PhD Conferral Mr. Alfons M.P.N. van Impelen, MSc.

Keywords: psychological research, symptoms, antisocial behaviour, psychological tests

"All that looks grave is not grievous. Not all those who wince are in pain; studies in furtherance of validity assessment"

The reliability of medical or psychological research can be undermined if patients are unwilling or unable to accurately describe their symptoms. This dissertation describes studies on the predictive value of antisocial behaviour for the unreliable description of symptoms and studies on the effectiveness of psychological tests to detect unreliable symptom presentation. Antisocial behavioural characteristics appear to have little predictive value for unreliable symptom presentations. Psychological tests, on the other hand, are extremely effective at detecting unreliable symptom presentation, but can be improved; the sensitivity to authentic symptoms could be reduced and strategies could be included to identify random answers and determine the motivations behind unreliable symptom presentation.