Always wondered this!

In the movie Sixth Sense, does Cole's mum see Malcolm? Always wondered this when I've watched the film...

I don't think so.

Malcolm is sitting in front of her during a scene in the living room but, as revealed in a commentary, it was something there to throw off the audience. Throughout the movie, he makes appearances around living people who act like he may be in front of them but they do not see him. Only mediums, like Cole can actually see him.