Overview
ISO 9186-2:2008 - Graphical symbols - Test methods - Part 2: Method for testing perceptual quality - specifies a standardized empirical procedure to verify that the elements of a graphical symbol are readily identifiable by the intended user population. The method focuses on identifiability and perceptual quality rather than semantic comprehension: respondents name or describe the elements they see, and the outcome is reported as a correct identification percentage for each presentation size.
Keywords: ISO 9186-2, graphical symbols, perceptual quality, identifiability, symbol testing, visual angle.
Key topics and technical requirements
- Test principle: Show symbols to representative respondents at two or more presentation sizes (including a required 80 mm × 80 mm size) and score the percentage who correctly identify all symbol elements.
- Presentation sizes: Standard series - 80, 40, 28, 20, 14 and 10 mm square. These correspond (at 2 m viewing distance) to z-factors 25–200 and visual angles ≈ 2.30°, 1.15°, 0.80°, 0.57°, 0.40°, 0.29° respectively.
- Apparatus & print quality: Printed presentation with at least 24 dots/mm (600 dpi) resolution; symbols normally as black on white unless specific colours are required in application.
- Viewing conditions: Viewing distance (2 ± 0.04) m, eye-line ~90° to symbol plane; lighting between 95–105 lux measured at the symbol; daylight excluded.
- Respondent task & scoring: Respondents name or describe symbol elements (image content). Score is the proportion who correctly identify all elements. Organizations may set pass thresholds (example: high criterion for large size e.g. 90%).
- Pre-test submission: Submitter provides application details, image content description, minimum visual angle(s) for identifiability, confirmation of design conformance and EPS/TIFF artwork.
Practical applications and users
ISO 9186-2 is used to:
- Validate symbol legibility and element recognizability before standardization or mass deployment.
- Troubleshoot symbols that passed comprehension tests but show ambiguous element perception.
- Assess performance at small display sizes or long viewing distances (e.g., signage, vehicle panels, icons).
Typical users:
- Standards bodies and submitters proposing symbols for ISO/CEN certification
- Graphic designers and sign designers
- Human factors and usability researchers
- Safety engineers, facilities managers and manufacturers of equipment or public information signage
Related standards
Using ISO 9186-2 helps ensure graphical symbols are not only meaningful but perceptually robust and fit for real-world viewing conditions.