Effects of marijuana on temporal discriminations in humans.
Marijuana has been reported to alter the discrimination of time. The present study used a psychophysical approach to examine the effects of marijuana on temporal discrimination in humans. Research participants were required to push one of two buttons depending on the duration of a conditional stimulus (a blue square on a computer monitor). Correct choices ('C' button after a 2-s stimulus; 'A' button after a 4-s stimulus) resulted in an increase in session earnings of 0.12 dollars. Intermediate durations (probe stimuli between 2 and 4 s) were also presented. Psychophysical functions relating the probability of judging a duration as 'long' (4 s) as a function of actual stimulus durations were characterized by a logistic function fitted to the data. Administration of both low (1/2 placebo and 1/2 2.2% Delta (9)-tetrahydrocannabinol cigarette) and high (3.89% Delta(9)-tetrahydrocannabinol) potency marijuana cigarettes produced a bias of judging intervals as long, consistent with an interpretation that subjective time passes more quickly when an individual is intoxicated by marijuana. Deliberation time, operationally defined as response latency, peaked on trials with sample durations that corresponded to the measure of central tendency, and shifted in a similar manner after marijuana administration. The data are consistent with other studies on the effects of marijuana on time estimation.
Human Psychopharmacology Laboratory, Department of Psychiatry & Behavioral Science, University of Texas-Houston Health Science Center, Houston, Texas 77030-3497, USA. lori.lieving@uth.tmc.edu
Lori M
LM
Lieving
Scott D
SD
Lane
Don R
DR
Cherek
Oleg V
OV
Tcheremissine
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D003627:Data Interpretation, Statistical; D004193:Discrimination Learning / Q000187:drug effects; D004192:Discrimination, Psychological / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000523:psychology*; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects; D013998:Time Perception / Q000187:drug effects*
D002245:Carbon Dioxide