Have you ever tried or heard of a whisper porn? Well, for some enthusiasts, the sound of whispering produces a warm, tingly sensation just like the stimulation they feel while watching a video.
Now, psychologists from Swansea University in Britain have published what they call the very first scientific paper on why some people love such ASMR (autonomous sensory meridian response) activities.
ASMR is a perceptual phenomenon characterised as a pleasurable tingling sensation in various parts of the body in response to visual, auditory, tactile, olfactory or cognitive stimuli.
For a layman, such activities are the feeling of a subtle euphoria that takes people into an almost trance-like state of relaxation - spreading goosebumps across the skin.
"The fact that it was so wide-reaching convinced me it was something that needed to be looked into rather than a niche interest at a corner of the web," said lead researcher Emma L Barratt.
For the study, 500 participants from Facebook and Reddit "ASMR" groups filled out a questionnaire about their ASMR viewing habits, why they watched the videos and what triggers they responded to.
The authors used the data to identify the sensation's most common triggers: whispering, personal attention and crisp sounds like crinkling of wrapping paper. The paper also highlighted some potentially interesting connections between ASMR and two other conditions: "flow states" and synesthesia.
According to study co-author Nick J. Davis, "flow" states are experienced by athletes and workers during the period of heightened focus and have a natural connection to ASMR.
David found that those who experienced "flow" states more often tended to respond to a greater number of ASMR triggers.
"It may be that ASMR is brought about by obtaining a flow-like state which is in part facilitated by witnessing others in such a state," the authors wrote.
As for synesthesia, a condition in which one form of sensory input activates a separate sense, the team also thought certain aspects of ASMR suggested a connection.
"ASMR seems to be a very multi-sensory experience," they noted.
The team is now interested in examining how non-invasive brain stimulation may be used to monitor and possibly enhance the ASMR experience.
The paper appeared in the open-access journal PeerJ.