Feedback Stimuli Research Articles

Does vibrotactile biofeedback for postural control interfere with cognitive processes?

BackgroundDirectional vibrotactile biofeedback for balance control can be instructed in the form of Repulsive (to move in the opposite direction of vibrations) or Attractive (to move in the direction of vibrations) stimulus encodings. However, which of these encodings is less cognitively demanding and poses less interference with high-level cognitive processes of conflict resolution remains unresolved.MethodsIn two between-subject studies with 30 (16 females) and 35 (23 females) healthy young adults, respectively, we investigated the cognitive load of Attractive and Repulsive vibrotactile biofeedback on 1) working memory (Study I) and 2) cognitive conflict resolution (Study II). Both studies also examined the effectiveness of both feedback stimulus encodings on balance control during quiet standing with eyes closed.ResultsBoth Attractive and Repulsive vibrotactile biofeedback increased balance stability (reduced trunk sway variability) in both the working memory and the conflict resolution study (Study I and II, respectively) with a greater increase of stability for the Repulsive encoding during multitasking demanding cognitive conflict resolution (Study II). Cognitive costs, measured in terms of the Linear Integrated Speed-Accuracy Score (LISAS), were greater for the Attractive encoding during multitasking with working memory demands. When cognitive conflict resolution was required as a secondary cognitive task, both stimulus encodings increased cognitive costs equally.ConclusionsThe effects of instructed Repulsive and Attractive stimulus encodings for the response-related interpretation of vibrotactile biofeedback of body sway were contrasted with respect to cognitive processing demands and balance stabilisation benefits. Both encodings improved balance stability but at certain cognitive costs. Regarding interference with specific high-level cognitive processes, however, a distinction has to be made between both encodings. Repulsive feedback encoding seems to cause less cognitive costs on working memory load and slightly greater stabilisation when cognitive conflict resolution is required. These results are discussed in the context of the known benefits of avoidance actions on cognitive control.

Assessing the Effectiveness of Audio-Visual vs. Visual Neurofeedback for Attention Enhancement: A Pilot Study with Neurological, Behavioural, and Neuropsychological Measures.

Electroencephalogram (EEG) based Neurofeedback training has gained traction as a practical method for enhancing executive functions, particularly attention, among healthy individuals. The neurofeedback protocols based on EEG channel locations, frequency bands, or EEG features has been tested. However, the improvement in attention was not measured by comparing different feedback stimulus types. We believe that multisensory nature feedback even with few training sessions may induce strong effect. Therefore, this study compares the effect of audio-visual and visual feedback stimuli for attention enhancement utilizing neurophysiological, behavioural and neuropsychological measures. Total 21 subjects were recruited, undergoing six alternate days of neurofeedback training sessions to upregulate EEG beta power of frontocentral (FC5). Dwell time, fractional occupancy and transition probability were also estimated from the EEG beta power. Audiovisual group (G1) as compared to visual group (G2) demonstrate a significant increase of global EEG beta activity alongside improved dwell time (t = 2.76, p = 0.003), fractional occupancy (t = 1.73, p = 0.042) and transition probability (t = 2.46, p = 0.008) over the course of six neurofeedback training sessions. Similarly, the group (G1) shows higher scores (t = 2.13, p = 0.032) and faster reaction times (t = 2.22, p = 0.028) in Stroop task, along with increased score in Mindfulness Attention Awareness Scale (MAAS-15) questionnaire (t = 2.306, p = 0.012). Audiovisual neurofeedback may enhance training effectiveness, potentially achieving the same outcomes in fewer sessions compared to visual-only feedback. However, sufficient training days are essential for effect consolidation. This highlights the feasibility of completing neurofeedback training, a significant challenge in practice.

Unravelling the origin of the reward positivity: a human intracranial event-related brain potential study.

