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3.2 What is cognition? 77

most dominant sense for sighted individuals, followed by hearing and touch. With
respect to interaction design, it is important to present information in a way that
can be readily perceived in the manner intended. For example, there are many
ways to design icons. The key is to make them easily distinguishable from one an-
other and to make it simple to recognize what they are intended to represent (not
like the ones in Figure 3.4).
Combinations of different media need also to be designed to allow users to rec-
ognize the composite information represented in them in the way intended. The
use of sound and animation together needs to be coordinated so they happen in a
logical sequence. An example of this is the design of lip-synch applications, where
the animation of an avatar's or agent's face to make it appear to be talking, must be
carefully synchronized with the speech that is emitted. A slight delay between the
two can make it difficult and disturbing to perceive what is happening-as some-
times happens when film dubbing gets out of synch. A general design principle is