Does the GNAT incongruent trial make cognitive conflict?Does the GNAT incongruent trial make cognitive conflict?Brain activities during Go/No-Go Association TaskBrain activities during Go/No-Go Association Task

Koichi Hioki1, Seiji Nakagawa2, Hiroshi Watanabe2, Hiroyuki Umemura2, Katsunori Matsuoka2

& Minoru Karasawa3

1 Graduate School of Humanities and Social Science, Kobe University, Japan,

2 Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology (AIST), Japan, 3 Kobe Uni

versity, Japan

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

INTRODUCTIONINTRODUCTIONThe aim of this study was to examine brain activities with magnetoencephalography (MEG) during the Go/No-Go Association Task (GNAT).

Social psychologists typically use questionnaires to study attitude toward specific objects (e.g., a minority group, self ). For example participants are asked, “Do you think that African Americans demand equal rights too much?” or “ Do you think that media and the government pay respect too much to African Americans?” However, as Wittenbrink, Judd, & Park (1997) pointed out, biases and distortion cannot be completely prevented when using self-report questionnaires.

In response to such problems, Greenwald, McGhee, & Schwartz (1998) created another measurement of social stereotypes. They noted that there are differences in reaction time to stereotype words between high and low prejudice person. They created the Implicit Association Test (IAT) as a measure for implicit prejudice. Later, Nosek ＆ Banaji (2001) created the Go/No-Go Association Task (GNAT) as an improved version of the IAT. They assumed that a high prejudice person has greater association between African Americans and negative words than a low prejudice person. For that reason, they predicted that a high prejudice person would be faster than a low prejudice person in identifying the pair words “Bad” and “Black“ among other stimuli. While in the case of identifying “Black” and “Good,” a low prejudice person would be faster than a high prejudice person.

High prejudice Low prejudice

Black + Bad Easy Difficult

Black + Good Difficult Easy

The GNAT is a dual task which requires both (1) classification judgments and (2) attribute judgments for stimulus items. The GNAT consisted of two blocks, one of the blocks constructed with “Good” as the target attribute, whereas “Bad” being the target in the other half. In sum, the GNAT consist of “identifying target category or Bad” trials (e.g. identifying “Bugs” and “Good” from distracters) and “identifying target category or Good” trials (e.g. identifying “Bugs” and “Bad” from distracters).

We calculate the GNAT score by subtracting reaction latency of “Bugs or Good” trials from “Bugs or Bad” trials. Therefore, it is thought that the GNAT score reflects the implicit positive impression one has towards Bugs. Thus the GNAT is considered to be a tool which measures the strength of the implicit association between a concept and an attribute category.

RESEARCH INTERESTRESEARCH INTERESTWe argue that GNAT is a tool which measures the strength of the implicit association between a concept and an attribute category. If this is true, while discriminating “Bugs” and “Good” from distracters( incongruent trials), we should be inducing a conflict state in our participants. On the other hand, while discriminating “Bugs” and “Bad” from distracters( congruent trials), a conflict state will not occur.

We believe that this could be tested and verified neurophysiologcally.

Bug and Happy？

While performing the incongruent trials, a cognitive conflict state should be induced.

And while performing the congruent trials (“Bugs” and “Bad”), a conflict state will not be induced.

?? 　← This can be tested neurophysiologcally 　

Table 1: Setting of the GNAT

Reaction latency “Bugs or Bad” trials

　　 － ) Reaction latency “Bugs or Good” trials

　 GNAT score of “Bugs”

↓

We assume it reflects implicit positive impression towards Bugs.However, there are an unsettled question of whether the GNAT score truly reflects “Implicit Association".

