Oral doses of extracts of marihuana were found to induce a greater concentration on the present and a foreshortening of the span of awareness into the future. Although there were individual differences in emotional reactions, the greater concentration on the present was associated, in general, with euphoric moods.
Melges FT, Tinklenberg JR, Hollister LE, Gillespie HK. Marihuana and the Temporal Span of Awareness. Arch Gen Psychiatry. 1971;24(6):564-567. doi:10.1001/archpsyc.1971.01750120080013