The Use of Iambic Pentameter in the

the size scale within an existing interface display. Participants in this experiment were
shown the ambiguous experimental primes and trained to group by a particular Gestalt
size scale (global or local). One half of participants were trained to group by global
properties and one half of participants were trained to group by local properties. A test
phase then followed the practice session and reaction times were recorded. Participants in
this experiment preformed equally well at grouping by a particular scale (global or local)
in a test phase when trained by the same scale or an alternative scale in a preceding
practice session.
It is interesting to think about why null results were found in Experiment 3. One
of the most likely reasons is that participants may not have had enough practice with each
particular size scale for this practice to have had an effect during the test phase. In this
experiment, participants only had about 10 minutes of practice with a particular size scale
before they were tested. This may not have been enough time to become accustomed to
using a particular size scale. In the real world, in situations in which users have years of
practice using a particular size scale, changing the size scale may dramatically reduce
efficiency for using new displays. Perhaps if participants had been trained to group by a
particular scale over an extended period of time, during multiple practice sessions, the
grouping results at test for alternative scales would have been significantly slowed.
Contribution to engineering
The reported results contribute to a greater understanding of how grouping should
be used in user interface displays. According to the three pilot studies, reliance on global
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