The Use of Iambic Pentameter in the

Given ambiguous grouping displays such as the one in Figure 18 and given what
is known about the time course of grouping in visual perception, it is logical to question
which grouping principles are more salient in interface displays at various points in time.
Addy (2000) began to address this question with his research, but his results were limited
to unlimited exposure time conditions. Perhaps it is too simplistic to think that some
grouping principles are always necessarily dominant over others in interface displays.
Rather, perhaps grouping principles can be manipulated by other factors to become
dominant over others in certain conditions. Further, perhaps these factors influence
grouping differentially at particular stimulus exposure durations.
There are likely to be a variety of factors that influence which grouping principles
are perceived as dominant at various points in time. One such factor may be the extent to
which each grouping principle is presented as being global or local, relative to other
grouping principles in an interface display. Recall that according to research on global
and local properties of spatial displays, global properties have been shown to be
perceived before local properties across exposure time (e.g., Navon, 1981; Sanocki,
1993). It would be interesting to determine if this discovery in vision extends to the
Gestalt principles of grouping and specifically whether it applies to these principles when
presented in user interface displays.
To test the time course of global and local Gestalt grouping in interface displays,
Schulz and Sanocki (2002) initially conducted three pilot experiments. Each of the three
pilot experiments utilized the same design, with stimuli varying slightly. Participants
60