The reward positivity (RewP) is an event-related brain potential (ERP) component that emerges approximately 250 to 350 milliseconds (ms) after receiving reward-related feedback stimuli and is believed to be important for reinforcement learning and reward processing. Although numerous localization studies have indicated that the anterior cingulate cortex (ACC) is the neural generator of this component, other studies have identified sources outside of the ACC, fuelling a debate about its origin. Because the results of EEG and MEG source localization studies are severely limited by the inverse problem, we addressed this question by leveraging the high spatial and temporal resolution of intracranial EEG. We predicted that we would identify a neural generator of the RewP in the caudal ACC. We recorded intracranial EEG in 19 refractory epilepsy patients who underwent invasive video-EEG monitoring at Ghent University Hospital, Belgium. Participants engaged in the virtual T-maze task (vTMT), a trial-and-error task known to elicit a canonical RewP, while scalp and intracranial EEG were simultaneously recorded. The RewP was identified using a difference wave approach for both scalp and intracranial EEG. The data were aggregated across participants to create a virtual "meta-participant" that contained all the recorded intracranial ERPs (iERPs) with respect to their intracranial contact locations. We used both a hypothesis-driven (focused on ACC) and exploratory (whole-brain analysis) approach to segment the brain into regions of interest (ROI). For each ROI, we evaluated the degree to which the time course of the absolute current density (ACD) activity mirrored the time course of the RewP, and confirmed the statistical significance of the results using permutation analysis. The grand average waveform of the scalp data revealed a RewP at 309 ms after reward feedback with a frontocentral scalp distribution, consistent with the identification of this component as the RewP. The meta-participant contained iERPs recorded from 582 intracranial contacts in total. The ACD activity of the aggregated iERPs were most similar to the RewP in left caudal ACC, left dorsolateral prefrontal cortex, left frontomedial cortex, and left white matter, with the highest score attributed to caudal ACC, as predicted. To our knowledge, this is the first study that uses intracranial EEG aggregated across multiple human epilepsy patients and current source density analysis to identify the neural generator(s) of the RewP. These results provide direct evidence that the ACC is a neural generator of the RewP.

Dual-system free-operant avoidance: Extension of a theory.

Our theory of positively reinforced free-operant behavior (Perez & Dickinson, 2020) assumes that responding is controlled by two systems. One system is sensitive to the correlation between response and reinforcement rates and controls goal-directed behavior, whereas a habitual system learns by reward prediction error. We present an extension of this theory to the aversive domain that explains why free-operant avoidance responding increases with both the experienced rate of negative reinforcement and the difference between this rate and that programmed by the avoidance schedule. The theory also assumes that the habitual component is reinforced by the acquisition of aversive inhibitory properties by the feedback stimuli generated by responding, which then act as safety signals that reinforce habit performance. Our analysis suggests that the distinction between habitual and goal-directed control of rewarded behavior can also be applied to the aversive domain. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Modeling the Impact of Head-Body Rotations on Audio-Visual Spatial Perception for Virtual Reality Applications.

Humans perceive the world by integrating multimodal sensory feedback, including visual and auditory stimuli, which holds true in virtual reality (VR) environments. Proper synchronization of these stimuli is crucial for perceiving a coherent and immersive VR experience. In this work, we focus on the interplay between audio and vision during localization tasks involving natural head-body rotations. We explore the impact of audio-visual offsets and rotation velocities on users' directional localization acuity for various viewing modes. Using psychometric functions, we model perceptual disparities between visual and auditory cues and determine offset detection thresholds. Our findings reveal that target localization accuracy is affected by perceptual audio-visual disparities during head-body rotations, but remains consistent in the absence of stimuli-head relative motion. We then showcase the effectiveness of our approach in predicting and enhancing users' localization accuracy within realistic VR gaming applications. To provide additional support for our findings, we implement a natural VR game wherein we apply a compensatory audio-visual offset derived from our measured psychometric functions. As a result, we demonstrate a substantial improvement of up to 40% in participants' target localization accuracy. We additionally provide guidelines for content creation to ensure coherent and seamless VR experiences.

Spatial tactile localization depends on sensorimotor binding: preliminary evidence from virtual reality.

