Why clowns taste funny: the relationship between humor and semantic ambiguity

Abstract

What makes us laugh? One crucial component of many jokes is the disambiguation of words with multiple meanings. In this functional MRI study of normal participants, the neural mechanisms that underlie our experience of getting a joke that depends on the resolution of semantically ambiguous words were explored. Jokes that contained ambiguous words were compared with sentences that contained ambiguous words but were not funny, as well as to matched verbal jokes that did not depend on semantic ambiguity. The results confirm that both the left inferior temporal gyrus and left inferior frontal gyrus are involved in processing the semantic aspects of language comprehension, while a more widespread network that includes both of these regions and the temporoparietal junction bilaterally is involved in processing humorous verbal jokes when compared with matched nonhumorous material. In addition, hearing jokes was associated with increased activity in a network of subcortical regions, including the amygdala, the ventral striatum, and the midbrain, that have been implicated in experiencing positive reward. Moreover, activity in these regions correlated with the subjective ratings of funniness of the presented material. These results allow a more precise account of how the neural and cognitive processes that are involved in ambiguity resolution contribute to the appreciation of jokes that depend on semantic ambiguity.

Figure 1.

Results from the ROI analysis, calculated for the main effects (ambiguity and joke/non-joke) and interaction. a, b, Top, Bars show beta values (peak voxels for each of the stimuli conditions). a, Bottom, Sagittal brain images showing the cortical ROIs. b, Bottom, Sagittal brain images showing the subcortical ROIs. All regions showed jokes versus non-jokes effects while ambiguity effect was only seen in left ITG (LITG) and left anterior IFG (L-ant-IFG; shaded bars for ambiguity). The interaction was significant in the left anterior IFG (shaded bars for interaction between jokes effect and ambiguity effect). Error bars display the SEM. L-post-IFG, Left posterior IFG.

Figure 2.

Top, Results from the focused ROI analysis, calculated for the funniness correlation. Bottom, Sagittal brain images showing the cortical ROIs (right) and the subcortical ROIs (left). Left posterior IFG (L-post-IFG), left anterior IFG (L-ant-IFG), left ventral striatum, and midbrain ROIs showed significant correlation with funniness ratings, corrected for multiple comparisons. Right IFG (R-IFG) and left ITG (LITG) were significantly correlated with funniness but at uncorrected levels.

Figure 3.

fMRI response for simple contrasts between jokes and non-jokes (red to yellow), ambiguous and unambiguous stimuli (blue to cyan), and the interaction (black to green). For display, contrasts are thresholded at p < 0.005, uncorrected for whole-brain comparisons for at least 10 consecutive voxels. Activation maps are rendered onto a sagittal canonical T1 brain image.

Figure 4.

fMRI response for simple contrast between jokes and non-jokes. a, For display, contrasts are thresholded at p < 0.001 uncorrected for whole-brain comparisons. Activation maps are rendered onto canonical T1 brain images. Top left, Sagittal view of the left ventral striatum activation; Top right, coronal view of the ventral striatum bilaterally spreading to the right amygdala. b, Top left, Sagittal views of midbrain activation; Top right, coronal views of midbrain activation. a, b, Bottom, Beta values (peak voxels for each of the stimuli conditions).

Figure 5.

fMRI response for simple contrast between jokes versus non-jokes (left) and unambiguous stimuli versus ambiguous stimuli (right). Contrasts are thresholded at p < 0.001 uncorrected for whole-brain comparisons and activation maps are rendered onto axial canonical T1 brain images. Left, Axial view; TPJ activity in the main jokes contrast (AJ + UJ) > (AS + US). Right, Axial view; TPJ activity for unambiguous versus ambiguous stimuli (UJ + US) > (AJ + AS). Middle, Bar graph shows mean beta values for each condition, showing higher activity for the jokes over the non-jokes and higher activity for combined unambiguous sentences and jokes over ambiguous sentences and puns.