Experienced psychonauts are aware of the fact that the psychedelic space can sometimes be tricky to navigate, and know that it is helpful to have techniques available to assist with that effort. Accurately identifying the intensity of an experience can help while the experience is still unfolding, and also once it has concluded and one is attempting to describe the ineffable to others.
Over the course of many years of experimentation with psychedelics, the well-known psychedelic chemist Alexander “Sasha” Shulgin developed a method that can be used to evaluate the perceived strength or intensity of a psychedelic experience. This method has since been named the Shulgin Rating Scale and was published in the introduction to his book PiHKAL: A Chemical Love Story (“PiHKAL” stands for “Phenethylamines I Have Known and Loved.”)
This rating scale only refers to the strength or intensity of an experience, not the content, which can be assessed in other ways. There are a total of five levels of effect, characterized by pluses and minuses, and one additional level that stands alone and is not comparable to the others. Although this scale was originally designed to work specifically with psychedelic substances, it can also be used with substances producing other types of effects, such as stimulants or depressants.
(-) or Minus
At this first level, there are no noticeable effects at all. A person who is at this level is said to be at “baseline” consciousness, which is their normal state. So if the effect of a substance is said to be a minus, then the person would have remained in the same exact state of body and mind they were in prior to its ingestion.
(±) or Plus-Minus
This is the first level at which the substance causes the person’s consciousness to shift away from “baseline.” However, at the plus-minus level the user cannot be completely sure that the change in consciousness is a direct result of having taken the substance. Because of this, there can be a lot of false positives in this category. Signs of activity may often prove to result from the person’s imagination as opposed to actual effect.