EXPRESS: A new experimental paradigm to investigate how imagery-based suggestions are embodied.

This study investigated how imagery-based-suggestions were embodied in perception and behaviour. In experiment 1, Participants listened to several suggestion scripts while stretching the left arm (they were required not to move). During 30s, the script invited participants to imagine the experimenter facing them. During the following 30s, they imagined him placing either a heavy dictionary or a light paper sheet on their hand (implicit suggestions). During the last 30s, suggestions explicitly described how the object pushed its support down. In two other conditions, participants really performed these actions with real objects. Results showed that after implicit and explicit suggestions, the arm lowered more in the dictionary condition than in the paper sheet one. Similar patterns were observed in conditions with real objects. In experiment 2, we used the same imagery-based-suggestions but added a condition where participants imagined the dictionary placed on a table. Moreover, we measured the participants' centre of pressure (CP). Results showed that after implicit and explicit suggestions, the participants' arm lowered more in the dictionary on the arm condition than in other conditions. After implicit suggestions, CP moved more rightward in the dictionary on the arm condition than the paper sheet one. Finally, perceived difficulty was lower in the paper sheet condition than in other conditions. Regarding embodied cognition theories, results suggest that participants behaved as if the sensorimotor processes activated by mental images became integrated to the processes related to the actual situation. Further studies are needed to test whether other processes might be complementary involved.