Feedback delay gradually affects amplitude and valence specificity of the feedback-related negativity (FRN)

Social power modulates individuals' neural responses to monetary and social rewards

Although previous research has shown that social power modulates individuals' sensitivity to rewards, it is currently unclear whether social power increases or decreases individuals' sensitivity to rewards. This study employed event-related potentials (ERPs) to investigate the effects of social power on individuals' neural responses to monetary and social rewards. Specifically, participants underwent an episodic priming task to manipulate social power (high-power vs. low-power) and then completed monetary and social delayed incentive tasks while their behavioral responses and electroencephalograms (EEG) were recorded. According to ERP analysis, during the anticipatory stage, low-power individuals exhibited a greater cue-P3 amplitude than high-power individuals in both monetary and social tasks. In the consummatory stage, though no impact of social power on the reward positivity (RewP) was found, low-power individuals showed a higher feedback-P3 (FB-P3) amplitude than high-power individuals, regardless of task types (the MID and SID tasks). In conclusion, these results provide evidence that social power might decrease one's sensitivity to monetary and social rewards in both the anticipatory and consummatory stages.

Curiosity Satisfaction Increases Event-related Potentials Sensitive to Reward

Successful learning depends on various factors such as depth of processing, motivation, or curiosity about information. A strong drive to learn something or the expectation of receiving a reward can be crucial to enhance learning. However, the influence of curiosity on the processing of new information and its similarity with reward processing is not well understood. This study examined whether states of curiosity influence specific ERPs associated with reward processing and whether these ERPs are related with later memory benefits. In an initial screening phase, participants indicated their curiosity and confidence in prior knowledge about answers to various trivia questions. In a subsequent study phase, we targeted different time windows related to reward processing during the presentation of trivia answers containing the reward positivity (RewP; 250-350 msec), the P3 (250-500 msec), and the late-positive-potential (LPP; 600-1000 msec). In a following surprise memory test, we found that participants recalled more high- than low-curiosity answers. The RewP, P3, and LPP showed greater positive mean amplitudes for high compared with low curiosity, reflecting increased reward processing. In addition, we found that the RewP and the P3 showed more positive mean amplitudes for later recalled compared with later forgotten answers, but curiosity did not modulate this encoding-related results. These findings support the view that the satisfaction of curiosity resembles reward processing, indicated by ERPs.

Prediction-error-dependent processing of immediate and delayed positive feedback

Learning often involves trial-and-error, i.e. repeating behaviours that lead to desired outcomes, and adjusting behaviour when outcomes do not meet our expectations and thus lead to prediction errors (PEs). PEs have been shown to be reflected in the reward positivity (RewP), an event-related potential (ERP) component between 200 and 350 ms after performance feedback which is linked to striatal processing and assessed via electroencephalography (EEG). Here we show that this is also true for delayed feedback processing, for which a critical role of the hippocampus has been suggested. We found a general reduction of the RewP for delayed feedback, but the PE was similarly reflected in the RewP and the later P300 for immediate and delayed positive feedback, while no effect was found for negative feedback. Our results suggest that, despite processing differences between immediate and delayed feedback, positive PEs drive feedback processing and learning irrespective of delay.

Feedback processing in cognitive and motor tasks: A meta-analysis on the feedback-related negativity

For motor learning, the processing of behavioral outcomes is of high significance. The feedback-related negativity (FRN) is an event-related potential, which is often described as a correlate of the reward prediction error in reinforcement learning. The number of studies examining the FRN in motor tasks is increasing. This meta-analysis summarizes the component in the motor domain and compares it to the cognitive domain. Therefore, a data set of a previous meta-analysis in the cognitive domain that comprised 47 studies  was reanalyzed and compared to additional 25 studies of the motor domain. Further, a moderator analysis for the studies in the motor domain was conducted. The FRN amplitude was higher in the motor domain than in the cognitive domain. This might be related to a higher task complexity and a higher feedback ambiguity of motor tasks. The FRN latency was shorter in the motor domain than in the cognitive domain. Given that sensory information can be used as an external feedback predictor prior to the presentation of the final feedback, reward processing in the motor domain may have been faster and reduced the FRN latency. The moderator variable analysis revealed that the feedback modality influenced the FRN latency, with shorter FRN latencies after bimodal than after visual feedback. Processing of outcome feedback seems to share basic principles in both domains; however, differences exist and should be considered in FRN studies. Future research is motivated to scrutinize the effects of bimodal feedback and other moderators within the motor domain.

