Law of Similarity:

Elements that look similar will be perceived as part of the same form. In the image below our eyes perceive the squares and circles separately because they look similar so we perceive them as part of the same form.

Fig.27: Law of Similarity: shapes that are similar are grouped together into a unit.

Law of Good Continuation:

Humans tend to continue contours whenever the elements of the pattern establish an implied direction.

Fig.28: Law of Good Continuation: the eye follows the circles and perceives a curve