Simple sentences
Following this helps:
- people in a hurry – simply written content is easier to scan and absorb instantly
- people who are stressed – if you're anxious you find it harder to comprehend things
- people who are multi-tasking – if you're holding a baby or a running business your attention's divided
- cognitive impairments – easy to understand words and sentences carry less cognitive load
- visual impairments – short and simple sentences convey meaning in a smaller visual field
- motor impairments – it's less tiring when you can understand what you read quickly
Guidelines
1. Make your average sentence 15 words long.
2. Avoid complex sentence structures.
1. Make your average sentence 15 words long.
The maximum sentence length for a good level of comprehension is 25 words. Split long sentences up into 2 or 3, or use bullet points.
Oxford Guide to plain English, GOV.UK and linguists agree 15 word sentences are fine but above 40 words is hard to understand.
2. Avoid complex sentence structures.
They are less easy to comprehend quickly. Understanding them requires more cognitive effort than simple sentences.
Complexity depends on:
- number of clauses in a sentence, the more clauses the more complex it is
- distribution of associated words across the sentence – how easily can the brain 'parse a phrase': recognise, connect and comprehend words that together convey meaning
Example:
"The red fox jumped over the gate." – easier to understand
"The fox, which was red, over the gate jumped." – harder to understand
Usability evidence: simple sentences
Oxford Guide to plain English
Jyoti Sanyal 'Indlish'
Author Ann Wylie
Writing for GOV.UK, UK Government website
'Sentence length: why 25 words is our limit', Inside GOV.UK, UK Government blog, 2014
'Content design', Sarah Richards, 2017
'The role of word difficulty and sentence length in text comprehension', T. M. Duffy and P. K. U'Ren, 1982
'The Influence of Semantics and Syntax on What Readers Remember', C. S. Isakson and J. H. Spyridakis, 1999
'How the brain attunes to sentence processing: Relating behavior, structure, and function', A. Fengler, L. Meyer, A. D. Friederici, National Center for Biotechnology Information
'Functional Analysis of Clause Complex in the Language of News Websites Texts: A Comparative Study of Two Articles', F. M. S. Eid, International Journal of Scientific and Research Publications, Volume 6, Issue 6, June 2016
Reading Level, Understanding SC 3.1.5, WCAG, 2008
'Readability Assessment of Internet-Based Consumer Health Information', T. M. Walsh and T. A. Volsko in Respiratory Care October 2008, 53 (10) 1310-1315
'The research basis of plain language techniques: Implications for establishing standards', Karen Schriver, PhD, Dr. A. L. Cheek, M. Mercer, Center for Plain Language, November 20, 2008, Mexico City
'Readability Levels of Health-Based Websites: From Content to Comprehension', M. Schutten, A. McFarland, PhD, International Electronic Journal of Health Education, 2009, 12:99-107
'Writing smaller', Clarity Journal no. 63, 2010
Plain Language Commission style guide, 2012
'Shorter Lines Facilitate Reading in Those Who Struggle', Matthew H. Schneps , Jenny M. Thomson, Gerhard Sonnert, Marc Pomplun, Chen Chen, Amanda Heffner-Wong, 2013
'Towards a better measure of readability: Explanation of empirical performance results', Leslie A. Olsen & Rod Johnson, Taylor & Francis Group, 2015
'What is plain language?', Plain Language Association International, 2015
Text complexity, ATOS, and Lexile® Measures, Renaissance Learning, 2016
'How to use Yoast SEO: The readability analysis?' Edwin Toonen, Yoast, 2018
The Crystal Mark standard Plain English Campaign, undated