A plug-in to aid online reading in Spanish
Luz Rello, Roberto Carlini, Ricardo Baeza-Yates, Jeffrey P. Bigham · 2015 · Proceedings of the 12th International Web for All Conference (W4A) · doi:10.1145/2745555.2746661
Summary
This paper presents CASSA, a free Chrome browser plug-in designed to help people read Spanish text on the web by providing simpler synonyms and definitions on demand for complex words. The tool builds on the CASSA (Context Aware Synonym Simplification Algorithm) resource, which contains 41,106 complex words in Spanish and over 4.2 million context-dependent synonym lists drawn from the Google Books Ngram Corpus and the Spanish OpenThesaurus. When a user selects text on a webpage and activates the plug-in, complex words are highlighted using configurable visual indicators (colors, boldface, squares, or underlines). Hovering over a highlighted word reveals simpler synonyms or, when no synonyms are available, a dictionary definition. The tool was designed in the context of prior research showing that while automatic lexical substitution did not improve readability for people with dyslexia, presenting simpler synonyms on demand caused texts to be perceived as significantly simpler. The plug-in also serves people with other cognitive impairments, reading difficulties, or those learning Spanish as a second language. The authors position this work within the broader landscape of text simplification research targeting populations including people with autism spectrum disorder, Down syndrome, aphasia, and dyslexia.
Key findings
User testing with 5 participants (2 with diagnosed dyslexia) using the think aloud protocol revealed several practical insights about assistive reading tool design. Installation was the biggest barrier — none of the participants had previously installed a Chrome extension, and two did not understand the word "extension." Participants found the synonym functionality satisfying but noted gaps where complex words lacked synonyms, leading the authors to add a definition fallback feature. The plug-in struggled with large text selections (causing noticeable delays) and did not work on HTTPS pages due to security restrictions. Despite these limitations, participants found the tool useful and easy to operate. A key design insight from prior research underpinning this tool is that on-demand synonym presentation is more effective than automatic text substitution — replacing words in place did not improve readability for dyslexic readers, but giving them the choice to access simpler alternatives did.
Relevance
This paper demonstrates a practical, lightweight approach to cognitive accessibility on the web — rather than attempting full automatic text simplification (which remains unreliable), it empowers users to access simpler language on demand without altering the original content. This "assist rather than replace" model is a valuable design pattern for accessibility tools targeting cognitive disabilities. The finding that automatic substitution failed while on-demand presentation succeeded has broader implications for how we design assistive technology: preserving user agency and context may be more effective than automated transformation. For Spanish-language accessibility specifically, the CASSA resource represents significant NLP infrastructure. The user testing, though small, highlights recurring challenges in assistive tool adoption — terminology barriers, installation friction, and the gap between developer assumptions and user mental models — that practitioners should consider when building browser-based accessibility tools.
Tags: text simplification · lexical simplification · dyslexia · cognitive accessibility · readability · browser extension · assistive technology · Spanish language
Standards referenced: WCAG 2.0