Frame
The problem in one sentence, the names research and practice give it, and the terms searched.
The problem, one sentence
Which typographic and layout choices (line length, size, spacing, contrast, structure, figures) change how fast, how accurately and how comfortably people read on screen?
Terms used in this folder
- cpl: characters per line, spaces included.
- ch: a CSS unit equal to the width of the digit "0"; a line of 70ch holds more than 70 average letters.
- Contrast ratio: (L1 + 0.05) / (L2 + 0.05) for relative luminances, from 1:1 to 21:1.
- Effect size: d or g, a standardised mean difference. MA: meta-analysis. RCT: randomised experiments. S: single study. R: review. P: practitioner opinion.
What the field calls it
| Topic | Field names |
|---|---|
| Overall | legibility (can letters be told apart); readability (how easily text is read); typography; accessible design |
| Line length | measure; characters per line (cpl) |
| Line spacing | leading; line height |
| Letter spacing | tracking; letter spacing; crowding |
| Size | point size; x-height; fluent range; critical print size |
| Contrast | luminance contrast ratio; polarity (dark on light vs light on dark) |
| Reading difficulty | dyslexia; visual crowding |
| Reading behaviour | scanning; F-pattern; information foraging |
| Grouping | Gestalt proximity; common region; chunking |
| Words and pictures | spatial contiguity; split attention; signalling; coherence |
| Standard | WCAG 2.2 (Web Content Accessibility Guidelines) |
What practitioners call it
| Practitioners say | The field says |
|---|---|
| line length, column width, "no more than 75 characters" | measure, cpl |
| body size 16px | fluent range, x-height |
| line height 1.5 | leading |
| contrast ratio, Lc (APCA) | luminance contrast, polarity |
| dark mode | polarity |
| F-pattern, layer-cake, scanning | information foraging, scanning |