Participant-generated imagery scripts produce greater EMG activity and imagery ability

In this study, we examined whether movement imagery results in greater physiological responses and greater imagery ability when the imagery script is generated by the participant than when generated by the experimenter. Electromyography (EMG) was used to measure left and right biceps brachii and triceps muscle activity in 19 participants during physical and imagined performance of a set of 16 repetitions of a dumbbell curl performed with the right arm. EMG was measured during a relaxed baseline, physical trial and experimenter-generated and participant-generated imagery conditions. The experimenter-generated scripts were based on previously published imagery studies using the same task, whereas the participant-generated scripts were based on the self-reported stimulus and response propositions of the participants. The results showed that self-reported imagery ability ratings were higher, and EMG activity in the right bicep was greater, when the participants generated their own imagery scripts than when the script was produced by the experimenter. Results also showed that this effect was specific to the task-relevant muscle and arm. These results support Lang's (1979, 1985) bioinformational theory and emphasize the importance of personalizing imagery interventions to produce a vivid imagery experience that is accompanied by task-specific physiological responses.