Familiarity Beats Transparency: How Adults With Low Literacy Really Understand Idioms in Easy German

When German public authorities write election notices, medical instructions, or consent forms in Easy German — the rule-governed variety known as Leichte Sprache — most style guides tell them one thing about idioms: avoid them, or at most allow the ones that are transparent, meaning their figurative sense can be worked out from the literal words. A new experimental study from Saarland University, published in Frontiers in Language Sciences, puts that advice to the test with the very readers Easy German is designed for, and the results upend the intuition. For adult readers with low literacy skills, what makes an idiom comprehensible is not how transparent it is, but how familiar it is and how implausible its literal reading happens to be.

Lena Wieland and Ingo Reich of the Department of German Studies at Saarland University in Saarbrücken conducted four interlocking experiments to answer a deceptively simple applied question: can adult low-literacy readers understand idioms in Easy German, and if so, which properties of the idioms and of the readers themselves reliably help or hinder comprehension? Their motivation is practical. Easy German texts often carry legal, medical, or civic consequences, so every recommendation in the rule sets — from Duden Leichte Sprache to the 2025 DIN specification and the Netzwerk Leichte Sprache rulebook — functions as an implicit hypothesis about how the target audience processes language. Until now, the hypothesis that figurative expressions are a systematic barrier had barely been tested experimentally in this population.

The researchers focused on German verb-phrase idioms, multiword expressions built around a verb whose overall meaning cannot be directly inferred from its parts. Examples include jemandem die Daumen drücken, literally to press the thumbs for someone, which means to wish someone luck; blau machen, literally to make blue, meaning to skip work or school; and zittern wie Espenlaub, to tremble like aspen leaves. Idioms vary along dimensions that psycholinguists have long studied: transparency, the degree to which figurative meaning can be inferred from the literal components, as in am Ball bleiben, to stay on the ball; and literal plausibility, how believable the literal scene would be as a real-world event. Being on cloud seven, the German counterpart of being on cloud nine, describes an implausible scene, whereas grabbing a bull by the horns is something one could in principle actually do.

The first experiment was a norming study conducted online through the Prolific platform with 60 literate native German speakers, split into two groups of 30. Each participant rated a subset of 71 verb-phrase idioms drawn from an initial pool of roughly 2,500 expressions compiled from dictionaries, corpora, and expert knowledge. After a production prompt in which they indicated whether they had heard the expression before and attempted a paraphrase, participants rated each idiom on seven-point scales for transparency — how easily the figurative meaning could be inferred from the literal words — and for the likelihood of the literal scenario, which the researchers reverse-coded so that higher values indicated a more plausible literal scene. From these ratings, the team selected 24 idioms instantiating a 2 × 2 design crossing high versus low transparency with high versus low literal plausibility, with no overlap between category bands and a balanced 7/5/7/5 distribution across cells.

Experiment 2 assessed literacy in the target population using otu.lea, a low-threshold adaptive diagnostic widely used in adult-literacy instruction, administered individually at the sheltered workshop of the cooperation partner AWO Teilhabe Saarland. The battery samples functional reading across word, sentence, and text levels, assigning alpha levels that reflect the highest level of reading comprehension a participant can reliably demonstrate. Because the raw output is categorical, the researchers converted it into a quasi-continuous literacy index ranging from 0 to 100, weighting each completed proficiency level by 0.25 and adding the proportion correct within the highest level reached. The final sample of 30 low-literacy adult native speakers produced scores ranging from 37.50 to 95.50, with a median of 70.00 — a spread that captures the substantial heterogeneity typical of institutional settings and allows literacy to be modeled as a continuous individual-difference predictor rather than a crude label.

Experiment 3 then posed the most basic question: can these readers access an idiom’s figurative meaning at all, without any contextual support? The same 30 participants received each of the 24 idioms bare, with the Easy German prompt Was heißt der Satz? — what does the sentence mean? — and gave oral explanations recorded verbatim by the experimenter. Responses were coded by trained raters as figurative, literal, or uncodable. The results were striking: 76.4 percent of the 720 trials yielded figurative interpretations, showing that a sizeable subset of the idioms was functionally familiar even without scaffolding, while 8.3 percent were literal construals and 15.3 percent were unfamiliar or uncodable, collapsing to 59.4 percent correct under the preregistered binary measure. A generalized linear mixed-effects model revealed that figurative accuracy rose reliably with literacy, with a coefficient of 0.028 per point on the literacy index, and was strongly related to literal plausibility, with a coefficient of 0.569.

