Everyone knows what it feels like to get tickled. That uncontrollable squirming and involuntary laughter. You try to worm out of the way. It's tough to breathe. Sometimes it's funny. Sometimes it's not.
Mr. Tickle knows that feeling well. He loves tickling others. But, as we know well, it's hard to recreate that feeling on yourself. That's because your response to tickling is really a response to strange exterior stimulation. There's a new study, though, that shows that people with a certain mental disorder may be more capable of tickling themselves.
Elmo loves getting tickled by you, but he can't tickle himself (and it's not just because his arms are too short). Generally, because we are performing the action on ourselves, our brains have the capacities to "warn" us of upcoming touches. This is the case for most people.
Unlike when we're startled by someone or tickled by an "evil" friend, we don't have the same physical reaction when we touch or tickle ourselves. Otherwise, we'd be constantly spooked by our own actions!
It's called the "forward model" of cognition. According to IFL Science, "The brain is able to predict the sensory outcomes of one's own actions. These outcomes are then processed with less intensity than externally generated sensations... This leads to a number of adaptive advantages, ensuring we don't get a fright each time we touch a part of our body like we do when someone unexpectedly grabs us."
This new study, however, shows that people with schizophrenia-like symptoms may be able to tickle themselves more readily than others. This is due to a disruption of those cognitive processes that allow us to warn ourselves of our own actions.
The "forward model" processes by which we prevent ourselves from being startled by our own touches are impaired in people with schizophrenia, which explains why those with the disorder may confuse their own actions or thoughts with those of an "external agent."
The study tested non-schizophrenic volunteers who were analyzed to determine their "schizoptypal traits." Certain traits that are present to a varying degree in people without the disorder can resemble aspects of schizophrenia. One of these is a "passivity experience," which, researchers wrote, involves "feeling as if you were a robot or zombie without a will of your own."
Once participants were evaluated, they were tickled by a researcher with a feather, then they were told to tickle themselves with the feather.
Every participant found the researchers' tickling equally as ticklish. But, people with stronger schizotypal traits were more tickled by the self-tickling task than those with low levels of schizotypal traits.
The study concluded that those with more schizotypal traits "had less efficient predictive mechanisms and were less able to predict the sensory consequences of their own actions."