6 April 1999
Brain Injury and Custard Pies
A study by scientists at the University of Toronto and the Baycrest Center for Geriatric Care in Toronto has found that people with damage to the right frontal lobe of their brains have difficulty getting ironic jokes the way they should. Instead they prefer slapstick humour.
The study is the first to show that the frontal lobe plays a pre-eminent role in our ability to appreciate humour. This adds to evidence that good humour may rely on the makeup of the brain.
"We always thought of humour as a defining human attribute, but an intangible part of our personality," says Dr. Prathiba Shammi, who led the study. "Now we know humour can be tested and scientifically scrutinized."
The responses of 42 adult volunteers to written and verbal jokes were compared. Half the group had a brain injury (a single focal brain lesion to either the frontal or non-frontal regions) caused by stroke, tumor or surgical removal. Their responses were measured against a normal control group.
It was found that people with right anterior frontal damage had disrupted ability to appreciate written and verbal jokes compared to the control group and people with focal lesions elsewhere in the brain. Individuals with right frontal damage chose wrong punch lines to written jokes and did not smile or laugh as much at verbal jokes. Instead they preferred slapstick humour - surprising but illogical endings, the signature of acts such as The Keystone Cops.
The ability to understand and produce humour requires the concerted functioning of several cognitive processes: holding a piece of information in mind while you manipulate it ('working memory'), looking at a situation in different ways or from different perspectives ('cognitive shifting') and abstract thinking.
Damage to the frontal lobes has long been related to changes in personality, with marked effects on a person's ability to tell jokes and respond to humour. Such individuals often exhibit silly euphoric behavior, inappropriate laughter, and have an addiction to telling jokes that are usually inappropriate in content.
Dr. Shammi gave an example of one of her jokes and the responses.
A teenager is being interviewed for a summer job.
"You'll get $50 a week to start off,'' says her boss. ''Then after a month you'll get a raise to $75 a week.''
Volunteers were offered three possible punch lines.
A. "I'd like to take the job. When can I start?"
B. "That's great! I'll come back in a month.'' (This was the "correct" choice)
C. "Hey boss, your nose is too big for your face!'' (This slapstick response was most often chosen by participants with right frontal damage).
The study was supported by the Medical Research Council of Canada.