Developmental researchers are often interested in event-related potentials (ERPs). Data-analytic approaches based on the observed ERP suffer from major problems such as arbitrary definition of analysis time windows and regions of interest and the observed ERP being a mixture of latent underlying components. Temporal principal component analysis (PCA) can reduce these problems. However, its application in developmental research comes with the unique challenge that the component structure differs between age groups (so-called measurement non-invariance). Separate PCAs for the groups can cope with this challenge. We demonstrate how to make results from separate PCAs accessible for inferential statistics by re-scaling to original units. This tutorial enables readers with a focus on developmental research to conduct a PCA-based ERP analysis of amplitude differences. We explain the benefits of a PCA-based approach, introduce the PCA model and demonstrate its application to a developmental research question using real-data from a child and an adult group (code and data openly available). Finally, we discuss how to cope with typical challenges during the analysis and name potential limitations such as suboptimal decomposition results, data-driven analysis decisions and latency shifts.
Effects of attentional distraction by unexpected and task-irrelevant sounds on task performance are discussed to comprise costs due to orienting of attention toward a distracting event and benefits due to enhanced level of arousal evoked by the processing of such events. Highly arousing distractor sounds may facilitate information and task processing resulting in reduced distraction effects compared to moderately arousing distractor sounds. By measuring pupil dilation responses as a marker of arousal and task performance as a marker of distraction, we disentangled orienting costs and arousal level changes through variations of the emotional content of distractor sounds. While participants (N=60) performed a visual categorization task, an auditory oddball sequence including standard sounds, highly arousing emotional and moderately arousing neutral novel sounds was presented. Multilevel analyses revealed prolonged reaction times to novel sounds compared to standard sounds. Distraction effects decreased when emotional novel sounds were presented compared to neutral novel sounds. Pupil dilation responses were increased in response to novel sounds compared to standard sounds. This increase was larger for emotional than for neutral novel sounds. None of the considered models supported a correlation at trial level between reduced distraction effects and arousal increase reflected by the pupil in response to emotional novel sounds, indicating at least partly independent underlying mechanisms. An exploratory analysis revealed an impact of the baseline pupil size, that indicates tonic level of arousal, on performance and distraction effects. Moreover, a positive correlation between the negative affect scale in the Adult Temperament Questionnaire and RTs was observed.
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