The cognitive effects of a promised bonus do not depend on dopamine synthesis capacity

Reward motivation is known to enhance cognitive control. However, detrimental effects have also been observed, which have been attributed to overdosing of already high baseline dopamine levels by further dopamine increases elicited by reward cues. Aarts et al. (2014) indeed demonstrated, in 14 individuals, that reward effects depended on striatal dopamine synthesis capacity, measured with [18F]FMT-PET: promised reward improved Stroop control in low-dopamine individuals, while impairing it in high-dopamine individuals. Here, we aimed to assess this same effect in 44 new participants, who had previously undergone an [18F]DOPA-PET scan to quantify dopamine synthesis capacity. This sample performed the exact same rewarded Stroop paradigm as in the prior study. However, we did not find any correlation between reward effects on cognitive control and striatal dopamine synthesis capacity. Critical differences between the radiotracers [18F]DOPA and [18F]FMT are discussed, as the discrepancy between the current and our previous findings might reflect the use of the potentially less sensitive [18F]DOPA radiotracer in the current study.

The cognitive effects of a promised bonus do not depend on dopamine synthesis capacity

ABSTRACTReward motivation is known to enhance cognitive control. However, detrimental effects have also been observed, which have been attributed to overdosing of already high baseline dopamine levels by further dopamine increases elicited by reward cues. Aarts et al. (2014) indeed demonstrated, in 14 individuals, that reward effects depended on striatal dopamine synthesis capacity, measured with [18F]FMT-PET: promised reward improved Stroop control in low-dopamine individuals, while impairing it in high-dopamine individuals. Here, we aimed to assess this same effect in 44 new participants, who had previously undergone an [18F]DOPA-PET scan to quantify dopamine synthesis capacity. This sample performed the exact same rewarded Stroop paradigm as in the prior study. However, we did not find any correlation between reward effects on cognitive control and striatal dopamine synthesis capacity. The discrepancy between the current and our previous findings might reflect the use of different radiotracers for indexing dopamine synthesis capacity.STATEMENT OF RELEVANCEReward motivation is generally thought to enhance cognitive control, but paradoxical negative effects of rewards on cognitive control have also been observed. A previous PET study demonstrated that reward effects on Stroop control depended on baseline striatal dopamine synthesis capacity, indexed by uptake of the radiotracer [18F]FMT. The sample size is this study was very small for a between-subject correlational design. Replicating the exact same Stroop paradigm within a larger sample is therefore crucial to robustly establish the mechanistic link between incentive motivation and cognitive control and advancing our understanding of who chokes under pressure and why, a topic of great societal relevance today. The present study did not reveal any correlation between reward effects on cognitive control and striatal dopamine synthesis capacity, indexed with [18F]FDOPA-PET. Future studies might consider putative differential sensitivity of the radiotracer [18F]FMT and [18F]FDOPA, while also addressing other indices of dopamine transmission.

Does a non-practiced cognitive automatism withstand the test of time?

The present study aimed to ascertain whether the automaticity of a learned-cognitive process persisted after lengthy and complete cessation of practice. The musical Stroop paradigm offers the opportunity to test this specific question by evaluating the automaticity of note naming, the flexibility in manipulating practice of which is much greater than that of other cognitive automatisms like reading. Participants who previously attained a high level of musical expertise and ceased all musical practice for at least 3 years exhibited a musical Stroop effect, which attests to the automaticity of note naming. The musical Stroop effect was still observed in a subset of participants who completely ceased musical practice for more than 10 years. Our results suggest that the absence of practice, even over a very long period of time, does not eliminate the automaticity of cognitive processes.

Cognitive Mechanism of Emotional Validity Influencing Conflict Control

Conflict control is the ability to choose relevant information and ignore disturbing information in task processing. Previous studies have found that emotions have a certain influence on conflict control, and the research results of positive emotions and negative emotions affect conflict control are inconsistent. This study attempted to explore the effects of different emotional valorization on conflict control, using images of happy, fearful and sad emotional faces to investigate the effects of different emotional valorization and different emotional types on conflict control. The experiment selected 40 participants and used the variable-face Stroop paradigm. The study found that no matter what emotional task, there is a significant conflict effect. The effects of different valency on conflict control are different. All three emotions have a significant effect on conflict control, and positive emotions play a role in promoting conflict control.

Context-specific proportion congruent effects: Compound-cue contingency learning in disguise

Conflict between task-relevant and task-irrelevant stimulus information leads to impairment in response speed and accuracy. For instance, in the colour-word Stroop paradigm, participants respond slower and less accurately to the print colour of incongruent colour words (e.g., “red” printed in green) than to congruent colour words (e.g., “green” in green). Importantly, this congruency effect is diminished when the trials in an experiment are mostly incongruent, relative to mostly congruent, termed a proportion congruent effect. When distracting stimuli are mostly congruent in one context (e.g., location or font) but mostly incongruent in another context (e.g., another location or font), the congruency effect is still diminished in the mostly incongruent context, termed a context-specific proportion congruent (CSPC) effect. Both the standard proportion congruent and CSPC effects are typically interpreted in terms of conflict-driven attentional control, frequently termed conflict adaptation or conflict monitoring. However, in two experiments, we investigated contingency learning confounds in context-specific proportion congruent effects. In particular, two variants of a dissociation procedure are presented with the font variant of the CSPC procedure. In both, robust contingency learning effects were observed. No evidence for context-specific control was observed. In fact, results trended in the wrong direction. In all, the results suggest that CSPC effects may not be a useful way of studying attentional control.

Symmetries of bilingual language switch costs in conflicting versus non-conflicting contexts

Previous studies have demonstrated that language switching in bilinguals can be affected by a number of variables, including the processing context. Here, we used a modified language-switching task combined with a Stroop paradigm, which manipulated the context of the task, to examine the impact of processing context on switch costs. The results of both Experiment 1 and Experiment 2 showed that the switch costs and the level of asymmetry in the switch costs are larger in the conflicting context than in the non-conflicting context, suggesting that the processing context affects the switch costs. In addition, the results of Experiment 2 revealed that individual variances in cognitive control capacity also play a role in the overall magnitude of the switch costs. Critically, processing context effects can be modulated by individual variance in cognitive control capacities. The results of this study are discussed within the framework of classic models of bilingual language control (e.g., the inhibitory control model).

Animacy and attentional processes: Evidence from the Stroop task

In visual perception, evidence has shown that attention is captured earlier and held longer by animate than inanimate stimuli. The former are also remembered better than the latter. Thus, as far as attentional processes are concerned, animate entities have a privileged status over inanimate entities. We tested this hypothesis further using an adaptation of the Stroop paradigm. Adults had to categorise the colours of words that referred to either animate or inanimate concepts. In two experiments, we found that it took longer to process the ink colour of animate than inanimate words. Indeed, this effect was found when the words were presented in an oral animacy Stroop task (Experiment 1) and in a manual animacy Stroop task (Experiment 2). Using ex-Gaussian analyses and examining the distribution of RTs as a function of vincentiles per animacy condition, we did not find a specific localisation of the animacy effect. The findings are interpreted as providing further evidence that animates are prioritised in processing because their fitness value is higher than that of inanimates.