Inner verbalisation can be willful, when we deliberately engage in inner speech (e.g., mental rehearsing, counting, list making) or more involuntary, when unbidden verbal thoughts occur. It can either be expanded (fully phonologically specified) or condensed (cast in a prelinguistic format). Introspection and empirical data suggest that willful expanded inner speech recruits the motor system and involves auditory, proprioceptive, tactile as well as perhaps visual sensations. We present a neurocognitive predictive control model, in which willful inner speech is considered as deriving from multisensory goals arising from sensory cortices. An inverse model transforms desired sensory states into motor commands which are specified in motor regions and inhibited by prefrontal cortex. An efference copy of these motor commands is transformed by a forward model into simulated multimodal acts (inner phonation, articulation, gesture). These simulated acts provide predicted multisensory percepts that are processed in sensory regions and perceived as an inner voice unfolding over time. The comparison between desired sensory states and predicted sensory end states provides the sense of agency, of feeling in control of one’s inner speech. Three types of inner verbalisation can be accounted for in this framework: unbidden thoughts, willful expanded inner speech, and auditory verbal hallucination.

We argue that making accept/reject decisions on scientific hypotheses, including a recent call for changing the canonical alpha level from p = 0.05 to p = 0.005, is deleterious for the finding of new discoveries and the progress of science. Given that blanket and variable alpha levels both are problematic, it is sensible to dispense with significance testing altogether. There are alternatives that address study design and sample size much more directly than significance testing does; but none of the statistical tools should be taken as the new magic method giving clear-cut mechanical answers. Inference should not be based on single studies at all, but on cumulative evidence from multiple independent studies. When evaluating the strength of the evidence, we should consider, for example, auxiliary assumptions, the strength of the experimental design, and implications for applications. To boil all this down to a binary decision based on a p-value threshold of 0.05, 0.01, 0.005, or anything else, is not acceptable.

Rumination is predominantly experienced in the form of repetitive verbal thoughts. Verbal rumination is a particular case of inner speech. According to the Motor Simulation view, inner speech is a kind of motor action, recruiting the speech motor system. In this framework, we predicted an increase in speech muscle activity during rumination as compared to rest. We also predicted increased forehead activity, associated with anxiety during rumination. We measured electromyographic activity over the orbicularis oris superior and inferior, frontalis and flexor carpi radialis muscles. Results showed increased lip and forehead activity after rumination induction compared to an initial relaxed state, together with increased self-reported levels of rumination. Moreover, our data suggest that orofacial relaxation is more effective in reducing rumination than non-orofacial relaxation. Altogether, these results support the hypothesis that verbal rumination involves the speech motor system, and provide a promising psychophysiological index to assess the presence of verbal rumination.