Relations between Touch Target Size and Drag Distance in Mobile Applications for Users with Autism Spectrum Disorders

In recent years, the development of mobile applications for people within the autism spectrum has proliferated to help enhance skills that could be diminished in users with this condition. However, the usability of these applications does not appear to be the focus of development because users with autism can have difficulty with fine motor skills. This article focuses on evaluating the optimal drag distance and the sizes of the interaction elements for users with Autism Spectrum Disorder. To accomplish this goal, a case study was conducted that involved 20 users with Autism Spectrum Disorder and 30 users with typical development, using a prototype generated and two applications for commercial use on 7-in. tablets. For both developed applications, a slight variation can be observed between the different groups of participants. In the interaction with Proyect@ Habilidades, the application has pictograms of 65 pixels and it has a maximum trailing distance of 340 pixels. Moreover, in Proyect@ Retratos, where there is a minimum deviation between users with levels of autism 1 and 2, it also has pictograms of 65 pixels but with a drag distance of 110 pixels. For this reason, according to the results, we suggest that in order to obtain better results in the interaction with applications aimed at users diagnosed with autism spectrum disorders, the applications should have pictograms of a range of 65 pixels with a drag interaction between 110 and 340 pixels. Considering in context a 7-in. tablet with a resolution of 1280 × 800 pixels.