3.9 Mirror Images, Water Images, Embedded Figures & Non-Verbal Series

Mirror Images

A mirror image is what appears when a plane mirror is placed beside the object, conventionally to its right. The transformation reverses left and right while leaving top and bottom unchanged.

For a string of characters, two things happen at once and both must be applied:

1. The order of the characters reverses.
2. Each individual character is itself laterally inverted.

So the mirror image of CIL MT has the characters in reverse order, each one flipped left to right.

Vertically symmetric letters

Some capital letters are symmetric about a vertical axis and therefore look identical in a side mirror:

$\textbf{A, H, I, M, O, T, U, V, W, X, Y}$

If a word is composed only of these letters, its mirror image is simply the word written backwards, with no character distortion. TOY mirrors to YOT.

Among digits, only 0 and 8 are vertically symmetric.

Water Images

A water image is the reflection seen in water lying below the object. It reverses top and bottom while leaving left and right unchanged. Crucially, the order of characters does not reverse — this is the standard discriminator between the two formats.

Horizontally symmetric letters

Letters symmetric about a horizontal axis are unchanged in a water image:

$\textbf{B, C, D, E, H, I, K, O, X}$

Among digits, 0, 3 and 8 are horizontally symmetric.

The letters H, I, O and X are symmetric both ways and so are unchanged in either transformation.

Practical Method

For a clock-face question, the mirror image of a time is obtained by subtracting from 11:60 (that is, from 12:00):

$\text{Mirror time} = 11{:}60 - \text{given time}$

So the mirror image of 4:20 is $11{:}60 - 4{:}20 = 7{:}40$. If the given time is between 12:00 and 1:00, subtract from 23:60 instead.

A water image of a clock is obtained by subtracting from 18:60, that is 6:60.

Embedded Figures

An embedded figure question gives a target shape and four complex figures, asking in which one the target is hidden. The target appears without rotation or change of size unless the question says otherwise.

A reliable search procedure

1. Identify a distinctive feature of the target — an unusual angle, a notch, a specific line junction, a protruding limb. Do not try to match the whole shape at once.
2. Count the line segments and vertices of the target. Any candidate figure must contain at least that many in the right arrangement.
3. Scan each option for the distinctive feature only. Most options can be eliminated in a second or two.
4. Trace the full target in the one or two survivors, checking that every segment is present and the proportions match.

The two commonest errors are accepting a figure whose proportions differ from the target, and rejecting the correct answer because the target is drawn at an unexpected orientation within the larger figure.

Non-Verbal Series

A non-verbal series gives a sequence of figures and asks for the next one. Almost every such series is generated by one of four transformations, sometimes in combination.

A systematic approach

1. Count elements in each figure and write the counts as a number series. If the counts change regularly, that is the rule.
2. Track one element at a time. Follow a single dot or arm through all the given figures rather than comparing whole figures.
3. Check rotation direction and magnitude. Fix a reference feature and measure how far it turns between consecutive figures.
4. Watch for two rules at once. A common structure is an outer element rotating clockwise while an inner element rotates anticlockwise, or a shape rotating while its shading alternates.
5. Verify against every given figure, not just the last two. A rule that explains only the final step is usually wrong.

Odd-one-out variants

Some items give five figures and ask which does not belong. The differentiator is usually one of: number of sides, number of enclosed regions, presence of a line of symmetry, direction of rotation, or open versus closed shapes. Test those five properties in that order.

Paper Strategy

Non-verbal items are quick when the rule is seen and very slow when it is not. Set a hard ceiling of about forty-five seconds. Because the CIL CBT carries no negative marking, an item that resists the rule should be answered on the strongest partial pattern and left, rather than allowed to consume the time budget needed for the arithmetic and engineering sections. Many candidates skip non-verbal preparation entirely, which makes these among the most improvable marks on Paper-I for a modest investment of practice.