The following rules were taken from Universal Prinicpals of Design. These are used to explain gestalt in design.
Closure – Closure is when elements are close together they are perceived as one single object. The person viewing the object will automatically supply the missing information to the object. Closure is a part of prinicpals of percerption within the gestalt.
Good Continuation – Good continuation is when objects that are aligned together, are seen as related to each other. Good continuation is part of the prinicpals of perception within the gestalt.
Law of prägnanz – Law of prägnanz is when the viewer see images that are amibigous as simple and complete shapes. Law of prägnanz is part of the prinicpals of perception within the gestalt.
References and further reading:
Universal Prinicpals of Design. William Lidwell, Kritina Holden, Jill Bulter. Rockport Publishers 2003. Page 86