Learning new words via feedback-Association between feedback-locked ERPs and recall performance-An exploratory study

Feedback learning is thought to involve the dopamine system and its projection sites in the basal ganglia and anterior cingulate cortex (ACC), regions associated with procedural learning. Under certain conditions, such as when feedback is delayed, feedback-locked activation is pronounced in the medial temporal lobe (MTL), which is associated with declarative learning. In event-related potential research, the feedback-related negativity (FRN) has been linked to immediate feedback processing, while the N170, possibly reflecting MTL activity, has been related to delayed feedback processing. In the current study, we performed an exploratory investigation on the relation between N170 and FRN amplitude and memory performance in a test for declarative memory (free recall), also exploring the role of feedback delay. To this end, we adapted a paradigm in which participants learned associations between non-objects and non-words with either immediate or delayed feedback, and added a subsequent free recall test. We indeed found that N170, but not FRN amplitudes, depended on later free recall performance, with smaller amplitudes for later remembered non-words. In an additional analysis with memory performance as dependent variable, the N170, but not the FRN amplitude predicted free recall, modulated by feedback timing and valence. This finding shows that the N170 reflects an important process during feedback processing, possibly related to expectations and their violation, but is distinct from the process reflected by the FRN.

Frontal theta reveals further information about neural valence-dependent processing of augmented feedback in extensive motor practice-A secondary analysis

Supplementing an earlier analysis of event-related potentials in extensive motor learning (Margraf et al., 2022a, 2022b), frontal theta-band activity (4-8 Hz) was scrutinized. Thirty-seven participants learned a sequential arm movement with 192 trials in each of five practice sessions. Feedback, based on a performance adaptive bandwidth, was given after every trial. Electroencephalogram (EEG) was recorded in the first and last practice sessions. The degree of motor automatization was tested under dual-task conditions in a pre-test-post-test design. Quantitative error information was transported in both feedback conditions (positive and negative). Frontal theta activity was discussed as a general signal that cognitive control is needed and, therefore, was expected to be higher after negative feedback. Extensive motor practice promotes automatization, and therefore, decreased frontal theta activity was expected in the later practice. Further, it was expected that frontal theta was predictive for subsequent behavioural adaptations and the amount of motor automatization. As the results show, induced frontal theta power was higher after negative feedback and decreased after five sessions of practice. Moreover, induced theta activity was predictive for error correction and, therefore, an indicator of whether the recruited cognitive resources successfully induced behavioural adaptations. It remains to be solved why these effects, which fit well with the theoretical assumptions, were only revealed by the induced part of frontal theta activity. Further, the amount of theta activity during practice was not predictive for the degree of motor automatization. It seems that there might be a dissociation between attentional resources associated with feedback processing and attentional resources associated with motor control.

Task parameters influence operant response variability in mice

RATIONALE

During operant conditioning, animals associate actions with outcomes. However, patterns and rates of operant responding change over learning, which makes it difficult to distinguish changes in learning from general changes in performance or movement. Thus, understanding how task parameters influence movement execution is essential.

OBJECTIVES

To understand how specific operant task parameters influenced the repetition of future operant responses, we investigated the ability of operant conditioning schedules and contingencies to promote reproducible bouts of five lever presses in mice.

METHODS

Mice were trained on one of the four operant tasks to test three distinct hypotheses: (1) whether a cue presented concurrently with sucrose delivery influenced the pattern of lever pressing; (2) whether requiring animals to collect earned sucrose promoted the organization of responses into bouts; and (3) whether only reinforcing bouts where interresponse time (IRT) variances were below a target promoted reproducible patterns of operant behavior.

