38
mice with a mutated oxytocin gene. Ferguson et al. (2001) showed that mouse
knock-outs show a profound social recognition deficit despite normal
olfactory and spatial learning abilities and that the social recognition ability can be
fully restored by an injection of oxytocin in the medial amygdala. Similarly, a high
level of this hormone seems to correlate with caring behaviour in rodents (Pedersen
et al. 1982).
In humans, oxytocin has also been shown to influence social behaviour and
cognition. It also plays an important role in creating the mother-infant bond.
Feldman and colleagues (2007) showed that a motherʼs level of oxytocin in the first
trimester predicts the strength of the motherʼs attachment to the infant.
In addition,
a boost to oxytocin levels in experimental settings commonly achieved by
administration of a nasal spray, seems to promote trust (Kosfeld et al. 2005;
Baumgartner et al. 2008) and generous behaviours (Barraza and Zak, 2009; Zak et
al. 2007). Oxytocin seems to influence social cognition (Theoridou et al. 2009),
increase some aspects of memory for social stimuli (Unkelbach et al. 2008;
Guastella et al. 2008) and to increase ʻmind-readingʼ ability (Domes et al. 2007).
Substantial effect sizes obtained in experiments on trust and generosity (for
example, participants were 80 per cent more generous in the oxytocin group than in
the placebo group in the Zak et al. (2007), and 30 per cent more trusting in the
experiment done by Baumgartner and colleagues (Baumgartner et al. 2008),
including some laboratory experiments that may have
relatively high ecological
validity (in Ditzen et al. [2008], couples were asked to argue, with researchers
measuring the frequency of positive behaviour such as listening,
confirming or
laughing during the conflict), show that the use of oxytocin in everyday life is
plausible. Moreover, oxytocin can be delivered in a practical way. Injections are not
required: several of the mentioned studies used a nasal spray to deliver oxytocin.
Several websites already market a nasal spray containing oxytocin,
8
although there
is a need to evaluate the quality and the amount of the active ingredient in the
commercial versions of the product to ensure that their effectiveness is similar to
that demonstrated in empirical studies. The marketing
claims on those websites
might need to be taken with a pinch of salt at the very least. On the other hand, the
8
e.g. http://oxytocinnasalspray.org; www.oxytocinstore.com.
39
justified scepticism about the oversimplifying claims used to market the product
need not lead us to conclude that oxytocin has no effect on behaviour, especially
given that the current evidence suggests a behavioural effect.
Given decent effect sizes in experiments, we may worry that in many circumstances
oxytocin might impede judgement and increase trust when trusting is unwarranted
or even harmful (Damasio, 2005). This view could be
supported by evidence that
oxytocin seems to restore trust following betrayals (Baumgartner et al. 2008). These
worries seem further justified given that although trust is an important social
resource (Giddens, 1991), it can sometimes also be socially maladaptive
(Greenspan et al. 2001). Some have even proposed that
commercial and military
applications could harness the potential of oxytocin to make people gullible
(Dethlefs, 2007). But is it indeed the case that an increase in oxytocin leads people
to trust others indiscriminately?
Mikolajczak et al. (2010b) suggest that the matter is somewhat more complex. They
point out that in previous experiments, participants rarely met the same partner
twice, nor did they have any idea that the person
they interacted with was
unreliable. Moreover, previous research suggested that the effects of oxytocin, for
example on aggressive behaviour (this is especially well-illustrated in research on
aggression in female rodents), are context dependent (Campbell, 2008; Pedersen,
2004). Mikolajczak et al.’s (2010b) doubts were confirmed in research that used a
customised economic trust game incorporating
repeated interaction, with some
Do'stlaringiz bilan baham: