Cognitive Effort Exertion Enhances Electrophysiological Responses to Rewarding Outcomes

Bumpy ride ahead: Anticipated effort as emotional evidence?

Conscious reportable (un)pleasantness feelings were shown to be successfully described by a process in which evidence favoring pleasant and unpleasant feelings accumulates until one response wins the race. This approach is challenged by (a) insufficient specification of "evidence," and (b) incomplete verification that participants report their truly experienced (un)pleasant feelings and not what they expect to feel. In each trial in this preregistered experiment, the (un)pleasant feeling reports regarding emotion evoking pictures was embedded in a period when participants expected a low-effort task (feature visual search) or a high-effort task (feature-conjunction search). Fitting the Linear Ballistic Accumulator model to the feeling report data shows that anticipated effort was associated with a higher rate of unpleasant evidence accumulation, but only when the emotion evoking pictures were normatively unpleasant and not when they were normatively pleasant. These results suggest that anticipated effort may be one source of "evidence," but only given a certain interpretation of the findings, and that genuinely felt emotions contribute to the emotion reports, assuming that participants intended to react to the pictures, as instructed, and not to the anticipated effort.

Disentangling effort from probability of success: Temporal dynamics of frontal midline theta in effort-based reward processing

The ability to weigh a reward against the effort required to acquire it is critical for decision-making. However, extant experimental paradigms oftentimes confound increased effort demand with decreased reward probability, thereby obscuring neural correlates underlying these cognitive processes. To resolve this issue, we designed novel tasks that disentangled probability of success - and therefore reward probability - from effort demand. In Experiment 1, reward magnitude and effort demand were varied while reward probability was kept constant. In Experiment 2, effort demand and reward probability were varied while reward magnitude remained fixed. Electroencephalogram (EEG) data was recorded to explore how frontal midline theta (FMT; an electrophysiological index of mPFC function) and component P3 (an index of incentive salience) respond to effort demand, and reward magnitude and probability. We found no evidence that FMT tracked effort demands or net value during cue evaluation. At feedback, however, FMT power was enhanced for high compared to low effort trials, but not modulated by reward magnitude or probability. Conversely, P3 was sensitive to reward magnitude and probability at both cue and feedback phases and only integrated expended effort costs at feedback, such that P3 amplitudes continued to scale with reward magnitude and probability but were also increased for high compared to low effort reward feedback. These findings suggest that, when likelihood of success is equal, FMT power does not track net value of prospective effort-based rewards. Instead, expended cognitive effort potentiates FMT power and enhances the saliency of rewards at feedback. SIGNIFICANCE STATEMENT: The way the brain weighs rewards against the effort required to achieve them is critical for understanding motivational disorders. Current paradigms confound increased effort demand with decreased reward probability, making it difficult to disentangle neural activity associated with effort costs from those associated with reward likelihood. Here, we explored the temporal dynamics of effort-based reward (via frontal midline theta (FMT) and component P3) while participants underwent a novel paradigm that kept probability of reward constant between mental effort demand conditions. Our findings suggest that the FMT does not track net value and that expended effort enhances, instead of attenuates, the saliency of rewards.

Neurobiological foundations and clinical relevance of effort-based decision-making

Applying effort-based decision-making tasks provides insights into specific variables influencing choice behaviors. The current review summarizes the structural and functional neuroanatomy of effort-based decision-making. Across 39 examined studies, the review highlights the ventromedial prefrontal cortex in forming reward-based predictions, the ventral striatum encoding expected subjective values driven by reward size, the dorsal anterior cingulate cortex for monitoring choices to maximize rewards, and specific motor areas preparing for effort expenditure. Neuromodulation techniques, along with shifting environmental and internal states, are promising novel treatment interventions for altering neural alterations underlying decision-making. Our review further articulates the translational promise of this construct into the development, maintenance and treatment of psychiatric conditions, particularly those characterized by reward-, effort- and valuation-related deficits.

Neural substrates of the interaction between effort-expenditure reward decision-making and outcome anticipation

OBJECTIVE

Reward anticipation is important for future decision-making, possibly due to re-evaluation of prior decisions. However, the exact relationship between reward anticipation and prior effort-expenditure decision-making, and its neural substrates are unknown.

METHOD

Thirty-three healthy participants underwent fMRI scanning while performing the Effort-based Pleasure Experience Task (E-pet). Participants were required to make effort-expenditure decisions and anticipate the reward.

RESULTS

We found that stronger anticipatory activation at the posterior cingulate cortex was correlated with slower reaction time while making decisions with a high-probability of reward. Moreover, the substantia nigra was significantly activated in the prior decision-making phase, and involved in reward-anticipation in view of its strengthened functional connectivity with the mammillary body and the putamen in trial conditions with a high probability of reward.

CONCLUSIONS

These findings support the role of reward anticipation in re-evaluating decisions based on the brain-behaviour correlation. Moreover, the study revealed the neural interaction between reward anticipation and decision-making.

Aberrant effort-based reward dynamics in anhedonia

Anhedonia is a transdiagnostic symptom and associated with a spectrum of reward deficits among which the motivational dysfunction is poorly understood. Previous studies have established the abnormal cost-benefit trade-off as a contributor to motivational deficits in anhedonia and its relevant psychiatric diseases. However, it remains elusive how the anhedonic neural dynamics underlying reward processing are modulated by effort expenditure. Using an effort-based monetary incentive delay task, the current event-related potential study examined the neural dynamics underlying the effort-reward interplay in anhedonia using a nonclinical sample who scored high or low on an anhedonia questionnaire. We found that effort prospectively decreased reward effect on the contingent variation negativity and the target-P3 but retrospectively enhanced outcome effect on the feedback-P3 following effort expenditure. Compared to the low-anhedonia group, the high-anhedonia group displayed a diminished effort effect on the target-P3 during effort expenditure and an increased effort-enhancement effect for neutral trials during the feedback-P3 period following effort expenditure. Our findings suggest that anhedonia is associated with an inefficient control and motivation allocation along the efforted-based reward dynamics from effort preparation to effort production.

Effort expenditure modulates feedback evaluations involving self-other agreement: evidence from brain potentials and neural oscillations

The influence of effort expenditure on the subjective value in feedback involving material reward has been the focus of previous research. However, little is known about the impact of effort expenditure on subjective value evaluations when feedback involves reward that is produced in the context of social interaction (e.g. self-other agreement). Moreover, how effort expenditure influences confidence (second-order subjective value) in feedback evaluations remains unclear. Using electroencephalography, this study aimed to address these questions. Event-related potentials showed that, after exerting high effort, participants exhibited increased reward positivity difference in response to self-other (dis)agreement feedback. After exerting low effort, participants reported high confidence, and the self-other disagreement feedback evoked a larger P3a. Time-frequency analysis showed that the high-effort task evoked increased frontal midline theta power. In the low (vs. high)-effort task, the frontal midline delta power for self-other disagreement feedback was enhanced. These findings suggest that, at the early feedback evaluation stage, after exerting high effort, individuals exhibit an increased sensitivity of subjective value evaluation in response to self-other agreement feedback. At the later feedback evaluation stage, after completing the low-effort task, the self-other disagreement feedback violates the individuals'high confidence and leads to a metacognitive mismatch.

Is providing choices always a good thing? the backfire effect of providing choices on competence restoration

Grounded in self-determination theory (SDT), the purpose of this research is to investigate the influence of providing choices following competence frustration on one's intrinsic motivation in a follow-up task. Study 1 conducted a between-group EEG experiment with 50 participants and used a component of event-related potentials (ERPs) to represent intrinsic motivation. Study 2 was a behavioural experiment with 149 participants, adopting the self-report method to measure intrinsic motivation. The stimuli and procedure in Study 1 are identical to Study 2. All participants were asked to complete a high-difficult time-estimation (TE) task during sessions 1-2, and a moderate-difficult stopwatch (SW) task during session 3 (no choices in the control group vs. providing choices in the experimental group). In Study 1, we observed a smaller reward positivity (RewP) difference wave in the experimental (vs. control) group during session 3. In Study 2, participants' intrinsic motivation in the experimental (vs. control) group is significantly lower. The results suggest that providing choices impairs the competence-frustrated participants' intrinsic motivation in the follow-up task and hinders competence restoration. Thus, the current research contributes original neuroscientific and subjective evidences for the adverse influence of providing choices on the competence-frustrated individual's intrinsic motivation, and suggests important practical implications.

Effort discounts reward-based control allocation: A neurodynamic perspective

The amount of cognitive and neural resources allocated to a task is largely determined by the reward we can expect. However, it remains under-appreciated how this reward-expectation-based control allocation is modulated by effort expenditure. The present event-related potential study investigated this issue through the lens of neural dynamics. Thirty-four participants completed an effort-based monetary incentive delay task while their EEG was recorded. Effort demand was manipulated by adding no (low effort) or much (high effort) noise to the target. Behaviorally, participants exhibited reward-related speeding regardless of effort expenditure, as revealed by faster RTs for reward than neutral trials. Our ERP results demonstrated a widespread facilitatory influence of reward expectation on neural dynamics extending from cue evaluation as indexed by the cue-P3, to control preparation as indexed by the contingent negative variation (CNV), and finally to control engagement as indexed by the target-P3. Critically, the neural facilitation was discounted by effort expenditure during both the control-preparation and control-engagement stages instead of the cue-evaluation stage. Overall, this study provides neurodynamic evidence that control allocation is determined by reward and effort via a cost-benefit analysis.

