Understanding Human-Computer Interaction: Goals, Ingredients, and Usability, Study Guides, Projects, Research of Psychology

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What is HCI?

Human Computer Interaction Fulvio Corno, Luigi De Russis Academic Year 2020/

2 ▪ What is HCI? ▪ What is usability? ▪ What is the Interaction Design Process, and how does it relate with Software Engineering processes? ▪ What is meant by User Centered Design?

Goals

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The goal of HCI

▪ The User (s) ▪ The Computer (s) ▪ The Task (s) to be accomplished ▪ The system must support the user’s task , with a focus on its usability o Useful o Usable o Used

Ingredients Goal

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The ingredients

▪ Sensory systems o Visual o Auditory o Haptic o Spatial ▪ Acting systems o Hands o Voice o Head, Body, … ▪ Cognitive processes o Perception o Memory ▪ Input peripherals o Keyboard, mouse o Trackpad, trackball o Touch surfaces or screens o Microphone o Sensors o Card readers o … ▪ Output peripherals o Screen o Audio (voice, sounds) o Haptics o VR/AR headsets o …

The human The computer

7 ▪ Psychology and cognitive science o User perceptual, cognitive and problem-solving skills ▪ Ergonomics o User’s physical capabilities ▪ Sociology o Understanding the wider context of the interaction ▪ Computer Science and Computer Engineering o Building the necessary artifacts (HW, SW) ▪ Business o Satisfying market needs ▪ Graphic design o Produce an effective interface presentation ▪ Technical writing o Documentation, manuals, on-screen content ▪ …

HCI is multidisciplinary

To help us in applying expertise from many different fields: ▪ Design methods and processes ▪ Models ▪ Heuristics ▪ Best practices ▪ Conventions ▪ Experiments and user studies

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Models of interaction

A general framework to understand how User and System interact

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Norman’s model of interaction

User System Evaluation Execution Output Input

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Norman’s model of interaction

User System Evaluation Execution Output Input

1. Establishing the goal - WHAT
2. Forming the intention - HOW
3. Specifying the action sequence
4. Executing the action

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Norman’s model of interaction

User System Evaluation Execution Output Input

1. Establishing the goal - WHAT
2. Forming the intention - HOW
3. Specifying the action sequence
4. Executing the action
5. Perceiving the system state
6. Interpreting the system state
7. Evaluating the system state The gulf of evaluation The gulf of execution

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Norman’s diagrams

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Human errors*

in the gulf of execution

▪ You have formulated the right action, but fail to execute that action correctly o E.g., click the wrong icon, or double-click too slow, … ▪ May be corrected by a better interface (spacing, layout, highlights, …) ▪ You don’t know the system well and you may not formulate the right goal o E.g., click 🔎 for Zoom, but it means Search ▪ The user’s mental model of the system’s state is not correct ▪ Requires more radical redesign, or additional training

Slip Mistake

17 ▪ Human errors should never be considered as faults of the user ▪ Rather, «they are usually a result of bad design» (Norman) ▪ Humans tend to be imprecise, distracted, not-omniscient o System design should anticipate this human behavior o Minimize the chance of inappropriate actions (evaluation) o Maximize the possibility of discovering and repairing an inappropriate action (execution) o Enable users to understand the state of the system and build an appropriate model

* About Human errors

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Example (presentation): what are the allowed

combinations?

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Tools, Techniques and Environments

for HCI design

User (task language) System (core language) Output Input User Interface (UI language) The gulf of evaluation The gulf of execution presentation performance observation articulation

• Screen design
• Visualization
• UI toolkits
• Dialogs
• Widgets
• Ergonomics