Our brain continuously maps our body in space. It has been suggested that at least two main frames of reference are used to process somatosensory stimuli presented on our own body: the anatomical frame of reference (based on the somatotopic representation of our body in the somatosensory cortex) and the spatial frame of reference (where body parts are mapped in external space). Interestingly, a mismatch between somatotopic and spatial information significantly affects the processing of bodily information, as demonstrated by the "crossing hand" effect. However, it is not clear if this impairment occurs not only when the conflict between these frames of reference is determined by a static change in the body position (e.g., by crossing the hands) but also when new associations between motor and sensory responses are artificially created (e.g., by presenting feedback stimuli on a side of the body that is not involved in the movement). In the present study, 16 participants performed a temporal order judgment task before and after a congruent or incongruent visual-tactile-motor- task in virtual reality. During the VR task, participants had to move a cube using a virtual stick. In the congruent condition, the haptic feedback during the interaction with the cube was provided on the right hand (the one used to control the stick). In the incongruent condition, the haptic feedback was provided to the contralateral hand, simulating a sort of 'active' crossed feedback during the interaction. Using a psychophysical approach, the point of subjective equality (or PSE, i.e., the probability of responding left or right to the first stimulus in the sequence in 50% of the cases) and the JND (accuracy) were calculated for both conditions, before and after the VR-task. After the VR task, compared to the baseline condition, the PSE shifted toward the hand that received the haptic feedback during the interaction (toward the right hand for the congruent condition and toward the left hand for the incongruent condition). This study demonstrated the possibility of inducing spatial biases in the processing of bodily information by modulating the sensory-motor interaction between stimuli in virtual environments (while keeping constant the actual position of the body in space).

The Role of the Human Cerebellum for Learning from and Processing of External Feedback in Non-Motor Learning: A Systematic Review

This review aimed to systematically identify and comprehensively review the role of the cerebellum in performance monitoring, focusing on learning from and on processing of external feedback in non-motor learning. While 1078 articles were screened for eligibility, ultimately 36 studies were included in which external feedback was delivered in cognitive tasks and which referenced the cerebellum. These included studies in patient populations with cerebellar damage and studies in healthy subjects applying neuroimaging. Learning performance in patients with different cerebellar diseases was heterogeneous, with only about half of all patients showing alterations. One patient study using EEG demonstrated that damage to the cerebellum was associated with altered neural processing of external feedback. Studies assessing brain activity with task-based fMRI or PET and one resting-state functional imaging study that investigated connectivity changes following feedback-based learning in healthy participants revealed involvement particularly of lateral and posterior cerebellar regions in processing of and learning from external feedback. Cerebellar involvement was found at different stages, e.g., during feedback anticipation and following the onset of the feedback stimuli, substantiating the cerebellum’s relevance for different aspects of performance monitoring such as feedback prediction. Future research will need to further elucidate precisely how, where, and when the cerebellum modulates the prediction and processing of external feedback information, which cerebellar subregions are particularly relevant, and to what extent cerebellar diseases alter these processes.

Effects of vibratory feedback stimuli through an oral appliance on sleep bruxism: A 14-week intervention trial

Background/purposeVarious biofeedback stimulation techniques for managing sleep bruxism (SB) have recently emerged; however, the effect of the successive application of vibratory feedback stimulation has not been clarified. This study aimed to elucidate the effect of vibration feedback stimulation via an oral appliance (OA) on SB. Materials and methodsThis prospective, single-arm, open-label intervention study included 20 participants diagnosed with “definite” SB who wore a specially designed OA for 98 nights at home. A force-based SB detection system triggered a vibrator attached to the OA. Vibratory stimulation was withheld during the first 3-week adaptation period (weeks 1–3), applied during the 9-week stimulation period (weeks 4–12), and withheld again during the post-stimulation period (weeks 13–14). The number and duration of SB events per hour of sleep were calculated based on piezoelectric signals recorded with the OA-based vibration feedback device and compared between weeks 3 and 4, 8, 12, and 14 and between weeks 12 and 14 using the Friedman test (post-hoc test with Bonferroni correction). ResultsThe duration of SB events significantly decreased after vibratory stimulation (weeks 3 versus 4, 8, and 12: P < 0.001, P = 0.026, and P = 0.033, respectively) and then significantly increased upon cessation of vibratory stimulation after the stimulation period (weeks 12 versus 14: P < 0.001). ConclusionContingent vibratory stimulation through an OA-based vibration feedback device may suppress SB-related masticatory muscle activity continuously for 9 weeks and may be an effective alternative for managing SB.

