In a study of the effects of cannabis on cognitive functioning, several cognitive and psychomotor tests were administered to four groups of subjects: (a) a high-dose group (equivalent to 6 mg of A° THC), (b) a low-dose group (equivalent to 3 mg of A" THC), (c) a placebo group, and (d) a control group. Cannabis was smoked in the form of marijuana. Even the subjects who received the low dose showed impairment on the Wechsler Adult Intelligence Scale Block Design Test and Memory-for-Designs Test. The high-dose subjects gave an impaired performance on several other cognitive tests. However, on some cognitive tests, mainly those measuring divergent production and oral fluency, the low-dose subjects performed the best and the high-dose subjects performed the worst. Consequently, there is a possibility, requiring further exploration, that cannabis at low dose levels can act as a stimulant and can improve performance on certain tests.Several studies have indicated that acute cannabis intoxication produces an impairment on several simple and complex cognitive tasks. The functions most frequently reported as affected by cannabis are short-term memory, temporal organization, sequential information processing, vigilance, encoding, time perception, and complex reaction time (Cass-