The most theoretically consequential finding was a robust interaction between transparency and plausibility, with a coefficient of −1.457: idioms that were simultaneously transparent and literally plausible produced the lowest figurative accuracy of all. This is the opposite of what a simple transparent-is-easier heuristic would predict. The researchers interpret it through the lens of constraint-based competition models, in which literal and figurative interpretations remain simultaneously active and compete for selection. Transparency, on this view, has two faces: it can bridge literal components to figurative meaning, but it can also make the literal scene more coherent. When that scene is already plausible, the literal candidate becomes especially strong, and if the analytic mapping needed to exploit transparency is not reliably available — as may be the case when literacy limits lexical knowledge, executive control, and metalinguistic resources — transparency amplifies competition rather than resolving it.

Experiment 4 moved from baseline access to idiom use under supportive conditions closer to real Easy German practice. The same cohort returned after roughly six months, a delay chosen to reduce carryover and make it unlikely that responses reflected simple memory of the earlier session; 26 of the 30 participants completed this phase. Each idiom was embedded in a short Easy German context, independently vetted for comprehensibility by readers from the same target population, and participants completed a two-step task: first a choose-all-that-apply endorsement among the idiom, a meaning-consistent literal paraphrase, and a length-matched distractor; then a ranking of the three options using an accessible gold-silver-bronze podium metaphor, with responses mediated by an experimenter to minimize device-related barriers. Mixed-effects modeling showed that idiom endorsement was predicted by functional familiarity — whether the participant had produced the correct figurative interpretation without context six months earlier — with a coefficient of 0.702, while literacy and transparency showed only marginal positive trends.

The ranking data added a second key conclusion: idioms are not categorically avoided. Participants reliably rejected distractors, ranking them far below idioms with an enormous ordinal effect, but literal paraphrases did not differ reliably from idioms in preference once meaning was available. In a conditional analysis restricted to trials where the distractor had been rejected, functional familiarity was the only reliable predictor of preferring the idiom over the literal paraphrase, corresponding to roughly 53 percent higher odds. In other words, when an idiom’s meaning is accessible, low-literacy readers treat it as broadly equivalent to a plain paraphrase — comprehension and acceptability, often conflated in guideline debates, come apart only when stored knowledge is missing.

The implications for Easy German practice are concrete. The authors argue for a shift from categorical prohibitions toward conditional, evidence-based guidance: prioritize idioms that are functionally familiar to the audience, ideally assessed empirically through community norming or corpora of Easy German usage; avoid idioms with highly plausible literal scenes in low-context settings, or ensure the context clearly licenses the figurative reading; treat transparency with caution, since transparent-and-plausible idioms proved particularly difficult without context; and use paraphrases as scaffolding rather than replacement, pairing an idiom with a short paraphrase when its discourse function matters. More broadly, the study demonstrates that task format is not a neutral window onto competence — open-ended explanation exposed literacy and plausibility effects, while contextualized multiple-choice revealed familiarity effects and fine-grained contextual-fit judgments. Figurative language, the findings suggest, need not be categorically excluded from accessible communication; it needs to be matched to the audience’s stored knowledge and supported by context.

Subject of Research: Idiom comprehension in adult readers with low literacy skills and its implications for Easy German accessibility guidelines

Article Title: Familiarity and literal plausibility, not transparency, drive idiom comprehension in adult readers with low literacy skills in Easy German

Article References: Wieland, L., & Reich, I. (2026). Familiarity and literal plausibility, not transparency, drive idiom comprehension in adult readers with low literacy skills in Easy German. Frontiers in Language Sciences, 5, Article 1872761. https://doi.org/10.3389/flang.2026.1872761

Image Credits: AI Generated

DOI: 10.3389/flang.2026.1872761

Keywords: Easy German, idiom comprehension, low literacy, transparency, literal plausibility, functional familiarity, psycholinguistics, Leichte Sprache, figurative language, accessibility, mixed-effects models, plain language