Restricting range restricts conclusions

Abstract

This opinion article discusses expertise approach and skill acquisition. Research on expertise is by definition focused on a restricted sample of individuals. Experts are people who consistently produce outstanding performance in their domains and as such are without exception located on the positive side of the skill distribution. The usual approach in the study of expertise is to compare the extreme group of the skill distribution, experts, with the extreme group at the other end, that of novices. This contrasting approach, which the authors call, “expertise approach”, has a long tradition. Its main advantage over the common approach in cognition, where all participants are at the same skill level, is the presence of a control group of novices that enables falsification of results obtained on experts. In that way, the expertise approach is not unlike the neuropsychological approach that contrasts results obtained on patients with the results of “normal” participants. The main goal of the expertise approach is to provide evidence relating to the cognitive and neural mechanisms behind processes such as object and pattern recognition, which would be difficult to obtain from subjects who possess approximately the same level of expertise. The skill acquisition process, which is one of the main topics of expertise, is of secondary importance in the expertise approach. The results obtained on the restricted range do not necessarily generalize to the whole range of values. The effects obtained with restricted range cannot and should not be used to make inferences about the mechanisms and factors that influence skill acquisition. (PsycINFO Database Record (c) 2016 APA, all rights reserved)