Understanding Modularity in Brain and Language Studies

1. ModularityDAY 13 – Sept 25, 2013 Brain & Language LING 4110-4890-5110-7960 NSCI 4110-4891-6110 Harry Howard Tulane University

2. Brain & Language - Harry Howard - Tulane University 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.

3. Brain & Language - Harry Howard - Tulane University Review EEG, ERP & MEG

4. Brain & Language - Harry Howard - Tulane University The basic fact about dipoles A dipole has a direction … … which in cortex is perpendicular to its surface

5. Brain & Language - Harry Howard - Tulane University Language areas of the brain

6. Brain & Language - Harry Howard - Tulane University The Broca-Wernicke-Lichtheimmodel (of the LH)

7. Brain & Language - Harry Howard - Tulane University Modularity Ingram §4

8. Brain & Language - Harry Howard - Tulane University But first …

9. Brain & Language - Harry Howard - Tulane University Fodor’s criteria for modularity

10. Brain & Language - Harry Howard - Tulane University 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.

11. Brain & Language - Harry Howard - Tulane University Coltheart’s grouping & my explanation • 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’ • by definition. • by definition. • in order to keep out all the other stuff. • in order to build the fixed structure. • because it was built in a specific way. • in order to keep out other stuff. • since there is no external access, it can’t be turned on or off. • because there is no other stuff to get in the way of optimizing speed. • because other stuff is necessary to analyze deeply.

12. Brain & Language - Harry Howard - Tulane University 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. • Coltheartwas inspired by connectionism, a mathematical technique for teaching computers how to learn, which gained popularity in the mid-80s, before Fodor’s work. • Language could be entirely learned.

13. Brain & Language - Harry Howard - Tulane University So how can Coltheart know? By a double disassociation. My example: If you don’t understand this, read about Coltheart’sexample of the chocolate factory.

14. Brain & Language - Harry Howard - Tulane University 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.

15. Brain & Language - Harry Howard - Tulane University NEXT TIME Ingram §5. ☞ Go over questions at end of chapter.