TALKING TO EACH OTHER
Corbett provided evidence for this by comparing the anomia displayed
by eight patients who had a form of dementia affecting their temporal
lobes with the difficulties shown by seven stroke-patients who had damage
either to the left, frontal part of their brains, or the temporo-parietal
junction. Superficially, the two groups of patients had remarkably similar
impairments. They all struggled to find the correct words for things,
and their factual knowledge and comprehension also seemed affected.
However, there were some important differences between the two groups.
The dementia patients appeared to have entirely lost their core knowl-
edge for certain word-meanings – if they struggled with a word in one
kind of task, such as matching words to pictures, then they would also
struggle with that word in other tasks, such as miming the meaning of a
word. Moreover, the more unusual a word, the more likely these patients
were to have a problem. By contrast, the stroke patients performed well on
simple tasks, such as pointing to a picture of a hammer when prompted
with the word, but struggled as soon as a task was made more complicated
- for example, pairing objects that are related by their function, such as
matching a hammer and chisel. Also, whereas the dementia patients could
either mime an object’s use or not, the stroke patients would frequently
get some of the mime correct, but would then perform an inappropriate
action, as if they were suddenly using a different type of object. For the
stroke patients, then, it was
as if their core knowledge
was intact but their search-
and-control system had
gone awry.
Other research has used
electroencephalography to
record the surface electrical
activity of the brain during
Electroencephalography (EEG):
when brain cells fire, they
generate electrical activity which
can be recorded by electrodes
placed on the scalp. Unlike
functional magnetic brain-
imaging, the spatial resolution
of EEG is poor. However,
its “temporal resolution” is
excellent, meaning that it can
be used to chart activity changes
over sub-second time-intervals.