Relevance of the listener’s motor system in recalling phrases enacted by the speaker

ABSTRACT

Memory for series of action phrases improves in listeners when speakers accompany each phrase with congruent gestures compared to when speakers stay still. Studies reveal that the listeners’ motor system, at encoding, plays a crucial role in this enactment effect. We present two experiments on gesture observation, which explored the role of the listeners’ motor system at recall. The participants listened to the phrases uttered by a speaker in two conditions in each experiment. In the gesture condition, the speaker uttered the phrases with accompanying congruent gestures, and in the no-gesture condition, the speaker stayed still while uttering the phrases. The participants were then invited, in both conditions of the experiments, to perform a motor task while recalling the phrases proffered by the speaker. The results revealed that the advantage of observing gestures on memory disappears if the listeners move at recall arms and hands (same motor effectors moved by the speaker, Experiment 1a), but not when the listeners move legs and feet (different motor effectors from those moved by the speaker, Experiment 1b). The results suggest that the listeners’ motor system is involved not only during the encoding of action phrases uttered by a speaker but also when recalling these phrases during retrieval.

KEYWORDS:

• Enactment
• motor system
• gesture observation
• memory for actions

Acknowledgements

The experimental material used in this paper is archived at the following database: https://osf.io/zw96y/ We thank Giuliana Mazzoni and Andrea Cavallo for helpful advice.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. Identical results were obtained carrying out mixed-effect logistic regression, implemented with the glmer() function from the lme4 package (version 1.1-14; Bates et al., 2017) in the R statistical programming environment. A model including Gesture and Group as fixed factor of interest, and Subjects and Item as fixed random effect with the maximal structure of random effects supported by the design (Barr, Levy, Scheepers, & Tily, 2013) detected the same Gesture*Group significant interaction (ß = .65, SE = .26, z = 2.46, p = .01). The model specification was: Recalled ∼ Gesture*Group + (1 + Gesture|Subjects) + (1 + Gesture*Group|Item). This analysis has been performed using the optimizer “bobyqa” to prevent non-convergence problems. Identical results were obtained also when carrying out non-parametric analyses.