阈下奖励调节认知控制的权衡

本研究采用奖励版的AX-CPT任务, 通过控制奖励线索和反馈的呈现方式, 设置出基线、阈上奖励、阈下奖励三种条件, 考察习得的奖励联结和奖励动机能否以潜意识的方式影响认知任务的表现和认知控制的权衡。结果显示：奖励线索只在阈上呈现时提高AX序列的任务表现; 与基线条件相比, 阈上和阈下奖励条件下认知控制的权衡均偏向主动性控制, 且这种偏向在两者间无显著差异。这表明习得的阈下奖励线索可以调节认知控制的权衡, 使被试像阈上奖励时那样偏向主动性控制。     

奖赏通过增强信号监测提升认知控制

认知控制是动态的、过程性的认知调控, 涉及监测和控制两个过程。先前研究表明奖赏可以提升认知控制, 但是奖赏是通过增强信号监测来提升认知控制的, 还是作用于控制过程来提升认知控制的, 是一个有待研究的重要问题。在本研究中, 我们设计了三个实验来调查这一问题。实验1采用Stop-Signal任务验证奖赏是否能提升认知控制; 实验2通过改变反应规则将Stop-Signal任务信号监测加工分离出来, 探讨实验1中奖赏的提升作用是否来源于奖赏对信号监测的增强; 实验3通过操纵注意资源损耗分析, 考察注意资源分配对信号监测的促进作用。实验1结果显示, 个体能更快地根据奖赏信息做出抑制反应。实验2结果表明, 在信号监测任务中, 个体能更加快速地监测到与当前抑制状态相冲突且和奖赏相关的反应信号, 据此可认为奖赏通过增强对相关信号的监测, 有助于个体更早地启动奖赏刺激信号所对应的反应, 更高效地控制冲突。实验3结果说明, 当任务难度增大, 注意资源损耗, 奖赏相关信号的反应时和正确率仍优于无奖赏信号, 说明注意资源的分配可以调节相关信号的监测速度。总体来看, 本研究通过一系列实验表明, 以目标为导向的行为发生过程中, 奖赏能有效提升认知控制效率, 其关键机制在于通过注意资源分配增强相关信号的监测。     

奖惩对行为抑制及程序阶段中自主生理反应的影响

采用停止信号任务探讨奖惩条件对行为抑制和程序阶段中自主生理反应的影响。结果显示：(1)奖惩组的反应时显著高于控制组, 抑制失败率则显著低于控制组; (2)奖励组与其它两组相比表现出心率显著增加和皮肤电活动显著降低; (3)各生理指标在准备、工作和奖惩阶段中的奖惩差异性显著(4)奖惩条件下皮肤电活动呈现出一致性程序阶段变化。结果表明：奖惩条件均对行为具有抑制作用, 但在自主生理反应上则有显著差异; 各生理指标在准备、工作和奖惩阶段的情绪效价显著; 皮肤电活动的程序阶段变化显著, 但其奖惩效价较为稳定, 很少接受程序阶段变化的影响。     

奖惩对行为抑制能力和自主生理活动影响的时效性

将45名被试随机分配为奖励组、惩罚组和对照组, 实验进程按时间发展过程被分为五阶段, 采用停止信号任务探讨奖惩刺激对行为抑制能力和自主生理活动影响的时效性。结果显示：奖惩刺激对行为反应时和抑制失败率影响仅在第二、三阶段差异显著, 对心率影响的显著差异在第三阶段结束、而对皮电和指温影响的显著差异仍持续到第五阶段。结果表明：奖惩刺激对行为的抑制作用具有时效性, 有效时间内表现为仅奖励能提高行为抑制能力; 奖惩刺激对心率的影响具有时效性, 但对其它生理指标的影响则未显示出时效性。     

Neural Correlates of Reward Processing in Adolescents With a History of Inhibited Temperament

ABSTRACT— Functional imaging data were acquired during performance of a reward-contingency task in a unique cohort of adolescents (ages 14–18 years) who were characterized since infancy on measures of temperamental behavioral inhibition. Neural activation was examined in striatal structures (nucleus accumbens, putamen, caudate) with a known role in facilitating response to salient reward-related cues. Adolescents with a history of behavioral inhibition, relative to noninhibited adolescents, showed increased activation in the nucleus accumbens when they believed their selection of an action would affect reward outcome. Neural responses did not differ between the two groups when participants made a prespecified response that they knew would result in reward or when they produced random motor responses that they knew would not be rewarded. These results link inhibited temperament and perturbed neural responses to reward-contingency cues.     

