Girls' and boys' brains respond differently to funny videos
When exposed to humour, women's brains exhibit more activity
than men's in reward-related regions. Some experts say this is consistent with
an idea derived from evolutionary theory that women are predisposed to be
humour appreciators whereas men are humour producers. According to this view,
women use a man's comedic skills as a way to appraise his genetic fitness.
An obvious objection here is with the word
"predisposed". Who's to say whether these gender differences are
innate or if they're a result of cultural influences? A new study has started
to answer this question by scanning the brains of girls and boys as they viewed
funny videos - the first time that gender-related brain differences in response
to humour have been examined in children.
Pascal Vrticka and his colleagues showed the funny clips,
including people falling over and animals performing tricks, to 22 healthy
children - 13 girls, 9 boys - aged from six to thirteen (data from a further
ten children was lost because they moved about too much in the scanner). For
comparison, the children also watched "positive" clips, featuring
dancers and snowboarders among other things, and neutral clips, which featured
nature videos and kids riding bikes. As they watched the clips the children's brains
were scanned with fMRI. The children also said how much they enjoyed the clips
and how funny they found them.
In response to funny clips (versus positive clips) the
girls' brains showed more heightened activity than the boys' in a range of
areas including bilateral tempero-occipital cortex, midbrain and amygdala. What
does this mean? "This finding indicates that girls more readily engaged in
incongruity resolution and experienced stronger mirth, positive feeling state,
and/or reward representation during humour appreciation," said the
researchers. This shows, they added, that the humour-related gender differences
found in adult brains already exist in young children.
In contrast to the situation for funny clips, the boys'
brains showed a stronger response than girls' brains to the positive clips,
including in ventromedial prefrontal cortex and amygdala. The researchers said
this shows the boys expected reward, not just in the funny clips but in the
positive unfunny clips. Because they anticipated reward, Vrticka's team said
the boys' experience of mirth was diminished when a joke actually came. Girls,
by contrast, were more surprised by the humour in the funny clips, which
therefore brought them more reward.
The same results applied when analysis was restricted to the
portion of participants who were opposite-sex siblings raised in the same
homes. This strengthens the case that it is at least partly biological
differences that lie behind the gender differences reported here (but this is
far from conclusive: opposite sex siblings can be exposed to different
environmental influences whether raised together or not).
The researchers said their findings support the idea that
women have evolved to be humor appreciators: "... the extant neuroimaging
data support the notion that mate selection by means of humor processing might
be more effective in females than males because the female brain, and
particularly the reward circuit, is biologically better prepared to respond
accordingly."
There's one very important problem with all this. The girls
didn't actually like or find the funny videos any funnier than the boys. Their
super efficient joke-sensitive neural reward circuits were firing away, but
this wasn't translated into actual amusement. Is this a classic case of researchers
treating brain imaging evidence as somehow more true or fundamental than
behavioural data?
Here's how they explained the lack of gender differences in
the kids' ratings of the videos: "... differential brain activity for
funny versus positive clips most likely reflects a sex bias for distinct
processing mechanisms, rather than divergent subjective experience." OK,
but how do they get from that interpretation to their conclusion that "our
data for the first time disclose that sex differences in humour appreciation
already exist in young children"?
Yes, this small study suggests girls' and boys' brains
respond differently to funny videos. But there were no differences in
subjective humour appreciation between the sexes and so, contrary to the
researchers' interpretation, the study could be taken as another example of how
the brains of men and women (and boys and girls) sometimes take a different
route to the same end result.
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