Is reaction time variability consistent across sensory modalities? Insights from latent variable analysis of single-trial P3b latencies.

Recent years have witnessed a steep increase in cognitive, differential and clinical neuroscience research on the neural basis of intra-subject variability of reaction times. Most theoretical accounts make the implicit assumption that individual differences in intra-subject variability are consistent across sensory modalities, but this remains largely untested. The present EEG study aims to fill this gap by analyzing, for the first time, stimulus- and response-locked single-trial P3bs across visual and auditory sensory modalities, and employing an innovative supra-task latent variables approach. We found unidimensionality of intra-subject variability variables across modalities as well as high correlations between the latency jitter of stimulus- and response-locked P3bs. These findings support the hypothesis that intra-subject variability represents a unitary construct, and that the processes underlying that generalises not only across different cognitive tasks, but also across different sensory modalities.