The Poster That Tested Well With the Wrong People
A student designed an A2 safety poster for a school workshop. The poster uses dark grey text on a mid-blue background, 18 pt body text, a busy photographic background behind the main warning, and a red 'DANGER' heading. The student tested comprehension with five fellow design students, who all read it correctly and rated it attractive. The teacher then showed it to a group of Year 8 students and two staff members with colour-vision deficiency. Year 8 students missed the main warning, and the staff members could not distinguish the red heading from the blue background. The student argues the poster works because the first test passed.
1. Explain why the first test was invalid as evidence of communication effectiveness.
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The first test used an unrepresentative sample and measured the wrong things. Design students are familiar with poster conventions, have typical colour vision, and were rating aesthetics, not comprehension under real conditions. The test therefore could not detect the actual weaknesses:
- Contrast: dark grey on mid-blue gives low luminance contrast, and 18 pt body text is small for a wall poster read at distance.
- Legibility: a busy photographic background behind the warning reduces figure–ground separation.
- Colour reliance: the red heading carries meaning through hue alone, which fails for viewers with colour-vision deficiency and on greyscale reproduction.
A valid test needs representative users (the actual audience, including Year 8 and staff), realistic viewing conditions (distance, lighting), and comprehension measures (can they state the warning?), not preference ratings. Passing one friendly test does not establish communication effectiveness.
2. Recommend specific design changes and explain the communication principles behind each.
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Changes and principles:
- Increase contrast: use near-black text on a light or white panel. Principle: luminance contrast drives legibility; WCAG-style contrast ratios give a measurable target.
- Increase type size: body text to at least 24–28 pt for wall viewing. Principle: reading distance and visual angle; larger type supports scanning from several metres.
- Remove the photographic background behind the warning: use a plain field or a solid banner. Principle: figure–ground separation and reduced visual noise improve detection of the critical message.
- Do not rely on red alone: pair colour with a symbol (triangle, exclamation) and the word 'DANGER' in high-contrast text. Principle: redundant coding, so meaning survives colour-vision deficiency and greyscale printing.
- Hierarchy: largest element should be the hazard, then the action, then detail. Principle: visual hierarchy guides attention in the order needed.
- Retest with the real audience at realistic distance.