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Human-Computer Interaction Cheat Sheet

The core ideas of Human-Computer Interaction distilled into a single, scannable reference — perfect for review or quick lookup.

PiqCue — piqcue.com/human-computer-interaction/cheatsheet

Quick Reference

Usability

The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context of use, as defined by ISO 9241.

User-Centered Design (UCD)

An iterative design framework in which the needs, wants, and limitations of end users are given extensive attention at each stage of the design process, from requirements gathering through prototyping and evaluation.

Affordance

A property of an object or interface element that suggests how it can be used. Originally coined by psychologist James Gibson and adapted for design by Don Norman, affordances signal possible actions to the user.

Mental Model

An internal representation that a user holds about how a system works. When a user's mental model matches the system's actual behavior, interaction is intuitive; mismatches lead to errors and frustration.

Fitts's Law

A predictive model of human movement stating that the time to move to a target is a function of the distance to the target and the size of the target. Larger, closer targets are faster to select.

Heuristic Evaluation

A usability inspection method in which evaluators examine an interface and judge its compliance with recognized usability principles (heuristics), such as Jakob Nielsen's ten usability heuristics.

Accessibility

The design of products, devices, services, or environments so that they are usable by people with the widest range of abilities, including those with visual, auditory, motor, or cognitive disabilities.

Interaction Design (IxD)

The practice of designing interactive digital products, environments, systems, and services with a focus on how users will interact with them, encompassing the behavior and responses of the system over time.

Cognitive Load

The total amount of mental effort being used in working memory during interaction with a system. Interfaces that impose excessive cognitive load lead to errors, slower performance, and user fatigue.

User Experience (UX)

The overall experience a person has when interacting with a product or system, encompassing not only usability but also emotional responses, perceived value, and the broader context of use before, during, and after interaction.

Key Terms at a Glance

Accessibility:The design of products and environments so they are usable by people with a wide range of abilities and disabilities.
Affordance:A quality of an object or interface that suggests how it should be used or interacted with.
A/B Testing:A controlled experiment comparing two design variants to determine which performs better on defined metrics.
Card Sorting:A user research method where participants organize topics into categories to inform information architecture.
Cognitive Load:The amount of mental effort required to process information and interact with a system.
Cognitive Walkthrough:A usability inspection method that evaluates an interface by simulating a user's problem-solving process at each step.
Design Thinking:A human-centered problem-solving approach involving empathy, ideation, prototyping, and testing.
Eye Tracking:A research technique that measures where and how long a user looks at different areas of an interface.
Fitts's Law:A predictive model stating that movement time to a target depends on the distance to and size of the target.
GOMS:Goals, Operators, Methods, and Selection rules — a model for analyzing and predicting user task performance.
Gulf of Execution:The gap between a user's goal and the actions available in an interface to accomplish it.
Gulf of Evaluation:The gap between the system's state and the user's ability to perceive and understand that state.
Heuristic Evaluation:An expert-based usability inspection method judging an interface against established usability principles.
Hick's Law:The time to make a decision increases logarithmically with the number of available choices.
Information Architecture:The structural design of shared information environments, organizing and labeling content for findability and usability.

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Human-Computer Interaction Cheat Sheet - Quick Reference Guide | PiqCue