Competing Core Processes in Attention-Deficit/Hyperactivity Disorder (ADHD): Do Working Memory Deficiencies Underlie Behavioral Inhibition Deficits?

The current study examined competing predictions of the working memory and behavioral inhibition models of ADHD. Behavioral inhibition was measured using a conventional stop-signal task, and central executive, phonological, and visuospatial working memory components (Baddeley 2007) were assessed in 14 children with ADHD and 13 typically developing (TD) children. Bootstrapped mediation analyses revealed that the visuospatial working memory system and central executive both mediated the relationship between group membership (ADHD, TD) and stop-signal task performance. Conversely, stop-signal task performance mediated the relationship between group membership and central executive processes, but was unable to account for the phonological and visuospatial storage/rehearsal deficits consistently found in children with ADHD. Comparison of effect size estimates for both models suggested that working memory deficits may underlie impaired stop-signal task performance in children with ADHD. The current findings therefore challenge existing models of ADHD that describe behavioral inhibition as a core deficit of the disorder.     

Working memory and behavioral inhibition in children with attention-deficit/hyperactivity disorder (ADHD): an examination of varied central executive demands,construct overlap,and task impurity

The stop-signal paradigm is the premier metric of behavioral inhibition in contemporary attention-deficit/hyperactivity disorder (ADHD) research. The stop-signal paradigm’s choice-reaction time component, however, arguably places greater demands on working memory processes (e.g., controlled-focused attention) relative to alternative inhibition metrics (i.e., go/no-go (GNG) tasks), and consequently obscures conclusions about inhibition and working memory deficits in affected children. The current study, therefore, aimed to determine whether shared variance between stop-signal behavioral inhibition and working memory performance in children with ADHD reflects overlap between the working memory and inhibition constructs or insufficient specificity of the stop-signal paradigm. Fifty-five children (8–12 years) with and without ADHD were administered established phonological (PH) and visuospatial (VS) working memory measures, as well as stop-signal and GNG tasks that vary with respect to demands on controlled-focused attention. Although working memory and GNG performance each uniquely predicted children’s inattention, stop-signal task performance was not a significant predictor of unique variance in inattention, above and beyond variance associated with working memory. Collectively, these findings suggest that performance on the stop-signal task, compared to the GNG task, is confounded by greater demands associated with working memory and consequently reflects an impure estimate of the inhibition construct.     

Don’t look! don’t touch! inhibitory control of eye and hand movements

Inhibitory control of eye and hand movements was compared in the stop-signal task. Subjects moved their eyes to the right or left or pressed keys on the right or left in response to visual stimuli. The stimuli were either central (angle brackets pointing left or right) or peripheral (plus signs turning into Xs left or right of fixation), and the task was either pro (respond on the same side as the stimulus) or anti (respond on the opposite side). Occasionally, a stop signal was presented, which instructed subjects to inhibit their responses to the go stimulus. Stop-signal reaction times (SSRTs) were faster overall for eye movements than for hand movements, and they were affected differently by stimulus conditions (central vs. peripheral) and task (pro vs. anti), suggesting that the eyes and hands are inhibited by different processes operating under similar principles (i.e., a race between stop and go processes).     

Attention-Deficit/Hyperactivity Disorder and Behavioral Inhibition: A Meta-Analytic Review of the Stop-signal Paradigm

Deficient behavioral inhibition (BI) processes are considered a core feature of attention deficit/hyperactivity disorder (ADHD). This meta-analytic review is the first to examine the potential influence of a wide range of subject and task variable moderator effects on BI processes--assessed by the stop-signal paradigm--in children with ADHD relative to typically developing children. Results revealed significantly slower mean reaction time (MRT), greater reaction time variability (SDRT), and slower stop-signal reaction time (SSRT) in children with ADHD relative to controls. The non-significant between-group stop-signal delay (SSD) metric, however, suggests that stop-signal reaction time differences reflect a more generalized deficit in attention/cognitive processing rather than behavioral inhibition. Several subject and task variables served as significant moderators for children's mean reaction time.     

