Localization of Function • 35The ERP is useful in distinguishing between form and meaning because the ERP
consists of a number of waves that occur at different delays after a stimulus is presented
and that can be linked to different functions. Two components that respond to differ-
ent aspects of language are the N400 component and the P600 component, where N
stands for “negative” (note that negative is up in ERP records) and P for “positive.” The
numbers 400 and 600 stand for the time at which the response peaks, in milliseconds.
● Figure 2.14 shows the response to “The cats won’t eat” plus the response to two
modifi ed versions of this phrase. In Figure 2.14a, the phrase “The cats won’t bake”
results in a larger N400 response. This component of the response is sensitive to the
meaning of words in a sentence, and is larger when words don’t fi t the sentence. In
Figure 2.14b, the phrase “The cats won’t eat-
ing” results in a larger P600 response. This
response is sensitive to the form of a sentence,
and is larger when the form is incorrect.
What is important about these results is that
they illustrate different physiological responses
to two different aspects of language: form and
meaning. Other experiments have shown that
the N400 response is associated with struc-
tures in the temporal lobe. For example, dam-
age to areas in the temporal lobes reduces the
larger N400 response that occurs when mean-
ings don’t fi t in a sentence. The P600 response
is associated with structures in the frontal lobe,
more toward the front of the brain. Damage
to areas in the frontal lobe reduces the larger
P600 response that occurs when the form of a
sentence is incorrect (Osterhout et al., in press;
Van Petten & Luka, 2006).
The studies of the effects of brain damage
and ERP results we have described as exam-
ples of modern research related to Broca and
Wernicke are only two results out of many.
Hundreds of experiments have shown that● FIGURE 2.13 (a) Person wearing electrodes for recording the event-related
potential (ERP). (b) An ERP to the phrase “The cats won’t eat.”(a)0 200 400 600 800+(b)The cats won’t eat...Time (ms)0Courtesy Natasha Tokowicz0 200 400 600 800+(a) How semantics affects N400N400The cats won’t EAT...
The cats won’t BAKE...0 200 400
Time (ms) Time (ms)600 800+P600The cats won’t EAT...
The cats won’t EATING...(b) How syntax affects P600(^00)
● FIGURE 2.14 (a) The N400 wave of the ERP is aff ected by the meaning of
the word. It becomes larger (red line) when the meaning of a word does not fi t
the rest of the sentence. (b) The P600 wave of the ERP is aff ected by grammar.
It becomes larger (red line) when a grammatically incorrect form is used.
(Source: From Osterhout et al., “Event-Related Potentials and Language,” in Trends in Cognitive
Sciences, Volume 1, Issue 6. Copyright © 1997 Elsevier Ltd. Reproduced with permission.)
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