ISO 9241-420:2011

Overview

ISO 9241-420:2011 - "Ergonomics of human-system interaction - Part 420: Selection of physical input devices" provides guidance for choosing physical input devices for interactive systems based on ergonomic factors. The standard helps match devices to user capabilities, task demands and context of use. It applies to a wide range of devices including keyboards, mice, pucks, joysticks, trackballs, touchpads, tablets/overlays, touch-sensitive screens, styli and light pens. ISO 9241-420 is focused on selection and evaluation of input devices, not on prescribing their detailed design.

Key topics and technical coverage

• Scope and definitions: Terms and definitions for input device selection and evaluation.
• Procedures for selection: General considerations, rationale and objectives for structured selection processes.
• Performance criterion: Guidance on what performance aspects to consider when assessing input devices.
• Methods and aids for selection:
  • Task analysis to map user goals and tasks to device capabilities.
  • Selection based on product description using device functional properties.
  • User tests and usability evaluations to validate device choices.
  • Selection based on dominant task primitives where specific interaction primitives drive device choice.
  • Special guidance for selecting keyboards and handheld/mobile text entry devices.
• Field assessment: Methods for in-situ evaluation of devices and acceptability trade-offs under real-world conditions.
• Informative annexes and tests: Annexes include practical tests and assessment methods (tracing, dragging, one-direction and multi-direction tapping tests, comfort assessment, mobile text entry, keyboard usability) and comprehensive tables (Annex H) linking device properties to generic requirements.

Practical applications and target users

ISO 9241-420 is intended for:

• User organizations selecting input devices for employees or customers.
• Systems integrators and UX/ergonomics specialists tailoring interactive systems to a context of use.
• Procurement teams who need evidence-based criteria for choosing input peripherals. Practical uses include selecting the best device or device combination for specific workflows (e.g., CAD workstations, control-room consoles, mobile data entry), conducting user tests to compare candidates, and performing field assessments to confirm usability and comfort.

Related standards

ISO 9241-420 is part of the broader ISO 9241 series on ergonomics of human–system interaction. Related parts commonly used alongside it include ISO 9241-210 (human-centred design) and ISO 9241-11 (usability) for designing and evaluating interactive systems.

Keywords: ISO 9241-420, ergonomics, input device selection, human-system interaction, keyboards, mice, touchscreens, usability, task analysis, field assessment.