Altered Putamen Activation for Social Comparison-Related Feedback in Social Anxiety Disorder: A Pilot Study

Introduction: Social anxiety disorder (SAD) is characterized by abnormal processing of performance-related social stimuli. Previous studies have shown altered emotional experiences and activations of different sub-regions of the striatum during processing of social stimuli in patients with SAD. However, whether and to what extent social comparisons affect behavioural and neural responses to feedback stimuli in patients with SAD is unknown. Materials and Methods: To address this issue, emotional ratings and functional magnetic resonance imaging (fMRI) responses were assessed while patients suffering from SAD and healthy controls (HC) were required to perform a choice task and received performance feedback (correct, incorrect, non-informative) that varied in relation to the performance of fictitious other participants (a few, half, or most of others had the same outcome). Results: Across all performance feedback conditions, fMRI analyses revealed reduced activations in bilateral putamen when feedback was assumed to be received by only a few compared to half of the other participants in patients with SAD. Nevertheless, analysis of rating data showed a similar modulation of valence and arousal ratings in patients with SAD and HC depending on social comparison-related feedback. Conclusions: This suggests altered neural processing of performance feedback depending on social comparisons in patients with SAD.

Neural abnormalities of reward processing in adolescents with bipolar disorders: An ERP study

Adolescent onset is common in bipolar disorders (BDs) and is associated with a worse illness course in adulthood. A model of BDs suggests that a dysregulated behavioral approach system (BAS), a neural system that mobilizes reward-seeking behavior, is at the root of BDs. Normative adolescence is often accompanied by dynamic changes to neural structures underlying the BAS and related cognitive processes. It is possible that adolescent-onset BDs is associated with abnormal BAS neurodevelopment. Consistently, the present study is the first to compare specific BAS-relevant anticipatory and consummatory reward processes as indexed by event-related potentials (ERPs) in adolescents with BDs and typically developing peers. Using a sample of 43 adolescents with BDs and 56 without psychopathology, we analyzed N1 and P3 responses to anticipatory cues and feedback-related negativity (FRN) and P3 responses to feedback stimuli during a monetary incentive delay (MID) task. Hierarchical linear models examined relationships between ERP amplitudes and diagnostic group, MID condition, sex, and age. During anticipation phase, adolescent boys with BDs exhibited significantly larger N1 amplitudes in loss than even or gain trials. During feedback phase, compared to their healthy peers, adolescents with BDs had smaller FRN amplitudes across all conditions. Additional effects involving age, sex and trial type were observed. The findings indicate subtle, non-ubiquitous BAS-relevant neural abnormalities involving early attentional processes during reward anticipation and reward learning following feedback in adolescents with BDs. Adolescents with BDs did not show overall hypersensitive neural responses to monetary reward anticipation or feedback observed in adults with BDs.

Neural correlates of evaluations of non-binary social feedback: An EEG study

PurposeIn complex and diverse social circumstances, decision making is affected by social feedback. Although previous studies have examined the electrophysiological correlates of social feedback with a binary valence, those related to non-binary feedback, or the magnitude of social feedback, remain unclear. This study investigated the electrophysiological correlates of non-binary social feedback and subsequent action selection processing. MethodsParticipants were asked to complete a Gabor patch direction judgment task in which they were required to make judgments before and after receiving social feedback. They were informed that the feedback stimuli represented the degree to which other participants made the same choice. Results & conclusionThe results revealed that feedback that was highly concordant with the participant's judgments elicited greater P300 activity, which was associated with the fulfillment of expectations regarding social reward. Moreover, moderately concordant feedback induced stronger theta band power, which may indicate monitoring of subjective conflict. Temporal changes in theta power during feedback phase may also relate to adjustments in prediction error. Additionally, when an initial judgment was maintained following social feedback, we observed a stronger increase in beta power, indicating an association with post-social-feedback action processing.

