Thread by @ManojDoss

First real microdosing study reveals that low doses of #LSD increase estimation of time intervals:
link.springer.com/article/10.100…
The authors refer to to this as "temporal dilation." However, similar to drug studies in episodic memory, there's an encoding vs. retrieval problem here. 1/n

If participants encode the initial interval in a temporally dilated state (time is perceived to be longer), then their reproductions will be longer. However, if the passage of time feels longer during reproduction, then shorter intervals should be reproduced. 2/n

For example, let's pretend you thought to yourself that an initial interval felt like 3 seconds (and it actually was). When you're reproducing it under a state in which time feels twice as long, you would think that 3 seconds passed when actually only 1.5 seconds had passed. 3/n

This means that participants in their study could have encoded the interval in a perfectly normal fashion but felt that time had "sped" up during the reproduction interval, thereby leading to longer estimation. My guess is that both effects are at play. Thoughts @neiloufar? 4/n

Nevertheless, this is interesting because full psychedelic doses (of psilocybin) do the opposite. That is, they decrease temporal estimation:
journals.sagepub.com/doi/10.1177/02…
5/n

A potential (boring) explanation is that time dilates in both low and high doses of psychedelics, but the focus of interest from the subject's perspective (encoding the interval vs. reproduction) shifts. 6/n

Because memory for the actual interval is likely impaired from a high dose, a schema may be used ("that was ~3 seconds") and one's "internal clock" would then try to match this schema. 7/n

In contrast, a low dose may not necessarily impair memory (and maybe even enhance it?) in which case one may try to match the passing of time with their (subjectively expanded) memory of the interval, though the passing of time should too be subjectively expanded. 8/n

Another issue is that after the interval passes, memory for the interval could compress or expand (longer intervals are typically compressed in memory; see below), and this may be differentially affected by low and high doses of psychedelics. 9/n

How would I get around some of these problems? Using an episodic memory task with drug effects on board during only encoding or only retrieval of course (via implementing a delay between encoding and retrieval; this was essentially my dissertation work). 10/n

For example, @hugospiers paradoxically found under non-drug conditions in a navigation task that subjects overestimated spatial distances for a route but underestimated the time the route actually took: sciencedirect.com/science/articl…
11/n

If drug effects isolated to encoding led to a reduction of this underestimation effect of time (or flipped it), I think that would be more conclusive of a subjective expansion of time, especially because these drugs impair memory encoding (typically, mo' memory, mo' time). 12/n

I think I'll end there, and in case I misunderstood something (I only skimmed the paper in a non-caffeinated state) or someone points out a massive hole in my logic, I may just delete this whole thread. 13/n

However, I feel that the discussion of the issues raised here demonstrates why a proper background in cognitive psychology/neuroscience is so important to the interpretation of drug effects (especially psychedelic drugs) on behavior. 14/n