A Harvard University scientist has opined that a person’s experience of pain intensifies when the receiver knows it was an intentional act.

In the study, participants who believed they were getting an electrical shock from another person on purpose, rather than accidentally, rated the very same shock as more painful.

Participants seemed to get used to shocks that were delivered unintentionally, but those given on purpose had a fresh sting every time.

The research, published in the current issue of Psychological Science, was led by Kurt Gray, a graduate student in psychology, along with Daniel Wegner, professor of psychology.

It has long been known that individual's own mental states can alter the experience of pain, but the findings suggest that a person's perceptions of the mental states of others can also influence how he or she feels pain.

"This study shows that even if two harmful events are physically identical, the one delivered with the intention to hurt actually hurts more," says Gray.

"Compare a slap from a friend as she tries to save us from a mosquito versus the same slap from a jilted lover. The first we shrug off instantly, while the second stings our cheek for the rest of the night," the expert added.

The study's authors suggest that intended and unintended harm cause different amounts of pain because they differ in meaning.

"From decoding language to understanding gestures, the mind distills meaning from our social environment. An intended harm has a very different meaning than an accidental harm," Gray said.