Muscular Dystrophies Based Fitts' Model

摘要

The aim of this paper is to present a validation of the muscular dystrophies based Fitts' model on two soft keyboards. There were designed by two physically disabled subjects. Soft keyboards allow them to access to emails and internet. However, they are not well optimized for disabilities because the keyboard layouts are of AZERTY type. We want to quantify their performance. For that, we have chosen as model the Fitts' law [1]. It depends on the size and amplitude of the targets as well as on the motor difficulties of the population studied. Fitts' law estimates the time necessary to reach a key. There are other laws based on it, mainly, Soukoreff s model [2]. [5] reported differences [5] between theoretical and experimental results are more considerable for disabled people than for able-bodied one. We carried out an experiment (www.irit.fr/MPH) [3] in order to adapt the Fitts' model. It consists in pointing on 5 target widths (8, 16, 24, 32 and 40 pixels) at 4 distances (80, 160, 240 and 480 pixels) so that subjects face a large representation range of index difficulty values (from 2 to 6) with their pointing device. It was carried out with three groups: 14 able-bodies, 4 spinal cord injuries (uppers limbs disability) and 9 muscular dystrophies (HM). We have obtained three Fitts' models adapted to each subject group with an integral method.