Deficits in doors P300 amplitude during adolescence associated with preschool-onset depression.

The psychophysiological underpinnings of preschool-onset depression (PO-MDD) remain underexplored. Moreover, there is currently a limited understanding of the potential impact that PO-MDD might have on neurobiological functions later in development such as general cognitive domains and reward processing. Thus, the current study sought to examine potential neurophysiological differences, measured via electroencephalography (EEG), in adolescents with and without a history of PO-MDD. Participants and their caregivers (N = 138) from a large longitudinal study completed semi-structured clinical interviews at a baseline visit (ages 3-7) to determine PO-MDD status. At a follow-up visit approximately 11 years later, adolescents (ages 13-19) completed the doors gambling task while EEG was recorded to measure event-related potentials (ERPs) elicited by both the doors and feedback stimuli, to index cognitive and reward processing functions (i.e., doors-P300, gain/loss feedback-P300, and RewP). Adolescents with a history of PO-MDD exhibited significantly smaller doors-P300 compared with adolescents with no history of PO-MDD, whereas there were no group differences in gain/loss feedback-P300 or RewP. Additionally, reduced doors-P300 was independently associated with lower baseline income-to-needs ratio, older age, and female gender. The current study suggests that reduced doors-P300 amplitude during adolescence might reflect impaired neurophysiological development related to PO-MDD. Thus, the P300 derived from the doors stimuli might be a valuable neural measure to further our understanding of potential neurophysiological differences associated with early-onset childhood depression.

Development of associations between elementary school students' mindsets and attentional neural processing of feedback in an arithmetic task.

The aim of this study was to examine the development of the associations between elementary school students' mindsets and the attentional neural processing of positive and negative feedback in math. For this, we analyzed data collected twice from 100 Finnish elementary school students. During the autumn semesters of their 3rd and 4th grade, the participants' general intelligence mindset and math ability mindset were measured with a questionnaire, and their brain responses elicited by performance-relevant feedback were recorded during an arithmetic task. We found that students' fixed mindsets about general intelligence and math ability were associated with greater attention allocated to positive feedback as indicated by a larger P300. These associations were driven by the effects of mindsets on attention allocation to positive feedback in grade 4. Additionally, 4th graders' more fixed general intelligence mindset was marginally associated with greater attention allocated to negative feedback. In addition, the effects of both mindsets on attention allocation to feedback were marginally stronger when the children were older. The present results, although marginal in the case of negative feedback and mainly driven by effects in grade 4, are possibly a reflection of the greater self-relevance of feedback stimuli for students with a more fixed mindset. It is also possible that these findings reflect the fact that, in evaluative situations, mindset could influence stimulus processing in general. The marginal increase in the effects of mindsets as children mature may reflect the development of coherent mindset meaning systems during elementary school years.

A bi-directional visual angle car-following model considering collision sensitivity

From the perspective of driver’s visual characteristics, the potential collision conflicts in car-following and lane-changing driving behaviors are analyzed. On this basis, a bi-directional visual angle car-following model considering the collision sensitivity is proposed. The effect of collision sensitivity coefficient, the proportion of backward-looking visual angle, and many types of vehicles on the dynamics and safety of the newly proposed model is explored. A linear local stability analysis was carried out by perturbation analysis, and the critical stability condition of the improved model was deduced. The evolution of small perturbation during the car-following and lane-changing process is numerically simulated. The same conclusion as the linear stability analysis is obtained: The driver observes different types of vehicles in the vehicle queue through the bi-directional visual angle as feedback stimuli, so as to optimize the velocity and perceive potential collision conflicts, which has significant practical significance for improving the stability of the traffic system and alleviating traffic congestion. Besides, the safety of the new model is evaluated by the improved visual time-to-collision (TTC) index. The results show that the newly introduced factors can effectively reduce the potential collision risk in multiple scenarios.

