The Interaction Between Unconsciousness And The Attentional Modulation On Unconscious Processing

With regard to the relationship between attention/consciousness and unconsciousousness or within themself, many studies have revealed unconscious effects on conscious processing (e.g., unconscious priming) and top-down modulation (spatial attention, attentional load, etc.) on unconscious processing. However, there is little research about whether unconscious processes could influence each other and how category-selective attention could modulate the unconscious processing, which are the two points the paper focuses on.Firstly, in this paper, it was investigated that whether and how unconscious processes could influence each other by using simultaneously presented face pictures with the same or a different unconscious valence (SUV versus DUV). In the first event-related potential (ERP) study, DUV elicited a smaller N2as compared to SUV. In the second functional magnetic resonance imaging (fMRI) experiment, the left middle frontal gyrus (MFG) was activated under DUV condition in comparison to SUV condition. These results reflected the unconscious mismatch detection. The effect in the two studies would indicate that at a certain processing level the brain tries to integrate the expression analyses of the two faces, which likely supports the idea of interactions between unconscious processes. The theoretical implications are also discussed in the light of the global neuronal workspace theory.Secondly, using fMRI, it was studied that whether and how category-selective attention could modulate the unconscious processing. Using a paradigm with different type of cue (word of "tool" or "face") followed by different unconscious stimuli (tool or face picture), the results showed that category-selective attention modulated unconscious face/tool processes in the middle occipital gyrus (MOG). Interestingly, MOG effects were of opposed direction for face and tool processes. During unconscious face processing, activation in MOG decreased under the face-selective attention compared with tool-selective attention. This result was in line with the predictive coding theory. However, during unconscious tool processing, activation in MOG increased under the tool-selective attention compared with face-selective attention. Although the participants did not know what was presented under both conditions, they could experience the changes of contour and orientation under condition of masked tools but could not under condition of masked faces. Therefore, the different effects might be ascribed to an interaction between top-down category-selective processes and bottom-up processes in the partial awareness level as proposed by Kouider et al.(2010), i.e. the changes of contour and orientation under the unconscious tool condition. Specifically, we supposed an "excessive activation" hypothesis.However, it was not clear whether the opposite results could be due to the changes of contour and orientation under condition of masked tools. Therefore, other two experimental tasks with partial awareness were designed in the second fMRI experiment: one with invariant tool contour and another with symmetrically variant tool contour. The second fMRI results showed that, during invariant tool contour task, activation in middle occipital gyrus decreased under the tool-selective attention compared with face-selective attention, which was consistant with predictive coding theory. During symmetrically variant tool contour task, there was no modulation effect. Combined with the first fMRI results that during unconscious tool processing, activation in MOG increased under the tool-selective attention compared with face-selective attention, the "excessive activation" hypothesis was approved and it is also speculated that category-selective attention competes with process at partial awareness level.This paper has important theoretic and practical significance. For the theoretic significance. it deepens the understanding of relationship between attention/consciousness and unconsciousness. It also amends the global neural workspace theory. In addition, this paper used new paradigm including repeating and simultaneously presenting unconscious stimuli. For the practical significance, the ideas of interaction between unconsciousness and top-down modulation on unconscious processes are significant for our understanding many behavior and phenomena which were interpretated difficultly from previous view.