How to test for phasic modulation of neural and behavioural responses

Abstract

Research on whether perception or other processes depend on the phase of neural oscillations is rapidly gaining popularity. However, it is unknown which methods are optimally suited to evaluate the hypothesized phase effect. Using a simulation approach, we here test the ability of different methods to detect such an effect on dichotomous (e.g., “hit” vs “miss”) and continuous (e.g., scalp potentials) response variables. We manipulated parameters that characterise the phase effect or define the experimental approach to test for this effect. For each parameter combination and response variable, we identified an optimal method. We found that methods regressing single-trial responses on circular (sine and cosine) predictors perform best for all of the simulated parameters, regardless of the nature of the response variable (dichotomous or continuous). In sum, our study lays a foundation for optimized experimental designs and analyses in future studies investigating the role of phase for neural and behavioural responses. We provide MATLAB code for the statistical methods tested.

Perception of rhythmic speech is modulated by focal bilateral tACS

“…We applied two different statistical analyses to data for both experiments: A pre-registered analysis, and an analysis optimized based on simulations (Zoefel, Davis, Valente, & Riecke, 2019), both described in the following. Although data for Experiment 1 was collected prior to the pre-registration of Experiment 2, the pre-registered analysis had not been applied to the data at that time.…”

“…Although data for Experiment 1 was collected prior to the pre-registration of Experiment 2, the pre-registered analysis had not been applied to the data at that time. The optimized analysis was selected exclusively based on results from simulations (Zoefel et al, 2019) and had not been applied to any of the datasets prior to selection.…”

“…not prone to false-positives; Asamoah, Khatoun, & Mc Laughlin, 2019a), and was similar to analyses that had been used in published papers at the time of pre-registration, it was unclear whether this was the optimal approach for detecting tACS-induced phase effects. Subsequently, and in parallel with data collection, we ran Monte-Carlo simulations designed to determine the optimal analysis for this and similar scientific questions (Zoefel et al, 2019). In this study, we simulated 2 x 1000 datasets with and without a phase effect on binary perceptual outcomes ("hit" vs "miss").…”

“…Based on these selection criteria, we determined that the MAX-OPP VS MIN-OPP analysis in Zoefel et al (2019) was optimal and we therefore applied this analysis to the data from the current experiment.…”

“…Enhancing or disrupting effects might exist but cannot be revealed as only the second most extreme values are compared against 0. We therefore also report a potentially more optimal procedure, inspired by the outcome of our Monte-Carlo simulations (Zoefel et al, 2019).…”