Motor response inhibition and execution in the stop-signal task: development and relation to ADHD behaviors.

The main aim of this study was to investigate the developmental course of motor response inhibition and execution as measured by the stop-signal task in a population-based sample of 525 4- to 12-year-olds. A further aspiration of the study was to enhance the limited knowledge on how the various stop-signal measures relate to ADHD behaviors in a normal sample. We also wanted to contribute to the theoretical understanding of the various stop-signal measures by examining the relations between the stop-signal measures and performance on tasks reflecting other aspects of response inhibition and execution. Our results showed that the ability to inhibit as well as to execute a motor response as measured by the stop-signal task improved with age during childhood. Of specific interest are the findings suggesting that this task captures the development of motor response inhibition in the late preschool years (age 5 years). Both of the inhibition measures derived from the stop-signal task (i.e., SSRT and probability of inhibition) related significantly to teacher ratings of inattention as well as to performance on tasks tapping other aspects of inhibition. The data provided by this study have thus contributed to the scarce knowledge on early development of motor response inhibition, as well as suggested that the stop-signal task may be a valuable tool for capturing deficient motor response inhibition in ADHD behaviors in normal samples.     

Reward anticipation enhances brain activation during response inhibition

The chance to achieve a reward starts up the required neurobehavioral mechanisms to adapt our thoughts and actions in order to accomplish our objective. However, reward does not equally reinforce everybody but depends on interindividual motivational dispositions. Thus, immediate reward contingencies can modulate the cognitive process required for goal achievement, while individual differences in personality can affect this modulation. We aimed to test the interaction between inhibition-related brain response and motivational processing in a stop signal task by reward anticipation and whether individual differences in sensitivity to reward (SR) modulate such interaction. We analyzed the cognitive–motivational interaction between the brain pattern activation of the regions involved in correct and incorrect response inhibition and the association between such brain activations and SR scores. We also analyzed the behavioral effects of reward on both reaction times for the “go” trials before and after correct and incorrect inhibition in order to test error prediction performance and postinhibition adjustment. Our results show enhanced activation during response inhibition under reward contingencies in frontal, parietal, and subcortical areas. Moreover, activation of the right insula and the left putamen positively correlates with the SR scores. Finally, the possibility of reward outcome affects not only response inhibition performance (e.g., reducing stop signal reaction time), but also error prediction performance and postinhibition adjustment. Therefore, reward contingencies improve behavioral performance and enhance brain activation during response inhibition, and SR is related to brain activation. Our results suggest the conditions and factors that subserve cognitive control strategies in cognitive motivational interactions during response inhibition.     

Response inhibition difficulties in preterm children aged 9–12 years: Relations with emotion and behavior

Previous studies with children have demonstrated inhibition difficulties associated with prematurity, but the question of potentially catching up with a delay in inhibition processes before adolescence still remains. Moreover, preterm adolescents are more at risk than their term-born peers for presenting behavioral problems such as emotional difficulties and attention deficit/hyperactivity disorder. In addition to examining response inhibition, this study addressed, for the first time, the impact of an emotional context on response inhibition abilities and its relation to behavioral problems in late school-aged preterm children. Fifty-eight preterm children aged 9–12 years were compared with 61 controls on two versions of a stop-signal task, the Delay Frustration Task, and the Strengths and Difficulties Questionnaire. Results showed general difficulties in inhibiting a response, rather than a specific impact of emotional context in preterm children. Compared with controls, these children exhibited more and longer button presses in a delay situation, as well as faster go reaction times associated with lower probability of inhibition in the stop-signal tasks. These difficulties reflected impulsivity and were associated with higher hyperactivity/inattention and conduct problems. Additionally, intrauterine growth restriction was found to be an additional perinatal risk factor for hyperactivity/inattention symptoms. These findings suggest that remaining inhibition difficulties in the preterm population at preadolescence could reveal increasing behavioral issues.     

Lack of inhibition: a motivational deficit in children with attention deficit/hyperactivity disorder and children with traumatic brain injury.

