| Abstract: | 分類為一項重要的人類認知歷程。然而分類的決策過程並非超然獨立地，反而與當下所處的 情境息息相關，其中先前的資訊所形塑的情境相當程度地左右當下的決策，但目前科學界對 此過程的內在機制仍所知有限。本計劃將結合行為研究、電腦模擬以及腦磁波儀的技術探索 此一議題。我們將研究當受試者對一連串臉部刺激物作連續分類判斷時，之前刺激物所塑造 的情境如何影響當下的分類決定。根據我們已有的初步實驗證據，本計劃欲達成以下具體目 標：一、當對臉部表情作連續分類判斷時，之前情境影響當下分類決定的神經機制為何。二、 當對臉部身份作連續分類判斷時，之前的情境是否影響當下分類決定。三、情感表現是如何 介入連續性的分類判斷。我們預期之前情境能影響人臉所傳達的多面訊息，包括臉部表情及 臉部身份。此外，我們也預期神經共振訊號能成為一項有用的指標，可以預測受試者作連續 分類判斷時的行為表現。最後，實驗結果也將揭櫫之前情境對當下分類決定的影響會隨受試 者的情緒狀態有所不同。由於過往的研究主要著重在人類如何對單一刺激物進行分類，因此 本計畫具其突破性。本計劃所得之結果也深具重要性，因其能幫助我們瞭解分類決策的心理 與神經機制。
The brain’s imposition of meaning upon a jumbled array of information is usually achieved through categorization. However, people do not make categorization decisions in a vacuum. Rather, decision processes are dynamic and are made in relation to a pertinent context. One particular crucial context is the sequential context provided by preceding material. Unfortunately, our understanding of sequential categorization decisions is still surprisingly limited. In this project, we will conduct a series of behavioral and magnetoencephalography (MEG) experiments together with computational modeling to tap into the mechanisms underlying sequential categorization decisions. The objective of this project is to elucidate the nature of sequential categorization decisions, with the emphasis on sequential effects in the context of face perception, i.e., whether and how the preceding context provided by preceding faces influences the categorization decisions of current faces when participants view a sequence of face stimuli. Our central hypothesis is that a previously presented face stimulus may guide categorization decisions on the current one and such impact could be observed in several facial dimensions, including facial expression and facial identity. Furthermore, the underlying neural mechanisms could be manifested in terms of neural oscillations revealed by MEG signals. The rationale of this project is that the completion of the proposed experiments will arrive at a better understanding of the temporal dynamics of categorization decisions. Guided by preliminary data, we will pursue the following specific aims: 1) the neural mechanism of sequential effects in facial expression categorization, 2) sequential effects in the categorization of facial identity, and 3) the role of emotional feeling in sequential effects. It is our anticipation that the combination of work proposed in Aim 1-3 will collectively reveal the nature of sequential categorization decisions by yielding the following expected outcomes. First, we expect to show that sequential effects are pervasive phenomena that could even exist in multi-dimensional, social stimuli such as faces. Then, we expect to characterize the neural signatures, neural oscillatory activity in different frequency bands for instance, reflecting how the categorization decisions on current stimuli are influenced by sequential context. Lastly, we anticipate demonstrating that the patterns of sequential effects would vary according to participants’ affective states. The proposed research is innovative, because in contrast to our project, majority of prior studies regard categorization decisions as static, isolated processes. This project is significant, because the outcomes of the experimental results in this project would provide a solid psychological and neural basis of sequential categorization decisions and in turn refine our understanding of decision-making and face perception. |
