MODULARITY
DAY 13 – SEPT 25, 2013
Brain & Language
LING 4110-4890-5110-7960
NSCI 4110-4891-6110
Harry Howard
Tulane University
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Course organization
• The syllabus, these slides and my recordings are
available at http://www.tulane.edu/~howard/LING4110/.
• If you want to learn more about EEG and neurolinguistics,
you are welcome to participate in my lab. This is also a
good way to get started on an honor's thesis.
• The grades are posted to Blackboard.
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REVIEW
EEG, ERP & MEG
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The basic fact about dipoles
A dipole has a direction …
… which in cortex is perpendicular
to its surface
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Language areas of the brain
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The Broca-Wernicke-Lichtheim model (of
the LH)
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MODULARITY
Ingram §4
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But first …
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Fodor’s criteria for modularity
Property
Vision
Language
Specific to a domain
color & edge detectors
phonetic feature detectors
Operates mandatorily
you can’t stop seeing (with
your eyes open)
you can’t stop hearing English
as English
Limits central access
how do you see?
how do you hear English as
English?
Acts quickly
image recognition < 200ms? word recognition < 200 ms?
Information is
encapsulated
other senses don’t affect
vision (but synesthesia)
other senses don’t affect
speech recognition
Analyzes ‘shallowly’
early vision extracts edges
early language only assigns
superficial structure
Fixed neural structure
eg V1
perisylvian region
Fails in a specific way
visual agnosia
BWL model
Matures in a specific way
(?)
stages in child acquisition
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The problem
• Fodor’s nine properties of modularity are organized
haphazardly.
• They should be grouped into those that are necessary to any sort
of modular process, and those that are just by-products of
modularity, perhaps in a specific process.
• We do this in the next slide.
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Coltheart’s grouping & my explanation
1.
2.
3.
4.
5.
6.
7.
8.
9.
Specific to a domain
Information is
encapsulated
Fixed neural
structure
Matures in a specific
way
Fails in a specific
way
Limits central access
Operates mandatorily
Acts quickly
Analyzes ‘shallowly’
1.
by definition.
2.
by definition.
3.
in order to keep out all the other stuff.
4.
in order to build the fixed structure.
5.
because it was built in a specific way.
6.
in order to keep out other stuff.
7.
since there is no external access, it can’t
be turned on or off.
8.
because there is no other stuff to get in
the way of optimizing speed.
9.
because other stuff is necessary to
analyze deeply.
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A new problem: What is meant by ‘built’?
• If it means, ‘constructed by neurogenesis in the developing
brain’ …
• … then the only modular abilities are sensory and motor, plus
language.
• [NOTE: sensory and motor pathways are peripheral in the nervous
system.]
• This is what Fodor means, and what Chomsky means, too.
• Language has to be a mutation, added to the others.
• However, if it means ‘learned’ …
• … then we may have dozens of modular abilities.
• This is what Coltheart means.
• Coltheart was inspired by connectionism, a mathematical technique for
teaching computers how to learn, which gained popularity in the mid80s, before Fodor’s work.
• Language could be entirely learned.
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So how can Coltheart know?
By a double disassociation.
My example:
dementia
aphasia
cognition
✖
✔
language
✔
✖
If you don’t understand this,
read about Coltheart’s example of the chocolate factory.
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Summary
• Fodor asks, given some notion of modularity, is there any
cognitive ability that satisfies it?
• Yes, following the nine criteria, just peripheral sensory and motor
processing, plus language.
• Coltheart asks, given some cognitive ability, is it modular?
• Yes, following just the top two criteria, just about any cognitive
ability could be modular.
• Connectionism supplies a theory of learning that shows how this
could happen.
• The truth is somewhere between the two.
• Language is learned, but humans have a genetic predisposition
(given by specific neural pathways) to learn it quickly and
accurately.
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NEXT TIME
Ingram §5.
☞ Go over questions at end of chapter.
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