DH

2.2 Feedback Cycles, Gulfs of Execution and Evaluation in HCI

Feedback Cycles

  • Feedback cycles are ubiquitous: actions produce results, which are fed back to inform future actions.
  • They apply to everyday tasks and human–computer interactions alike (and even AI/cyber-physical systems).
  • Core idea: act → observe result → adjust next action.

Gulf of Execution

  • Definition: the distance between a user’s goals and the actions required to realize them.
  • Three progression steps:
    • Identify the goal in the context of the system.
    • Identify the necessary actions to achieve that goal.
    • Execute those actions in the interface.
  • Common problem: mismatch between what the user thinks they should do and what they actually have to do; learning new systems can widen this gulf.
  • Examples:
    • Transition from VCR/DVR to on-demand interfaces.
    • Heating chili in a microwave: intent phrasing vs actual controls.
  • Key design tension: discoverability vs efficiency; novices need findable actions, experts may want fast shortcuts.
  • Five quick tips to bridge the gulf:
    1) Make functions discoverable.
    2) Let the user mess around safely (undoable actions).
    3) Be consistent with other tools and conventions.
    4) Know your user (novice vs. expert needs).
    5) Feed forward: help predict what will happen next.

Gulf of Evaluation

  • Definition: the distance between the effects of the user’s actions and the user’s understanding of those results.
  • Three parts:
    • The actual output (visual, auditory, haptic).
    • Interpretation: can the user understand what the output means?
    • Evaluation: can the user determine whether goals were realized?
  • Examples:
    • On-demand video: screen blackout can be misinterpreted; a buffering indicator can help interpretation.
    • Thermostat: heat turns on, but user may not be sure if it actually happened without obvious indicators.
  • Five quick tips to bridge the gulf:
    1) Give feedback constantly (at each step).
    2) Give feedback immediately (acknowledge input even if full result isn’t ready).
    3) Match feedback to the action (subtle for small actions, stronger for big actions).
    4) Vary feedback (include non-visual cues like auditory or haptic feedback).
    5) Leverage direct manipulation to make results feel tangible.

Norman’s Seven Questions for Interface Design

  • Don Norman’s questions to guide design across execution and evaluation:
    1) How easily can one determine the device’s function?
    2) How easily can one tell what actions are possible?
    3) How easily can the user determine the mapping from intent to actions?
    4) How easily can the user perform the physical actions?
    5) After action, how easily can the user perceive the state?
    6) How easily can the user tell if the system is in the desired state?
    7) How easily can the user map state to interpretation and compare to the goal?
  • These questions align with the two gulfs and the overarching execution/evaluation cycle.

Norman’s Phases and Related Vocabulary

  • Phases: visceral (raw perception/physical activity), behavioral (planning/specifying/performing/interpretation), reflective (planning, evaluating against goals).
  • Alternative terminology: raw reaction, deliberation, metacognition.
  • This mapping connects to familiar design concepts and to knowledge-based AI diagrams.
  • Example concept: small, clear feedback correlates with good design; ambiguous feedback with bad design.

Practical Examples and Implications

  • Everyday systems illustrate gulf navigation:
    • Car ignition: button location and feedback affect how easily a user starts the car; lacking timely brake-press confirmation creates a gulf of execution.
    • Credit card readers: sliding input lacks reliable feedback; insertion provides richer feedback but raises memory-reminder concerns.
  • Key lesson: focus on the underlying user task (e.g., paying for purchases) rather than historical interaction methods; incremental improvements should align with the user task.
  • Applications across domains:
    • Healthcare relies on interpretable feedback for symptom management.
    • Gesture-based interfaces face challenges in interpreting feedback from gesture recognition.
    • Touch interfaces often provide more immediate, understandable feedback than gesture-based systems.

Takeaways and Next Steps

  • Feedback cycles explain how users learn and adapt through interaction with systems.
  • Bridging gulfs of execution and evaluation is central to usable design.
  • Seven Norman questions provide a practical checklist for designing interfaces that connect user intent to action and interpretation.
  • Next: explore methods for crossing these gulfs and applying them to real systems.