By Lew Harris
Jan. 9, 2001
Jo-Anne Bachorowski began studying the differences in the ways that
people laugh depending on the sex and familiarity of the company
they are keeping, the assistant professor of psychology has been
thrust into the media limelight.
which she conducted with graduate student Moria Smoski and Cornell
psychology professor Michael J. Owren, has been the subject of articles
in the Los Angeles Times, Scientific American, Elle and Self magazines,
the Canadian Discovery Channel and Discovery.com. Their work has
been particularly well received in the United Kingdom, where she
and Owren have appeared in a total of seven interviews on various
In the study,
they first recorded how 120 undergraduates laughed in different
kinds of social pairings while they watched humorous scenes from
discovered that people produce a wide variety of laugh sounds with
a remarkable range of vocal pitch. In particular, they determined
that individuals vary both the number and kinds of laughs they produce
depending on the sex of their social partner and whether their social
partner is a friend or stranger.
"We think that
laughter is one of a package of subtle yet effective tools, like
physical proximity and eye gaze, that people use, albeit unconsciously,
to shape the emotional and behavioral responses of others," Bachorowski
They found that
individual women, for example, produced laughs with markedly high
and variable pitch when in the company of male strangers.
of the study include:
- Men's laughter
is linked to the history of their relationship with their social
partner. When paired with friends of either sex, men laughed significantly
more than men who were tested alone or with a male or female stranger.
- Women's laughter
is linked to the sex of their social partner. Females paired with
a male friend produced more laughs than females tested alone,
with a female friend, or with a male stranger.
- When paired
with male strangers, women's laughter tends to be higher pitched,
indicative of smaller body size, possibly exploiting men's propensity
to be attracted to females with juvenile features.
- People have
a rich repertoire of laugh sounds, with some sounding more like
bird chirps, pig snorts, frog croaks and chimpanzee pants than
normal human utterances.
- Laughs can
be separated into three basic categories: (1) High-pitched, song-like
laughs, which fit our stereotyped notions of laughter; (2) Snort-like
laughs, with sounds produced primarily through the nose; and (3)
Grunt-like laughs produced through the mouth.
In a second
study, which is in press in the journal Psychological Science,
Bachorowski and Owren asked other listeners to rate examples of
the different laugh types in terms of their friendliness, sexiness,
how interested they would be in meeting the laugher, whether they
thought the laugh should be included in a laugh track, and the extent
to which it elicited a positive emotional response.
of the rating scheme, the researchers found that listeners were
more likely to rate comparatively stereotypical, song-like laughs
more positively than the other types.
support the notion that one important function of laugh acoustics
is to influence the emotional responses of listeners," Bachorowski
From an evolutionary
perspective Owren and Bachorowski speculate that human laughter
evolved as a way to form alliances. First came the smile, which
communicated a positive disposition to other individuals. Over time,
however, smiles became increasingly easy to fake, so a more complex
signal was needed. That is where laughter came in. Because laughter
uses more neural systems and has greater energy costs, it is more
difficult to fake. So, at some point, laughter supplanted smiling
as an honest signal of an interest in joining forces. Their perspective
on the evolution of positive emotional expressions appears in a
chapter of the book, Emotions: Current Issues and Future Development,
published by Guildford Press.
was funded by the National Science Foundation.