Around 67% of the global population—approximately 5.4 billion people—regularly use internet-based technologies, most in highly developed countries. With this rapid expansion, reading has become central to online activity and essential for accessing information (Leu et al., 2015). Concerns remain about the accessibility of digital content, not only for cognitively vulnerable groups (e.g., individuals with disabilities, older adults) but also for the general population (Droutsas et al., 2025; Van Der Geest & Velleman, 2014; Henni et al., 2022; Mason et al., 2021). Since online reading often involves critical domains such as health and e-government, accessibility is increasingly viewed as an equity and rights issue, as reflected in the European Accessibility Act (European Parliament & Council of the European Union, 2016) and Article 21 of the UN Convention on the Rights of Persons with Disabilities (United Nations, 2006). 15% of Europeans present dyslexia or learning difficulties, and 45.3% of Spaniards over 85 show cognitive impairment (Observatorio Nebrija del Español, 2024). In this context, Easy-to-Read (hereafter, E2R) has emerged as a key strategy for ensuring accessible communication (Fărcașiu et al., 2023).

E2R recommendations include using plain language (e.g., high-frequency words), simple syntactic structures (e.g., avoiding subordinate clauses), visual aids (e.g., pictograms, icons), and accessible design features (e.g., sans-serif fonts, left-aligned text) (González-Sordé & Matamala, 2024). Although research on E2R is limited, it is a growing topic with increasing institutional support (Fărcașiu et al., 2023; Inclusion Europe, 2019). Complementary efforts have focused on digital adaptations of accessible content. In this regard, the Web Content Accessibility Guidelines (WCAG) produced by the World Wide Web Consortium (W3C) are the primary worldwide technical standard. These principles, adopted into the European standard EN 301549 and the Spanish UNE 153101:2018 EX (Asociación Española de Normalización, 2022), define criteria for ensuring that digital material is perceivable, operable, understandable, and robust (W3C, 2022).

These recommendations are based on empirical data from human–computer interaction and psycholinguistics. However, it is especially important to investigate how specific typographic elements influence reading comprehension. While most psycholinguistic research has concentrated on linguistic characteristics (e.g., word frequency, word length), the importance of visual and spatial features in word recognition and reading fluency has gotten less attention (Moret-Tatay & Perea, 2011). The function of typography in text accessibility is a paradigmatic example. In this respect, research has consistently shown that sans-serif fonts are preferable to serif fonts. According to empirical research, serifs do not help visual word identification; rather, their presence may impede lexical access (Moret-Tatay & Perea, 2011). This situation is especially true for people with visual or cognitive disabilities, as sans-serif fonts are viewed as cleaner and more legible on screens due to their reduced letterforms, which minimise visual clutter and improve character differentiation (British Dyslexia Association, 2012). For example, Bernard et al. (2001) investigated the impact of font type on the reading duration of online text among older adults. The study revealed that older adults read serif typefaces significantly slower than sans serif ones. Similarly, Russell-Minda et al. (2007) discovered in their review that the strongest evidence in the study literature suggests that sans-serif fonts (i.e., Arial, Helvetica, Verdana, or Adsans) are generally more legible than serif fonts such as Times New Roman, particularly for readers with impaired vision.

In addition to font type, other typographic features such as font size and line spacing are also crucial for text accessibility. Research on text-heavy webpages (i.e., Wikipedia) has shown that larger font sizes (18 pt or more) combined with default line spacing (1.5) can significantly improve both readability and comprehension (Rello et al., 2013). Complementing these findings, Rello and Marcos (2012) employed an eye-tracking study to compare five different line spacing values (0.8, 1.0, 1.2, 1.4, and 1.8). Their results indicated a clear preference for 1.4-line spacing, which was associated with shorter fixation times, suggesting more efficient reading processes.

Text alignment also plays a role in readability. Ling and van Schaik (2007) conducted a study to compare the effects of left-aligned and justified text on visual search performance and user preferences while reading web pages. The findings revealed that left-aligned text produced much higher accuracy and faster reaction times than justified text. The findings imply that when developing web material for efficient reading or information retrieval, using left-aligned text provides measurable benefits to user performance.