RESULTS

(1) Signaling reinforcer delivery with a cue increased learning rates but resulted in mice pressing the lever in fast succession until the cue turned on, rather than executing discrete bouts. (2) Requiring mice to collect the reinforcer between bouts had little effect on behavior. (3) A training strategy that directly reinforced bouts with low variance IRTs was not more effective than a traditional fixed ratio schedule at promoting reproducible action execution.

CONCLUSIONS

Together, our findings provide insights into the parameters of behavioral training that promote reproducible actions and that should be carefully selected when designing operant conditioning experiments.

Reward timing matters in motor learning

Reward timing, that is, the delay after which reward is delivered following an action is known to strongly influence reinforcement learning. Here, we asked if reward timing could also modulate how people learn and consolidate new motor skills. In 60 healthy participants, we found that delaying reward delivery by a few seconds influenced motor learning. Indeed, training with a short reward delay (1 s) induced continuous improvements in performance, whereas a long reward delay (6 s) led to initially high learning rates that were followed by an early plateau in the learning curve and a lower performance at the end of training. Participants who learned the skill with a long reward delay also exhibited reduced overnight memory consolidation. Overall, our data show that reward timing affects the dynamics and consolidation of motor learning, a finding that could be exploited in future rehabilitation programs.

Delaying feedback compensates for impaired reinforcement learning in developmental dyslexia

A theoretical framework suggests that developmental dyslexia is characterized by abnormalities in brain structures underlying the procedural learning and memory systems while the declarative learning and memory systems are presumed to remain intact or even enhanced (Procedural Deficit Hypothesis). This notion has been supported by a substantial body of research, which focused on each system independently. However, less attention has been paid to interactions between these memory systems which may provide insights as to learning situations and conditions in which learning in dyslexia can be improved. The current study was undertaken to examine these important but unresolved issues. To this end, probabilistic reinforcement learning and episodic memory tasks were examined in participants with dyslexia and neurotypicals simultaneously within a single task. Feedback timing presentation was manipulated, building on prior research indicating that delaying feedback timing shifts striatal-based probabilistic learning, to become more hippocampal-dependent. It was hypothesized that if the procedural learning and memory systems are impaired in dyslexia, performance will be impaired under conditions that encourage procedural memory engagement (immediate feedback trials) but not under conditions that promote declarative memory processing (long delayed feedback trials). It was also predicted that the ability to incidentally acquire episodic information would be preserved in dyslexia. The results supported these predictions. Participants with dyslexia were impaired in probabilistic learning of cue-outcome associations compared to neurotypicals in an immediate feedback condition, but not when feedback on choices was presented after a long delay. Furthermore, participants with dyslexia demonstrated similar performance to neurotypicals in a task requiring incidental episodic memory formation. These findings attest to a dissociation between procedural-based and declarative-based learning in developmental dyslexia within a single task, a finding that adds discriminative validity to the Procedural Deficit Hypothesis. Just as important, the present findings suggest that training conditions designed to shift the load from midbrain/striatal systems to declarative memory mechanisms have the potential to compensate for impaired learning in developmental dyslexia.

Acting in Temporal Contexts: On the Behavioral and Neurophysiological Consequences of Feedback Delays

Feedback on success or failure is critical to increase rewards through behavioral adaptation or learning of dependencies from trial and error. Learning from reward feedback is thereby treated as embedded in a reinforcement learning framework. Due to temporal discounting of reward, learning in this framework is suspected to be vulnerable to feedback delay. Together, investigations of reinforcement learning in learned decision making tasks show that performance and learning impairments due to feedback delay vary as a function of task type. Performance in tasks that require implicit processing is affected by the delayed availability of feedback compared to tasks that can be accomplished with explicit processing. At the same time, the feedback related negativity, an event related potential component in the electroencephalogram that is associated with feedback processing, is affected by feedback delay similarly independent of task type. With the idea of fully implicit or explicit processing as opposite endpoints of a continuum of reciprocal shares of the implicit and explicit processing systems with feedback delay as the determinant of where on this continuum processing can be located, a common explanatory approach of both, behavioral and electrophysiological findings, is suggested.

