Adaptively shortened pull down menus: location knowledge and selection efficiency

Adaptively shortened pull down menus, as introduced by Microsoft with the 'personalized menus' in Office 2000 and assumed to speed up menu selection, are examined. Displacement of items in this adaptively changing menu is argued to conflict with the user's location knowledge, leading to increased selection times and error rates. In a controlled experiment with 31 subjects, a standard menu was compared with a shortened and a gapped menu variant. The gapped menu variant served to distinguish effects from displacement and effects resulting from reduced item number. Selection times and error rates were smaller for the standard menu than for the shortened variant. The gapped menu, whilst it has longer distances, was faster than the shortened menu, but slower than the standard menu. According to our findings, the assumption that adaptively shortened pull down menus facilitate menu selection is weakened.