An anonymous reader quotes a report from Tonic: The perception of time is a fundamental process of the brain, linked tightly to attention, emotions, memory, psychiatric and neurological disorders, and even consciousness — but while scientists have been anecdotally noting how drugs can change time perception for decades, very few have been able to address the question rigorously with tightly designed studies. Cognitive neuroscientist Devin Terhune says he’s been interested in understanding the neurochemical mechanisms involved in the distortions in the perception of time, and these drugs are one way to do that. Psychedelics act on specific pathways and chemicals in the brain, and if they also change the perception of time, we could learn exactly how it happens. At the end of November, Terhune and his co-authors published a randomized, double-blind, placebo-controlled study in Psychopharmacology on the effects of microdoses of LSD on people’s perception of time. They found that even at small doses, LSD seems to change the way people interpret time, though the specifics of how and when are still to be determined.
In the new work, 48 healthy people were split up into four groups. One group got a placebo, and the other three received different small doses of LSD: 5, 10, or 20 micrograms. Then, they did what’s called a temporal reproduction task. In this task, you see something on a screen for a certain amount of time — in the study it was a blue circle — and are asked to remember and recreate how long you saw it. The participants were shown a blue circle for periods of time from 800 milliseconds all the way up to 4,000 milliseconds, in increments of 400 milliseconds. Terhune and his colleagues looked to see how accurate the different groups of people were in reproducing those intervals, and found that the people in the LSD groups tended to hold down the space bar for significantly longer periods of time than the placebo condition. The researchers call this “over-reproduction.” “Terhune says that they saw these changes in time perception without any major conscious effects from the drug,” the report adds. “They asked people to report if they felt anything from taking the LSD, like perceptual distortions, unusual thoughts, if they felt high, or if it affected their concentration. There were a couple of weak effects, but statistically, the change in time perception happened independent of any subjective influence of the drug.”