recommend reading: 2 articles

gender differences in initiation of negotiation
http://www.ne.su.se/polopoly_fs/1.99257.1346412310!/menu/standard/file/anna_sandberg.pdf

 

Social Incentives for Gender Differences in the Propensity to Initiate Negotiations
http://research.chicagobooth.edu/cdr/docs/babcock.pdf