You can't tickle yourself...or can you? The effect of a hypnotic suggestion on sensory attenuation phenomenon

Abstract

The internal motor simulation mechanism is widely believed to generate anticipatory sensory outcomes on the basis of the efferent copy of the motor commands. What is currently unknown is whether the motor prediction mechanism can integrate non-motor inputs such as a hypnotic suggestion in generating sensory predictions. Seventy-two undergraduate students (M=12, F=60) were recruited via Plymouth University participation pool, to undergo a randomised hypnotic suggestion (IV) of either an alien- hand or an alien-foot. The participants were asked to apply tactile stimulation to their left palm (DV) before and after the suggestion and report the tickling sensations. The results revealed an unexpected trend, which just fell short of statistical significance, not only did the control participants get more ticklish over time, but also some participants in the test group felt more in control as a result of alien-hand suggestion. This study found no evidence to support the idea of higher-level functioning forward model. The discussion explores possible explanations for the unexpected findings and highlights a couple of limitations. Finally, implications of the findings are noted with scope of direction for future studies exploring action control theories.