Among the other principles of 
grouping that Wertheimer 
singled out were common fate 
and closure. Common fate 
refers to the tendency to group 
those units that move together 
in the same direction and at 
the same speed. Where grouping 
would not otherwise occur in 
stationary displays, as in a 
well-camouflaged animal 
standing still, it will occur as 
soon as the display moves. 
When the animal moves, its 
various visible parts move 
together, and it is suddenly 
perceived. Similarly, clouds 
that do not appear to be 
separate when stationary are 
perceived as separate the 
moment they are seen to move 
relative to one another.

    Closure is the tendency, 
other things being equal, to 
group into unified structures 
those components that together 
constitute a closed entity 
rather than an open one. 
However, closure is better 
known not as a principle of 
grouping but as a tendency, 
noted by the Gestaltists, to 
complete otherwise incomplete 
units. One might regard the 
perception of the unit that 
appears behind another in an 
interposition pattern as a 
manifestation of closure.