Design of a Haptic Zoom: levels and steps

When the subjects handle a haptic zoom (kinaesthetic zoom through a sensory substitution device), they don´t have any difficulty to make the distinction between a zoom-in and a zoom-out and this, while basing themselves on the number of pins activated under the finger. In a similar way to the visual zoom, the haptic zoom-in gives them access to the detail and to position themselves with precision on the object whereas the haptic zoom-out, less used, is used only to benefit of a global perception in order to better centre themselves on the objects present in the perception space. The second result underlines that the subjects do not handle more than 25 levels and this, even if they have the possibility of handling more (100 or 1000)