accomplished? What chunking strategies were exploited? Interestingly, the volunteer in
question (“S.F.”) was a keen varsity track-athlete who used his knowledge of running
times to chunk the digits to be remembered into familiar units of 3–4 digits. For example,
he might break up six digits such as 2 2 0 4 1 6 into two chunks using the time taken to
run a marathon (2 hours and 20 minutes) followed by that to run a mile (4 minutes and 16
seconds). Remarkably, in keeping with the domain specificity principle explained earlier,
SF’s extraordinary memory skill was confined to numbers only. Thus he was no better
than average in his ability to recall long strings of letters. The clear implication of this
study is that people’s memory-span can be increased if they practise chunking techniques
based on specialist knowledge or personal interest To illustrate, SF managed to increase
his short-term memory-span for digits ten-fold by practising extensively.
Box 6.6 shows us that practice can circumvent certain information-processing limitations
of the mind. Put differently, Chase and Ericsson’s (1981) study showed that remarkable
changes in performance (albeit in one field only) could be produced in otherwise
unexceptional performers simply by practising rigorously over time. Augmenting this
line of evidence was other research which showed that practice could induce actual
anatomical changes in athletes. For example, evidence indicates that years of intensive
practice can increase the size and endurance of athletes’ hearts as well as the size of their
bone structure (Ericsson, 2001a). Thus the playing arm of a professional tennis player is
often more heavily muscled and larger boned than his or her non-dominant arm. In
summary, a recurring theme of research in modern neuroscience is the malleability or
plasticity of anatomical and physiological mechanisms.
The second important influence on Ericsson’s work emerged from studies which his
research team conducted on the practice habits of eminent musicians. Specifically,
Ericsson et al. (1993) interviewed violinists of different levels of ability at the Berlin
music academy in order to analyse the nature, type and frequency of their practice
sessions. These interviews were supplemented by diary studies. Results showed that not
only did the expert group practise longer than their less successful counterparts (e.g., by
the age of 20, they had spent over 10,000 hours in practice compared with about 2,000
hours accumulated by amateur pianists at the same age) but they also practised
differently—spending more time on perfecting their skills (4–5 hours a day on average)
than in mindlessly repeating elementary drills. From this evidence, Ericsson et al. (1993)
concluded that “across many domains of expertise, a remarkably consistent pattern
emerges: The best individuals start practice at earlier ages and maintain a higher level of
daily practice” (ibid., p. 392). Furthermore, these researchers proposed that practice,
rather than innate talent, was the main cause of expertise or achievement level—not a
correlate of it. More precisely, Ericsson suggested that expertise is a direct function of the
total amount of “deliberate practice” (or “individualised training on tasks selected by a
qualified teacher”; Ericsson and Charness, 1994, p. 738) that has been undertaken by
performers. This proposition is the cornerstone of his theory. But what exactly is
“deliberate practice” and how does it change over time?
Sport and exercise psychology: A critical introduction 174