Right hemisphere sensitivity to word & sentence level context:
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Right hemisphere sensitivity to word & sentence level context: Evidence From Event-Related Brain Potentials. Coulson, S. Federmeier, K.D., Van Petten, C., and Kutas, M. (2005) JEP: Learning, Memory, and Cognition. Gist . Question : Is right hemisphere message blind? Measurement : ERP

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Right hemisphere sensitivity to word & sentence level context: Evidence From Event-Related Brain Potentials.

Coulson, S. Federmeier, K.D., Van Petten, C., and Kutas, M. (2005)

JEP: Learning, Memory, and Cognition.


Gist context:

  • Question: Is right hemisphere message blind?

  • Measurement: ERP

  • Paradigm: associate priming without/within sentence context

  • Answer: RH is not message blind, but there is indeed hemispheric asymmetries in the use of word and sentence contexts


Message blind rh the hypothesis
Message-blind RH context: --the hypothesis

  • LH

    has the ability to integrate syntactic, semantic, and pragmatic information to construct a message-level representation of meaning.

  • RH

    its language competence extends only to word-level priming mechanisms


Message blind rh why people made this claim
Message-blind RH context: --why people made this claim?

  • LH

  • priming in RT to words embedded in normal or scrambled sentences (Faust et al. 1995)

  • Larger priming effect when the amount of context is increased (Faust et al. 1993)

  • Longer RT to words in implausible sentence context than plausible context (Faust, 1998)

  • RH

  • Contexts do not seem to facilitate or hinder the language process

    so…RH seems to be blind to these message level information..


Message blind rh however
Message-blind RH context: --however…..

  • LH

  • RH

  • Should be sensitive to some message level information, since when RH is damaged

    • patients cannot understand certain kinds of jokes, metaphoric language, and sarcastic utterances

  • Some studies did find sentence congruity effect in the RH (Chiarello, Liu, & Faust, 2001; Faust, Bar-lev, & Chiarello, 2003)



Experimental design ex1
Experimental design (EX1) context:

Primes are centrally presented, and

targets are lateralized to either visual field (split visual field display).




Procedure
PROCEDURE context:

1000~1200ms

++++

200ms

spare

0ms

200ms

tire

300ms

2500ms

?


Prediction
Prediction context:

  • Ex1[word level context effect]

    • Since both hemispheres are sensitive to word level info, similar-sized N400 context effects are expected



EX1 context:

LVF/rh


EX1 context:

LVF/rh

N400

LPC


EX1 context:

RVF/lh


Experimental design ex2
Experimental design (EX2) context:

The cloze probability were matched between the two types of congruous sentences (associated & unassociated) and also between the two types of incongruous sentences. This was done to ensure that the message level constraints are similar in the associated and unassociated conditions.


Prediction1
Prediction context:

  • Ex1[word level context effect]

    • Since both hemispheres are sensitive to word level info, similar-sized N400 context effects are expected

  • Ex2[sentence level context effect]

    • LH:

      • A large N400 congruity effect

      • Negligible effects of association

    • RH: (if the message blind RH model holds)

      • A large N400 association effect

      • Negligible effects of context congruity



EX2 context:

LVF/rh

N400

LPC


EX2 context:

RVF/lh

N400

LPC


Summary
Summary context:

  • word level: association effects for both LVF/rh and RVF/lh presentation

  • sentence level: robust congruity effects for both LVF/rh and RVF/lh presentation

    the message-blind RH model is not supported

  • At the sentence level, the congruity effect lead to a dramatic attenuation of the association effect.

    • Lexical context is less important in sentence contexts


unassociated context:

Association effect

associated

Association effect

unassociated

associated

5 µV

Congruity effect

incongruous

congruous


Summary1
Summary context:

  • Although both hemispheres make use of word level as well as sentence level contexts, they seem to use them in different ways.

  • LH seems to make use of lexical association only when the sentence context is incongruous.

  • RH shows a smaller lexical association effect at the word level, which suggests that RH might be weaker to use this source of semantic context.

  • RH shows the association effect in congruous sentences there might be a greater reliance on word level relationships in the lexical integration processes in understanding sentences


Questions
Questions context:

  • Is the LPC the same thing as the P600?

  • Do blinks also produce surges that might overshadow brain activity on the EEG?

  • How common is subject attrition due to excessive artifacts?

  • Onset or peak? Which point is more interesting? In what situations would one or the other be the focus?

  • What if they ran their experiments on brain damaged patients ?

  • Why was a naming paradigm chosen for the target as opposed lexical decision?

  • Great Britain norms vs. US participants ….isn’t it problematic?

  • Is the hemispheric asymmetry in reliance on lexical relationships has to do with other abilities commonly associated with RH function (e.g., spatial abilities).




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