Another example of how minimal modifications can affect reading fluency is letter spacing. Perea and Gomez (2012) showed that modest increases in interletter spacing (+ 1.0 and + 1.5) reduced fixation durations during sentence reading, suggesting that wider spacing facilitates early word processing and fluency. Similarly, Perea et al. (2012) found that slightly increased spacing (+ 1.2) enhanced word recognition in adults, young readers, and especially children with dyslexia. However, in natural text reading with skilled adults, Perea et al. (2016) observed shorter fixations but more of them, yielding no overall differences in reading time or comprehension. Later work indicated that reading speed generally improved with greater spacing, particularly for slower readers, with benefits plateauing at around 30–40% extra spacing. Dick (2017) identified an optimal range between 0.12 and 0.15 times the font size, which informed the WCAG 2.1 guideline of 0.16 for word spacing and twice the font size for paragraph spacing (W3C, 2022).

Contrast is also important for readability. WCAG 2.1 requires a minimum contrast ratio of 3:1 to guarantee that text is legible for users with moderately low vision in ordinary lighting situations. This threshold is established by both the ISO 9241-3 standard (Ergonomic requirements for office work with visual display terminals - Part 3: Visual display requirements) and the ANSI/HFS 100–1988 standard.

More specifically, research in Human-Computer Interaction (HCI) has long shown that black text on a white backdrop provides the best legibility for most digital reading tasks (Mithun et al., 2019). However, using pure black text against a pure white backdrop can create eye discomfort for some users, particularly those with dyslexia (Uccula et al., 2014). This condition may potentially affect the broader population. For example, Conlon and Sanders (2011) studied the reading performance of university students with and without visual discomfort and discovered that those who were uncomfortable had lower reading comprehension when reading black-on-white text. The authors attributed their findings to the strong visual contrast, which can cause perceptual distortions and physical symptoms such as eye strain and headaches. In recognition of these challenges, the European Commission, for example, implemented a more accessible colour scheme on its websites, with EC Grey (#404040) as the default font colour on a white background to reduce visual strain while maintaining adequate contrast and readability (European Commission, 2025).

Rivero-Contreras et al. (2021) investigated the impact of E2R recommendations, particularly visual help and lexical simplification, on sentence processing in people with and without dyslexia. They used eye-tracking to investigate text- and word-level reading behaviour in 20 young adults with dyslexia and 20 age-matched controls. Participants read 60 sentences with varying word frequencies and associated pictures. The results indicated that both visual help and lexical simplification aided sentence processing, particularly lexical-semantic access. In a follow-up study, Rivero-Contreras et al. (2023) assessed the effects of visual support and lexical simplification on sentence processing in adult readers (aged 16–58) from various educational backgrounds. Thirty university-educated people and thirty adults with lower education levels read 60 phrases with various word frequencies and associated visuals. Eye-tracking data demonstrated that both visual help and lexical simplification aided sentence processing in both groups, with non-university individuals reading substantially slower overall. The findings illustrate how E2R adjustments might aid understanding and offer practical applications for improving readability in varied adult populations.

However, some research on healthy people reveals that improving fluency through simpler text presentations may not always result in better learning. For example, some research among university students has demonstrated that presenting texts in difficult-to-read fonts, such as Haettenschweiler, or low-quality photocopies resulted in better learning outcomes than easier-to-read fonts, such as Arial (Diemand-Yauman, Oppenheimer, and Vaughan, 2011). Some studies have found null effects for font size (i.e., words printed in Arial 48 pt. serving as the fluent condition vs. words printed in Arial 18 pt. serving as the disfluent condition; resulting in similar text recall) or font type (i.e., similar lexical processing for words with diacritics vs. similar lexical processing for " ãmîgô" [friend] compared with "amigo") (Duñabeitia et al., 2023).

Similarly, research in groups with disabled people has highlighted serious questions about the practical efficacy of E2R materials. Hurtado et al. (2014) discovered that E2R formats did not consistently improve comprehension among people with intellectual disabilities, with some participants—particularly those with milder impairments—confused due to the integration of visuals and text. Sutherland and Isherwood (2016) conducted a systematic review that emphasised the variety in efficacy among people with intellectual impairments, highlighting the importance of individualised approaches rather than depending on uniform formats.

