Effects of response force parameters on medial-frontal negativity

The relationship between response dynamics and the formation of confidence varies across the lifespan

Accurate metacognitive judgments, such as forming a confidence judgment, are crucial for goal-directed behavior but decline with older age. Besides changes in the sensory processing of stimulus features, there might also be changes in the motoric aspects of giving responses that account for age-related changes in confidence. In order to assess the association between confidence and response parameters across the adult lifespan, we measured response times and peak forces in a four-choice flanker task with subsequent confidence judgments. In 65 healthy adults from 20 to 76 years of age, we showed divergent associations of each measure with confidence, depending on decision accuracy. Participants indicated higher confidence after faster responses in correct but not incorrect trials. They also indicated higher confidence after less forceful responses in errors but not in correct trials. Notably, these associations were age-dependent as the relationship between confidence and response time was more pronounced in older participants, while the relationship between confidence and response force decayed with age. Our results add to the notion that confidence is related to response parameters and demonstrate noteworthy changes in the observed associations across the adult lifespan. These changes potentially constitute an expression of general age-related deficits in performance monitoring or, alternatively, index a failing mechanism in the computation of confidence in older adults.

The gamma model analysis (GMA): Introducing a novel scoring method for the shape of components of the event-related potential

BACKGROUND

Research using the event-related potential (ERP) method to investigate cognitive processes has usually focused on the analysis of either individual peaks or the area under the curve as components of interest. These approaches, however, do not analyse or describe the substantial variation in size and shape across the entire individual waveforms.

NEW METHOD

Here we show that the precision of ERP analyses can be improved by fitting gamma functions to components of interest. Gamma model analyses provide time-dependent and shape-related information about the component, such as the component's rise and decline. We demonstrated the advantages of the gamma model analysis in a simulation study and in a two-choice response task, as well as a force production task.

RESULTS

The gamma model parameters were sensitive to experimental variations, as well as variations in behavioural parameters.

COMPARISON WITH EXISTING METHODS

Gamma model analyses provide researchers with additional reliable indicators about the shape of an ERP component's waveform, which previous analytical techniques could not.

CONCLUSION

This approach, therefore, provides a novel toolset to better understand the exact relationship between ERP components, behaviour and cognition.

Performance monitoring and response conflict resolution associated with choice stepping reaction tasks

Choice reaction requires response conflict resolution, and the resolution processes that occur during a choice stepping reaction task undertaken in a standing position, which requires maintenance of balance, may be different to those processes occurring during a choice reaction task performed in a seated position. The study purpose was to investigate the resolution processes during a choice stepping reaction task at the cortical level using electroencephalography and compare the results with a control task involving ankle dorsiflexion responses. Twelve young adults either stepped forward or dorsiflexed the ankle in response to a visual imperative stimulus presented on a computer screen. We used the Simon task and examined the error-related negativity (ERN) that follows an incorrect response and the correct-response negativity (CRN) that follows a correct response. Error was defined as an incorrect initial weight transfer for the stepping task and as an incorrect initial tibialis anterior activation for the control task. Results revealed that ERN and CRN amplitudes were similar in size for the stepping task, whereas the amplitude of ERN was larger than that of CRN for the control task. The ERN amplitude was also larger in the stepping task than the control task. These observations suggest that a choice stepping reaction task involves a strategy emphasizing post-response conflict and general performance monitoring of actual and required responses and also requires greater cognitive load than a choice dorsiflexion reaction. The response conflict resolution processes appear to be different for stepping tasks and reaction tasks performed in a seated position.

Brief Report: Some Remarks About the Response Relatedness of the Error Negativity

The error negativity (Ne) is a prominent response-related potential reflecting error processing or response monitoring processes. Despite the huge amount of literature dealing with the Ne, only few studies investigated how close the Ne is related to the kind of response collected by the experimental setup. The present study investigated whether the Ne differs between force locked and force level related (aka button press) data. Indeed, the Ne was more pronounced for force onset compared to level trigger and appeared to be related to the steepness of the raise of force. These results implicate that the parameterization of the Ne has to be treated with caution under certain circumstances and it appears to be advisable to use force onset or the electromyogram to detect response onset if timing or latency is relevant.