what

• Baddeley and Hitch (1974) felt that the STM was not just one store, but a number of different stores
• if you do two things at once (dual task performance) and they are both visual tasks, you perform them less well than if you do them separately
• if you do 2 things at the same time and one is visual where as one involves sound, you do them as well simultaneously as you would do them separately
• this suggests that there is one store for visual processing and a separate store for processing sounds. this formed the basis of the WMM where slave systems are organised by a central executive