The predictive and discriminant validity of the zone of proximal development

Dynamic measurement procedures are supposed to uncover the zone of proximal development and to increase predictive validity in comparison to conventional, static measurement procedures.

Two alternative explanations for the discrepancies between static and dynamic measurements were investigated. The first focuses on Vygotsky's learning potential theory, the second considers the role of anxiety tendency during test taking. If test anxious tendencies are mitigated by dynamic testing procedures, in particular the availability of assistance, the concept of the zone of proximal development may be superfluous in explaining the differences between the outcomes of static and dynamic measurement.

Participants were students from secondary education in the Netherlands. They were tested repeatedly in grade three as well as in grade four. Participants were between 14 and 17 years old; their average age was 15.4 years with a standard deviation of .52.

Two types of mathematics tests were used in a longitudinal experiment. The first type of test consisted of open-ended items, which participants had to solve completely on their own. With the second type of test, assistance was available to participants during the test. The latter so-called learning test was conceived of as a dynamic testing procedure. Furthermore, a test anxiety questionnaire was administered repeatedly. Structural equation modelling was used to analyse the data.

Apart from emotionality and worry, lack of self-confidence appears to be an important constituent of test anxiety. The learning test appears to contribute to the predictive validity of conventional tests and thus a part of Vygotsky's claims were substantiated. Moreover, the mere inclusion of a test anxiety factor into an explanatory model for the gathered data is not sufficient. Apart from test anxiety and mathematical ability it is necessary to assume a factor which may be construed as mathematics learning potential.

The results indicate that the observed differences between a conventional, static testing procedure and an experimental, dynamic testing procedure for mathematics cannot be explained sufficiently by a differential bias towards test anxiety. The dynamic testing approach renders scores which add to the predictive validity of conventional testing procedures. Since this gain in predictive validity is not a result of the removal of bias towards test anxiety, this result should be understood as supportive for the validity of the concept of the zone of proximal development.