Does straightening your back increase confidence? Background: I have always felt moderately socially insecure. Today I noticed that when I straighten my back from its normal crestfallen position, I feel a little more confident, and as if I were in attack mode.

Is there any relationship between straightening your back and confidence or other personal characteristics?
Brinol et al (2009)  suggest that your intuitions generalize.
From the abstract:


  Building on the notion of embodied attitudes, we examined how body
  postures can inﬂuence self-evaluations by affecting thought conﬁdence,
  a meta-cognitive process. Speciﬁcally, participants were asked to
  think about and write down their best or worse qualities while they
  were sitting down with their back erect and pushing their chest out
  (conﬁdent posture) or slouched forward with their back curved
  (doubtful posture). Then, participants completed a number of measures
  and reported their self-evaluations. In line with the self-validation
  hypothesis, we predicted and found that the effect of the direction of
  thoughts (positive/negative) on self-related attitudes was
  signiﬁcantly greater when participants wrote their thoughts in the
  conﬁdent than in the doubtful posture. These postures did not inﬂuence
  the number or quality of thoughts listed, but did have an impact on
  the conﬁdence with which people held their thoughts.


References


Briñol, P., Petty, R. E. &amp; Wagner, B. (2009). Body posture effects on self-evaluation: A self-validation approach. European Journal of Social Psychology, 39, 6, 1053-1064. PDF