How have you tried to socialize with them so far? What have you done and what has their reaction been?
I generally start by just sitting in a corner of the room and reading a book out loud so they can hear me (or talking to myself). After a while, I push my glasses (or something with my scent) towards them. Most cats will sniff it. Then I lay down and just look like I am about to doze off. If they look directly at you, blink really really slowly. Stay calm, no sudden movements...talk quietly. Some come fast...some take several sessions...some stay fraidy-cats for a long time!
...Always in my heart... Mocha....Nov. 13, 2002 - Dec. 6, 2013
.... Slave to Bengal Cats....Luna, Mystik, Simba, Komet, Meli,
Spark, and Star
.....and a collection of kittens at various times.