Studies reported by the Academy of Medical Sciences have shown that Provigil does indeed improve aspects of memory: mainly verbal working memory, planning performance, working memory and executive inhibitory control (ability to stay on-task).
Other important aspects of cognitive function such as attention, however, were not affected by Modafinil. This study found Modafinil did not enhance spatial memory span, rapid visual information processing or attentional set-shifting. This study also found that Modafinil did not enhance attention.
The reason many use Modafinil is that it doesn’t seem to have any short- or long-term side-effects and it is not addictive (although it’s lack of side-effects may well have been exaggerated).
Ritalin was originally developed to treat ADHD yet adults have begun using it as a cognitive enhancer. It seems to work best in young people, enhancing spatial working memory and cognitive flexibility. Effects on other aspects of cognition such as verbal learning and long-term memory are relatively small.
In most people Ritalin tends to improve mood, increase activity and arousal, but it’s effects are more varied and can include anxiety, tiredness and lowered mood.
Verdict: Amongst the chemical cognitive enhancers Modafinil is currently fashionable for grown-ups. But is it really that much better than caffeine? This study and this study suggest that in warding off sleep Modafinil is no more effective than caffeine – and caffeine is legal and readily available. Probably better to stick to tea or coffee.