Identifying Sequential Changes
The previous lesson introduced the concept of sequential change. This lesson provides a systematic method for identifying exactly what changes and how it changes — even when the pattern is not immediately obvious.
The Comparison Method
The most reliable way to identify a sequential change is to compare consecutive pairs of boxes and list every difference.
Step 1: Compare Box 1 to Box 2
Ask:
- Has any shape moved? Where was it, where is it now?
- Has any shape rotated? What was its orientation, what is it now?
- Has any shape changed colour/size? What was it, what is it now?
- Has any shape been added or removed? What appeared or disappeared?
- Has any shape been replaced by a different shape?
Write down (or mentally note) every difference.
Step 2: Compare Box 2 to Box 3
Ask the same questions. The differences should be identical in nature to Step 1.
Step 3: Verify with Box 3 to Box 4
Same check. If the change is consistent across all three transitions, you have identified the pattern.
Step 4: Apply the Change Once More
Take the final box and apply the identified change to predict the next box.
Systematic Change Detection: A Worked Example
Sequence:
- Box 1: A large black triangle in the centre. A small white circle in the top-left corner. Two small grey squares at the bottom, side by side.
- Box 2: A large black triangle in the centre. A small white circle in the top-right corner. Two small grey squares at the bottom, side by side.
- Box 3: A large black triangle in the centre. A small white circle in the bottom-right corner. Two small grey squares at the bottom... wait, the squares are at the bottom and the circle is also at the bottom-right? Let me adjust: Two small grey squares in the middle row, side by side.
- Box 4: A large black triangle in the centre. A small white circle in the bottom-left corner. Two small grey squares in the middle row, side by side.
Comparison Box 1 → Box 2:
- Triangle: Same position, same colour, same size → Static
- Circle: Moved from top-left to top-right → Changed position
- Two grey squares: Same position, same colour, same size → Static
Comparison Box 2 → Box 3:
- Triangle: Static
- Circle: Moved from top-right to bottom-right → Changed position
- Squares: Static
Comparison Box 3 → Box 4:
- Triangle: Static
- Circle: Moved from bottom-right to bottom-left → Changed position
- Squares: Static
Pattern: The circle moves clockwise through the four corners: top-left → top-right → bottom-right → bottom-left.
Prediction for Box 5: The circle moves to the top-left (completing the cycle). Everything else stays the same.
Handling Multiple Simultaneous Changes
When two or more features change at once, track each change on a separate "channel."
Worked Example: Rotation + Colour Cycling
Sequence:
- Box 1: A black arrow pointing up
- Box 2: A grey arrow pointing right (90° CW)
- Box 3: A white arrow pointing down (90° CW)
- Box 4: A black arrow pointing left (90° CW)
Channel 1 — Direction: Up → Right → Down → Left (90° CW each step)
Channel 2 — Colour: Black → Grey → White → Black (3-step cycle, restarts)
Prediction for Box 5:
- Direction: Left + 90° CW = Up
- Colour: Black + one step = Grey
- Answer: A grey arrow pointing up
Detecting Non-Obvious Changes
Some changes are harder to spot because they are subtle or because the visual noise of other elements draws attention away.
Technique 1: Count Everything