METHODMETHODParticipants: 5 Japanese graduate and undergraduate students. Trials: Participants were provided informed consent and sat in MEG (Neuromag-122TM ,4-D Neuroimaging Ltd., Finland) which settled in a shielded room. Participants then performed two types of block. One was the Congruent Block (identifying “Bugs” and “Bad” from distracters) and the other was the Incongruent Block (identifying “Bugs” and “Good” from distracters). Both blocks contain 200 trials, one half of which was deemed to elicit “Yes” responses (press a button) while the other half designed for “No” responses (ignore). Data Sampling: During the GNAT task, participants were scanned by 122 coils of MEG. Data was sampled by 400Hz and digitally filtered frequencies below 0.5Hz and above 30Hz.

RESULTSRESULTS

GNAT score: As shown in Table 2, all participants showed shorter reaction latency in the Congruent trials (“Bugs or Bad” ) than in the Incongruent trials (“Bugs or Good”) F (1, 4) > 64.31, p <.01. In other words, the Congruent trials were easier to perform than the Incongruent trials.

Table 2: All participants’ reaction latencies and GNAT scores (ms)

Fig.1: Graphs of root meant MEG data

*Red line represent Incongruent trials and blue line represent Congruent trials.

**Higher scores means higher activation of brain region

*** 0ms indicate onset timing of stimulus

MEG data: We calculated 12 root means of each hemisphere of 5 participants. The coils used to calculate are represented as red triangles in Fig.1 (all MEG data shown in Appendix). We conducted Condition (2: Congruent / Incongruent) x Time (66: divided from -150ms to 1500ms into 66 time windows;

25ms each) ANOVA on root meant MEG data.We found some significant interactions between Condition and Time at the right hemisphere Fs (65,260) > 1.37, ps < .05. And follow–up analysis of Time indicated simple main effects of Condition at about 300ms – 500 ms after stimulus onset ( these results are indicated as green circles in Fig.1).

Fig.2: MEG coils (Right Side View)

APPENDIXAPPENDIX: All MEG data

MEG data of left hemisphere MEG data of right hemisphere

REFERENCESREFERENCESFan, Flombaum, McCandliss, Thomas, & Posner, 2003, Cognitive and Brain Consequences of Conflict, NeuroImage,18, 42-57.Greenwald, McGhee, & Schwartz, 1998, Measuring Individual Differences in Implicit Cognition: The Implicit Association Test, JPSP,74 (6), 1464-1480.Nosek, ＆ Banaji, 2001, The Go/No-Go Association Task, Social Cogn. 19 (6),625-664.Wittenbrink, Judd, ＆ Park, 1997, Evidence for Racial Prejudice at the Implicit Level and Its Relationship With Questionnaire Measures, JPSP,72 (2), 262-274.

Participant Bug_Bad Bug_Good GNAT score1 627.86 687.10 -59.242 471.60 588.68 -117.073 579.66 662.73 -83.074 648.77 718.11 -69.335 546.55 652.07 -105.52

CONCLUSIONCONCLUSION Analysis of reaction time showed that incongruent trials took longer than congruent trials. Furthermore, the MEG data revealed brain activities over midline central scalp regions (above the Anterior Cingulate Cortex, ACC) in only incongruent trials. These activities occurred at about 400 ms after the stimulus appeared (i.e., about 250 ms before the response). In conclusion, our data suggest that incongruent GNAT trials induce cognitive conflict and that the time lag is caused by cognitive conflict during stimulus judgment.

Furthermore, MEG coils have a useful characteristic that the scanned data reveal brain region activities which located directly below the coil. Therefore, we can assume that the GNAT incongruent trials induced activities of the ACC and the left inferior parietal lobule at about 300ms after stimulus (shown as red circles in Fig.2). And it is known that when a conflict state occurs, the ACC will also be activated (Fan, Flombaum, McCandliss, Thomas, & Posner, 2003).

Therefore, the results suggest that the GNAT time-lag(score) may reflect cognitive conflict and such conflict is induced before participants respond.

A:anteriorP:posterior

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Whole-head neuromagnetometor (Nuromag-122TM, Nuromag Ltd., Finland)