It is better when expected: aligning speech and motor rhythms enhances verbal processing

ABSTRACT

Rhythm is a powerful way to shape the processing of complex sounds such as speech or music by generating temporal expectancies in the listener. Here, we investigated if multisensory expectancies generated by aligning speech and motor rhythms may enhance verbal processing. Participants listened to rhythmically regular German sentences and detected word changes occurring on stressed or unstressed syllables. Participants were cued to produce finger taps simultaneously with the auditory speech rhythm. Finger taps were aligned or misaligned with stressed syllables. Detection of word changes was facilitated when manual movements were temporally aligned with the auditory speech rhythm. Moreover, motor alignment enhanced sensitivity to detect changes on stressed syllables compared to a perceptual control condition. Thus, rhythmic speech structure reinforced by concurrent movement in multisensory contexts has beneficial effects on verbal processing. This finding lends support to models of expectancy-driven speech processing.

KEYWORDS:

• Speech perception
• multisensory rhythm
• verbal processing
• temporal expectancies
• temporal prediction

Acknowledgements

We thank the IPS (LMU Munich), Franziska Flieger, Franziska Holzheimer, Elena Maslow, Judith Oebels and Alina Schmajew for help with stimulus preparation and testing.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. A MIDI delay of 81 ms was subtracted from all motor data. One per cent of the DT data were discarded due to particularly slow responses (>3 s), 9% were not available because of failures in recording participants’ motor response (five participants were therefore excluded from analysis).

2. In order to assure that the unequal sample sizes did not impact on differences observed between groups, we ran the same ANOVAs with equal sample sizes by randomly choosing a sample of 32 participants in the tapping condition (half of the participants received stimuli in weak, half in strong positions; half of the participants began with congruent alignment, half with incongruent alignment). The ANOVAs yielded the same effects and interactions as with the larger sample except for the main effect of Task in DT. Main effects of Position were found for d′, C and DT (d′: F(1, 60) = 8.33, p = .005; C: F(1, 60) = 5.80, p = .019; DT: F(1, 60) = 29.63, p < .001). A main effect of Alignment was found for C (F(1, 60) = 5.10, p = .028) and Task × Alignment interactions for d′ and DT (d′: F(1, 60) = 7.17, p = .01, DT: F(1, 60) = 6.52, p = .013).

3. As the baseline had no alignment condition (no cue was present), t-tests were the most appropriate means of statistical comparison.

Additional information

Funding

This work was supported by the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007–2013) under REA grant agreement n°327586 to S.F., the LMU Munich's Institutional Strategy LMUexcellent within the framework of the German Excellence Initiative to S.F., the Institut Universitaire de France (IUF) to S.D.B. Both authors were financially supported by a bilateral travel grant of the DAAD and Polish Ministery of Science and Higher Education.