# A Methodology to Evaluate User Experience for People with Autism Spectrum Disorder
## 1 Introduction  
Autism Spectrum Disorder (ASD) is a condition characterized by deficits in social communication and social interaction, as well as restricted repetitive patterns of behavior, interests, and activities [1]. Some characteristics that people with ASD can present are: a tendency towards visual and structured thinking [2], delay of fine motor skills development [3], difficulties when generalizing skills to real-world contexts [4], susceptibility to experiencing depression and frustration [5], exhibit of hyper- or hypo-reactivity to sensory input or an unusual interest in sensory aspects of the environment [1], and that they prefer to use technology as it provides a safe and trustworthy environment [6].  
It is important that the process to evaluate the user experience (UX), as well as the evaluation methods and instruments, are selected and adapted considering the specific characteristics of users with ASD, to ensure a positive and rewarding experience when interacting with systems, products or services.  
Multiple studies have looked on how to evaluate UX in systems, products, or services used by people with ASD, however most of these studies do not present sufficient details of the evaluations performed and show a lack of empirical evidence [6]. Investigations have proposed different ways to evaluate UX and usability in their proposals, through different evaluation methods, which are defined as \"a procedure composed of a series of well-defined activities for the collection of data related to the interaction of the end user (...)\" [7], such as the system usability scale (SUS) [8] and heuristic evaluation [9], and instruments, which are a set of elements used by an evaluation method that can varydepending on the application's context. Many of the evaluation methods and instruments used in the evaluations are not adapted to the characteristics and needs of people with ASD.  
Considering this, the objective of this paper is to present a three-stage methodology to evaluate the user experience for people with ASD, as there is a need for a formal methodology to evaluate user experience that is built upon the needs and characteristics of users with ASD and provides proper guidelines and evaluation methods for them.  
This methodology was developed by researching the characteristics of the users through a systematic literature review [6], proposing a set of adapted UX factors [10], selecting evaluation methods suitable for the needs of users with ASD, and defining a logical step-by-step process to select evaluation methods to execute, plan the experiments, select evaluators and participants, carry out the selected methods, and perform qualitative and quantitative analysis, which results in a detailed report on the UX of the system, product or service evaluated.  
A preliminary version of the methodology was published in 2021 [11], which was reviewed and validated through the opinion of three experts in UX and later via an expert judgement validation by 22 experts with knowledge on UX, ASD and/or both, which resulted in the proposal presented in this paper.  
This document is organized as follows: Section 2 presents the theoretical background; Section 3 describes relevant related work; Section 4 shows the process to create the methodology; Section 5 presents the UX evaluation methodology for people with ASD; Section 6 presents the validation process; and Section 7 presents our conclusions and future work.