Issues relating to using head switches with scanning systems.

A classic problem with head switches is the ‘rest’ position and un-intentinoal switch presses. Users tend to need a position in which to rest their head between the head switches and this can often cause un-intentional activations. One solution is to move/redesign the switch configuration to minimise this, however another solution is to consider the scanning mode.

Using ‘Step scan’ (i.e. Move, Move, Move, Choose - where Move=switch1, Choose=switch2) can solve this problem too. This is because the user can rest on the ‘Move’ switch without any penalty (in terms of erroneous selections) - the only consequence is the progression of the highlighter, which does not affect efficacy.

In other words - the ‘Move’ switch is ‘silent’.

Anyway - I just twigged this today, perhaps I am behind the times?!

— Simon Judge 2006/06/22

Generally step scanning removes the need for timing but the student does obviously need to be able to physically operate the two switches. Something to watch is that two switch scanning (especially head scanning can (does) have repercussions on the whole physical posture and tone of the student. I sometimes try the choose switch as a hand switch and the move switch as a single head switch. Most of our pupils if thy are using head switches have poor hand/arm control Since the choose switch is used less frequently it can be operated by a less controlled movement.

Actually very few of our pupils are capable of controlling scanning access but It is also much easier to assist scan in a step scanning mode. for example see Linda Burkhart’s article on www.lburkhart.com/hand2sw4s.htm.

— Richard Walter (Meldreth Manor School) (sumarised from mailing list)