Semantic fMRI neurofeedback: a multi-subject study at 3 tesla

Objective. Real-time functional magnetic resonance imaging neurofeedback (rt-fMRI-NF) is a non-invasive procedure allowing the self-regulation of brain functions via enhanced self-control of fMRI based neural activation. In semantic rt-fMRI-NF, an estimated relation between multivariate fMRI activation patterns and abstract mental states is exploited for a multi-dimensional feedback stimulus via real-time representational similarity analysis (rt-RSA). Here, we assessed the performances of this framework in a multi-subject multi-session study on a 3 T MRI clinical scanner. Approach. Eighteen healthy volunteers underwent two semantic rt-fMRI-NF sessions on two different days. In each session, participants were first requested to engage in specific mental states while local fMRI patterns of brain activity were recorded during stimulated mental imagery of concrete objects (pattern generation). The obtained neural representations were to be replicated and modulated by the participants in subsequent runs of the same session under the guidance of a rt-RSA generated visual feedback (pattern modulation). Performance indicators were derived from the rt-RSA output to assess individual abilities in replicating (and maintaining over time) a target pattern. Simulations were carried out to assess the impact of the geometric distortions implied by the low-dimensional representation of patterns’ dissimilarities in the visual feedback. Main results. Sixteen subjects successfully completed both semantic rt-fMRI-NF sessions. Considering some performance indicators, a significant improvement between the first and the second runs, and within run increasing modulation performances were observed, whereas no improvements were found between sessions. Simulations confirmed that in a small percentage of cases visual feedback could be affected by metric distortions due to dimensionality reduction implicit to the rt-RSA approach. Significance. Our results proved the feasibility of the semantic rt-fMRI-NF at 3 T, showing that subjects can successfully modulate and maintain a target mental state when guided by rt-RSA derived feedback. Further development is needed to encourage future clinical applications.

Modulation of neurocognitive functions associated with action preparation and early stimulus processing by response-generated feedback

Receiving feedback on action correctness is a relevant factor in learning, but only a few recent studies have investigated the neural bases involved in feedback processing and its consequences on performance. Several event-related potentials (ERP) studies investigated the feedback-related negativity, which is an ERP occurring after the presentation of a feedback stimulus. In contrast, the present study investigates the effect of providing feedback on brain activities before and after the presentation of an imperative stimulus with the aim to show how this could have an impact on cognitive functions related to anticipatory and post-stimulus task processing. Participants performed a standard visuomotor task and a modified version of the same task in which feedback sounds were emitted when participants committed performance errors. Overall, results showed that in the feedback task subjects have better cognitive control than in the standard task. All behavioral measures were improved in the feedback task. At the brain level, all the studied components were modulated by the presence of the feedback cue. Results pointed to a possible increase of anticipatory activity in the prefrontal cortex, a reduction of perceptual awareness in areas previously associated with the anterior insular cortex, and an increase of activity associated with selective attention in sensory cortices.

Pain feedback interferes with reward positivity production.

The reinforcement learning (RL) theory of the reward positivity (RewP) proposes that RewP indexes a reward prediction error (RPE) signal processed in the anterior cingulate cortex (ACC). According to this theory, RewP is an event-related potential (ERP) that is more positive-going for feedback stimuli that predict better-than-expected outcomes (positive feedback) than for feedback stimuli that predict worse-than-expected outcomes (negative feedback). Despite strong evidence for this hypothesis, findings have been equivocal for tasks involving painful outcomes. We hypothesized that the RewP is modulated by high-level task goals such that outcomes that are congruent with the goals elicit positive RPEs even if their immediate consequences are negative. Accordingly, changes in high-level task goals should modulate RewP amplitude for tasks that involve seeking pain compared to tasks that involve avoiding pain. We recorded the electroencephalogram from participants who were instructed to navigate a virtual T-Maze to find reward-predictive feedback in a reward condition and pain-predictive feedback in a pain condition. We expected more positive-going ERPs to reward feedback in the reward condition and more positive-going ERPs to pain feedback in the pain condition. Despite behavioral results indicating that participants complied with task instructions, contrary to our predictions, we did not find a RewP to pain feedback. We suggest that pain feedback interfered with the effect of high-level task goals on RewP amplitude, which is indicative of conflict at different levels of task hierarchy.

