The interface is the place where the interaction between two complex and non-homonegeous systems occurs, and the interface creates the translation of the dialogue between one system and the other.

In our case, humans and computers are complex systems, and therefore there will be a greater chance of errors in making this translation.

The use of interaction models allows us to highlight translation problems very soon and to compare solutions.

Abowd & Beale’s interaction model

Abowd & Beale's interaction model outlines how users interact with systems to achieve goals within specific domains. It emphasizes:

• Goal Achievement: Users aim to achieve goals within an application domain through tasks manipulating domain concepts.
• Interaction as Dialogue: Input and Output form the dialogue between users and systems, with each using its own language.
• Translator Role: Designers must translate between user and system languages for effective interaction.

1. Four Phases of Evaluation: The model divides interaction evaluation into four phases:

   

   • Articulation: The user's goal, expressed in a task-oriented language, is assessed for ease of expression and task coverage. Happens trough the input.
   • Execution: The system compute its calculation.
   • Presentation: System operations produce output representing a new state, evaluated for capturing relevant system changes.
   • Observation: Users interpret system output in relation to their goals, evaluated for ease of understanding and goal coverage.

• Emphasis on Translation: The model focuses on translating human tasks into system tasks rather than solely relying on system metrics, prioritizing effective communication between user and system languages.

ACM's HCI Classification:

• Association for Computing Machinery outlines HCI areas like ergonomics, dialogue and screen design, and considering social and organizational contexts as integral parts of interaction evaluation.

Social and Organizational Contexts:

• Interaction occurs within wider contexts, considering factors like social dynamics, workplace hierarchies, and individual motivations, as highlighted by Alan Cooper in his interaction design model.

Ergonomics in Interaction Design:

• Ergonomics studies physical interaction characteristics, including controls, displays, environmental conditions, and health-related aspects.
• It emphasizes organizing controls and displays for efficiency, considering physical environment conditions, and being mindful of color usage considering variations in perception and potential deficiencies.

Layout Significance: The physical arrangement of controls and displays is crucial, impacting the tasks they support, especially in critical applications where proximity of commands can have varied and critical effects.

Grouping Strategies: Commands are organized based on:

• Functional Groupings: Related commands placed together.
• Sequential Groupings: Ordered to reflect activation sequences, crucial in specific contexts like aviation.
• Frequency Groupings: Frequently used commands grouped visibly for easier access.

Environmental Conditions: Considerations include:

• Comfortable Access: Controls at an accessible height for users, including those on wheelchairs.
• Light Reflection: Display placement to avoid glare from windows or lights.
• User Comfort: Preventing discomfort for users of various sizes by avoiding overcrowding controls.

Other Ergonomic Aspects:

• Health-Related Concerns: Long-term effects of physical aspects (temperature, light, noise) on users.
• Use of Colors: Considering limitations in color perception and individual variations, avoiding sole reliance on colors for differentiation, especially against local cultural expectations. Suggested testing on black-and-white resolution for readability in designs for color-related issues.

Dialogue design

Various dialogue design styles in interaction between users and computers, along with their pros and cons: