BACKGROUND: Modafinil, a putative cognitive enhancing drug, has previously been 
shown to improve performance of healthy volunteers as well as patients with 
attention deficit disorder and schizophrenia, mainly in tests of executive 
functions. The aim of this study was to investigate the effects of modafinil on 
non-verbal cognitive functions in healthy volunteers, with a particular focus on 
variations of cognitive load, measures of motivational factors and the effects 
on creative problem-solving.
METHODS: A double-blind placebo-controlled parallel design study evaluated the 
effect of 200 mg of modafinil (N = 32) or placebo (N = 32) in non-sleep deprived 
healthy volunteers. Non-verbal tests of divergent and convergent thinking were 
used to measure creativity. A new measure of task motivation was used, together 
with more levels of difficulty on neuropsychological tests from the CANTAB 
battery.
RESULTS: Improvements under modafinil were seen on spatial working memory, 
planning and decision making at the most difficult levels, as well as visual 
pattern recognition memory following delay. Subjective ratings of enjoyment of 
task performance were significantly greater under modafinil compared with 
placebo, but mood ratings overall were not affected. The effects of modafinil on 
creativity were inconsistent and did not reach statistical significance.
CONCLUSIONS: Modafinil reliably enhanced task enjoyment and performance on 
several cognitive tests of planning and working memory, but did not improve 
paired associates learning. The findings confirm that modafinil can enhance 
aspects of highly demanding cognitive performance in non-sleep deprived 
individuals. This article is part of a Special Issue entitled 'Cognitive 
Enhancers'.