A Review of Research-Based Automatic Text Simplification Tools (2023)

Abstract: In the age of knowledge, the democratisation of information facilitated through the Internet may not be as pervasive if written language poses challenges to particular sectors of the population. The objective of this paper is to present an overview of research-based automatic text simplification tools. Consequently, we describe aspects such as the language, language phenomena, language levels simplified, approaches, specific target populations these tools are created for (e.g. individuals with cognitive impairment, attention deficit, elderly people, children, language learners), and accessibility and availability considerations. The review of existing studies covering automatic text simplification tools is undergone by searching two databases: Web of Science and Scopus. The eligibility criteria involve text simplification tools with a scientific background in order to ascertain how they operate. This methodology yielded 27 text simplification tools that are further analysed. Some of the main conclusions reached with this review are the lack of resources accessible to the public, the need for customisation to foster the individual’s independence by allowing the user to select what s/he finds challenging to understand while not limiting the user’s capabilities and the need for more simplification tools in languages other than English, to mention a few.

## introduction in the age of knowledge and information, the democratisation of information facilitated through the internet may not be as pervasive owing to potential challenges posed by written language, particularly among specific segments of the population. a great deal of the daily life processes are written and may produce lexical, syntactic and/or semantic difficulties in general, but particularly for those most vulnerable, such as people with cognitive disabilities, autism spectrum disorders, non-native speakers, children, and others. the guidelines provided by organisations like the plain language association international (plain) foot_0 and easy-to-read movement (aenor, 2018) already highlight both the need for and the promotion of text understandability via the simplification of specific language phenomena. therefore, enhancing text readability and comprehensibility becomes essential to uphold the right to cognitively accessible texts. currently, these simplification tasks are laborious and timeconsuming as they are conducted manually. thus, natural language processing (nlp) techniques, particularly automatic text simplification (ats), are demanded by society to address this issue. the objective of this paper is to present the existing tools for ats, paying particular attention to those whose target audience is a specific group of people with special needs. consequently, an analysis of these tools is conducted to determine the specific languages, language phenomena and linguistic levels they simplify; the approaches followed; their intended target audience (i.e. individuals with cognitive impairment, language difficulties, attention deficit, and others); and other relevant aspects. this study is framed as part of a larger project, the cleartext project foot_1 , that aims at the creation of a text simplifying tool for the simplification of spanish texts from the public administration to help people with mild to moderate cognitive impairment. in order to accomplish our goal, a preliminary assessment of the existing ats tools is required to ascertain the advancements made, methodologies employed, and potential areas for refinement in our own simplification tool. ## on the right to understand the inherent difficulty in certain written texts has caused society to demand more transparent and accessible texts. this has resulted in several movements, like the plain language movement and the easy-to-read movement. the plain language movement defends understandable language that ensures the fulfilment of the text's purpose. in fact, eagleson (1997) even affirms that "[...] it is the writer's responsibility to be clear. it is not the reader's responsibility to understand". as this is not always the case, ats tools provide citizens with the necessary means to access otherwise unreachable information. while the plain language movement has the entire society as target audience, the easy-to-read movement is concerned with increasing both the reading and comprehension of texts for those more vulnerable. the individuals that may benefit from easy-to-read materials may be subsumed under two categories: (1) people with disabilities and (2) readers with a limited language proficiency @xcite . the former category encompasses individuals with conditions such as aphasia, dementia, autism, intellectual disabilities (spanning mild to moderate and profound), neuropsychiatric disabilities (e.g., attention deficit hyperactivity disorder (adhd)), deafblindness, deafness or hearing impairments (dhh), asperger syndrome, tourette syndrome, dyslexia, and other reading difficulties. the latter category comprises non-native speakers, individuals with limited reading abilities, and children. ## automatic text simplification automatic text simplification (ats) can be defined as "a technology to produce adaptable text by reducing their syntactic and lexical complexity so that they become readable for a target user group" @xcite . ## methodology this tool review was carried out by following a fivestep methodology detailed below. a systematic review of studies was undergone by searching two databases: web of science foot_2 and scopus foot_3 . step 0. research scope definition and eligibility criteria. we are not concerned with an exhaustive analysis of ats tools but rather with those tools which are (1) ats tools with (2) a scientific background, in other words, the tool is supported by a research group. thus, papers dealing with other simplification aspects, i.e. simplification tool metrics, datasets or corpora, tools for automatic assessment of conceptual text complexity, methods, individual parsers, paraphrasing, lexical resources, tools to enhance readability, etc., are not considered. step 1. search method and bibliographic database query. this step entails the initial search of generic terms dealing with ats until april of 2023. for this purpose, and as we previously mentioned, scopus and web of science were the selected databases we used. the query utilised was "text simplification" and "tool" for both databases, which yielded 115 papers: all fields included in case of web of science produced 31 results and only article title, abstract and keywords in scopus provided 84 results. step 2. result fine-grain filtering. this step consists of selecting the papers that are within our scope (i.e. papers presenting a simplification tool) and dismissing those beyond our scope. for instance, the paper dealing with the alector parallel corpus @xcite or coco, a tool for the assessment of conceptual complexity @xcite , were discarded. in addition, preliminary studies where the tool is a prototype not yet developed (i.e. the tool is not named and the simplification levels are not explained) were also not taken into account, as for instance the case of @xcite or @xcite . repeated papers in both databases and tools presented by several papers were considered only once. after this step, specific domain (if any); (2) the tool's approach; ## simplification tools review as mentioned previously in step 0, commercial tools were discarded. although some deductions of what these tools are able to do can be ascertained, there is no way to know which operations (i.e. split, replace, reorder, etc.) the text has undergone in the simplification process. nonetheless, we acknowledge the usefulness of such tools for the general population, regardless of the shortcomings these often might have: character limitation, payment access restrictions and others. as a way of example, some commercial tools that help users in text simplification without any character limitations are simplish foot_5 and rewordify foot_6 . next, we present the tools selected following the previously explained methodology and analyse the language, language levels and domains they simplify, as well as their respective approaches, intended target users, and accessibly and availability considerations. ## conclusions and future work in this paper we conducted a review of researchbased ats tools to determine which language they simplify, what simplifications are applied, which approaches are followed, who are the target users (e.g. people with disorders and disabilities, students, children, and others) and whether or not these tools are accessible to the public and available for researchers. from this analysis some general conclusions are reached concerning what these tools have to offer, what they are lacking and other future considerations in nlp: after this preliminary study, the results indicate different paths that research groups could improve upon, like simplifying more language levels, customising simplifications by having into account the user's needs, maintaining tool accessibility and including other languages that still require simplification tools, among others. thus, we encourage to continue researching, implementing and providing robust ats tools to facilitate access information to society at large. in the context of the cleartext project, the goal is a two-fold simplification approach by addressing both disability-related and individual-specific language obstacles. in this way, we enable users to determine the extent to which they address the language obstacles associated with their specific disabilities, while considering that each individual exhibits unique idiosyncrasies and varying impairment degrees.