Staring into someone's eyes for 10 seconds? Romantic. Staring into someone's eyes for 10 straight minutes? Kind of creepy—and, apparently, hallucinogenic.

That's what a recent small study in Italy found. In the study, pairs of people from a group of 20 young, healthy volunteers were instructed to sit in a dimly lit room and stare into one another's eyes for 10 minutes. A different group of 20 participants were asked to stare at a blank wall for 10 minutes. 

Afterward—in addition to presumably being very bored—each of the participants self-reported what the experience was like. Regardless of whether they were facing the wall or another person, all 40 volunteers said they experienced symptoms of dissociation, such as feeling less connected to reality, perceiving changes in sound and color perception, and having the sense that time was dragging. This is consistent with earlier studies [PDF] that tested the effects of staring at a single point for a relatively long stretch of time. 

But more curiously, 90 percent of those who were involved in staring at another person reported witnessing hallucinations in which their partner's face became distorted to resemble a monster, their own face, or the face of someone they knew. Most people reported that over the course of the 10-minute experiment, they experienced two to four distinct hallucinations.

In a press release, Dr. Giovanni Caputo, the lead author, explained the phenomenon might occur as "the brain snaps back to reality after zoning out and the mind projects subconscious thoughts onto the face of the other person."

Dr. David Spiegel, a Stanford psychologist who was not directly involved in the study but has researched dissociation, explained to the Huffington Post, "Some of this might have to do with the interpersonal intensity of gazing directly at another person. We relate to others in part by imagining ourselves in them."