of prediction and individual differences in word-pair semantic - - PowerPoint PPT Presentation

An EEG investigation of the role

• f prediction and individual

differences in word-pair semantic priming

Xiao Yang Graduate Research Competition March 29, 2016

The role of prediction

General question:

• Do speakers make predictions about upcoming speech

content?

 If so, what makes one a better predictor?

Linguistic phenomenon of our interest:

• Word-pair semantic priming

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Word-pair semantic priming

• After encountering a prime, it is easier to activate a semantically

related target, than an unrelated one.

3 (prime) (target) CAP hat KEY hat

Related Unrelated

Using EEG to study priming effects

EEG (electroencephalogram)

• records real-time voltage fluctuations in the brain
• captures the brain activities triggered by a particular

linguistic event (e.g. encountering a related or unrelated word)

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EEG component of interest: N400

• N400: A negative-going wave peaking at 300-500ms
• N400 priming effect: Related word pair elicits N400

reduction in amplitude (Lau et al., 2013)

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CAP hat

KEY hat

unrelated

related

(Negative plotted up ↑)

Mechanism of N400 priming effect

What’s the priming due to? Possible mechanism 1:

• The activation of the prime word passively spreads to

semantically related words in the mental dictionary.

• If so, then the N400 priming effect is based solely on

the semantic relatedness between the prime and the target.

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Mechanism of N400 priming effect

Possible mechanism 2:

• The priming is in part due to an active process of

prediction; the comprehender can actively generate an expectation for specific words that are semantically related to appear.

• If so, then the N400 priming effect can be conditioned

by some external cues that influence the comprehender’s expectation about whether the word pair will be semantically related or not.

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CAP HAT KEY Mechanism 1: Passive association between mental lexicon

CAP HAT KEY

cap

CAP HAT KEY

cap

CAP HAT KEY

cap

CAP HAT KEY Mechanism 2: Active prediction

CAP HAT KEY

cap

CAP HAT KEY

cap

CAP HAT KEY

cap

Since “cap” just appeared, I bet “hat” will appear soon

Relatedness cue

• Relatedness cue has been shown to modulate reaction time in

behavioral studies on word-pair priming (Hutchison (2007))

• For a given trial, a relatedness cue is presented before the word

pair, indicating how likely it is to encounter a related word pair (proportional cue reflects real proportions)

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80% Related CAP hat

Cue (1000ms) Prime (500ms) Target (900ms)

hat 20% Related KEY

Experiment design: Conditions

• 160 prime-target word pairs
• 280 filler pairs, used to establish relatedness proportion

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Related Condition Unrelated Condition Relatedness Cue Prime Target Prime Target 80% Related CAP hat KEY hat 20% Related CAP hat KEY hat

Experiment design: offline measure

• Does each participant exhibit the same level of

sensitivity to the cue manipulation?

• Previous study on older adults has shown that actively

generating predictions could involve similar mechanisms to verbal abilities (DeLong et al. (2012))

• Therefore individual participant’s sensitivity to the cue

could be related to their personal verbal fluency

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Experiment design: offline measure

• Individual variation in verbal fluency can be measured

by an offline ‘letter and category’ task, as an index of each participant’s verbal fluency (Spreen & Strauss (1998))

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Within 1 minute, tell me all the words for office supplies that you can think of. Paper, Stapler, Eraser, Sticky note, Pen, …

Experiment procedure

• Participants:

 22 KU undergraduate students (all native English speakers)

• Procedure:

 Offline measures (verbal fluency, attentional control, and working memory)  EEG recording while the stimuli are visually presented

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Research questions

• 1. What’s the effect of Relatedness on N400 amplitude?

 Related pairs will lead to N400 reduction

• 2. Would participants actively make prediction using the relatedness

cue?

 If so, ’80% related’ will likely lead to greater N400 reduction (as suggested by Lau et al.

(2013)’s results)

• 3. Will an individual’s verbal fluency have an effect on whether they

show predictive effects?

 If verbal fluency correlates with sensitivity to the relatedness cue, then it suggests some relation between verbal fluency and their sensitivity to the cue manipulation

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Results

• The main effect of Relatedness

 Related word pairs elicited N400 reduction compared to unrelated pairs

• The effect of Relatedness Cue

 Marginally significant between 80% and 20% cue

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All participants, 80% Related All participants, 20% Related

Results

• Participants with high verbal fluency shows bigger N400

priming effect than low verbal fluency participants, when the cue is ’80% related’.

 The priming is in part due to actively generating predictions by using the cue (for high verbal fluency participants)

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Low VF participants, 80% related High VF participants, 80% related

Conclusion

• Word-pair semantic priming involves actively generating

predictions about the upcoming word

• Individuals with higher verbal fluency were more

sensitive to the relatedness cue

 Verbal fluency is an individual difference that modulates comprehender’s ability to make use of the cue and generate lexical predictions  Consistent with previous N400 priming studies using verbal fluency measures among older population (DeLong et al. (2012))  Current study shows for the first time that verbal fluency show a similar correlation among younger adults

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Thank you!

Project team members: Lauren Covey, Caitlin Coughlin, María Teresa Martínez García, Adrienne Johnson, Xiao Yang, Cynthia S. Q. Siew, Travis Major, Robert Fiorentino, and Spring 2014 Neurolinguistics II class members

Reference: DeLong, K. A., Groppe, D. M., Urbach, T. P., & Kutas, M. (2012) Thinking ahead or not? Natural aging and anticipation during reading. Brain & Language, 121, 226-239. Hutchison, K. A. (2007). Attentional control and the relatedness proportion effect in semantic priming. Journal of Experimental Psychology: Learning, Memory, and Cognition, 33(4), 645. Lau, E. F., Holcomb, P. J., & Kuperberg, G. R. (2013). Dissociating N400 effects of prediction from association in single-word contexts. Journal of Cognitive Neuroscience, 25(3), 484-502. Spreen O., Strauss E. (1998). A compendium of neuropsychological tests: Administration, norms, and commentary 2nd Edition. Oxford University Press; New York.

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Results (Cont’d)

Participants with high verbal fluency shows smaller N400 priming effect than low verbal fluency participants, when the cue is ’20% related’.

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Low VF participants, 20% related High VF participants, 20% related