Programs are used by somebody

• Designing for human hardware/software capabilities and limitations (Human-Factors)

• Short term memory: Miller’s magic number

• Long term memory: recognition vs. recall

• Limits of perception: color pollution

• Designing for how the user thinks about the tasks the application is supporting (Psychology & Sociology)

• How do they organize the work?

• What strategies do they use to accomplish tasks?

• How is information recorded and communicated?

• What is their conceptual model?