Neurophysiological evidence of motor preparation in inner speech and the effect of content predictability.

Self-generated overt actions are preceded by a slow negativity as measured by electroencephalogram, which has been associated with motor preparation. Recent studies have shown that this neural activity is modulated by the predictability of action outcomes. It is unclear whether inner speech is also preceded by a motor-related negativity and influenced by the same factor. In three experiments, we compared the contingent negative variation elicited in a cue paradigm in an active vs. passive condition. In Experiment 1, participants produced an inner phoneme, at which an audible phoneme whose identity was unpredictable was concurrently presented. We found that while passive listening elicited a late contingent negative variation, inner speech production generated a more negative late contingent negative variation. In Experiment 2, the same pattern of results was found when participants were instead asked to overtly vocalize the phoneme. In Experiment 3, the identity of the audible phoneme was made predictable by establishing probabilistic expectations. We observed a smaller late contingent negative variation in the inner speech condition when the identity of the audible phoneme was predictable, but not in the passive condition. These findings suggest that inner speech is associated with motor preparatory activity that may also represent the predicted action-effects of covert actions.

Longitudinal bifactor modeling of anxiety, depression and schizotypy - The role of rumination as a shared mechanism.

A bifactor model with a general (p) factor reflecting shared variance and specific factors reflecting additional variance in individual symptoms has been introduced to explain common co-occurrence among anxiety, depression and schizotypy. However, longitudinal evidence is lacking and the validity of bifactor modeling is debatable. The current study aimed to examine the presence of the p factor together with specific factors in accounting for relationships between anxiety, depression and schizotypy both cross-sectionally and longitudinally, and to investigate the relationship between these factors and rumination. A validated sample of university students were surveyed on levels of anxiety, depression, schizotypy and rumination at baseline (N = 2291), one year (N = 1833) and two years (N = 1656). Models were estimated using exploratory structural equation modeling (ESEM) and compared at each time point. Longitudinal invariance of the best-fitting model was examined and all potential within- and between-factor stability pathways were tested in an SEM framework. A bifactor model with a p factor and four specific factors (representing residual information of composite anxiety and depression, cognitive-perceptual, interpersonal and disorganized schizotypy respectively) consistently outperformed a correlated-factors model. The bifactor structure appeared longitudinally stable. Within-factor stabilities were moderate, and between-factor pathways reflected a few significant interactions, mostly involving the p factor. Rumination was independently associated with p and four specific factors at each time point. Therefore, there is a p factor accounting for concurrent and sequential co-occurrence of anxiety, depression and schizotypy. Rumination explained partly the p and specific factors. Transdiagnostic interventions should target rumination.