Feral cats are comfortable in the home, but still don't trust me!

I am fostering two kittens who were found on the street and taken into care. 

The were separated from a feral colony. The first week was tough and they mostly hid. We've been together three weeks now and they're comfortable in the home. They come out to eat, use their litter, walk around when I'm sleeping. However, whenever I go near them, or walk into the room they hide and hiss until i'm too far away to bother them. I can never touch them or pet them. They're not biting or attacking because they won't get close enough to me to do that. 

Any thoughts on how to help socialize them?

Thanks!

Hello and welcome to TCS.

Do you spend time talking to them? Playing with them? It is important to try doing these things. It is actually better to isolate them to one room if possible.

Sit or lay down on the floor in the room they are hiding in. Talk to them a lot. You could even just read a book out loud. This gets them used to your voice. Use wand toys to attempt to use play to entice them out. These allow them to keep their distance, but allow them to start feeling good about you being near. It can be used to entice them closer and closer to you. Use food or treats also.

Playing soft music and using feliway diffusers can help calm them.

Do a search on Youtube for socializing feral kittens.  There is a 3 part series and it is fantastic.  It starts by showing the rescue of the kittens and moves along to how to work with them.  Gerber Stage 1 Chicken/Turkey baby food is your friend. 

Thank you for rescuing these babies and time and patience is your friend.