Field of view alteration

Field of view alteration is the experience of a perceived change in the observable open area a person can visibly see. This commonly results in visual distortions most commonly compared to that of fisheye lens photography or "seeing the world through that of a fishbowl". In addition to this, the effect can also manifest in the form of seeing the world with a horizontally wider field of view that is comparable to that of a panoramic photo, or with an entirely reduced field of view that is commonly referred to as "tunnel vision".

However, it is worth noting that since a drug-induced increase in one's visible field of view is most likely a physiological impossibility, it suggests that this effect is simply an optical illusion that merely distorts the appearance of a person's visual perception.

Field of view alteration is often accompanied by other coinciding effects, such as acuity enhancement and depth perception distortions. It is most commonly induced under the influence of moderate dosages of psychedelic compounds, such as LSD, psilocybin, and mescaline.