6.4 Matching Diagrams to Written Descriptions & Person-in-Disguise Comparison
Key Takeaways
- Two of the ten sample questions in the official APCAT Candidate Brochure are observation items using formats prep material rarely drills: diagram-matches-description and same-person-in-disguise.
- Diagram items are solved by decomposing the written description into atomic, independently checkable claims and eliminating any diagram that violates one.
- The four recurring diagram traps are direction of travel, the wrong named street, inside versus outside lane, and collision geometry (head-on versus sideswipe).
- On disguise items, hair, facial hair, eyewear, and clothing carry no evidential weight because they can be altered in minutes; decide on bony structure instead.
- Compare one structural feature across all five images at once rather than judging each photograph as a whole.
6.4 Matching Diagrams to Written Descriptions & Person-in-Disguise Comparison
Executive Summary: Two of the ten sample questions published in the official APCAT Candidate Brochure are observation items, and both use formats that general "police exam" prep material rarely drills: matching one of four diagrams to a written incident description, and picking which of four photographs shows the same person in disguise. Both are pure elimination problems. Neither rewards a global impression of "which one looks right" — each rewards decomposing the target into atomic features and killing options one violated feature at a time. This section teaches that method.
Why These Two Formats Deserve Their Own Section
Observation items on the APCAT are not tests of eyesight. They are tests of disciplined comparison under time pressure. The brochure's own rationales make this explicit: for both sample items, the published explanation eliminates three options by naming a specific mismatched feature, then keeps the survivor. That is the exact behaviour the item is scored on.
The strategic point: on these items you are almost never asked to find the right answer. You are asked to destroy the wrong ones. Three of the four options each contain at least one disqualifying flaw, and each flaw is objective and checkable. If you find yourself weighing which diagram "feels" closest, you have already switched to the wrong mode.
Format A: Which Diagram Best Fits the Description?
The item gives you a short narrative — typically a collision or a movement of persons — and four schematic diagrams. Exactly one diagram is consistent with every clause of the narrative.
The Atomic Claim Method
Do not read the description as a story. Read it as a list of independently falsifiable claims, and write them down as a checklist on your scrap paper.
Take a description modelled on the official sample: "An eastbound car attempted to make a left turn onto Robin Boulevard, but turned into the inside southbound lane instead. The car hit a southbound vehicle head-on."
That single sentence contains five separate, checkable claims:
| # | Atomic claim | What to look for in the diagram |
|---|---|---|
| 1 | A car is travelling eastbound | An eastbound vehicle must exist at all |
| 2 | It turns left | The turn arc must be to the vehicle's left, i.e. northward from an eastbound heading |
| 3 | The turn is onto Robin Boulevard | Not onto any other named street on the diagram |
| 4 | It ends up in the inside southbound lane | Not the outside/curb southbound lane |
| 5 | The collision is head-on with a southbound vehicle | Not a sideswipe, not a rear-end, and the other car must be southbound |
Now sweep the four diagrams against the checklist, in order, and stop the moment a diagram fails any claim:
+-----------------------------------------------------------------------------+
| ELIMINATION SWEEP - STOP AT THE FIRST FAILURE |
+-----------------------------------------------------------------------------+
| | Claim 1 | Claim 2 | Claim 3 | Claim 4 | Claim 5 | VERDICT |
| Diagram A | PASS | PASS | FAIL | - | - | OUT (wrong |
| | | | (turns onto the wrong street) | street) |
| Diagram B | PASS | PASS | PASS | PASS | PASS | SURVIVES |
| Diagram C | FAIL | - | - | - | - | OUT (no |
| | (no eastbound vehicle at all) | eastbound) |
| Diagram D | PASS | PASS | PASS | FAIL | - | OUT (outside |
| | | (collision in the outside lane) |
+-----------------------------------------------------------------------------+
Notice how thin the margin is between B and D. They differ on one claim — inside versus outside southbound lane — and nothing else. That is the designed trap: the distractor is correct on four of five claims. Candidates who read for gist pick D roughly as often as B.
The Four Recurring Diagram Traps
- Direction of travel. "Eastbound" describes where the car is going, not where it started. On a north-up diagram, an eastbound car travels toward the right of the page, and its left turn takes it northward (up the page). Getting this backwards flips your entire analysis.
