I think avoiding eye contact is an instinctual reaction to a distressing situation. Babies do it when stressed. My mother used to shout "LOOK AT ME WHEN I AM TALKING TO YOU!!!!" -- which only made my distress greater. Her abuse was the thing that made me not want to look at her. As an adult I have had trouble looking at people, but when I started to understand more about why I did it, and began to think that maybe those people were not really my mother and were not about to hit me, it became easier to practice looking at them more. Now it is not something I think about much: there is no requirement that you have to look at someone all the time!