THE MORE widespread use of marihuana and marihuana-like drugs in the general population and the controversy about their possible harmful, as well as beneficial, effects have led to an increased interest in studying these compounds during the last few years. At the same time, the identification of l-Δ¹-3,4 trans-tetrahydrocannabinol (THC) as a constituent of marihuana and its synthesis by Gaoni and Mechoulam^1,2 have made possible the systematic study of this substance, which is presumed to be the most active element in marihuana (l-Δ¹ is also referred to as l-Δ⁹; l-Δ¹ follows terpene nomenclature, which was used by Mechoulam and Gaoni, whereas l-Δ⁹ follows standard chemical abstracts nomenclature).

The major aim of the present study is the delineation of some of the psychological effects of THC. This paper will deal primarily with the systematic measurement of