Psychological
LSD's psychological effects (colloquially called a "trip") vary greatly from person to person, depending on factors such as previous experiences, state of mind and environment, as well as dose strength. They also vary from one trip to another, and even as time passes during a single trip. An LSD trip can have long-term psychoemotional effects; some users cite the LSD experience as causing significant changes in their personality and life perspective. Widely different effects emerge based on what Timothy Leary called set and setting; the "set" being the general mindset of the user, and the "setting" being the physical and social environment in which the drug's effects are experienced.
Some psychological effects may include an experience of radiant colors, objects and surfaces appearing to ripple or "breathe", colored patterns behind the closed eyelids (eidetic imagery), an altered sense of time (time seems to be stretching, repeating itself, changing speed or stopping), crawling geometric patterns overlaying walls and other objects, morphing objects, a sense that one's thoughts are spiraling into themselves, loss of a sense of identity or the ego (known as "ego death"), and other powerful psycho-physical reactions. Many users experience a dissolution between themselves and the "outside world". This unitive quality may play a role in the spiritual and religious aspects of LSD. The drug sometimes leads to disintegration or restructuring of the user's historical personality and creates a mental state that some users report allows them to have more choice regarding the nature of their own personality.
If the user is in a hostile or otherwise unsettling environment, or is not mentally prepared for the powerful distortions in perception and thought that the drug causes, effects are more likely to be unpleasant than if he or she is in a comfortable environment and has a relaxed, balanced and open mindset.