オタワで行なった脳波実験の論文がようやくアクセプトされました。お力添えを頂いた方々に心から感謝いたします。
この論文も、環境によって決められた一つの正答がある場合の意思決定（externally guided decision making）と、環境により決められた一つの正答がない場合の意思決定(internally guided decision making)の違いを示したものです。
具体的には、internally guided decision making（職業選択、色の好み判断）のときの迷い（競合）の程度を反映する事象関連電位（N2）の振幅が、安静時の脳活動の個人差により変化するというものです。そのような関連性はexternally guided decision makingでは認められませんでした。まだ相関レベルの関係性ですので、今後この関連性の背後にあるプロセスについて詳細に検討していけたらと思っております。
Abstract
Most experimental studies of decision-making have specifically examined situations in which a single correct answer exists (externally guided decision-making). Along with such externally guided decision-making, there are instances of decision-making in which no correct answer based on external circumstances is available for the subject (internally guided decision-making, e.g. preference judgment). We compared these two different types of decision-making in terms of conflict-monitoring and their relation with resting-state brain activity. Current electroencephalography (EEG) data demonstrated that conflict-related N2 amplitudes (i.e., difference between large-conflict and small-conflict conditions) in externally guided decision-making were modulated by the type of external stimulus (i.e., large-conflict stimulus pair or small-conflict stimulus pair) but were not found to be correlated with resting-state brain activity (i.e. resting-state EEG power). In contrast, conflict-related N2 amplitudes in internally guided decision-making were found to be correlated with resting-state brain activity, but were not found to be modulated by the type of stimulus itself: the degree to which the type of external stimulus modulates the conflict during stimulus encoding varies according to individual differences in intrinsic brain activity. Considering those results comprehensively, we demonstrate for the first time resting-state and stimulus-related differences between externally and internally guided decision-making.
Conclusion
We compared decision-making of different types: externally and internally guided decision-making. The conflict-related N2 in externally guided decision-making was modulated by the type of external stimulus (i.e., large-conflict pairs or small-conflict pairs) but was not found to be correlated with intrinsic brain activity. In contrast, the conflict-related N2 in internally guided decision-making was found to be correlated with intrinsic brain activity but was not found to be modulated by the type of external stimulus itself either in occupation or color-similarity judgment tasks: In internally guided decision-making, whether the combination of stimuli modulates the conflict at the level of stimulus encoding was varied with the trait aspect of the intrinsic brain activity. Although regulatory processes that operate during externally guided decision-making have been well identified, they are less than clear in the case of internally guided decision-making. This study of internally guided decision-making is expected to be of great interest in the field of decision-making itself in that it sheds some light on a form of decision-making that is prevalent in actual daily life. Beyond the field of decision-making, this line of investigation is also expected to contribute to improvement of our understanding of the function of resting-state brain activity.