Learning to deal with delayed outcomes: EEG oscillatory and slow potentials during the prefeedback interval

It is well established that the stimulus-preceding negativity (SPN) decreases in amplitude as a task is mastered, a phenomenon generally attributed to the reduction in anticipatory attention as feedback becomes less needed. Typically, the experiments supporting this assumption have used relatively short delays (<3 s). However, we found in a previous study that this decline in amplitude, although present during the 2.5-s prefeedback delay of a patterned key-pressing task, was absent with an 8-s delay. We reexamined this finding using a 6-s delay and found that the SPN diminished at frontal sites as participants learned a sequence of four keypress durations, but that this modulation was limited to the early half of the delay (maximum at 2 s). Decline of lateralized sensorimotor theta activity across trials was also limited to early portions of the delay. These findings suggest that processes other than anticipatory attention to feedback may be more relevant for explaining SPN diminution. Such processes could include adjustment and maintenance of action-outcome expectancies (e.g., forward models) during the prefeedback interval.

Dissociating the effect of reward uncertainty and timing uncertainty on neural indices of reward prediction errors: A reward positivity (RewP) event-related potential (ERP) study

Accurate reward predictions include forecasting both what a reward will be and when a reward will occur. We tested how variations in the certainty of reward outcome and certainty in timing of feedback presentation modulate neural indices of reward prediction errors using the reward positivity (RewP) component of the scalp-recorded brain event-related potential (ERP). In a within-subjects design, seventy-three healthy individuals completed two versions of a cued doors task; one cued the probability of a reward outcome while the other cued the probability of a delay before feedback. Replicating previous results, RewP amplitude was larger for uncertain feedback compared to certain feedback. Additionally, RewP amplitude was differentially associated with uncertainty of presence/absence of reward, but not uncertainty of feedback timing. Findings suggest a dissociation in that RewP amplitude is modulated by reward prediction certainty but is less affected by certainty surrounding timing of feedback.

Valence-dependent Neural Correlates of Augmented Feedback Processing in Extensive Motor Sequence Learning - Part I: Practice-related Changes of Feedback Processing

Several event-related potentials (ERPs) are associated with the processing of valence-dependent augmented feedback during the practice of motor tasks. In this study, 38 students learned a sequential arm-movement-task with 192 trials in each of five practice sessions (960 practice trials in total), to examine practice-related changes in neural feedback processing. Electroencephalogram (EEG) was recorded in the first and last practice session. An adaptive bandwidth for movement accuracy led to equal amounts of positive and negative feedback. A frontal located negative deflection in the time window of the feedback-related negativity (FRN) was more negative for negative feedback and might reflect reward prediction errors in reinforcement learning. This negativity increased after extensive practice, which might indicate that smaller errors are harder to identify in the later phase. The late fronto-central positivity (LFCP) was more positive for negative feedback and is assumed to be associated with supervised learning and behavioral adaptations based on feedback with higher complexity. No practice-related changes of the LFCP were observed, which suggests that complex feedback is processed independent from the practice phase. The P300 displayed a more positive activation for positive feedback, which might be interpreted as the higher significance of positive feedback for the updating of internal models in this setting. A valence-independent increase of the P300 amplitude after practice might reflect an improved ability to update the internal representation based on feedback information. These results demonstrate that valence-dependent neural feedback processing changes with extensive practice of a novel motor task. Dissociating changes in latencies of different components support the assumption that they are related to distinct mechanisms of feedback-dependent learning.

