The content. criterion and face validity of human performance tests in psychopharmacology research were examined in an earlier paper. Most evidence on test meaning and interpretation, however, comprises construct validity. This is critically scrutinized here, through a brief analysis of human performance theory (Broadbent, Sanders, Sternberg), and taxonomies of human performance function (Fleishman, Holding). While much construct evidence is rather nebulous and untestable (non-disprovable), it is probably the most accurate representation of current views on performance assessment. Tests gradually fall out of favour (or) into favour, rather than being shown to be clearly invalid (or) valid. Factor analysis, and task discrimination, are, however, two procedures for placing test interpretation/meaning on a sounder empirical basis. Returning to the overall problem of how best to investigate test validity. several proposals are made. Further criterion information should be sought, in large-scale studies, designed specifically to compare the practical utility of different tests and test batteries. There needs to be greater atmosphere of critical debate on test meaning, in order to clarify the performance functions being assessed. Factor analysis and task discrimination procedures also need to be more widely employed. Lastly, although many tests can be seen as measures of ‘information processing’, the inference that they provide indices of ‘real-life performance’, can rarely be made on current evidence.

Performance tests in human psychopharmacology (3): Construct validity and test interpretation

Using delayed auditory feedback (delay 0.175 s) a standardized form of mental stress was investigated in 8 healthy male volunteers. After a resting period and a period of undelayed reading, the volunteers were exposed for 5 min to the DAF stress. During the DAF period heart rate increased by 10% and systolic and diastolic blood pressure increased by 9% and 18%, respectively. As a measure of acute sympathetic activation, plasma concentrations of norepinephrine and epinephrine rose by 68% and 49%, respectively. The activity of dopamine-β-hydroxylase in plasma was increased by 25%. From these results it can be concluded that the DAF procedure provides a suitable method for inducing a standardized mental stress in normal subjects, which can be measured as changes in biochemical and cardiovascular variables.

D. Koeppen

Papers

Methods for the Assessment of Psychotropic Drug Effects in Healthy Volunteers