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

Human Aspects of System Design System Design Process Molecularization System Definition Limitation & Constraints Transformation Iteration Competition Relevance

Human Aspects of System Design Molecularization OVERALL TASK Sub - Task A Characteristics of a System Design Process Sub - Task CSub - Task B

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

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

Human Aspects of System Design Characteristics of a System Design Process Iterative Cycle Design Test and Evaluation New Information Regarding the System

Human Aspects of System Design 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

Human Aspects of System Design Six Major Stages in the Design Process Definition Implementation Testing and Evaluation Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 Stage 6

Human Aspects of System Design 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

Human Aspects of System Design 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 Six Major Stages in the Design Process 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.

Human Aspects of System Design STAGE 2 : Definition of the system Define system functions to meet performance criteria Six Major Stages in the Design Process 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)

Human Aspects of System Design STAGE 3 : Basic Design Allocation of functions to human, computer, and software Six Major Stages in the Design Process - 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

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

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

Human Aspects of System Design (2) Balance of Value Six Major Stages in the Design Process Human Performance Machine Performance Excellent Unsatisfactory Uh Pm Pmh Ph UmUmh

Human Aspects of System Design (3) Utilitarian and cost-based allocation (4) Affective and cognitive support allocations Six Major Stages in the Design Process - 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

Human Aspects of System Design STAGE 4 : Interface Design Six Major Stages in the Design Process - 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

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

Human Aspects of System Design STAGE 5 : Facilitator Design Six Major Stages in the Design Process 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

Human Aspects of System Design STAGE 6 : Testing and Evaluation Six Major Stages in the Design Process 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