Valence-dependent neural correlates of augmented feedback processing in extensive motor sequence learning - Part II: Predictive value of event-related potentials for behavioral adaptation and learning

To examine the neural processing of valence-dependent augmented feedback, 38 students learned a sequential arm movement task with 192 trials in each of five practice sessions. The degree of motor automatization was tested under dual-task-conditions. Electroencephalogram (EEG) was recorded in the first and last practice session. This study is an additional analysis of the data from Margraf et al. [Margraf, L., Krause, D., & Weigelt, M. (this issue). Valence-dependent neural correlates of augmented feedback processing in extensive motor sequence learning - Part I: Practice-related changes of feedback processing.]. While Part I focused on changes in neural feedback processing after extensive motor practice, Part II examines coherences between neural feedback processing and short-term behavioral adaptations, as well as different dimensions of long-term learning (i.e., accuracy, consistency, and automaticity). It was found that more negative amplitudes of the feedback-related-negativity (FRN) after negative feedback were predictive for goal-independent changes of behavior in the early practice phase, whereas more positive amplitudes of the late fronto-central positivity (LFCP) after negative feedback were predictive for goal-directed behavioral adaptations (error reduction), independent from the practice phase. Unexpectedly, more positive amplitudes of the P300 after positive feedback were also predictive for goal-directed behavioral adaptations. Concerning long-term learning and motor automatization, a positive correlation was found for the reduction of dual-task costs (DTC) and LFCP-amplitudes after positive feedback in the early practice.

Social comparison impacts stimulus evaluation in a competitive social learning task

When we perform an action, the outcome that follows it can change the value we place on that behaviour, making it more or less likely to be repeated in the future. However, the values that we learn are not objective: we interpret the outcomes that we receive for ourselves relative to those that share our environment, i.e. we engage in social comparison. The temporal dynamics of physiological responses to stimulus valuation in social learning tasks are poorly understood, particularly in human participants. Therefore, we recorded stimulus-locked event-related potentials with 64-channel EEG to examine stimulus valuation, following the design of a study previously used in macaques. Pairs of participants performed a social learning task in which they received outcomes sequentially for a presented stimulus (partner first) by pressing a button in response to a cue. There were two conditions: one in which stimulus values varied for the participant but output a constant rate of reward for the partner (self-variable blocks), and another condition in which this payout was reversed (other-variable blocks). We then measured participants' self-reported competitiveness. Approximately 200 ms post-stimulus, an ERP related to stimulus evaluation and attentional processing appeared to encode own stimulus value in self-variable blocks. In other-variable blocks the same pattern of activity was reversed, even though the value of the stimulus for the participant did not depend on the stimulus presented. Outcome-locked analyses further showed that attention dedicated to the partner's outcome was greater in more competitive participants. We conclude that subjective stimulus value can be reflected in early stimulus-locked ERP responses and that competitive participants may be more invested in their own performance relative to the other player, hence their increased interest in the outcome of their partner.

Congruency of intervening events and self-induced action influence prediction of final results

Predicting self-induced stimuli is easier than predicting externally produced ones and the amplitude of event-related brain potentials (ERP) elicited by self-induced stimuli is smaller than that elicited by externally produced ones. Previous studies reported that these phenomena occurred strong when stimuli were presented immediately after self-induced action. To be able to adapt to changes, however, it is necessary to predict not only an event that follows a self-induced action but also a subsequent final result. We investigated whether congruency among self-induced actions, intervening events, and final results influences the processing of final results. The congruency of an intervening event with self-induced action was task-irrelevant information for the required response to a final result. The results showed that the P1 amplitude elicited by the final result (i.e., somatosensory stimulus) when an intervening event was congruent with self-induced action was smaller than other elicited amplitudes. This suggests that the congruency of an intervening event and self-induced action may facilitate prediction of a final result, even when this congruency is irrelevant to the ongoing task.

Stress effects on learning and feedback-related neural activity depend on feedback delay

