152 Understanding Rational Decision Making
Appropriate Prosody, Intonation, and Articulation
A speaker’s articulation, intonation, and prosody all impact the listener’s ability to perceive and
recognize the speaker’s words. Appropriate prosody and intonation help listeners segment the
continuous stream of sounds coming from the speaker into distinct and intelligible words.^49 Inap-
propriate prosody, on the other hand, can seriously impair word recognition^50 as can disfl uent
speech that includes frequent fi ller words, repetitions, false starts, and word fragments.^51 Almost
any disruption to fl uent speech can make it diffi cult for listeners to resume processing the speak-
er’s words. However, silent pauses between words can actually help listeners recognize subsequent
words.^52
Listeners’ perception of speech will also be impaired when phonemes and words are inaudible,garbled, or unfamiliar. Retention of the speaker’s message can be affected as well. A test of listen-
ers’ memory for a message that contained six high-quality arguments supporting a recommended
position fi nds that lowering the perceptibility of the message with a poor-quality audio recording
reliably lowers message retention.^53
Easy-to-Discern Graphic Elements
Viewers’ perception of graphs involves both sensing and recognizing the graphic elements in them.
Perceptual research indicates that small solid symbols such as triangles, squares, and circles often
become diffi cult to perceive when clustered together in the same line graph.^54 On the other hand,
distinctively shaped symbols such as a solid triangle, an “x,” a solid circle, and an empty square are
easy to discriminate.
The use of different colors, or color coding, can help viewers more rapidly discriminate ele-ments of some graphs.^55 Color coding graphic elements provides the perceptual cues viewers need
to recognize the different elements within a graph and to search the graph effi ciently.^56 By making
the different elements of maps more visually distinct, color coding improves map comprehension.^57
However, for people who suffer from color blindness, differences among color-coded items can
be impossible to discern. In the United States, about 7% of the male population and 0.4% of the
female population have trouble distinguishing red from green. Fortunately, black-and-white graphs
with highly differentiated symbols are almost as easy for viewers with normal vision to discern as
graphs that use color.^58
Aids to Attention
The second of the six cognitive processes required in audience decision making is attention. Pro-
fessionals aid audience decision making when they make text, speech, or graphics easy for their
audiences to attend to.
Titles and Section Headings
Titles and section headings can attract attention both to themselves and to the sections of text they
precede. They can affect what information in a document or slide presentation is attended to and
how that information gets organized in the reader’s memory.^59 In addition, differences in the size
of section headings provide the most visible cue to the hierarchical organization of topics within
a text.^60