Recent research has demonstrated that both brain-injured children and children with attention deficit/hyperactivity disorder (ADHD) suffer from response inhibition deficits. To investigate whether these deficits can be influenced by motivational factors, the stop-signal task was performed with and without reward contingencies for successful inhibition. Three groups of children between 8 and 12 years of age, participated in the study: 31 children with ADHD, 37 with traumatic brain injuries (TBI), and 26 normal controls. Results indicated that, although all groups showed comparable learning effects, reward contingencies had different effects on the groups. Whereas the performance of children with ADHD under reward contingencies were brought up to the performance level of normal controls, rewards were found less effective at improving response inhibition in children with TBI. The results further support a motivational/energetic explanation of the inhibitory deficit in children with ADHD, and of a primary response inhibition deficit due to structural brain damage in children with TBI.     

Lack of Inhibition: A Motivational Deficit in Children With Attention Deficit/Hyperactivity Disorder and Children With Traumatic Brain Injury*

Recent research has demonstrated that both brain-injured children and children with attention deficit/hyperactivity disorder (ADHD) suffer from response inhibition deficits. To investigate whether these deficits can be influenced by motivational factors, the stop-signal task was performed with and without reward contingencies for successful inhibition. Three groups of children between 8 and 12 years of age, participated in the study: 31 children with ADHD, 37 with traumatic brain injuries (TBI), and 26 normal controls. Results indicated that, although all groups showed comparable learning effects, reward contingencies had different effects on the groups. Whereas the performance of children with ADHD under reward contingencies were brought up to the performance level of normal controls, rewards were found less effective at improving response inhibition in children with TBI. The results further support a motivational/energetic explanation of the inhibitory deficit in children with ADHD, and of a primary response inhibition deficit due to structural brain damage in children with TBI.     

Dissociable effects of fear and disgust in proactive and reactive inhibition

Numerous studies have demonstrated that negative emotional distracters impair inhibitory control. Nevertheless, two issues have emerged in prior studies. First, fear and disgust were inappropriately treated as a single category, which is particularly concerning given that they have been recently demonstrated to exert different impacts on inhibitory control. Second, inhibitory control might not be a unitary construct, as it can be further divided into proactive and reactive inhibition. Therefore, the present study aimed to investigate whether fearful and disgusting distracters have differential effects on proactive and reactive inhibition. Twenty-four female participants were instructed to perform a modified stop-signal task superimposed on a fearful, disgusting, or neutral image cue. Results showed that fearful distracters improved reactive inhibition when compared to disgusting and neutral distracters, while disgusting distracters enhanced proactive inhibition when compared to fearful distracters. Further, reactive and proactive inhibition was positively correlated under fearful, disgusting, and neutral contexts. This study is the first to provide evidence that fear and disgust may affect proactive and reactive inhibition differently. These results add to a growing literature linking emotion and inhibitory control, and they expand our understanding of the relationship between emotion and inhibition.     

Reward Priority of Visual Target Singletons Modulates Event-Related Potential Signatures of Attentional Selection

ABSTRACT— We examined visual search for color singleton targets, whose shape was discriminated. Critically, we varied the reward priority of singleton colors (correct fast performance was worth more bonus points for red singletons than for green singletons, or vice versa) to test whether event-related potential signatures of visual selection can be affected by distinct reward priorities for different target types, even when every target has to be selected for report. The N2pc component was earlier and larger for high- than for low-reward targets. This influence of reward on the N2pc correlated with the subject-by-subject impact of reward level on efficiency of behavioral performance. Later postselection processing was also affected by reward level. These results demonstrate that visual selection of task-relevant items is rapidly modulated by reward-related priorities, even when every target has to be selected for response.     

The impact of an unpredictable context and intolerance of uncertainty on the electrocortical response to monetary gains and losses

There is growing evidence that unpredictability and uncertainty can alter reward system functioning. The present study examined the impact of (1) a task-irrelevant unpredictable relative to predictable context and (2) individual differences in intolerance of uncertainty (IU) on the reward-related positivity (RewP), an event-related potential (ERP) response to monetary gains relative to losses. Specifically, 64 participants listened to predictable and unpredictable tone sequences while electroencephalography was recorded during a monetary gambling task. Participants also completed the Intolerance of Uncertainty Scale, which measures both cognitive distress (prospective IU) and behavioral inhibition (inhibitory IU) elicited by uncertainty, in addition to the Depression Anxiety Stress Scale-21 and Penn State Worry Questionnaire. Results indicated that the RewP was reduced during the unpredictable relative to the predictable context. Greater self-reported anxiety elicited by the unpredictable context was associated with a decreased RewP, and a decreased RewP was associated with poorer lose-shift behavioral adjustment. Furthermore, the RewP mediated the relationship between self-reported anxiety elicited by the unpredictable context and lose-shift behavioral adjustment. The IU subscales demonstrated the opposite relationship with the RewP across both contexts—inhibitory IU was associated with an attenuated RewP and prospective IU was associated with an enhanced RewP. In contrast, anxiety, depression, stress, and worry symptomatology were not associated with the RewP. This is the first study to demonstrate that an unpredictable context and individual differences in the degree to which people cannot tolerate uncertainty impact an ERP measure of reward system functioning.     

