Continuity - Continuity is a Gestalt concept that refers to the visual tendency to create continuous figures. Continuity is most commonly (though not exclusively) exhibited in the perception of lines and refers to the tendency to "carry the line forward." More specifically, there is the tendency to continue smooth figures forward over abrupt changes in direction.
Below, continuity describes the tendency to see the left figure above as two curved lines.
The right figure illustrates the two curved lines, one red and one blue.
While the illustration below is one possible perception of the previous example, continuity describes a tendency for smooth figures over abrupt changes in direction. This example exhibits abrupt changes in direction at the intersection of the two lines.
Continuity also describes grouping. The figure above is generally perceived as a line rather than individual circles.
Limbourg brothers. Pentecost.
Good continuity is exhibited across the line of heads.
Good continuity is exhibited between the horizontal and vertical elements.