Frame rate suppression from Dextromethorphan

Frame rate suppression (also called visual strobing, choppy vision, or stroboscopic vision) is a distinctive visual effect in which the normally smooth flow of visual experience becomes perceived as a series of discrete, separate frames or snapshots. Movement appears jerky and discontinuous, similar to watching a video rendered at a very low frame rate, a zoetrope animation, or reality under a strobe light. The individual may perceive their hand moving through space not as a smooth arc but as a series of frozen positions.

Under normal conditions, the visual system creates the perception of smooth, continuous motion through temporal integration -- the brain blends sequential visual inputs into a seamless stream. This process depends on properly functioning temporal processing in the visual cortex, particularly the motion-processing area V5/MT (middle temporal area) and its connections to other visual areas. When substances disrupt this temporal integration, the underlying discrete sampling nature of neural visual processing becomes perceptible.

Dissociatives are the substance class most consistently associated with frame rate suppression. NMDA receptor blockade, the primary mechanism of dissociative drugs (ketamine, DXM, PCP, MXE), appears to selectively impair the temporal integration of visual information. The NMDA receptor plays a critical role in sustained neural firing and temporal summation -- processes essential for the smooth temporal binding of sequential visual inputs. When NMDA function is reduced, the visual system's ability to interpolate between discrete neural "snapshots" is compromised, and the frame-by-frame nature of visual processing becomes apparent.

The dose-response relationship is notable: at low dissociative doses, motion may simply appear slightly less smooth than usual. At moderate doses, the frame rate effect becomes clearly apparent, with movement looking distinctly choppy. At high doses, the frame rate can drop so low that movement appears as widely spaced still images, and the visual scene may freeze entirely for brief moments before updating to a new position.

Some psychedelics can produce a milder form of frame rate suppression, particularly at high doses where visual processing is broadly disrupted. Cannabis at high doses occasionally produces this effect as well. The combination of a dissociative with a psychedelic can produce particularly pronounced frame rate suppression.

The effect is generally fascinating rather than distressing and resolves completely as the substance is metabolized. However, the disruption to motion perception significantly impairs the ability to navigate safely, judge the speed of approaching vehicles, or perform any task requiring accurate motion tracking. Physical activity and especially driving should be avoided entirely.