Forget LSD: eyes are the new high. Of course, we’re not talking about consuming them, but rather staring intensely into a pair for a prolonged period of time. Apparently, this can make people enter into an altered state of consciousness.

This intriguing discovery was made by vision researcher Giovanni Caputo from the University of Urbino in Italy, but it isn’t his first staring contest study. A few years ago, the scientist recruited 50 volunteers and got them to gaze upon their reflections in a mirror for 10 minutes in a dimly lit room. For many of them, it took less than one minute to start experiencing something trippy.

Their faces began to warp and change, taking on the appearance of animals, monsters or even deceased family members; a phenomenon imaginatively named the “strange-face illusion.” But it seems the bizarre effects are even more dramatic when the mirror is swapped for another person.

As described in Psychiatry Research, Caputo recruited 40 young adults and sorted them into pairs. Each pair then sat in chairs in a dimly lit room, positioned one meter (3.3 feet) apart. The illumination was set to a level that still allowed participants to pick up fine facial features, but color perception was diminished. Half of the pairs sat opposite one another, gazing at each other’s neutral expressions, while the others sat back-to-back, staring at the wall. To make sure any effects were not the result of expectation, participants weren’t informed of the nature of the study, but instead told it would involve a meditative experience.