Chronometric comparisons of imagery to action: Visualizing versus physically performing springboard dives

Despite considerable research on the learning of simple motor acts (e.g., finger tapping), we know relatively little about the changes that occur in higher order representations of complex motor skills as expertise develops (Annett, 1995; Colley, 1989; Holding, 1989; Jeannerod, 1994; MacKay, 1989; Rosenbaum, Inhoff, & Gordon, 1984; Schmidt, 1988). In the present study, the relation between the performance and the cognitive representations of complex motor skills was investigated. Motor imagery research has emphasized the similarity between the mental imagery of an action and its physical execution (Decety, 1996; Decety, Jeannerod, & Preblanc, 1989; Decety & Michel, 1989; Jeannerod, 1995, 1997). The present study focuses on how they might differ. Here, motor imagery was compared with the physical performance of springboard diving. The issue was whether the temporal relation between imagery and motor skill performance could reveal expertise-related differences in the content and structure of motor representations. Motor representations, or motor programs, have been defined as a set of movement components that are structured before a movement sequence begins (Keele, 1968). In addition, in this study, the factors that influence motor imagery separately from motor representation were examined. Several studies have suggested that physical and visualized motor skill performance share cognitive processes (Jeannerod, 1994; Requin, 1991). In hierarchical theories of motor control (MacKay, 1982, 1989; Shaffer, 1980, 1982) and theories of mental practice (Feltz & Landers, 1983; Feltz, Landers, & Becker, 1988), it is speculated that the two types of performance share the higher, cognitive levels of the hierarchy but differ in terms of the level at which performance output occurs. In experiments assessing practice and transfer effects for speech production, MacKay (1981) demonstrated that there are similarities between mental and physical practice and that mental execution times reflect internal processing. Internal speech execution times were faster than corresponding physical execution times, suggesting that internal action did not involve the activation of the movement’s motor components. The mental practice literature also supports a close relation between imagery and action (Feltz & Landers, 1983; Feltz et al., 1988). Mental practice is the cognitive rehearsal of a motor skill that purportedly decreases errors in physical performance. Nonetheless, an athlete’s expertise appears to influence the benefit that he or she receives from mental practice (Driskell, Copper, & Moran, 1994; Richardson, 1967). Two current explanations for the positive influences of mental practice have been proposed. First, mental practice facilitates complex skills for which there is symbolic control of movements. It permits the rehearsal of a skill and an opportunity to code parts of the skill into meaningful cognitive units (Driskell et al., 1994). Minas (1978) suggested that mental practice reinforces