This dissertation investigates how cognitive control influences subliminal semantic processing. Unlike the traditional view that unconscious processing is stereotypical and independent of cognitive control, recent evidence shows that unconscious processing can be elaborate and flexible. Subliminal processing can occur at a semantic level and be modulated by top-down attention. On this basis, the temporal attention window theory and global workspace theory are proposed to explain the interaction between cognitive control and subliminal processing, arguing that the top-down attention is necessary for elaborate subliminal processing. However, the reported absence of priming in near absence of attention could be attributed to the insufficient sensitivity of the response time measure. To clarify the role of top-down attention in subliminal semantic processing, five experiments were conducted to assess semantic priming with a cursor motion method and investigate the role of top-down attention in elaborate subliminal processing. These experiments demonstrated that semantic priming could be reliably assessed by cursor motion measures such as the area under the curve (AUC). By directly comparing the AUC measure with the conventional response time measure (RT), larger priming effects were found for the AUC data than the RT data, suggesting that the AUC was more sensitive than the RT to semantic priming. Also, by applying the cursor motion method to numeric comparison tasks, the necessity of attention in subliminal semantic processing was examined. Results showed that top-down attention helped subliminal semantic processing, but semantic priming was still significant in near absence of attention. In addition, the influence of cue colors on semantic priming was examined; results indicated that priming effects elicited by cue colors were limited. Furthermore, the stimulus-onset asynchrony (SOA) was manipulated to investigate the time course of top-down attention and subliminal semantic processing. It was found that top-down attention extended the lifespan and amplified the magnitude of subliminal semantic processing, suggesting that the temporal attention window lasts for more than 1000ms. Taken together, it can be concluded that assistance from top-down attention prolongs and magnifies semantic priming yet may not be necessary for elaborate subliminal processing.
This dissertation investigates how cognitive control influences subliminal semantic processing. Unlike the traditional view that unconscious processing is stereotypical and independent of cognitive control, recent evidence shows that unconscious processing can be elaborate and flexible. Subliminal processing can occur at a semantic level and be modulated by top-down attention. On this basis, the temporal attention window theory and global workspace theory are proposed to explain the interaction between cognitive control and subliminal processing, arguing that the top-down attention is necessary for elaborate subliminal processing. However, the reported absence of priming in near absence of attention could be attributed to the insufficient sensitivity of the response time measure. To clarify the role of top-down attention in subliminal semantic processing, five experiments were conducted to assess semantic priming with a cursor motion method and investigate the role of top-down attention in elaborate subliminal processing.
These experiments demonstrated that semantic priming could be reliably assessed by cursor motion measures such as the area under the curve (AUC). By directly comparing the AUC measure with the conventional response time measure (RT), larger priming effects were found for the AUC data than the RT data, suggesting that the AUC was more sensitive than the RT to semantic priming. Also, by applying the cursor motion method to numeric comparison tasks, the necessity of attention in subliminal semantic processing was examined. Results showed that top-down attention helped subliminal semantic processing, but semantic priming was still significant in near absence of attention. In addition, the influence of cue colors on semantic priming was examined; results indicated that priming effects elicited by cue colors were limited. Furthermore, the stimulus-onset asynchrony (SOA) was manipulated to investigate the time course of top-down attention and subliminal semantic processing. It was found that top-down attention extended the lifespan and amplified the magnitude of subliminal semantic processing, suggesting that the temporal attention window lasts for more than 1000ms. Taken together, it can be concluded that assistance from top-down attention prolongs and magnifies semantic priming yet may not be necessary for elaborate subliminal processing.
