Performance Evaluation Tests for Environmental Research (PETER): Auditory Digit Span Task

Abstract

Auditory digit span was evaluated as an instrument for repeated measurements experimentation. Twelve subjects were tested for one hour on each of 12 consecutive workdays in a standard environment. Both forward and backward digit span were measured. It was found that forward digit span was suitable for repeated measures after ten days of practice at 30 minutes per day. The criteria for suitability were predictability of the mean scores, constancy of the standard deviations and differential stability of the intertrial correlations. These criteria are sufficient conditions both for repeated measures Analysis of Variance, and for interpretation of experimental effects. Although the backward digit span scores did not meet these criteria, they became more and more correlated with the forward digit span scores as the experiment progressed. This indicates that the mental content of the two tests of memory converged with practice. One implication of this finding is to question the meaningfulness of factor structure after only limited practice. The forward auditory digit span test was recommended for inclusion in a battery of Performance Evaluation Tests for Environmental Research (PETER).