Tone of Voice and Mind : The Connections between Intonation ...

40 Chapter 2
D. The central dogma
In the discussion of the hemispheric contributions to language processing, a
remarkable similarity between the effects due to RH damage and callosal damage
was noted (Sections A and B); that similarity suggests that normal RH contributions
to language are realized through transmission of RH information
to the LH across the corpus callosum. Moreover, the most obvious possibility
for explaining HERA (Section C) was that the RH contributes to languageprocessing
by communicating callosally with the LH, rather than using its information
for direct control over the relevant somatic musculature (the organs
of speech). The HERA effect is a clear illustration of hemispheric cooperation
thatwouldnotbepredictedbyasimple“LH-dominance” model of language
processing. This pattern of information processing in the human brain can
be summarized in what I have referred to as the “central dogma” of human
neuropsychology (Cook 1986, 1989, 2002a, b):
RH ←→ LH → striate musculature
It is “central” because it involves truly fundamental language and handedness
functions that are characteristic of the human brain. And it is “dogma” because
it is a fundamental tenet of clinical neuropsychology – fully established in
that realm, but remaining scientifically “incomplete” in so far as neuron-level
mechanisms remain uncertain.
The central dogma for psychology suggests that the function for which
the left hemisphere has become specialized is the sequentialization (Greenfield
1991; or perhaps “response selection,” Rushworth et al. 1998) of motor behavior.
With practice, all forms of motor activity become at least partly automatized
and the sequence of flexion and extension of individual muscles is executed
with little or no conscious attention. As a consequence, it is easy to forget
the motor control difficulties inherent to even “simple” manual tasks. Truly unfamiliar
tasks – such as eating with chopsticks – are surprisingly difficult until
sufficient practice has been had. But even eating soup with the non-dominant
hand can be sloppy – not because we are unfamiliar with soupspoons, but
because the rather trivial balancing act needed to keep the spoon horizontal
is not something we normally do with the left hand. For anyone still unimpressed
with the complexity required for “simple” motor control tasks, try
enunciating a new sentence in a foreign language learned in high school. Overlearned
phrases like “Comment allez-vous?” may sound almost like French, but
any brand-new concatenation of consonants and vowels is likely to leave your
Parisian friends dumbfounded! Both speech and hand movements require se-