Grip force and emotional face processing

This is a preregistered secondary analysis of an existing, publicly available dataset (OSF: https://osf.io/d2gb6/) in which 26 right-handed participants viewed happy, sad, and neutral faces in a go/no-go task while bimanual grip force was recorded. Using a Bayesian framework, we test whether spontaneous grip-force change following an emotional face is better explained by the stimulus's arousal (intensity) or its valence (signed direction), collapsing across hands. Arousal and valence are entered as two orthogonal contrasts in a set of Bayesian linear mixed-effects models (brms), compared via leave-one-out cross-validation and Savage–Dickey Bayes factors within two a-priori time windows. The two accounts are adjudicated by a pre-committed decision rule. Because the data and an earlier (unpublished) frequentist analysis exist, prior exposure is disclosed and the confirmatory analyst works masked. Initial emotional state is examined as an exploratory moderator.