A study was undertaken to determine the activation profile and psychometric performances in 10 adult volunteer subjects. The activation profile was evaluated by measuring heart and respiratory rates and also the H reflex (motor response). Psychometric performances during two attention tests were measured by the subjects' scores. The subjects were then submitted to a per os psychotrope drug treatment at a liminar therapeutic dose. Psychometric performances were decreased in subjects given a strong psychoactivator drug (amphetamine, genozolone), while they could be increased to an optimal level with a less active psycho-activation (Pyrisuccidéanol). Under the same conditions, the motor response, tested using the H-reflex, varied in the same way as the psychometric performance curve. However, the cardiac and respiratory rates show changes induced by the administered drugs. These results show some conditions were performance and activation are dissociated under the effect of psycho-active drugs.