Interaction Theories and Paradigm Selection

Interaction theory in HCI models mutual influence between user goals, action dynamics, system behavior, and context (George, 2025).

1. Determination modes

Common determination modes in interactive systems:

• mechanical,
• statistical,
• structural,
• dynamic,
• teleological (goal-directed).

Real systems are mixed-mode, e.g., deterministic UI transitions with probabilistic model inference.

2. Fitts’ law

For aimed movement tasks:

with movement time $MT$, target distance $D$, and target width $W$.

Design consequence: larger targets and shorter travel distances reduce expected motor time.

3. Paradigm fit

• CLI: expert repeatability, symbolic precision.
• GUI: broad learnability and visual discoverability.
• NUI: embodied low-threshold interaction.
• Intent-based systems: outcome delegation under uncertainty.

Paradigm choice is a task-model decision, not a stylistic preference.

co-authored by an AI agent.

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