5.2 Odd-One-Out

5.2 Odd-One-Out

Quick Answer: In an odd-one-out item, three of the four figures share one structural property and the fourth breaks it. Enumerate candidate properties — shape family, element count, symmetry, rotation family, shading — until exactly three figures match and one does not. That one is the answer. The trap is matching on a superficial look-alike instead of the structural rule.

Odd-one-out items are the second most common non-verbal type on the PAF GD Pilot Initial Test. You receive four figures and must pick the one that does not belong. Unlike series items, nothing is changing across positions — the rule is a single shared property, and one figure violates it.

The Property Checklist

Run the four figures through the same candidate properties, in order. The first property that cleanly separates three from one is your rule.

Worked Example 1 — Shape Family

Figures described in words: Figure A is a square. Figure B is a rectangle. Figure C is a triangle. Figure D is a parallelogram.

Run the checklist. Shape family: A, B, and D are all quadrilaterals (four sides); C is a triangle (three sides). Element count, symmetry, rotation, and shading are not even needed — shape family already separates three from one. The triangle (C) is the odd one out.

Worked Example 2 — Element Count

Figures described in words: All four figures are circles. Figure A contains two small dots. Figure B contains two small dots. Figure C contains three small dots. Figure D contains two small dots.

Shape family is identical (all circles), so move to element count. A, B, and D each contain two dots; C contains three. The odd one out is C — the circle with three dots.

Worked Example 3 — Symmetry

Figures described in words: Figure A is an isosceles triangle pointing up. Figure B is a rectangle. Figure C is a scalene triangle (no equal sides). Figure D is an arrow pointing up with a vertical shaft.

Shape family: two triangles, one rectangle, one arrow — no clean 3-vs-1 split. Element count: no consistent internal elements. Symmetry: A has a vertical line of symmetry, B has one, D has one, but C (the scalene triangle) has no line of symmetry. The odd one out is C — the only figure with no vertical symmetry.

Worked Example 4 — Rotation Family

Figures described in words: All four figures are identical arrows. Figure A points up. Figure B points up. Figure C points down. Figure D points up.

Shape, element count, symmetry, and shading are all identical. Rotation family: A, B, and D point up; C points down. The odd one out is C — the only downward-pointing arrow.

The Superficial-Match Trap

PAF distractors are designed to look obviously different from each other so that a superficial impression ('three are pointy, one is round') feels like the rule. Always convert the impression into a structural property you can count or test. 'Pointy' is not a property; 'three sides' is. If you cannot state the rule as a countable property, you have not found it yet.

Worked Example 5 — Compound Rule (Shape Family AND Shading)

Figures described in words: Figure A is a shaded square. Figure B is a shaded rectangle. Figure C is an unshaded parallelogram. Figure D is a shaded triangle.

Run the checklist in order. Shape family alone gives a 3-vs-1 split: A, B, and D are three-sided-or-more polygons but D is a triangle while A and B are quadrilaterals — that is a 2-vs-2 split, not clean. Try shading: A, B, and D are all shaded; C is unshaded. That is a clean 3-vs-1 split, so the structural rule is 'shaded figure' and the odd one out is C. Notice that shape family, the first property you test, fails to separate here — the rule lives further down the checklist. This is why you run every property in order and do not stop at the first feature that merely 'looks' different. A compound rule (shading AND quadrilateral) is not needed when a single property already produces a clean 3-vs-1 split; prefer the simplest rule that explains three figures.

The Two-Versus-Two Trap

A common PAF pattern presents four figures where the first property you test yields a 2-vs-2 split (two quadrilaterals and two triangles, say). A 2-vs-2 split is NOT the answer — the rule must separate THREE figures from ONE. When you hit 2-vs-2, do not guess; move to the next property on the checklist. Eventually a property such as symmetry, shading, or element count will produce the clean 3-vs-1 split, and that property is the real rule. Candidates who stop at the first 2-vs-2 split and pick one of the two 'minority' figures are choosing between two equally-wrong options — both break the as-yet-undiscovered rule.

Order of Testing Matters

The checklist is ordered from cheapest property to test (shape family — count the sides, done in seconds) to the most expensive (shading, which can be ambiguous under poor print quality). Test in order and stop at the first clean 3-vs-1 split. If you reach the end with no clean split, re-examine the figures for a property you have not enumerated: number of intersections, presence of a right angle, or whether the figure is a polygon at all.

A Mermaid View of the Method

The flow below shows the odd-one-out decision process. Stop at the first property that cleanly separates three figures from one.