Measuring motor imagery using psychometric, behavioral, and psychophysiological tools. Exerc. Sport Sci. Rev., Vol. 39, No. 2, pp. 85Y92, 2011. This review examines the measurement of motor imagery (MI) processes. First, self-report measures of MI are evaluated. Next, mental chronometry measures are considered. Then, we explain how physiological indices of the autonomic nervous system can measure MI. Finally, we show how these indices may be combined to produce a measure of MI quality called the Motor Imagery Index. Key Words: motor imagery, mental imagery, psychometric measures, mental chronometry, autonomic nervous system, electrodermal and cardiac activities. MOTOR IMAGERY Motor imagery (MI), or the mental simulation of motor movement, is the cognitive rehearsal of an action without actually executing it (9,26). As the mental representation of a movement without the concomitant production of the muscle activity necessary for its implementation, MI has attracted increasing interest from researchers in sport science, psychology, and cognitive neuroscience During the past 15 years or so, we have conducted a number of studies on theoretical, practical, and rehabilitation issues involving MI. First, we have investigated the brain mechanisms underlying motor skill rehearsal and movement planning (11). Second, we have shown with others that the MI technique of mental practice (''seeing'' and ''feeling'' a movement in one's imagination before executing it) can increase physical strength performance (30) and enhance skill learning (3) and technical performance in athletes (4,32). Finally, we confirmed that MI training can facilitate rehabilitation from physical injury or neurological damage ((5) see (22) for a review). Elsewhere, we have provided a detailed account of research findings on MI (12). Considering that MI is a multidimensional construct (see model developed by Guillot and Collet (10)), we have measured its underlying processes using a combination of psychometric tests (18), qualitative procedures (19,25), chronometric methods in which MI processes are investigated by comparing the duration required to execute real and imagined actions (8), and psychophysiological techniques (1). Although these approaches have each yielded some interesting results (12), they have not yet been combined adequately to provide an aggregate index of MI quality. Therefore, the purpose of this review is to propose a rationale for our novel hypothesis that it is possible to calculate an index of MI quality by quantitatively combining psychometric, qualitative, chronometric, and psychophysiological measures. Our proposed Motor Imagery Index (MII) has significant implications for researchers and practitioners because it can be used to understand individual differences in MI and to assess the efficacy of MI interventions. PSYCHOMETRIC APPROACH For more than a century, researchers have used standardized self-report questionnaires to measure individual differences in imagery dimensions such as vividness (i.e., the clarity or sensory richness of an image) and controllability (i.e., the ease and accuracy with which an image can be manipulated mentally, see (24)). We have investigated both of these dimensions of imagery in sport settings. For example, we found that elite canoe-slalom competitors reported significantly greater use of MI than did less proficient counterparts when preparing for races (17). We investigated the effects of MI on the learning (through both physical and mental practice) of volleyball technique among intermediate performers of this sport (32). We found that a combination of MI and physical practice produced the most efficien
