strength. Thus Yue and Cole (1992) used a variation of the mental practice research
design to show that imagery training could increase finger strength. More recently, Yue
and his colleagues extended this paradigm to other types of strength training. Thus Uhlig
(2001) reported that Yue and his research team required ten volunteers to take part in an
imagery-training exercise involving a mental work-out five times a week. This “mental
gym” exercise, which consisted of the imaginary lifting of heavy weights with their arms,
increased the bicep strength of the participants by 13.5 per cent! Control participants,
who missed such mental work-outs, did not show any significant gains in muscle
strength. In contrast to these studies, however, Herbert, Dean and Gandevia (1998)
discovered that imagined training produces increases in the strength of the elbow flexor
muscles which did not differ significantly from those attained by a control group.
Nevertheless, another problem for symbolic theories is that they find it difficult to explain
how MP enhances the performance of experienced athletes who, presumably, already
possess well-established blueprints or motor schemata for the movements involved.
Finally, and perhaps most worryingly, most cognitive theories of MP are surprisingly
vague about the theoretical mechanisms which are alleged to underlie imagery effects.
Bio-informational theory of mental practiceThe bio-informational theory of imagery grew out of Lang’s (1979) attempt to understand
how people respond emotionally and psychophysiologically to feared objects. It was
subsequently applied to research on MP in motor skills by Bakker, Boschker and Chung
(1996).
Influenced by the ideas of Pylyshyn (1973), Lang (1979) began with the claim that
mental images are not “pictures in the head” but propositional representations in long-
term memory. These propositional representations are abstract, language-like cognitive
codes that do not physically resemble the stimuli to which they refer. Three types of
information about the imagined object or situation are coded in these propositional
representations. First, stimulus propositions are statements that describe the content of the
scene or situation being imagined. For example, if one were to visualise a penalty-kick in
football, stimulus information might include the sight of the opposing goalkeeper, the
sound of the crowd, and the feel of the ball in one’s hands as one places it on the penalty-
spot. Next, response propositions are statements that describe how and what the person
feels as s/he responds to the scenario imagined. For example, stepping up to take a
penalty-kick is likely to cause some degree of tension and physiological arousal in the
player. Images that are composed of response propositions tend to be more vivid than
those containing only stimulus propositions (Bakker et al., 1996). Finally, meaning
propositions refer to the perceived importance to the person of the skill being imagined.
For example, if there were only a few seconds left in the match, and one’s team is a goal
down, then the hypothetical penalty-kick is imbued with great significance. Lang’s
(1979) theory postulates that information from these three types of propositions is
organised in an associative network in the mind.
Within this network, the response propositions are of special interest to imagery
researchers. This is so because these propositions are believed to be coded as bodily
responses which are primed by efferent outputs to the muscles of the body. In other
words, the propositions regulating imagined responses reflect how a person would
Using imagination in sport: mental imagery and mental practice in athletes 139