Here's an interesting study I came across -
http://archpsyc.ama-assn.org/cgi/con...tract/57/2/133
What's particularly interesting about this study is that the dosage they used (600mg/wk test cyp) is a lot closer to a typical bodybuilder cycle.
Now psychiatry is not my specialty, but this seems to suggest that taking testosterone will slightly increase aggression, but doesn't seem to cause psychological changes in most men. However a small number do become much more agressive. This does seem to suggest that there's a certain percentage of men who can't handle extra testosterone.