All the sows I've had so far have been pretty amenable. Where they are is a relatively high pedestrian traffic area, and they get spoken to regularly. Being on concrete I muck out twice each day while they are feeding and make a point of giving them a brush down.
Currently I've now only one sow (Mrs Pig) so that makes the attention she gets even greater. She rears up on hind legs, front trotters over the top bars of the pen, and demands attention - just loves her face being brushed ! I encourage our holiday cottage guests to make a fuss of them, and most of the guests love it as much as the pig!
With this litter I am making a conscious effort to get them used to my voice, poking my head in the sty and speaking to them when mum is out in the yard area feeding. I'm hoping to get this batch used to being handled, but this needs care - has to be done when they are young, but not so as to alienate the mother.