Whenever you do an academic assignment make sure you write down the full reference of each source as you find it. Many psychology students, including myself in the past, fail to do this.
Taking notes from the source for possible inclusion in the written assignment is fine but if you do decide to use the material, you can find yourself wasting hours of your valuable time trying to retrace the books you used, returned to the library etc.
Writing references as you go along may mean you record a host of references that you don't actually end up using; however, the time wasted doing this pales into significance compared with the alternative.