The role of mental imagery in pantomimes of actions towards and away from the body

This study aimed to explore the relationship between action execution and mental rotation modalities. To this end, pantomime gesture (i.e. the mime of the use of an object) was used as its execution relies on imagery processes. Specifically, we tried to clarify the role of visuo-spatial or motor and body-related mental imagery processes in pantomime gestures performed away (AB, e.g. drawing on a sheet) and towards the body (TB, e.g. brushing the teeth). We included an "actual use" condition in which participants were asked to use a toothbrush and make 3, 6, or 9 circular movements close to their mouth (as if they were brushing their teeth) or to use a pencil and make 3, 6, or 9 circular movements on a desk (as if they were drawing circles). Afterwards, participants were asked to pantomime the actual use of the same objects ("pantomime" condition). Finally, they were asked to mentally rotate three different stimuli: hands, faces, and abstract lines. Results showed that participants were faster in AB than TB pantomimes. Moreover, the more accurate and faster the mental rotation of body-related stimuli was, the more similar the temporal duration between both kinds of pantomimes and the actual use of the objects appeared. Instead, the temporal similarity between AB pantomimes and pencil actual use, as well as, the duration of AB pantomime and actual use, were associated with the ability to mentally rotate abstract lines. This was not true for TB movements. These results suggest that the execution of AB and TB pantomimes may involve different mental imagery modalities. Specifically, AB pantomimes would not only require to mentally manipulate images of body-parts in movement but also represent the spatial relations of the object with the external world.