Humour is very important to humans, and therefore to psychology. According to Brownell and Gardner (1998):
Humour plays a powerful and unique role in human life,
with wide-ranging effects on many aspects of functioning.
Humour is a basic ingredient of binding in society; it provides
an effective means of communicating a wide range of ideas,
feelings and opinions.
Lacking, or losing (such as through brain injury) a sense of humour can very be damaging to one's social interactions and self-esteem. Having difficulty appreciating and understanding humour is a key feature of many psychological and neuropsychological conditions, including Autistic Spectrum Disorders, psychotic conditions, certain acquired brain injuries and some forms of dementia.
For these reasons there has been extensive neuropsychological research on humour. This research has shown that damage to the right hemipshere, particularly the frontal lobe most disrupted the ability to appreciate humour. Interestingly, this was also correlated with other cognitive processes, such as visual search, ability to focus attention and to hold relevant information in mind and mentally manipulate it (working memory). This makes sense, as appreciating a joke involves: being able to listen and focus on the joke, holding relevant information in mind and relating it back to the punchline, and/or scanning cartoons or other visual material. Humour is a complex business!Disorders of humour such as foolishness and a tendency toward making inappropriate jokes have also been reported in patients with damage to the frontal lobes.
It is thought that the right frontal lobe may be unique in integrating cognitive and affective information, to allow us to appreciate jokes and other emotive material.
Neuroimaging studies have revealed that the physical expression of laughter involves the amygdala (emotion centre), thalamic, hypothalamic and subthamalic regions (sensory relay areas) and the brainstem, as well as the premotor/frontal area through to the motor cortex (to aid the motor movements involved when laughing). These studies have confirmed that the perception of humour involves the right frontal cortex, as well as the prefrontal cortex (higher level executive area and personality), temporal regions (memory centres) and possibly the cerebellum.
Because they are associated with different parts of the brain, disorders of laughter can occur independently of disorders of humour. Difficulties with expressing laughter are most commonly associated with a type of stroke known as pseudobulbar palsy, when laughter can be intermixed with crying. 'Laughing' seizures are associated with a tumour in the hypothalamus. These individuals may have an intact sense of humour but may have difficulty expressing laughter approriately.
Finally, just to show that neuropsychologists have a sense of humour, the following (mildly edited) joke is taken from the Humour in Neuropsychology webpage:
A group of 40-year-old buddies discuss and discuss where they should meet for dinner. Finally it is agreed upon that they should meet at the Gausthof zum Lowen restaurant because the waitresses there have low cut blouses.
10 years later, at 50 years of age, the group meets again and once again they discuss and discuss where they should meet. Finally it is agreed that they should meet at the Gausthof zum Lowen because the food there is very good and the wine selection is good also.
10 years later at 60 years of age, the group meets again and once again they discuss and discuss where they should meet. Finally it is agreed they should meet at the Gausthof zum Lowen because they can eat there in peace and quiet and the restaurant is smoke free.
10 years later, at 70 years of age, the group meets again and once again they discuss and discuss where they should meet. Finally it is agreed that they should meet at the Gausthof zum Lowen because the restaurant is wheel chair accessible and they even have an elevator.
10 years later, at 80 years of age, the group meets again and once again they discuss and discuss where they should meet. Finally it is agreed that they should meet at the Gausthof zum Lowen because that would be a great idea because they have never been there before.
Brownwell, H.H., & Gardner, H. (1988). Neuropsychological insights into humour. In J. Durant, & J. Miller (Eds.), Laughing matters: a serious look at humour (pp.17-34). New York, Wiley.