Tracers

Tracers is a visual effect in which moving objects appear to leave a smeared trail of afterimages through the space they have just occupied.

As a drug effect it is acute and dose-proportional, easing as the substance wears off. It ranges from a subtle lengthening of motion blur to vivid, overlapping streaks — most pronounced when a bright object moves against a dark background.

Tracers are among the most frequently reported visual effects across psychoactive substances. They are most commonly induced at moderate to high doses under psychedelics such as LSD, psilocybin mushrooms, and DMT, and also under stimulants such as amphetamine and MDMA; they also appear under depressants such as eszopiclone and zopiclone and under deliriants such as Amanita muscaria and myristicin.

Tracers are felt as a persistence of vision: the eye registers where an object was as clearly as where it is, leaving a layered smear of ghost images that dissolves moments after the object stills.

Fast movements generate longer trails; a waved hand becomes a translucent fan, a passing light a comet tail. Attending to the effect — deliberately waving the hand to study it — tends to amplify it. At higher doses under psychedelics, trails may take on color and texture, becoming fully three-dimensional.

Tracers arise through different pathways depending on the drug class:

• Psychedelics — act on 5-HT2A receptors in visual cortex, disrupting the normal suppression of prior-frame visual information and producing abnormal persistence of motion signals.
• Stimulants — alter dopaminergic and noradrenergic signaling in ways that heighten visual sensitivity and prolong the decay of motion afterimages.
• Depressants — eszopiclone and zopiclone produce visual perseveration through GABAergic modulation of early visual processing.
• Deliriants — produce widespread disruption of visual processing that includes motion-trail phenomena alongside other perceptual distortions.

How much each pathway contributes in a given case is not fully understood.

Who experiences tracers, and how strongly, varies widely. Higher doses raise both likelihood and intensity, and the effect is most pronounced in low-light or high-contrast conditions — a moving light against darkness is a reliable trigger.

Attention and expectation shape the experience: deliberately tracking movement tends to make trails appear longer and more vivid. Set and setting play a smaller role than with mood-contingent effects, and prior experience with a substance does not reliably diminish them.