110 Understanding Rational Decision Making
Listeners’ Perception of Speech
Much like the way reading audiences perceive text, listening audiences perceive speech sound by
sound and word by word in the order it is spoken. But there are signifi cant differences between
speech and text that cause speech perception to be more complex than text perception. Speech
is not presented as discrete units the way printed letters and words are. Instead it is presented as a
continuous stream of sound. Speech sounds—the consonants and vowels that form the words of a
language—overlap each other as they are spoken in a process called coarticulation.^54 To make speech
perception even more complex, different speakers, unlike different writers, produce the same words
in different ways^55 and at different speaking rates.^56
Brain Regions Activated. Listeners’ encoding of spoken words takes place in three regions ofthe brain: the temporal voice areas located at the top of the temporal lobes of the left and right
hemispheres^57 and Broca’s area located in the left frontal lobe (see Figure 3.4 , p. 108).^58 Disorders
associated with these three regions include voice agnosia and autism.
When listening to speech, listeners must map the acoustic signals they perceive onto speechsounds or phonemes. Through a process of elimination, they are able to recognize the word being
spoken even before the speaker has fi nished saying it.^59 As listeners hear each successive sound in a
word, for example “elephant,” they narrow down the list of possible words they might be hearing.
They activate approximately 1,000 words that start with the “e” sound as soon as they perceive the
“e” sound in elephant. They quickly narrow that list to about 100 words that start with “el” once
FIGURE 3.6 A Reader’s Eye-Fixation Pattern Reading an Online Newspaper
Source: Gibbs and Bernas (2009, p. 158)