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Action and feedback

Fitts's Law and target distance

Give controls enough room to hit and put related actions within a sensible reach.

Research finding

Source review

How to read the evidence

The idea in plain language

What it means.

Fitts modelled aimed movement using distance and target width. A larger target or a shorter movement can make pointing easier within the model's conditions. Keeping related actions near the point of interaction applies this same relationship. For interfaces, consider the whole interaction: where the pointer or hand starts, competing controls, keyboard access and the consequence of a mistake.

Evidence and interpretation

What supports it.

Research finding

Controlled motor-performance experiments support the size-and-distance relationship. Web target-size criteria are separate accessibility requirements, not numbers derived directly from Fitts's equation.

From principle to interface

Where you could use it.

Proposed applications, not tested outcomes. The expected effects are hypotheses to check with realistic tasks and users.

Application 1

Edit a row in a table

Place a clearly labelled Edit control beside each record and give its hit area enough space without overlapping adjacent rows.

Expected effect to test

The action is close to the item being changed and easier to select accurately.

Keep in view

Keep keyboard focus visible and provide an accessible name that identifies the relevant record.

Application 2

Delete a saved project

Keep Delete comfortably selectable, separate it from Save, name the project in the confirmation when needed, and offer recovery when the system supports it.

Expected effect to test

The person can act deliberately and understand the consequence.

Keep in view

Shrinking a destructive target is not a safety mechanism. Use clear meaning, appropriate confirmation and reliable reversal.

Turn the idea into a check

Use it deliberately.

  • Measure the actual clickable area and spacing, not just the visible icon.
  • Check WCAG 2.2 SC 2.5.8: 24 by 24 CSS pixels at Level AA, with defined spacing alternatives and exceptions; SC 2.5.5 uses 44 by 44 at Level AAA with exceptions.
  • Check reach, zoom, keyboard operation and accidental activation on representative devices.

Where the rule gets complicated

Keep the limits attached.

  • CSS pixels, physical pixels, points and density-independent platform units are different measurements.
  • A viewport edge is not automatically an infinitely large target; pointer confinement and device behavior matter.
  • A convenient thumb zone varies with hand, device, grip and assistive technology.

A named principle does not settle an accessibility requirement, prove a conversion lift or replace testing the particular interface.

Application and implementation boundaries

What the application check shows.

Limited evaluationAccount-free ·

The example kept a comfortably sized Delete target, keyboard confirmation, cancellation and recovery. Target geometry alone did not provide the safety boundary.

Methods: Local application example. A completed check covers the stated sample; it is not a safety certification.

Target
Original IonBin synthetic interface example; no external product or human-participant study.
Version or capture
2026-10-19 local fixture
Integrity scope
SHA-256 f85d1056afd667225a1e0364edfb8f25b4693ffa7b2b8c7d7af5b92338b85ee4 identifies the exact HTML fixture only.

Test conditions

  • 155.0.8059.82 Chromium; fresh context with all network requests blocked.
  • Synthetic inputs, memory-only state, reduced-motion preference, 1280px and 320px viewports.

Individual checks and observations

  1. Target size

    pass

    Local application example: Exercise the original local application fixture and inspect the resulting controls or DOM state.

    Observed: Delete button measured 99.5625 by 44 CSS pixels at 1280px viewport.

  2. Confirm focus

    pass

    Local application example: Exercise the original local application fixture and inspect the resulting controls or DOM state.

    Observed: Keyboard activation opened confirmation with focus on Keep draft.

  3. Cancel is nondestructive

    pass

    Local application example: Exercise the original local application fixture and inspect the resulting controls or DOM state.

    Observed: Cancel retained the synthetic draft and returned focus to Delete.

  4. Recovery

    pass

    Local application example: Exercise the original local application fixture and inspect the resulting controls or DOM state.

    Observed: Confirmed deletion changed only memory state; Restore brought it back.

  5. Small screen

    pass

    Local application example: Exercise the original local application fixture and inspect the resulting controls or DOM state.

    Observed: At 320px the fixture had no horizontal document overflow and retained the 44px minimum example target.

Security findings and boundaries

Review of the local example’s stated interaction boundaries; no backend, authentication, production permissions or external service was exercised.

Practical advice · caution

Confirmation is only a UI boundary

The synthetic confirmation protected tab-memory state. A real service still needs server authorization, duplicate-action handling and a recovery policy.

Practical caveats

  • Measure the clickable area at relevant zoom and device sizes, then separately check consequence and reversal.

What remains untested

  • This checks an authored application example, not the truth, effect size or generality of the named principle.
  • No users, assistive-technology participants, physical devices or production task outcomes were evaluated.

Security limits

  • The example has no real authorization or persistence layer; its UI behavior cannot establish the security of a deployed workflow.

Evaluation sources

  1. Fitts, The Information Capacity of the Human Motor System (1954)

    Original paper, university-hosted copy.

  2. W3C: Target Size Minimum

    WCAG 2.2 AA size, spacing and exceptions.

  3. W3C: Target Size Enhanced

    Separate AAA criterion.

  4. W3C: Error Prevention for Legal, Financial and Data Actions

    Reversal, checking or confirmation for the criterion's specified consequential submissions.

Download this evaluation record (JSON)

Go to the source

Research and further reading.

  1. Fitts, The Information Capacity of the Human Motor System (1954)

    Original paper, university-hosted copy.

  2. W3C: Target Size Minimum

    WCAG 2.2 AA size, spacing and exceptions.

  3. W3C: Target Size Enhanced

    Separate AAA criterion.

  4. W3C: Error Prevention for Legal, Financial and Data Actions

    Reversal, checking or confirmation for the criterion's specified consequential submissions.

Related questions

More on action and feedback.

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