Neural correlates of successful costly punishment in the Ultimatum game on a trial-by-trial basis.

Costly punishment describes decisions of an interaction partner to punish an opponent for violating rules of fairness at the expense of personal costs. Here, we extend the interaction process by investigating the impact of a socio-emotional reaction of the opponent in response to the punishment that indicates whether punishment was successful or not. In a modified Ultimatum game, emotional facial expressions of the proposer in response to the decision of the responder served as feedback stimuli. We found that both honored reward following acceptance of an offer (smiling compared to neutral facial expression) and successful punishment (sad compared to neutral facial expression) elicited a reward positivity, indicating that punishment was the intended outcome. By comparing the pattern of results with a probabilistic learning task, we show that the reward positivity on sad facial expressions was specific for the context of costly punishment. Additionally, acceptance rates on a trial-by-trial basis were altered according to P3 amplitudes in response to the emotional facial reaction of the proposer. Our results are in line with the concept of costly punishment as an intentional act following norm-violating behavior. Socio-emotional stimuli have an important influence on the perception and behavior in economic bargaining.

Outcome valence and stimulus frequency affect neural responses to rewards and punishments.

The Reward-Positivity (RewP) is a frontocentral event-related potential elicited following reward and punishment feedback. Reinforcement learning theories propose the RewP reflects a reward prediction error that increases following more favorable (vs. unfavorable) outcomes. An alternative perspective, however, proposes this component indexes a salience-prediction error that increases following more salient outcomes. Evidence from prior studies that included both reward and punishment conditions is mixed, supporting both accounts. However, these studies often varied how feedback stimuli were repeated across reward and punishment conditions. Differences in the frequency of feedback stimuli may drive inconsistencies by introducing salience effects for infrequent stimuli regardless of whether they are associated with rewards or punishments. To test this hypothesis, the current study examined the effect of outcome valence and stimulus frequency on the RewP and neighboring P2 and P3 components in reward, punishment, and neutral contexts across two separate experiments that varied how often feedback stimuli were repeated between conditions. Experiment 1 revealed infrequent feedback stimuli generated overlapping positivity across all three components. However, controlling for stimulus frequency, experiment 2 revealed favorable outcomes that increased RewP and P3 positivity. Together, these results suggest the RewP reflects some combination of reward- and salience-prediction error encoding. Results also indicate infrequent feedback stimuli elicited strong salience effects across all three components that may inflate, eliminate, or reverse outcome valence effects for the RewP and P3. These results resolve several inconsistencies in the literature and have important implications for electrocortical investigations of reward and punishment feedback processing.

Win, lose, or draw: Examining salience, reward memory, and depression with the reward positivity.

The reward positivity (RewP) is a putative biomarker of depression. Careful control of stimulus properties and manipulation of both stimulus valence and salience could facilitate interpretation of the RewP. RewP interpretation could further be improved by investigating functional outcomes of a blunted RewP in depression, such as reduced memory for rewarding outcomes. This study sought to advance RewP interpretation first by advancing task design through use of neutral (i.e., draw) control trials and counterbalanced feedback stimuli. Second, we examined the RewP's association with memory and the impact of depression. Undergraduates completed self-report measures of depression and anhedonia prior to a modified doors task in which words were displayed in colored fonts that indicated win, loss, or draw feedback. Memory of the feedback associated with each word (i.e., source memory) was tested. Results showed that RewP response to wins was more positive than to losses, which was more positive than to draws. The RewP was not associated with depression or anhedonia. The low depression group showed a source memory advantage for win words, but the high depression group did not. Source memory showed small relations to the RewP, but these did not survive Bonferroni correction. Results suggest the RewP is sensitive to salience and highlight challenges in detecting an association between the RewP and depression in modified doors tasks. Findings indicate that depression is related to dysfunctional source memory for reward but not loss and that future research should probe the possible associations between the RewP and memory in depression.