4 - Task Analysis for Interface Design — Topics & Learning Outcomes

Module Topics

Foundations of Task Analysis

• What Is Task Analysis? — Task analysis is a systematic process for studying and understanding how users accomplish goals, breaking complex behaviors into discrete, observable steps.
• The Role of User Goals — Every task analysis begins with clearly identifying user goals, which define the end state a user is trying to reach through interaction with a system.
• Why Task Analysis Informs Interface Structure — The decomposed steps produced by task analysis directly map onto interface components, navigation flows, and interaction sequences.
• Observable vs. Cognitive Steps — Tasks include both observable physical actions, such as clicking or typing, and internal cognitive steps, such as deciding or recalling information.

Hierarchical Task Analysis (HTA)

• Principles of HTA — Hierarchical task analysis organizes tasks in a parent-child tree structure, where each high-level goal is progressively broken down into smaller, actionable subtasks.
• HTA Notation and Diagrams — HTA is typically represented as a numbered tree diagram or an indented outline, using plans to specify the order and conditions under which subtasks are performed.
• Decomposition Process in HTA — Decomposition in HTA proceeds by asking 'what does the user need to do to accomplish this task?' at each level until reaching steps that are atomic enough to inform design.
• Applying HTA to Interface Design — The completed HTA tree translates directly into design artefacts such as sitemaps, user flows, and screen wireframes.

Cognitive Task Analysis (CTA)

• What CTA Adds Beyond HTA — Cognitive task analysis extends beyond observable actions to capture the knowledge, judgments, and mental models users rely on when performing tasks.
• Key CTA Techniques — Common CTA techniques include think-aloud protocols, critical decision method interviews, and knowledge audits, each suited to different task types and research constraints.
• Identifying Decision Points and Mental Models — CTA explicitly maps the points in a task where users must make judgments, and documents the mental models they use to interpret system states and choose next actions.
• Representing CTA Findings — CTA results are typically documented in annotated task diagrams, decision ladders, or structured tables that capture actions alongside their associated cognitive demands.
• CTA Findings in Interface Design — CTA outputs directly inform decisions about information architecture, feedback mechanisms, error prevention, and the depth of guidance provided within an interface.

Comparing and Selecting Analysis Methods

• Strengths and Limitations of HTA — HTA is highly efficient for structured, procedural tasks and produces clear, actionable documentation, but it can underrepresent cognitive complexity and user variability.
• Strengths and Limitations of CTA — CTA provides deep insight into user cognition and decision-making but is more resource-intensive to conduct, analyze, and document than HTA.
• Choosing the Right Method — Method selection should be guided by task type, project constraints, the target user population, and the specific design questions the analysis must answer.
• Scoping a Task Analysis — Before conducting any analysis, the scope must be defined by specifying which user groups, goals, and task scenarios are included and which are excluded.

Data Collection for Task Analysis

• Observation Methods — Direct observation of users performing tasks in context provides the most accurate baseline data for task analysis, capturing actual behavior rather than reported behavior.
• Interview and Protocol Methods — Structured and semi-structured interviews complement observation by eliciting user explanations of their goals, reasoning, and decision-making during tasks.
• Using Existing Documentation — Existing materials such as user manuals, support logs, and workflow documentation can supplement primary data collection and speed up initial task decomposition.
• Participant Selection — The validity of task analysis data depends on selecting participants who accurately represent the target user population for the interface being designed.

Producing Task Analysis Documentation

• Components of a Task Analysis Document — A complete task analysis document includes a scope statement, user and goal definitions, the hierarchical or cognitive task diagram, plans or annotations, and design implications.
• Writing Clear Task Descriptions — Each task and subtask should be described with an action verb and a clear object, stating precisely what the user does rather than what the system does.
• Validating the Task Analysis — Completed task analyses should be reviewed against user data and evaluated by team members or subject matter experts to identify gaps, errors, or missing steps.
• Linking Task Analysis to Design Artefacts — Each section of the task analysis should be explicitly connected to a corresponding design artefact, ensuring that structural and cognitive findings are traceable through the design process.
• Group Project Documentation Requirements — For the group project, teams are required to produce a full task analysis document covering at least one primary user goal using both HTA and CTA methods.

Applying Task Analysis to the Group Project

• Identifying Your Project's Primary User Goal — The first step in applying task analysis to the group project is agreeing on a single, well-defined primary user goal that is sufficiently complex to require full decomposition.
• Dividing Data Collection Responsibilities — Effective group task analysis requires clear allocation of data collection roles, with each team member responsible for gathering data from at least one participant or source.
• Building the HTA as a Team — The hierarchical task diagram should be constructed collaboratively, with the full team reviewing and agreeing on the structure before it is finalized.
• Integrating CTA Findings into the Document — Once the HTA structure is agreed upon, the team adds cognitive annotations by reviewing interview and think-aloud data for decision points, knowledge requirements, and cognitive load indicators.
• Reviewing and Finalizing the Project Document — Before submission, the full task analysis document must be reviewed for completeness, consistency, and clear linkage between findings and design implications.

Student Learning Outcomes

By the end of this module, students will be able to:

Course Outcomes (reference)