Dissociable neural after-effects of cognitive and physical effort expenditure during reward evaluation

The reward after-effect of effort expenditure refers to the phenomenon that previous effort investment changes the subjective value of rewards when obtained. However, the neural mechanisms underlying the after-effects of effort exertion are still not fully understood. We investigated the modulation of reward after-effects by effort type (cognitive vs. physical) through the lens of neural dynamics. Thirty-two participants performed a physically or cognitively demanding task during an effort phase and then played a simple gambling game during a subsequent reward phase to earn monetary rewards while their electroencephalogram (EEG) was recorded. We found that previous effort expenditure decreased electrocortical activity during feedback evaluation. Importantly, this effort effect occurred in a domain-general manner during the early stage (as indexed by the reward positivity) but in a domain-specific manner during the later and more elaborative stage (as indexed by the P3 and delta oscillation) of reward evaluation. Additionally, effort expenditure enhanced P3 sensitivity to feedback valence regardless of effort type. Our findings suggest that cognitive and physical effort, although bearing some surface resemblance to each other, may have dissociable neural influences on the reward after-effects.

Need for cognition moderates the relief of avoiding cognitive effort

When making decisions, humans aim to maximize rewards while minimizing costs. The exertion of mental or physical effort has been proposed to be one those costs, translating into avoidance of behaviors carrying effort demands. This motivational framework also predicts that people should experience positive affect when anticipating demand that is subsequently avoided (i.e., a "relief effect"), but evidence for this prediction is scarce. Here, we follow up on a previous study [1] that provided some initial evidence that people more positively evaluated outcomes if it meant they could avoid performing an additional demanding task. However, the results from this study did not provide conclusive evidence that this effect was driven by effort avoidance. Here, we report two experiments that are able to do this. Participants performed a gambling task, and if they did not receive reward they would have to perform an orthogonal effort task. Prior to the gamble, a cue indicated whether this effort task would be easy or hard. We probed hedonic responses to the reward-related feedback, as well as after the subsequent effort task feedback. Participants reported lower hedonic responses for no-reward outcomes when high vs. low effort was anticipated (and later exerted). They also reported higher hedonic responses for reward outcomes when high vs. low effort was anticipated (and avoided). Importantly, this relief effect was smaller in participants with high need for cognition. These results suggest that avoidance of high effort tasks is rewarding, but that the size off this effect depends on the individual disposition to engage with and expend cognitive effort. They also raise the important question of whether this disposition alters the cost of effort per se, or rather offset this cost during cost-benefit analyses.

Rewarding outcomes enhance attentional capture and delay attentional disengagement

Attentional capture and disengagement are distinct process involved in attentional orienting. Most current studies have examined either the process of attentional capture or disengagement by manipulating stimuli associated with either positive (gains) or negative outcomes (losses). However, few studies have investigated whether attentional capture and disengagement are modulated by reward and loss outcomes. In the current study, we want to examine whether positive or negative outcomes could modulate distinguishing process of attentional capture and disengagement. Here, we manipulated different colored singleton stimuli associated with reward or loss outcomes; these stimuli were either presented at the center of screen or at the peripheral location. The participants' task was to search the target and identify the orientation of line segment in target as quickly as possible. The results showed that people had difficulty disengaging from a central reward-distractor, in comparison to loss- and neutral-distractor when target was presented at peripheral location. Similarly, peripheral reward-distractor captured more attention than loss- and neutral-distractor when target was presented at the center of screen after central fixation disappeared. Through our discoveries, we can conclude that positive rewards can increase attentional capture and delay attentional disengagement in healthy people.

Expending effort may share neural responses with reward and evokes high subjective satisfaction

Throughout our daily lives, the levels of effort we invest in various tasks are influenced by reward processing. The subjective expectation after expending effort is a primary factor affecting reward processing. However, recent studies indicate that individual differences in reward anticipation influence this subjective valuation. To better understand the relationship between effort expenditure and the subjective valuation of rewards, in this study, we perform an experiment in which we manipulate effort, control reward expectation implicitly, and measure the subjective valuation of rewards using event-related potentials (ERPs) and physical effort through behavioral measures (number of keystrokes). In the reward-task paradigm, 30 subjects performed effort and control trials, with the reward probability comparable across the effort and control conditions. We also examined the ERPs associated with the valuation of subjective rewards, including reward positivity (RewP) and set reward expectation controlled as the baseline. The results showed that the ERP amplitudes, the number of keystrokes, and explicit satisfaction ratings were all significantly greater in the effort condition than in the control condition. The participants maintained high levels of effort throughout the sessions associated with the experiment. The results of this study suggest that when reward expectations are controlled, effort expenditure evokes neural responses similar to reward feedback being given, which is linked with increased subjective satisfaction.