People close their eyes while kissing to allow the brain to properly focus on the task in hand, psychologists have said.
A study on vision and tactile sensory experience at Royal Holloway, University of London, concluded the brain finds it difficult to process another sense while also concentrating on the visual stimuli.
Cognitive psychologists Polly Dalton and Sandra Murphy found “tactile [sense of touch] awareness depends on the level of perceptual load in a concurrent visual task".
Study participants were instead assigned visual tasks to complete while their tactile sense was measured.
To measure visual sense, participants completed letter-searching tasks of varying difficulty. The tactile response was measured by responding to a small vibration applied to one of their hands.
An analysis found people were less responsive to the tactile sense as their eyes did more work.
When kissing and engaging in other activities pleasurable to the tactile sense, such as sex and dancing, people want to focus on touch, rather than other, potentially distracting, sensory experiences.
"Shutting out the visual input leaves more mental resources to focus on other aspects of our experience."