Depending on feedback timing, the neural structures involved in learning differ, with the dopamine system including the dorsal striatum and anterior cingulate cortex (ACC) being more important for learning from immediate than delayed feedback. As stress has been shown to promote striatum-dependent learning, the current study aimed to explore if stress differentially affects learning from and processing of immediate and delayed feedback. One group of male participants was stressed using the socially evaluated cold pressor test, and another group underwent a control condition. Subsequently, participants performed a reward learning task with immediate (500 ms) and delayed (6,500 ms) feedback while brain activity was assessed with electroencephalography (EEG). While stress enhanced the accuracy for delayed relative to immediate feedback, it reduced the feedback-related negativity (FRN) valence effect, which is the amplitude difference between negative and positive feedback. For the P300, a reduced valence effect was found in the stress group only for delayed feedback. Frontal theta power was most pronounced for immediate negative feedback and was generally reduced under stress. Moreover, stress reduced associations of FRN and theta power with trial-by-trial accuracy. Associations between stress-induced cortisol increases and EEG components were examined using linear mixed effects analyses, which showed that the described stress effects were accompanied by associations between the stress-induced cortisol increases and feedback processing. The results indicate that stress and cortisol affect different aspects of feedback processing. Instead of an increased recruitment of the dopamine system and the ACC, the results may suggest enhanced salience processing and reduced cognitive control under stress.

Subjective preferences differentially modulate the processing of rewards gained by own vs. observed choices

The present EEG study investigated the impact of subjective reward preferences and agency on outcome processing. 47 healthy adults (11 male; 36 female) with preferences for either milk or white chocolate completed two runs of a gambling task involving their preferred chocolate (high preference outcomes, HPOs), non-preferred chocolate (medium preference outcomes, MPOs), and a lesser liked non-chocolate reward (low preference outcomes, LPOs). In the 'active' run, subjects chose between three different response options to receive the outcomes. In the 'observational' run, they observed another person's choices and subsequent outcomes. Cluster-based permutation analyses of event-related potential (ERPs) revealed that early processing in the P2 time window reflected outcome salience, differentiating HPOs and MPOs from LPOs, especially for outcomes following own choices, while not distinguishing between HPOs and MPOs. In contrast, processing in later stages, i.e., the typical time windows for feedback-related negativity (FRN) and P300, showed evidence of differential coding of HPOs and MPOs and was also modulated by agency. ERPs clearly differentiated between all three outcome types in the FRN and P300 time windows for outcomes following active but not for observed choices. The present study adds to evidence for modulation of outcome processing by contextual and inter-individual factors. In particular, our findings suggest that subjective preferences are complementarily represented in subjective reward valuation and in motivational value representations indexed by the FRN and the P300.

Modulation of feedback processing by social context in social anxiety disorder (SAD)-an event-related potentials (ERPs) study

The ability to learn from feedback, especially under social scrutiny, is an essential prerequisite for successful interaction with the environment. Patients suffering from social anxiety disorder (SAD) have been proposed to show altered processing of and learning from feedback, especially depending on social context. However, the neural basis and behavioral consequences of altered reinforcement learning in SAD are not clear yet. In the present event-related potentials (ERPs) study, 34 SAD patients and 30 healthy control subjects (HC) performed an adapted version of a probabilistic feedback learning task in two distinct social conditions. In the observation condition, participants were observed by a confederate; in the control condition, they performed the task without being observed. Patients as compared to healthy controls experienced more subjective discomfort under social observation. Moreover, they showed better learning from negative feedback in the control condition, but reduced learning from negative feedback in the observation condition. This effect correlated with reduced differentiation of positive and negative feedback in the time range of the feedback-related negativity (FRN) under high action-feedback contingency. In addition, SAD patients demonstrated increased FRN amplitudes in the first half of the observation condition, in particular to positive feedback. The present results demonstrate that processing of and learning from feedback are altered in SAD, especially under social scrutiny. In particular, it appears that SAD patients do not process positive information adequately on the neural level, which may impair their ability to differentiate between negative and positive outcomes.

Effects of feedback delay on learning from positive and negative feedback in patients with Parkinson's disease off medication

Phasic dopamine (DA) signals conveyed from the substantia nigra to the striatum and the prefrontal cortex crucially affect learning from feedback, with DA bursts facilitating learning from positive feedback and DA dips facilitating learning from negative feedback. Consequently, diminished nigro-striatal dopamine levels as in unmedicated patients suffering from Parkinson's Disease (PD) have been shown to lead to a negative learning bias. Recent studies suggested a diminished striatal contribution to feedback processing when the outcome of an action is temporally delayed. This study investigated whether the bias towards negative feedback learning induced by a lack of DA in PD patients OFF medication is modulated by feedback delay. To this end, PD patients OFF medication and healthy controls completed a probabilistic selection task, in which feedback was given immediately (after 800 ms) or delayed (after 6800 ms). PD patients were impaired in immediate but not delayed feedback learning. However, differences in the preference for positive/negative learning between patients and controls were seen for both learning from immediate and delayed feedback, with evidence of stronger negative learning in patients than controls. A Bayesian analysis of the data supports the conclusion that feedback timing did not affect the learning bias in the patients. These results hint at reduced, but still relevant nigro-striatal contribution to feedback learning, when feedback is delayed.

