Do women use the perceived ratio of index and ring finger
lengths as a clue to man's health status rather then his aggressiveness?
Dmitriy A. Putilov, Lida Putilov
Novosibirsk State University, Psychology Faculty, Novosibirsk,
Russia
Introduction. In humans, the ratio
of index and ring finger lengths (2D/4D ratio) shows sexual
dimorphism with men tending to have lower 2D/4D ratio compared
to women. The studies initiated by Manning indicate that this
dimorphism is a predictor of behavior that seems to be subject
of sexual selection. It was found that the ratio is negatively
associated with high testosterone levels, high achievements
in sport, high scores on mental rotation test, darker skin,
etc. Usually, the sexually dimorphic features (i.e. the relative
sizes of breast, shoulders, hip, waist, etc.) serve as the
honest signal (they are used by the members of the opposite
sex as the clues to the mate quality). If the sexually dimorphic
2D/4D ratio similar to other dimorphic features in providing
a clue of to mate quality (i.e. his masculinity/femininity),
it can help to a young women to judge a man on his personality
traits related to high testosterone levels, such as health
and aggression. The first feature seems to be a definitely
desired feature for a sexual partner, and the perceived ratio
might serve as a clue for man's health status. However, the
situation with another feature - aggression - is not so clear,
because not only very low, but also very high levels of aggression
would be undesired feature of a sexual partner.
Hypotheses. We hypothesized that
perceived 2D/4D ratio of man's hand modulates the judgment
of his health status by female subjects, but not by male subjects.
We also hypothesized that women are not designed to judge
the level of aggression, because the function of the preference
for this feature might be too complex (i.e. U-shape). In particular,
we anticipate that young women judge a hand with lower perceived
ratio as belonging to healthier man, while there is no such
a bias for judgment of a man's hand by a man. Moreover, we
anticipate that neither women, nor men are able to judge a
low perceived ratio as belonging to more or less aggressive
man, because they are not searching for high or low aggression
levels as desirable traits of a potential sexual partner.
Method. When someone puts his/her
hand on the table and turn it to the left, the perceived 2D/4D
ratio became higher. By contrast, the perceived ratio became
lower, if his/her hand turned right. Using this feature, we
created 5 pairs of photos of the same right hand with high
and low perceived 2D/4D ratio by turning the hands of 5 men
left and right. These 5 pairs of photos were shown to 30 female
subjects and 30 male subjects (aged between 16 and 28) in
the random order with a request to judge health status and
level of aggression of these hands owners (from 1, bad health
or low aggression, to 5, excellent health or high aggression).
The protocol is shown in Appendix.
Results. Tables 1 and 2 of the appendix
give the measurements of finger lengths on photos. They indicate
that, indeed, a hand in left-turn position is looking as having
lower 2D/4D ratio compared to the same hand in right-turn
position. Tables 3-4 of the appendix show subjective scores
for health and aggressiveness of men's hands. There is no
significant difference in judgments of aggressiveness between
left-turn and right-turn positions. The same is true for judgment
of health status by male subjects. The only significant difference
is found for females' judgments of health status. The higher
heath status is associated with left-turn position (higher
perceived 2D/4D ratio). The difference reaches the level of
significance for the hand of the 1st man, and the similar
tendency was noted for the 5th man hand. The mean difference
(averaged over 5 hands) is highly significant (p=0.002).
Discussion. As we anticipated,
the significant difference was found for the predicted feature
(health, but not aggression) and in predicted subsample (female
but not male subjects). However, the association pattern was
the opposite to the anticipated pattern: higher health status
is related to higher perceived 2D/4D ratio that points on
lower testosterone levels. Prior to producing another interpretation
of our results, they require replication (i.e. in the study
of man's preference for higher 2D/4D ratio of woman's hand
as reflecting her personality and reproductive traits related
to higher oestrogen levels).
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