neuroadaptive changes in frontostriatal brain systems. Human studies in cocaine-dependent individuals have shown alterations in brain structure, but it is less clear how these changes may be related to the clinical phenotype of cocaine dependence characterized by impulsive behaviours and compulsive drug-taking. Here we compared self-report, behavioural and structural magnetic resonance imaging data on a relatively large sample of cocaine-dependent individuals (n = 60) with data on healthy volunteers (n = 60); and we investigated the relationships between grey matter volume variation, duration of cocaine use, and measures of impulsivity and compulsivity in the cocaine-dependent group. Cocaine dependence was associated with an extensive system of abnormally decreased grey matter volume in orbitofrontal, cingulate, insular, temporoparietal and cerebellar cortex, and with a more localized increase in grey matter volume in the basal ganglia. Greater duration of cocaine dependence was correlated with greater grey matter volume reduction in orbitofrontal, cingulate and insular cortex. Greater impairment of attentional control was associated with reduced volume in insular cortex and increased volume of caudate nucleus. Greater compulsivity of drug use was associated with reduced volume in orbitofrontal cortex. Cocaine-dependent individuals had abnormal structure of corticostriatal systems, and variability in the extent of anatomical changes in orbitofrontal, insular and striatal structures was related to individual differences in duration of dependence, inattention and compulsivity of cocaine consumption.
Assuntos
Mapeamento Encefálico , Transtornos Relacionados ao Uso de Cocaína/complicações , Transtorno da Personalidade Compulsiva/etiologia , Transtorno da Personalidade Compulsiva/patologia , Corpo Estriado/patologia , Lobo Frontal/patologia , Adulto , Feminino , Humanos , Individualidade , Imageamento por Ressonância Magnética , Masculino , Fibras Nervosas Mielinizadas/patologia , Vias Neurais/patologia , Análise de Componente Principal , Escalas de Graduação Psiquiátrica , Estatística como Assunto , Adulto JovemRESUMO
Evidence suggests that the right inferior frontal cortex (IFC) plays a specialized role in response inhibition. However, more recent findings indicate a broader role for this region in attentional control. Here, we used functional magnetic resonance imaging to examine the functional role of the right IFC in attention, inhibition, and response control in 2 experiments that employed novel variations of the go/no-go task. Across the 2 experiments, we observed a graded response in the right insula/IFC, whereby increasing response control demands led to an increase in activation. The results are consistent with the hypothesis that this region plays a key role in the integration of bottom-up, sensory information with top-down, response-related information to facilitate flexible, goal-directed behavior.
Assuntos
Atenção/fisiologia , Função Executiva/fisiologia , Rede Nervosa/fisiologia , Inibição Neural/fisiologia , Lobo Parietal/fisiologia , Córtex Pré-Frontal/fisiologia , Adolescente , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Modelos Neurológicos , Rede Nervosa/anatomia & histologia , Lobo Parietal/anatomia & histologia , Córtex Pré-Frontal/anatomia & histologia , Adulto JovemRESUMO
Camouflaging of autistic traits may make autism harder to diagnose. The current study evaluated the relations between camouflaging intent, first impressions, and age of autism diagnosis. Participants comprised autistic and non-autistic adults (n = 80, 50% female) who completed the Camouflaging of Autistic Traits Questionnaire. They were later video-recorded having a conversation with a person unaware of their diagnostic status. Ten-second clips from half these videos were later shown to 127 non-autistic peers, who rated their first impressions of each participant. Results showed that autistic participants were rated more poorly on first impressions, males were rated less favourably than females, and male raters were particularly harsh in their evaluations of autistic males. Camouflaging intent did not predict first impressions but better first impressions were linked with a later age of diagnosis.
Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Adulto , Transtorno Autístico/diagnóstico , Feminino , Humanos , Intenção , Masculino , Grupo Associado , Inquéritos e QuestionáriosRESUMO
BACKGROUND: Impaired response inhibition in individuals with cocaine use disorder (CUD) is hypothesized to depend on deficient noradrenergic signaling in corticostriatal networks. Remediation of noradrenergic neurotransmission with selective norepinephrine reuptake inhibitors such as atomoxetine may therefore have clinical utility to improve response inhibitory control in CUD. METHODS: We carried out a randomized, double-blind, placebo-controlled, crossover study with 26 participants with CUD and 28 control volunteers investigating the neural substrates of stop-signal inhibitory control. The effects of a single dose of atomoxetine (40 mg) were compared with placebo on stop-signal reaction time performance and functional network connectivity using dynamic causal modeling. RESULTS: We found that atomoxetine speeded Go response times in both control participants and those with CUD. Improvements in stopping efficiency on atomoxetine were conditional on baseline (placebo) stopping performance and were directly associated with increased inferior frontal gyrus activation. Further, stopping performance, task-based brain activation, and effective connectivity were similar in the 2 groups. Dynamic causal modeling of effective connectivity of multiple prefrontal and basal ganglia regions replicated and extended previous models of network function underlying inhibitory control to CUD and control volunteers and showed subtle effects of atomoxetine on prefrontal-basal ganglia interactions. CONCLUSIONS: These findings demonstrate that atomoxetine improves response inhibition in a baseline-dependent manner in control participants and in those with CUD. Our results emphasize inferior frontal cortex function as a future treatment target owing to its key role in improving response inhibition in CUD.
Assuntos
Inibidores da Captação Adrenérgica , Cocaína , Humanos , Cloridrato de Atomoxetina/farmacologia , Cloridrato de Atomoxetina/uso terapêutico , Inibidores da Captação Adrenérgica/farmacologia , Inibidores da Captação Adrenérgica/uso terapêutico , Voluntários Saudáveis , Estudos Cross-Over , Inibição Psicológica , Córtex Pré-Frontal , Cocaína/farmacologiaRESUMO
Response inhibition, whether reactive or proactive, is mostly investigated in a narrow cognitive framework. We argue that it be viewed within a broader frame than the action being inhibited, i.e., in the context of emotion and motivation of the individual at large. This is particularly important in the clinical domain, where the motivational strength of an action can be driven by threat avoidance or reward seeking. The cognitive response inhibition literature has focused on stopping reactively with responses in anticipation of clearly delineated external signals, or proactively in limited contexts, largely independent of clinical phenomena. Moreover, the focus has often been on stopping efficiency and its correlates rather than on inhibition failures. Currently, the cognitive and clinical perspectives are incommensurable. A broader context may explain the apparent paradox where individuals with disorders characterised by maladaptive action control have difficulty inhibiting their actions only in specific circumstances. Using Obsessive Compulsive Disorder as a case study, clinical theorising has focused largely on compulsions as failures of inhibition in relation to specific internal or external triggers. We propose that the concept of action tendencies may constitute a useful common denominator bridging research into motor, emotional, motivational, and contextual aspects of action control failure. The success of action control may depend on the interaction between the strength of action tendencies, the ability to withhold urges, and contextual factors.
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Hoarding Disorder (HD) is under recognised and under-treated. Though HD develops by early adulthood, patients present only later in life, resulting in research based largely on samples of predominantly older females. Whilst formerly associated with Obsessive-Compulsive Disorder (OCD), it is now recognised that individuals with HD often have inattention symptoms reminiscent of Attention Deficit/Hyperactivity Disorder (ADHD). Here, we investigated HD in adults with ADHD. Patients in an ADHD clinic (n = 88) reported on ADHD, HD and OCD-related symptoms, and compared with age, gender and education matched controls (n = 90). Findings were assessed independently in an online UK sample to verify replication using a dimensional approach (n = 220). Clinically significant hoarding symptoms were found in â¼20% versus 2% of ADHD and control groups, respectively, with those with hoarding being on average in their thirties and with approximately half being male. Greater hoarding severity was noted even in the remaining patients compared with controls (d = 0.89). Inattention was the only significant statistical predictor of hoarding severity in patients. Similarly, inattention, alongside depression and anxiety were the greatest predictors of hoarding in the independent sample where 3.2% identified as having clinically significant hoarding. Patients with ADHD had a high frequency of hoarding symptoms, which were specifically linked to inattention. HD should be routinely assessed in individuals with ADHD, as they do not typically disclose associated difficulties, despite these potentially leading to impaired everyday functioning. Research in HD should also investigate adults with ADHD, who are younger and with a greater prevalence of males than typical HD samples.
RESUMO
High levels of intolerance of uncertainty (IU) could contribute to abnormal decision making in uncertain situations. Patients with Obsessive Compulsive Disorder (OCD) often report high IU, indecisiveness and the need to seek greater certainty before making decisions. The Beads task is a commonly used task assessing the degree of information gathering prior to making a decision and so would be predicted to show impairments in OCD patients. Results to date have found mixed support for this, possibility due to methodological issues. Here, a group of OCD patients (n = 50) with no comorbidities was compared with age, gender, and verbal-IQ matched controls (n = 50) on the most commonly used version of the Beads task. An independent sample of healthy volunteers with high versus low OC symptoms, and high versus low IU were also assessed (n = 125). There was no evidence that patients with OCD differed from control volunteers in the degree of information gathering prior to making a decision. Medication status and age did not appear to mediate performance. Similarly, there were no association in healthy volunteers between task performance and OC or IU characteristics. Additional measures examining the degree of certainty initially showed support for greater uncertainty in patients, but this was due to deviations from task instructions in a subset of patients. We conclude that despite the large sample size and good matching between groups, the Beads task in its most widely used form is not a useful measure of IU or of information gathering in OCD. The results argue against a robust behavioural difference in OCD when compared to controls. Recommendations for future studies employing the task are discussed.
Assuntos
Tomada de Decisões , Transtorno Obsessivo-Compulsivo/psicologia , Incerteza , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Testes NeuropsicológicosRESUMO
Response inhibition is essential for navigating everyday life. Its derailment is considered integral to numerous neurological and psychiatric disorders, and more generally, to a wide range of behavioral and health problems. Response-inhibition efficiency furthermore correlates with treatment outcome in some of these conditions. The stop-signal task is an essential tool to determine how quickly response inhibition is implemented. Despite its apparent simplicity, there are many features (ranging from task design to data analysis) that vary across studies in ways that can easily compromise the validity of the obtained results. Our goal is to facilitate a more accurate use of the stop-signal task. To this end, we provide 12 easy-to-implement consensus recommendations and point out the problems that can arise when they are not followed. Furthermore, we provide user-friendly open-source resources intended to inform statistical-power considerations, facilitate the correct implementation of the task, and assist in proper data analysis.
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Consenso , Comportamento Impulsivo/fisiologia , Inibição Psicológica , Desempenho Psicomotor/fisiologia , Animais , Tomada de Decisões , Função Executiva/fisiologia , Humanos , Modelos Animais , Modelos Psicológicos , Testes Neuropsicológicos , Tempo de ReaçãoAssuntos
Cognição/efeitos dos fármacos , Cognição/fisiologia , Indústria Farmacêutica/ética , Saúde , Adolescente , Adulto , Idoso , Doença de Alzheimer/tratamento farmacológico , Transtorno do Deficit de Atenção com Hiperatividade/tratamento farmacológico , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Criança , Indústria Farmacêutica/tendências , Humanos , Memória/efeitos dos fármacos , Memória/fisiologia , Medição de Risco , EstudantesRESUMO
Fifteen children with ADHD aged 8 to 12 years and age and gender matched controls performed two different stopping tasks to examine response performance and inhibition and their respective moment-to-moment variability. One task was the well-established stop-signal task, while the other was a novel tracking task where the children tracked a spaceship on the screen until an alarm indicated they should stop. Although performance was discrete in the stop signal task and continuous in the tracking task, in both tasks latencies to the stop signal were significantly slowed in children with ADHD. Go performance and variability did not significantly differ between ADHD and control children in either task. Importantly, stopping latency in the novel spaceship tracking task also was more variable in children with ADHD. As stopping variability cannot be measured using the standard stop signal task, the new task offers compelling support for the heretofore untested prediction that stopping is both slowed and more variable in children with ADHD. The results support a response inhibition impairment in ADHD, whilst limiting the extent of an intra-trial variability deficit.