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Golden Rule or valence matching?
Methodological problems in
Hamlin et al.
The Golden Rule (1) is commonly articulated as “Do unto others
as you would have them do unto you.” We commonly apply
this rule to ourselves and to others. For example, we expect others
to act positively toward prosocial individuals and negatively to-
ward antisocial individuals. Hamlin et al. (2) suggested that we
begin to form these expectations at just 8 mo of age. They assessed
infants’ preferences when a helpful or hindering act was directed
toward an individual who previously acted prosocially or anti-
socially. Surprisingly, 8-mo-old infants applied the Golden Rule,
preferring an individual who helped, rather than hindered, a pro-
social individual, and preferring an individual who hindered,
rather than helped, an antisocial individual (2).
An alternative explanation of the finding raised by Hamlin
et al. (2) is that infants’ preferences are driven by valence
matching. To rule out this possibility, Hamlin et al. (2) included
a control condition in which infants’ preferences were tested
when the antisocial behavior was directed toward the victim,
rather than the perpetrator, of a previous antisocial act. To do
this, they had an individual act prosocially toward one target (i.e.,
the helpee) and antisocially toward a different target (i.e., the
hinderee), and with the hinderee as the target, they then tested
infants’ preference for a prosocial or antisocial individual. If
infants simply match on valence, they should prefer the antisocial
individual because, even though the hinderee was the target of
the antisocial act, the scenario it is associated with is negatively
valenced. In contrast, if 8-mo-old infants can make “nuanced
social judgements” (2), they should realize that the hinderee was
the victim, rather than the perpetrator, of the previously anti-
social act, and should thus prefer the prosocial individual.
Consistent with the latter view, infants displayed a significant
preference for the prosocial individual. Unfortunately, Hamlin
et al. (2) did not take into account the fact that infants are
likely to only attach valence to the individual associated with the
positive or negative outcome.
To understand our explanation, one needs to pay attention to
the temporal proximity of events in the scenarios. For example,
in one scenario, a protagonist attempts to open a box four
times, and on the fifth attempt, a prosocial individual approaches
and helps to open the box, or an antisocial individual approaches
and jumps on the box. Opening the box leads to a positive out-
come (i.e., the protagonist diving toward the rattle), whereas
jumping on the box leads to a negative outcome (i.e., slamming
the box shut). Because of their temporal proximity to the positive
and negative outcomes, it is likely that the prosocial and
antisocial individuals become associated with them, and there-
fore the positive and negative valence they hold. In contrast,
the protagonist is unlikely to attract any valence because its
actions (attempting to open the box) began long before each
outcome, hindering the association. Therefore, Hamlin et al.’s
(2) hinderee attracts neither positive nor negative valence and
fails to rule out the valence-matching hypothesis.
Damian Scarf1, Kana Imuta, Michael Colombo, and Harlene Hayne
Department of Psychology, University of Otago, Dunedin 9054,
1. Blackburn S (2001) Ethics: A Very Short Introduction (Oxford Univ Press, Oxford).
2. Hamlin JK, Wynn K, Bloom P, Mahajan N (2011) How infants and toddlers react to
antisocial others. Proc Natl Acad Sci USA 108:19931–19936.
Author contributions: D.S., K.I., M.C., and H.H. wrote the paper.
The authors declare no conflict of interest.
1To whom correspondence should be addressed. E-mail: firstname.lastname@example.org.
www.pnas.org/cgi/doi/10.1073/pnas.1204123109PNAS Early Edition
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