spreads and chokes terminology in photoshop is expand & contract with the selections as Hoofd mentioned. You would make a selection & save the selection as a channel, name it whatever you want. Then "expand" the selection & save it to a new channel, named whatever 2. Then deselect your work & reload the first channel & then apply the "contract" to it and save it also as a new channel named whatever 3. Then you have all 3 channels to work with to make your spreads & chokes.