[Plugin: Social Login] Default role for new user

I found out that when a new user register to my site through Social Login, they are given the role “Subscriber”. If there anyway to set the default role to “Contributor” for newly registered user? I’m also using multisite installation & Multisite User Management plugin but it doesn’t affect the default role of new user registered through Social Login.

http://wordpress.org/extend/plugins/oa-social-login/