Research on the communication trait of verbal
aggressiveness, which includes behavior like name
calling, ridicule, insults, racial epithets and
threats, has tended to focus on its social causes.
However, a new study by a team of researchers led by
Allison Z. Shaw, PhD, assistant professor of
communication at the University at Buffalo, has
found that verbal aggression may have biological
causes that can be identified by the ratio of length
of a person’s ring finger (second digit) to the
length of the index finger (fourth digit).
It is the first study to use the 2D:4D ratio –
considered a measure of prenatal testosterone
exposure – as a determinant of verbal aggression.
Shaw says prior research has suggested that the
2D:4D ratio can be used as a measure of exposure to
androgens in utero (testosterone being a type of
androgen) and a number of studies have shown a
correlation between the 2D:4D ratio and various
physical and behavioral traits.
A study led by The University of Warwick and The
Institute of Cancer Research (ICR) found men whose
index finger is longer than their ring finger were
one third less likely to develop the disease than
men with the opposite finger length pattern. The
relative length of index and ring fingers is set
before birth, and is thought to relate to the levels
of sex hormones the baby is exposed to in the womb:
less testosterone equates to a longer index finger.
The new research team hypothesized that if prenatal
exposure to testosterone influences the 2D:4D ratio
and high levels of prenatal testosterone exposure
are linked to verbal aggression, then digital ratio
could predict the trait of verbal aggression.
To test this, they first measured the finger length
of adult subjects from the point where fingers meet
the palm to the tip, then photocopied each hand,
palm down and made the same measurements. From these
results they calculated each subject’s 2D:4D ratio.
The subjects then filled out the Verbal Aggression
Scale and the HEXACO Personality Inventory and the
Argumentativeness Scale.
The team found that men and women with smaller 2D:4D
ratio reported themselves to be more verbally
aggressive.
Shaw points out that, when expressed in limited
contexts, verbal aggression can be beneficial to an
individual but when expressed injudiciously, may
have negative influences by provoking job loss, for
example, or making it difficult to maintain close
personal relationships.
“These findings have implications for our
understanding of the proximal and distal causes of
verbal aggression,” Shaw says.
“They suggest,” she says, “that verbally aggressive
behavior may be provoked by biologically based
differences in people’s attention to potentially
threatening stimuli (such as a sigh), their
appraisal of the stimuli as threatening and the
resulting decision to respond and produce messages
that are verbally aggressive.
“This study is the first step in gaining a better
understanding of this process,” says Shaw, “and may
allow us to develop more sophisticated techniques to
inhibit such types of responses.”
The study, “The Effect of Prenatal Sex Hormones on
the Development of Verbal Aggression,” was published
in the Journal of Communication (Vol. 62 No. 5) and
its authors include Michael R. Kotowski, assistant
professor of communication, University of Tennessee,
and Franklin J. Boster and Timothy R. Levine, both
professors of communication at Michigan State
University.
See also
Finger Length Linked to Prostate Cancer Risk
For more information
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