For each Keyhole question in the PAT of the DAT, you are presented with a 3D object and must determine which of the five openings in the answer choices would allow the object to pass through with a perfect fit. The object can pass through the opening in any orientation, but it cannot be rotated while it is passing through. The external outline of the object is the exact size and shape of the opening without being too big or small or having extra protrusions. In the example below, the cube could fit through any of the apertures, but the only correct answer is the square projection of the cube that is an exact fit.
Note that none of the features present within an object, such as overlapping shapes, appear in the answer choices; instead, the focus is merely on the outline alone. Because of this, the correct opening generally corresponds with one of three projections (reductions of 3D images to flat, 2D images) that can be drawn for the object: the top-bottom projection, the front-back projection, or the side projection. One way to visualize these projections is to think of what shadow would be created if you were to shine a bright light on the object from one direction. Regardless of how you visualize the projections, the most efficient way to arrive at the correct answer is to determine the three main projections of the object and pick the choice that matches one of these. The following example illustrates this technique:
The correct choice is therefore (E). Note how choice (D) is a distractor designed to trap test takers who go for the obvious features of the object without paying attention to the finer aspects; this is a common perceptual ability trap.
If you have difficulty visualizing the correct projection, try to imagine what would happen if you were to flatten the object against the wall relative to the top/bottom, front/back, or left/right sides. Whichever way you crush the original object, the part that remains will represent a correct aperture for the problem. A good example of this occurs when crushing a soft drink can. If you crush it from top to bottom, you are left with a circular disc. If you crush it from left to right or from front to back, though, you are instead left with a rectangular piece. Therefore, if your original object is a circular cylinder, the correct projection would be either a rectangle or a circle.
With practice, focusing on the three main projections will allow you to spend no more than the recommended 12.5 minutes on the 15 questions in the Keyholes subsection, which equates to 50 seconds per question.