Introduction - In hypnosis, imaginative suggestions (IS) consist in invitations to experience an imaginary state or situation (e.g., your arm is heavy). They partly rely on mental imagery processes and can be efficient even without any prior hypnotic induction. Santarcangelo et al. (2005) showed for instance that when participants are required to extend the arm while listening to a script suggesting that this arm is heavy and is falling, the vertical arm movements are influenced by the script. Our study had two goals. First, we aimed to test whether Santarcangelo et al.’s (2005) re- sults could be replicated when (1) participants have to keep their posture stationary, (2) the script doesn’t explicitly suggest any movement, and (3) no prior hypnotic induction was done. Second, the relation between participant and practitioner is thought to influence IS efficiency (Lynn et al., 1991). The mirror game (a procedure in which two participants imitate each other and synchronize their movements) is known to influence the mutual perception of participants (Feniger-Schaal et al., 2018). We aimed to test whether practicing it with the experimenter would influence the participant’s response to IS. Methods - Each participant performed four phases in a counterbalanced order. Each phase unfolded as follows. First, participant either did the mirror game with the experimenter or had to move independently. Second, he extended his left arm in parallel to the floor at shoulder level. He had to keep this position, with closed eyes, while listening to a script that described a realistic scene. From 0s to 30s, the script suggested to imagine someone in front of him carrying either a heavy dictionary (HD) or a light paper sheet (LPS). From 30s to 60s, it suggested that this object was put on his hand. From 60s to 90s, it suggested that a second similar object was added. Third, participant had to rate the task difficulty and his state of consciousness during the task. All factors, IS (HD vs LPS) and mirror game (with vs without) were manipulated within participant. We recorded arm movements. Results/discussion - Our protocol showed several results. First, participants lowered more their arms and rated the effort as more difficult in the HD condition than in the LPS one. Second, in comparison to LPS condition, the HD one made the participants feel a more unusual consciousness state. Third, the mirror game enhanced the feeling of unusual consciousness state in comparison to the no mirror game condition, but it didn’t modulate the IS influence. These results give clues about the imagery processes that underlie the efficiency of IS, even without prior hypnotic induction. They also offer new perspectives to investigate interactions between IS and consciousness state. References - Feniger-Schaal, R., Hart, Y., Lotan, N., Koren-Karie, N., & Noy, L. (2018). The Body Speaks: Using the Mirror Game to Link Attachment and Non-verbal Behavior. Frontiers in Psychology, 9, 1560 Lynn, S. J., Weekes, J. R., Neufeld, V., Zivney, O., & et al. (1991). Interpersonal climate and hypnotizability level: Effects on hypnotic performance, rapport, and archaic involvement. Journal of Personality and Social Psychology, 60 (5), 739-743 Santarcangelo, E. L., Cavallaro, E., Mazzoleni, S., Marano, E., Ghelarducci, B., Dario, P., Micera, S., & Sebastiani, L. (2005). Kinematic strategies for lowering of upper limbs during suggestions of heaviness: A real-simulator design. Experimental Brain Research, 162 (1), 35-45