Before anyone knew what was happening, their attention was captured. In the information processing model, four cognitive processes occur. If you want to notice it, change it . Humans are very sensitive to change. Attention can be directed through carefully designed changes.
Sudden changes have the greatest impact on attention.
If you want it noticed, use a horizontal-vertical orientation. There is a natural tendency for people to follow horizontal or vertical lines. Diagonal lines do not receive the same amount of attention. Readers tend to follow these lines according to the direction of their reading system. For example, readers of English, read from left to right and from top to bottom.