Electrophysiological Response to the Informative Value of Feedback Revealed in a Segmented Wisconsin Card Sorting Test

Feedback has two main components. One is valence that indicates the wrong or correct behavior, and the other is the informative value that refers to what we can learn from feedback. Aimed to explore the neural distinction of these two components, we provided participants with a segmented Wisconsin Card Sorting Task, in which they received either positive or negative feedback at different steps. The informative value was manipulated in terms of the order of feedback presentation. The results of event-related potentials time-locked to the feedback presentation confirmed that valence of feedback was processed in a broad epoch, especially in the time window of feedback-related negativity (FRN), reflecting detection of correct or wrong card sorting behavior. In contrast, the informative value of positive and negative feedback was mainly processed in the P300, possibly reflecting information updating or hypothesis revision. These findings provide new evidence that informative values of feedback are processed by cognitive systems that differ from those of feedback valence.

Slow Is Also Fast: Feedback Delay Affects Anxiety and Outcome Evaluation

Performance-related feedback plays an important role in improving human being’s adaptive behavior. Using event-related potentials (ERPs), previous studies have associated a particular component, i.e., reward positivity (RewP), with outcome evaluation processing and found that this component was affected by waiting time before outcome evaluation. Prior research has also suggested that anxious individuals are more prone to detecting threats and susceptible to negative emotions, and show different patterns of brain activity in outcome evaluation. It is quite common that a decision-maker cannot receive feedback immediately; however, few studies have focused on the processing of delayed feedback, especially in subjects who exhibit trait anxiety. In this study, we recruited two groups of subjects with different trait anxiety levels and recorded ERPs when they conducted a time-estimation task with short (0.6–1 s) or long delayed (4–5 s) feedback. The ERP results during the cue phase showed that long waiting cues elicited more negative-going feedback-related negativity (FRN)-like component than short waiting cues in the high trait anxiety (HTA) group. More importantly, the two groups showed different patterns of ERP in the feedback condition. In the low trait anxiety (LTA) group, more positive-going RewP was found in the short-delayed than in the long-delayed condition. In contrast, no difference was found in the HTA group. This pattern may reflect the hyperactivity of the reward systems of HTA individuals in uncertain environments (e.g., the long-delay condition) compared with LTA individuals. Our results provide a direction for future research on the neural mechanisms of reinforcement learning and anxiety.

Mediofrontal Negativity Signals Unexpected Timing of Salient Outcomes

The medial prefrontal cortex (mPFC) and ACC have been consistently implicated in learning predictions of future outcomes and signaling prediction errors (i.e., unexpected deviations from such predictions). A computational model of ACC/mPFC posits that these prediction errors should be modulated by outcomes occurring at unexpected times, even if the outcomes themselves are predicted. However, unexpectedness per se is not the only variable that modulates ACC/mPFC activity, as studies reported its sensitivity to the salience of outcomes. In this study, mediofrontal negativity, a component of the event-related brain potential generated in ACC/mPFC and coding for prediction errors, was measured in 48 participants performing a Pavlovian aversive conditioning task, during which aversive (thus salient) and neutral outcomes were unexpectedly shifted (i.e., anticipated or delayed) in time. Mediofrontal ERP signals of prediction error were observed for outcomes occurring at unexpected times but were specific for salient (shock-associated), as compared with neutral, outcomes. These findings have important implications for the theoretical accounts of ACC/mPFC and suggest a critical role of timing and salience information in prediction error signaling.