PE-Shift covers certain physiological side effects that may seem unusual, or alarming, but which are not supernatural or a sign that a physical shift is occuring.  It is well known that a mental or emotional state can produce a measurable physiological effect. The mechanisms of such effect are generally well understood in most cases. Examples would include an erection and/or increased heart rate following sexual excitement, temporary muscle paralysis due to extreme fear, and increased localized blood flow causing facial erythema (reddening) due to embarrassment or anger.

On the extreme end of this spectrum with more debatable and less well understood mechanisms are phenomena such as stigmata, placebo effect and other emotionally or psychologically induced states resulting in physiological effect. Examples from this extreme end of the spectrum might include yogis being observed in the laboratory in deep trance slowing their metabolism beyond "normal" parameters, or shamans and other ecstatic religious practicioners reporting effects such as rigid paralysis, paresthesia (tingling and other localized sensations), fasciculation (involuntary muscle twitching), erythema (reddening of the skin), etc.

Medical science does acknowledge that a mental, emotional or psychologically induced state can cause significant physiological effects, though this acknowledgment should not be misinterpreted out of wishful thinking to justify mythical effects that are beyond the boundaries of what has actually been observed. Psychologically induced physiological effects do not constitute p-shifting, but medically observable phenomena that are likely to have common and well understood biological mechanisms.