Appreciation of different styles of humor: An fMRI study

Humor styles are important in facilitating social relationships. Following humor styles theory, this functional magnetic resonance imaging (fMRI) study is the first to use “one-liner” humor to investigate the neural correlates involved in appreciating humor styles that differ in terms of target (self or other) and motivation (benign or detrimental). Interestingly, we observed greater activation in response to humor that facilitates relationships with others (self-defeating and affiliative humor) than to humor that enhances the self (self-enhancing and aggressive humor). Self-defeating humor may play an important role in Chinese culture in facilitating social relationships at one’s own expense. Psychophysiological interaction (PPI) analysis revealed temporal pole (TP)-frontal functional connectivity underlying the appreciation of self-directed humor, and temporo-parietal junction (TPJ)-frontal connectivity underlying the appreciation of other-directed humor. Amygdala-frontal coupling was observed during the appreciation of detrimental humor, while nucleus accumbens (NAc)-temporal coupling and midbrain-frontal coupling appear to play a role in the affective experience of amusement in response to benign humor. This study contributes to our understanding of the neural correlates of appreciating different humor styles, including humor that facilitates social relationships.


Four humor styles
The present study developed one-line humor stimuli based on the model of humor styles by Martin et al. The Humor Styles Questionnaire (HSQ) measures a multidimensional personality trait. However, the present study uses one-liner humor to replace the self-report HSQ, in order to investigate appreciation of humor designed to facilitate social relationships and enhance the self.
Four distinct humor styles emerge from the combination of two dimensions, motivation (benign and detrimental) and target (self and others). Therefore, sense of humor can be divided into the following styles: self-enhancing humor (SE; benign, self-directed humor used to enhance the self directly), affiliative humor (AF; benign, other-directed humor used to facilitate social relationships), self-defeating humor (SD; detrimental, self-directed humor used to facilitate social relationships at one's own expense), and aggressive humor (AG; detrimental, other-directed humor used to enhance the self at the expense of others) (Table S1).

Stimuli
In contrast to the use of the self-report HSQ in previous studies, the present study developed 'humorous one-liners' and the matched stimuli, 'non-humorous oneliners' (baseline). The corresponding baseline non-humorous one-liner stimuli were constructed with neutral sentences of matching length and punctuation.
In our previous fMRI studies of verbal humor, the stimuli were verbal jokes composed of two components, the setup and punch line. The present study instead used "one-liner" humor using the exaggeration technique, which conceptually overlaps with nonsense or absurd humor. Using this technique, some element of a situation was exaggerated in terms of quality or quantity to such an extreme as to violate common sense understanding.

AG
You are innocent and pure; your brain hasn't changed since you were 3 years old. 你天真無邪，三歲以後你腦裡的東西就再也沒變過。 CON The scenery in these old towns has not changed in over a decade. 走訪舊城鎮，這裡的景色十多年來幾乎再也沒變過。 Note: SE = self-enhancing humor; AF = affiliative humor; SD = self-defeating humor; AG = aggressive humor; CON = one-liner non-humor (control baseline)

Behavioral studies
We performed two behavioral studies to choose the stimuli. In the first behavioral study, 78 participants evaluated the stimuli using pencil and paper.
Participants included 49 males and 29 females, ranging in age from 18 to 23 (19.71 ± 0.89). Participants rated one-liner humor and one-liner non-humorous stimuli. The material for each condition was 140 sentences, with a total of 700 sentences used.
Participants rated stimuli printed on paper, classified the stimuli and rated the degree of comprehensibility, funniness, and exaggeration on a 9-point scale, with a higher score indicating a higher degree. We also controlled for gender content in the stimuli.
If the content of one-liner humor was associated with gender differences, then two versions of the stimulus were used for males and females, and participants read the material corresponding to their genders.
The overall correct classification rate was 90.43%, indicating that participants could correctly judge the five types of stimuli. The comprehensibility was 8.32 ± 0.62, indicating that participants could perceive what the stimuli were intended to express.
The overall average of funniness for one-liner humor was 5.26 ± 2.29, meaning that one-liner humor could indeed amuse our participants. According to the rating results, we chose 135 sentences to represent each type of stimuli, for a total of 675 sentences.
The length of each sentence was 19 to 24 Chinese characters, the mean and standard deviation of Chinese characters in a sentence was 21.77 ± 1.16 (Table S3). The procedure of the experiment was as follows. First, participants read the oneliner stimulus and pressed the space bar once they understand the stimulus.
Participants then classified the stimuli and rated the levels of comprehensibility, funniness, and exaggeration on a 7-point scale. Participants inputted the rating on the number buttons of the keyboard, with larger numbers indicating higher levels. After rating was completed, the monitor displayed "break". Once participants recovered, they pressed the space bar to read the next stimulus and rating task. Participants took breaks after responding to each series of several sentences, prompted by the monitor displaying "take a rest". Participants returned to the task by pressing the space bar.
An interval had 45 trials, and each stimulus style had 9 trials. The trials were assigned in a random interval. For every trial, the screen displayed a cross for 600 ms to notify participants that the trial was beginning. Then, a stimulus was displayed in the center of screen, and participants pressed the space bar at their self-paced reading time to rate the stimulus, including the degree of comprehensibility, funniness, and exaggeration. The screen displayed "break" after each rating task was completed.
Participants continued to the next trial by pressing the space bar after emotional recovery. The screen displayed "The End" when all tasks were finished. The entire experiment took 60 minutes, including rest time.