- The wrong named street. Diagrams usually show two or three named roadways. A distractor performs exactly the right manoeuvre onto the wrong one.
- Inside versus outside lane. The inside lane is the one nearest the centre line; the outside lane is nearest the curb. This single word decides many of these items.
- Collision geometry. Head-on means front-to-front. A distractor may show the correct vehicles in the correct lanes meeting at a T-bone or sideswipe angle.
Timing rule: build the checklist once, then sweep. Building the checklist costs about fifteen seconds and makes the sweep nearly mechanical. Re-reading the narrative once per diagram costs four times as long and is where candidates lose the item.
Format B: Which Picture Shows the Same Person in Disguise?
The item shows a target photograph of a person and four further photographs. One is the same person after deliberately altering their appearance; three are different people.
Sort Every Feature Into Alterable or Immutable
This is the whole technique, and it inverts ordinary intuition. Your eye is drawn to hair, glasses, and facial hair — which are exactly the features a person changes to disguise themselves, and therefore exactly the features that carry no evidential weight.
+-----------------------------------------------------------------------------+
| DISGUISE ANALYSIS: WHAT COUNTS AND WHAT DOES NOT |
+-----------------------------------------------------------------------------+
| IGNORE - ALTERABLE IN MINUTES | COMPARE - STRUCTURAL / BONY |
| * Hair length, style, colour | * Shape of the nose and its bridge |
| * Beard, moustache, stubble | * Mouth width and lip shape |
| * Glasses, hats, hoods | * Eye shape and spacing between eyes |
| * Cosmetics, jewellery, piercings | * Jawline and chin form |
| * Clothing of any kind | * Ear shape; attached vs free lobes |
| | * Brow ridge; permanent scars, moles |
+-----------------------------------------------------------------------------+
The official sample resolves precisely this way: three candidate pictures are eliminated because the mouth, nose, or eyes differ from the target, and the surviving picture matches on every structural feature and differs only in having less hair — an alteration the person could make in minutes.
The Three-Pass Comparison Drill
- Pass 1 — Mask the alterables. Mentally black out hair, facial hair, headwear, and eyewear on the target and on all four options. If you are working on paper, cover them with your thumb.
- Pass 2 — Compare one structural feature across all five images at once. Check the nose in every image before moving to the mouth. Comparing feature-by-feature across images is far more reliable than comparing image-by-image, because it forces a like-for-like judgement and defeats the "overall vibe" impression.
- Pass 3 — Confirm the survivor. The correct answer should match on every structural feature. If your survivor mismatches on even one bony landmark, you have the wrong picture; re-run pass 2 on the feature you skipped.
The core inversion to remember: a difference in hair is evidence of disguise, not evidence of a different person. A difference in nose shape is evidence of a different person, full stop. Candidates who eliminate the correct answer usually do so because it "looked different" — which was the disguise doing its job.
Key Takeaways for Section 6.4
- Both official observation formats are elimination problems: three options each contain a specific, objective, disqualifying flaw.
- For diagram items, convert the narrative into a written checklist of atomic claims, then sweep the diagrams and stop at each first failure.
- The highest-frequency diagram traps are direction of travel, the wrong named street, inside versus outside lane, and collision geometry.
- For disguise items, ignore hair, facial hair, and eyewear entirely; decide on bony structure — nose, mouth, eyes, jaw, and ears.
- Compare one feature across all images at once rather than assessing each image as a whole.
A description reads: "A westbound van made a right turn onto Delta Avenue and struck a pedestrian in the crosswalk." On a north-up diagram, in which direction does the van travel after completing the turn?
Three diagrams show an eastbound car turning left onto the correct named street and colliding with a southbound car. Diagram B shows the impact in the lane nearest the centre line; Diagram D shows it in the lane nearest the curb. The description specifies the inside southbound lane. Which diagram is correct, and why?
In a person-in-disguise item, the target photograph shows a man with a full beard and long hair. One option shows a clean-shaven man with short hair whose nose bridge, eye spacing, jawline, and ear lobes all match the target exactly. How should this option be treated?
Which approach is most reliable for working through the four photographs in a disguise item under time pressure?