" Brain activities during Go/No-Go Association Task "

Kouichi Hioki1,Katsunori Matsuoka2, Hiroshi Watanabe2, Hiroyuki Umemura2

1Kobe University Graduate school of letters, Kobe, Japan. 2National Institute of Advanced Industrial Science and Technology, Human Stress Signal Research Center, Japan.

E-mail:kohioki@lit.kobe-u.ac.jp

Plan of presentation

What is Go/No-Go Association Task(GNAT) Our Opinion Neurophysiological knowledge Method and result Conclusion

What is Go/No-Go Association Task(Dilemma of social psychology)

Although discrimination still exists, White Americans tend to answer that they don’t have prejudice to African Americans(Wittenbrink, Judd, Park., 1997.).

↓ Some distortion is included in measurement in

question papers.

What is GNAT

Greenwald, McGhee, & Schwartz, (1998) noted that there are some differences in reaction time to stereotype words between high and low prejudice person.

And they created Implicit Association Test(IAT) as a measure for implicit prejudiced degree.

Then, Nosek ＆ Banaji(2001) created Go/No-Go Association Task(GNAT) as an improved version of IAT.

What is GNAT

Bugs Good

FleaCockroachSpiderLilyRoseSunflowerHonerPoisonLuckyHappyEvilSad

What is GNAT

Flower Bad

FleaCockroachSpiderLilyRoseSunflowerHonerPoisonLuckyHappyEvilSad

What is GNAT

GNAT is considered to be the tool which measures the strength of the implicit association between a concept and an attribute category.

However, it remains an unsettled question whether the GNAT score is a score which reflected "Association" truly.

Our Opinion

While performing the incongruent trials (e.g., discriminating “Flower” and “Bad” from distracters), we should be making the conflict state occur.

And while performing the congruent trials(“Flower” and “Good”) , a conflict state will not occur.

They can be checked on Neurophysiologcally.

Neurophysiological knowledge

Conflict state: The characteristic which a stimulus has crosses

(“Bug”=bad ⇔ “Good” = good)

and the amount of information which should be processed increases.

・ When a conflict state occurs, Anterior Cingulate Cortex(ACC) will also be activated

（ Fan, Flombaum, McCandliss, Thomas, & Posner, 2003 ） .

Hypothesis While performing the incongruent trials

(e.g., discriminating “Flower” and “Bad” from distracters), we should be making the conflict state occur.

While performing the congruent trials(“Flower” and “Good”) , a conflict state will not occur.

In Incongruent trials.

→Negative brain waves would be checked In Congruent trials.

→Negative brain waves wouldn’t be checked

Method Participants:4 male participants Recorded Event Related Potentials(ERP) with 5

tin electrodes during GNAT trials . Trial:Congruent Trial(72trials): Discriminating “Flower” and “Good”

from distractersIncongruent Trial (72trials) : Discriminating “Flower” and “Bad” from

distracters

Data Sampling

Sampling late: 1000Hz. Base line: left earlobe Filter: Below 0.5Hz. Above 30Hz. Fz/Cz/C3/C4/Pz （ The10‐20system ）

Results

All the participants showed short reaction time in Congruent Trials.

Waveforms(Congruent Trial)

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FZ CZ PZ C3 C4

μV

Waveforms(Incongruent Trial)

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FZ CZ PZ C3 C4

μV

Waveforms(FZ)

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-1500

-1200

-900-600

-300response

300600

9001200

Fz(Congruent) Fz(Incongruent)

μV

Conclusion All the participants showed short reaction

time in Congruent Trials. Only in Incongruent trials, the

negative waveform has been checked at after about 200ms from the reaction .

The ACC activated only in GNAT Incongruent trials.

Therefore, we can say the GNAT time –lag may reflect cognitive conflict.