rgbrock1,
On the Dash the INCR REF (increased reference speed) switch is used whenever the aircraft is in or is going to enter icing conditions (i.e. flight in cloud, rain etc. and the temperature is below 5 degrees).
It increases the speed at which the aircraft will activate the stick shaker and stick pusher in responce to a slow speed stall situation. It does this because when aircraft wings and other surfaces have any ice built up on them the wing is less efficient and therefore the wing will stall at a faster speed than it would when it is clear.
Hope this helps
Rob