A single study in humans was reported in 1978. The double-blind trial of PRL-8-53 in 47 healthy volunteers measured its effects on a variety of cognitive measures. 5 mg of the drug was administered orally 2-2.5 hours before the study tasks.[1] Subjects were given 12-item word lists to memorize as part of the trial. While initial word acquisition performance on PRL-8-53 was only 107.46% of baseline, subjects recalled words at 132.5-142.7% of the baseline rate 24 hours after testing, and at 145.2-146.2% after a week. Stronger effects were noted in the bottom 60% of subjects (who recalled 6 or fewer words on placebo at 24h), with 24 hour retention improved to 187.5-191% of baseline, and one week retention to 200-205%. Subjects over 30 displayed even more substantial results, with improvements to 208-222% and 236-252% of baseline performance at one day and one week respectively.[1] Both visual reaction time and fine motor control improved to a statistically insignificant degree.[1] No side effects were reported during the trial.[1]