Abstract: Process interference or sharing of attentional resources between cognitive tasks and balance control during upright standing has been well documented. Attentional costs increase with greater balancing demands of a balance activity, for example in standing compared to sitting. The traditional approach for analyzing balance control using posturography with a force plate integrates across relative long trial periods of up to several minutes, which blends any balance adjustments and cognitive operations within this period. In the present study, we pursued an event-related approach to assess if single cognitive operations resolving response selection conflict in the Simon task interfere with concurrent balance control in quiet standing. In addition to traditional outcome measures (response latency, error proportions) in the cognitive Simon task, we investigated the effect of spatial congruency on measures of sway control. We expected that conflict resolution in incongruent trials would alter short-term progression of sway control. Our results demonstrated the expected congruency effect on performance in the cognitive Simon task and the mediolateral variability of balance control within 150 ms before the onset of the manual response was reduced to a greater degree in incongruent compared to congruent trials. In addition, mediolateral variability before and after the manual response was generally reduced compared to variability following target presentation, where no effect of congruency was observed. Assuming that response conflict in incongruent conditions requires suppression of the incorrect response tendencies, our results may imply that mechanisms of cognitive conflict resolution may also carry over to intermittent balance control mechanisms in a direction-specific manner

Abstract: Standing compared to sitting, for instance at work, is associated with positive physical and mental health consequences. Indeed, studies suggest that performance in cognitive conflict tasks (e.g., Color Stroop tasks) is improved when subjects perform the task while standing compared to sitting (Rosenbaum et al., 2018; Smith et al., 2019). However, a recent study failed to replicate these findings in five attempts (Caron et al., 2020). We aimed to shed light on these discrepant results by means of two conceptual replications and a meta-analysis. Replication experiments showed typical congruency effects in the Color Stroop task, but failed to find any influence of posture on the Stroop effect even when we subjected data to a more sensitive analysis that controlled for individual variances between participants. Additionally, an explorative Bayesian analysis confirmed that both replications provided strong evidence against an interaction between body posture and the Stroop effect. Meta-analytic results showed that the confidence interval of the overall effect size for a modulation of the Stroop effect by body posture includes the null. Together, our results question whether standing modulates the Stroop effect in Color Stroop tasks and points out limitations of the influence of body posture on cognitive control tasks