Pattern Completion
What Pattern Completion asks
Pattern Completion presents a large geometric design with a missing region. You choose the option that restores the design. On NNAT3 Level G the designs are denser than in lower levels: overlapping outlines, shaded and unshaded regions, nested shapes, and gaps that cut across several elements. The test is checking whether you can infer the whole from partial evidence, not whether you can match a pretty patch.
Rules that decide the answer
- Boundary continuity. Every line that enters the gap must leave it at the same angle, thickness, and position. Count the lines on each side before looking at options.
- Global structure. Look for symmetry axes, repeated translations, alternating fills, or concentric rings. The missing piece must satisfy the rule everywhere, not just at one edge.
- Element conservation. Shapes cut by the gap must keep their size, count, and orientation. A patch that adds a new line or changes a curve's radius is wrong.
- Layer logic. Where outlines overlap, decide which shape sits in front; hidden lines should continue behind the front shape.
Worked example
A square contains a thick diagonal band from the top-left corner to the bottom-right, crossed by evenly spaced thin vertical lines. The missing region is a central octagon. The correct patch continues the vertical lines at the same spacing and keeps both edges of the diagonal band parallel and the same width. A patch with correct band edges but shifted vertical lines fails boundary continuity; a patch with the band running bottom-left to top-right fails orientation; a patch with a wider band fails size conservation.
Traps
The common error is choosing a patch that completes only the most obvious edge. Another is accepting reversed shading, because light and dark regions often alternate across a design. Finally, check that the patch does not rotate a curved element: a circle looks unchanged, but a crescent or arc does not.