Elongated targets are easier along the long axis than the short axis

What it is

For a narrow rectangle, divider, or linear control, approach along its long axis provides greater effective width in the direction of movement; approach along its short axis gives less tolerance and is generally harder. This is a direct visible case of projected width for two-dimensional targets.

Why it happens

Projection onto the movement axis determines where movement can stop while still acquiring the target. The long axis supplies a broad stopping interval; the short axis leaves a narrow one and demands finer correction. Equal target area does not remove this directional difference; common starting points determine which axis matters in practice.

Studying it

Hold target shape and distance fixed, then repeat acquisition from long- and short-axis directions, comparing time, endpoint variability, and misses. Reveal target location and use matched start cues to avoid visual search. Log actual entrance direction for toolbars, lists, and edge controls.

Where it stops holding

Circular or short-axis-expanded hit areas, and random multi-direction approaches, change or average the relation. Touch also adds contact area and neighbour effects. The finding describes movement geometry, not a demand to make every elongated visual element square.

Applying it

• Align the long axis of narrow buttons, sliders, or drop zones with typical approach, or expand the real hot zone along the short axis.
• For fixed-orientation fine lines, offer snapping, magnification, or handles instead of relying on one precise hit.
• Inspect short-axis misses and repeated correction on real paths, not control area in a mockup alone.

Related

• Same group: B1.12.1 Two-dimensional targets require both width and height; minimum-edge and projected-width models differ · B1.12.2 Approach angle changes effective width, so the same button differs by direction · B1.12.4 Hit area, not visual size, determines difficulty when they differ
• Nearby: B1.01 Fitts's law · B1.05 Steering law
• Search terms: effective target width · elongated target · approach direction