Solution: All four strings of shapes follow the same general pattern. The pattern of shapes is: Circle, Square, Diamond, Triangle. However, whenever the sequence makes a 90 degree turn, the next shape in the sequence is skipped. For example, the first sequence starts as follows: Circle, Square, Turn (instead of Diamond), Triangle, Circle, Square, Turn (Diamond), Triangle, Turn (Circle), Square, Diamond, etc.

The second sequence contains the mistake. The Circle right in the center should be a Square, as it follows a Triangle then a Turn.