Human Aspects of System Design

1. Human Aspects of System Design Introduction • Designing the human element into a system is paramount to its success • One error incorporated by the human into the system could bring a major catastrophe • Some Examples: 3 Mile Island Jack Hammers VCR clocks / programming

2. System Design Process • Molecularization • System Definition • Limitation & Constraints • Transformation • Iteration • Competition • Relevance

3. Molecularization Characteristics of a System Design Process OVERALL TASK Sub - Task A Sub - Task B Sub - Task C

4. Characteristics of a System Design Process Requirements of the system define options Limitations and processes that are unsure • - such as the height required for • the legible picture on a computer screen. - such as the budget changing, new team members, innovative ways of manufacturing, or how parts interrelate.

5. Physical Requirements Behavioral Implications Physical Manifestations Characteristics of a System Design Process Transformation Time and Cost Constraints

6. Characteristics of a System Design Process Iterative Cycle Test and Evaluation Design New Information Regarding the System

7. Characteristics of a System Design Process Competition between groups within the design team Relevance to the design - between sales, administration, manufacturing, HF - more money / members / power = more influence • - must convince others of the • importance of your contribution • in order to get it accepted

8. Six Major Stages in the Design Process Testing and Evaluation Definition Implementation Stage 1 Stage 4 Stage 6 Stage 3 Stage 2 Stage 5

9. Six Major Stages in the Design Process STAGE 1 : System Requirements Determine the objectives and principles of the process Objective - purposes of the system - general terms - details what system is to do to meet objectives - defines constraints System Performance Specifications

10. Six Major Stages in the Design Process Two HF activities appropriate at Stage 1 (1) Identify all users of the machine (2) Identify the activity-related needs of users which the system will be responsible for Examples: An oven will be used by a wide range of users, including families, single people, and the elderly. Children may use the door as a stepping stool (possibly to get to the counter) and thus tipping the entire range over onto them, possibly killing them.

11. Six Major Stages in the Design Process STAGE 2 : Definition of the system Define system functions to meet performance criteria General - not assigned to human, computer, or software Functions could be short or long, simple or complex, no real definition as to the length Functional Flow Diagrams (Figure 22-2 in book)

12. Six Major Stages in the Design Process STAGE 3 : Basic Design Allocation of functions to human, computer, and software • - sometimes this is considered by • economic considerations or the • shear superiority of one over another • - also, there is a gray area, where both • human and machine can both do • the job equally well

13. Six Major Stages in the Design Process Some Guidelines for Designers Humans • reason inductively • sense unusual events • sense unexpected events • develop new solutions Machines • monitor for prespecified events • store and retrieve coded information • exert considerable physical force • perform repetitive activities reliably

14. Six Major Stages in the Design Process Guidelines to Allocate Functions (1) Mandatory Allocation • - allocate functions based on • system requirements, hostile • environments, safety • considerations, or legal or labor constraints • - these allocations should be made first

15. Excellent Pm Uh Pmh Machine Performance Ph Umh Um Unsatisfactory Excellent Six Major Stages in the Design Process (2) Balance of Value Human Performance

16. Six Major Stages in the Design Process (3) Utilitarian and cost-based allocation (4) Affective and cognitive support allocations - functions may be allocated to humans simply because they are present Affective support - the emotional requirements of humans, such as needing challenging work and feeling personally secure Cognitive support - the human need for the information to be relevant so that they can be ready to make decisions when required

17. Six Major Stages in the Design Process STAGE 4 : Interface Design • - this stage is performed concurrently with STAGE 5 only after the proper allocations of functions have taken place • - this stage deals with designing : • spaces • displays • controls • computer dialogs • and more • - this stage is most important for HF considerations, though it is usually seen as a chore for most engineers

18. Six Major Stages in the Design Process Primary Activities of HF Team in this stage gather and interpret HF and human performance data conduct human performance studies conduct attribute evaluations of suggested designs

19. Six Major Stages in the Design Process STAGE 5 : Facilitator Design • Main Focus of this stage: Plan for materials that will promote acceptable human performance • Some Examples : • Instruction Manuals • Performance Aids • Training Devices • Training Programs • Selection • Some Guidelines for Instruction Manuals: • avoid information overload • use only concrete information • remember that learning will come from doing • users want minimal hassle in setting up

20. Six Major Stages in the Design Process STAGE 6 : Testing and Evaluation • Evaluation - the measurement of system development products (including hardware, procedures, and personnel) • to verify that they will do what they are supposed to do • Human Factors Evaluation -- the examination of these products to ensure the adequacy of attributes that have implications for human performance • Special Considerations for HF evaluations • Subjects • Criteria • Experimental Procedures and Controls • Research Setting