The study was conducted in accordance with the Declaration of Helsinki and was approved by the ethics committee of Universidad Nebrija (approval code: UNNE-2020-008). Written informed consent was obtained from all participants at the start of the experiment, and a small financial compensation (€12) was provided a few days after participation.

Previous research has highlighted an ongoing debate regarding the design and actual impact of E2R recommendations. Although these adaptations are intended to support individuals with cognitive vulnerabilities, empirical evidence supporting their effectiveness—particularly in terms of reading comprehension—remains mixed. For example, a recent systematic review by Rivero-Contreras and Saldaña (2020) found that most studies evaluating E2R materials did not report significant improvements in comprehension and that their methodological quality was often limited. Moreover, the evidence for the general population is lacking (i.e., Schmutz et al., 2016; 2019). Thus, the aim of the present study was to evaluate the effectiveness of E2R recommendations on reading comprehension and visual processing efficiency among nondisabled Spanish-speaking young adults from the general population. In this regard, two hypotheses were proposed. The first (H1) predicted that participants in the E2R condition would achieve higher comprehension scores and shorter reading times than those in the Control and Hard-to-Read conditions, or at least perform comparably to the Control condition. The second (H2) predicted that participants in the E2R condition would exhibit fewer and shorter fixations and fewer but larger saccades than those in the Control and Hard-to-Read conditions, or at least perform comparably to the Control condition.

H1 showed no significant differences between conditions, but participants achieved slightly higher accuracy in the E2R format. This aligns with Schmutz et al. (2016, 2019), who also reported improved comprehension with simplified content in nondisabled users. However, unlike Schmutz et al. (2019), who did not observe differences in reading time, our results showed significantly shorter reading times in the E2R condition compared to the Hard-to-Read format. This discrepancy may be due to methodological differences: the present study included a control condition and focused on typographic and structural presentation, whereas Schmutz and colleagues manipulated alternative accessibility features (e.g., form labelling, navigation order).

Regarding H2, results from eye-tracking measures suggest that the E2R condition facilitated more efficient reading. Reading efficiency—defined as the ability to extract meaning from text with minimal perceptual and cognitive load (Liu et al., 2022) is typically characterised by shorter fixation durations and longer saccades, both of which were observed in the E2R condition relative to the others. Fixation duration, an indicator of cognitive load during word recognition, was significantly lower in E2R. Similarly, saccade amplitude was greater in E2R, consistent with broader attentional spans and fluent reading. However, this finding should be interpreted with caution, as larger saccades may partly reflect increased paragraph spacing in the E2R layout, rather than purely perceptual facilitation. Finally, the number of fixations was slightly reduced in E2R compared to the Hard-to-Read condition, although this trend did not reach statistical significance.

In practical terms, these results supplement the broader discussion on accessibility and usability in digital environments. The results suggest that E2R recommendations may offer processing advantages even for nondisabled adults, without compromising comprehension. From a practical standpoint, these results may advocate for the adoption of a large-scale implementation of E2R criteria in the design of public communications, educational materials, and digital content, particularly in cognitively demanding contexts. By ensuring that content is both accessible and efficient to process, E2R adaptations may facilitate more inclusive communication strategies that align with legal and normative frameworks for accessibility.

Nonetheless, some limitations should be considered. First, the sample was relatively homogeneous, which may limit the generalisability of the results to broader or more diverse populations, such as older adults or individuals with cognitive disabilities. Second, the materials were short, fictional texts presented in a controlled setting, which may constrain the ecological validity of the findings. Lastly, although some outcome variables revealed clear effects, others yielded more modest differences that might benefit from increased measurement sensitivity. Future research should replicate these findings with larger samples as well as complementary measures of user experience (e.g., acceptability ratings) and cognitive effort (e.g., pupillometry).

This study examined the impact of E2R text formatting on reading comprehension and visual processing efficiency in nondisabled Spanish-speaking adults. While comprehension scores did not differ significantly across conditions, participants performed slightly better in the E2R format. Eye-tracking data revealed that E2R texts may facilitate more efficient visual processing, as reflected by shorter fixation durations and longer saccades—key indicators of reduced cognitive load and fluent reading. These findings suggest that E2R adaptations in terms of text formatting, originally developed for populations with cognitive vulnerabilities, may also benefit the general population by promoting easier and more efficient access to written information.