From quick reading, the paper A Preliminary Study Of Shy Males Interacting With A Virtual Female seems useful. I Need to reread it with time and think if I can use it in my dissertation. From Abstract of the paper:
This paper describes a preliminary experiment that studied the reactions of male participants to an approach by an attractive and friendly virtual woman in a Cave-like system. […] Our results show that the participants tended to respond to the situation at the subjective, behavioural and physiological level as if it were real. (Pan & Slater, 2007)
Pan, X. & Slater, M. (2007). A Preliminary Study Of Shy Males Interacting With A Virtual Female. In Presence 2007: The 10th Annual International Workshop on Presence, Pp. 101-108, Barcelona, Spain. URL: http://www.cs.ucl.ac.uk/staff/S.Pan/PanandSlater.pdf.