Differential effects of social and non‐social reward on response inhibition in children and adolescents

An important issue in the field of clinical and developmental psychopathology is whether cognitive control processes, such as response inhibition, can be specifically enhanced by motivation. To determine whether non‐social (i.e. monetary) and social (i.e. positive facial expressions) rewards are able to differentially improve response inhibition accuracy in typically developing children and adolescents, an ‘incentive’ go/no‐go task was applied with reward contingencies for successful inhibition. In addition, the impact of children's personality traits (such as reward seeking and empathy) on monetary and social reward responsiveness was assessed in 65 boys, ages 8 to 12 years. All subjects were tested twice: At baseline, inhibitory control was assessed without reward, and then subjects were pseudorandomly assigned to one of four experimental conditions, including (1) social reward only, (2) monetary reward only, (3) mixed social and monetary reward, or (4) a retest condition without reward. Both social and non‐social reward significantly improved task performance, although larger effects were observed for monetary reward. The higher the children scored on reward seeking scales, the larger was their improvement in response inhibition, but only if monetary reward was used. In addition, there was a tendency for an association between empathic skills and benefits from social reward. These data suggest that social incentives do not have an equally strong reinforcing value as compared to financial incentives. However, different personality traits seem to determine to what extent a child profits from different types of reward. Clinical implications regarding probable hyposensitivity to social reward in subjects with autism and dysregulated reward‐seeking behaviour in children with attention‐deficit/hyperactivity disorder (ADHD) are discussed.     

Stopping ability in younger and older adults: Behavioral and event-related potential

This study examines age-related differences in inhibitory control as measured by stop-signal performance. The participants were 24 adults aged 20–30 years and 24 older adults aged 61–76 years. The task blocks were pure choice reaction-time blocks, global stop-signal blocks (with an auditory stop signal), and selective stop-signal blocks (with valid and invalid stop signals). There was a decline in reactive inhibitory control for the older group reflected by greater stop-signal reaction times and reduced P3 peak amplitudes in both global and selective stop-signal task blocks. The decreased reactive inhibitory control might result from speed-accuracy tradeoffs. Conversely, no age-related decline in proactive inhibitory control was observed. This was reflected by slower response times (RTs) and reduced P3 peak amplitudes during GO trials in blocks with stop-signals relative to those in blocks of pure choice reaction-time tasks, and in which the RT and amplitude differences were similar between groups. The results further show age-related compensation responses associated with proactive inhibition, such as increased activation at the frontal site among older participants, resulting in no differences in P3 peak amplitudes between electrode sites, and smaller differences at the Fz site than other sites compared with younger adults. For older adults, the P3 peak amplitude at the Fz site was significantly correlated with the RT of proactive inhibitory control. This shows that larger RT differences were associated with larger reductions in P3 peak amplitudes in the stop-signal blocks relative to the pure choice blocks. These results appear to support age-related compensation hypotheses.     

Horse-race model simulations of the stop-signal procedure

In the stop-signal paradigm, subjects perform a standard two-choice reaction task in which, occasionally and unpredictably, a stop-signal is presented requiring the inhibition of the response to the choice signal. The stop-signal paradigm has been successfully applied to assess the ability to inhibit under a wide range of experimental conditions and in various populations. The current study presents a set of evidence-based guidelines for using the stop-signal paradigm. The evidence was derived from a series of simulations aimed at (a) examining the effects of experimental design features on inhibition indices, and (b) testing the assumptions of the horse-race model that underlies the stop-signal paradigm. The simulations indicate that, under most conditions, the latency, but not variability, of response inhibition can be reliably estimated.