Don’t try to deny it, we have all tried to tickle ourselves. But it never works. At best, you probably feel a slight sensation on your skin, a bit awkward, like an insect was crawling all over you or like you were brushing your skin with a feather. However, it is impossible to tickle yourself to the point of laughing, like you would if another person was tickling your sides or your feet.
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This strange physiological phenomenon has been the subject of multiple studies and is said to be linked to how our brains work in terms of predicting certain feelings and then ignoring them.
The sensory attenuation mechanism
Laughing when you are being tickled is a perfectly normal reaction. Scientists have since discovered that the feelings we get in situations like this cause us to feel panicked, which we respond to by laughing uncontrollably. Even if we know that we’re going to be tickled, there is still a fear of being touched, even hurt, so we automatically laugh, sometimes even before we’ve been tickled.
So why doesn’t the same thing happen when we tickle ourselves? Multiple studies lead by neuroscientists and psychologists have proved the existence of a phenomenon known as ‘sensory attenuation’. This all comes down to the cerebrum, a part of the brain that is linked to muscle control. This area is able to differentiate between feelings that we inflict on ourselves, and unexpected sensations.
Does it have to be a human tickling us to make us laugh?
Does the source of these external stimuli make a difference to the result? Does it really need to be a human tickling us to make us laugh? Researchers have distinguished two different types of tickling, known as knismesis and gargalesis. Knismesis is a slight sensation, such as an insect crawling over your skin, which is a bit unpleasant and strange, but doesn’t cause us to laugh. The element of surprise plays a big role in this sensation, but we can also replicate this feeling on ourselves.
Gargalesis on the other hand, seems to be linked to contact with another human. For some scientists, tickle fights are the most basic forms of conflict, and so have determined that being tickled and laughing could be a way to protect ourselves in hostile situations. However, in an article published in 1984, psychiatrist Donald Black highlights that the most sensitive areas for tickling, like the neck and our sides, are also the areas that are more exposed to wounds during combat. But the element of surprise can also enhance gargalesis.
For some researchers, it doesn’t necessarily have to be a real person tickling you for you to laugh. Psychologist Christine Harris from the University of San Diego has also conducted a study that uses a robot to do the tickling.
‘They smiled, laughed and wiggled as much as when they knew it was a person. Ticklish laughter, rather than being social interaction, appears to be a reflex,’ she says.
For the moment, it is certainly impossible to make yourself laugh by tickling yourself. But if you really want to do it without another human, you’ll need to get your hands on a robot tickler!
