Attentional sensitization of conscious and unconscious priming - Specifying top-down mechanisms
Final Report Abstract
Unconscious automatic processes are traditionally thought to occur autonomously and independently of topdown control. In challenging this traditional view, we propose an attentional sensitization model of unconscious cognition, which assumes that attentional influences originating from task sets enhance taskrelevant unconscious processes while attenuating task-irrelevant unconscious processes. In the first funding period of this project, this model was successfully tested with a novel induction task paradigm, which allowed us to assess the effects of task sets (e.g., semantic vs. perceptual classification) on unconscious processes. Unconscious processes can be probed by priming visible targets by masked (unconscious) visual stimuli leading to facilitation of target processing. While studies in the first funding period focused on masked semantic and visuo-motor shape priming, studies of the second period, the topic of this report, mainly investigated unconscious evaluative and spatial priming, in order to test the generality of the model. Evaluative priming refers to a facilitation of the processing of stimulus valence and evaluative decisions (pleasant or unpleasant?). Spatial priming is defined as facilitation of the processing of spatial dimensions (upward or lower position?). In the second funding period, we further specified the mechanisms underlying attentional sensitization of unconscious cognition in 24 experiments using behavioral as well as neural measures (event-related potentials, ERPs, and functional magnetic resonance imaging, fMRI). At a theoretical level, we extended our model by specifying the neural mechanisms underlying attentional sensitization. We proposed that attentional sensitization is achieved by a temporal functional coupling of brain areas depending on the active task set. This model has been successfully tested in an fMRI study using functional connectivity analyses showing that temporal coupling of brain areas as a function of task sets predicted the magnitude of subliminal priming. Furthermore, based on a literature review, together with U. Ansorge (Vienna) and W. Kunde (Würburg) we formulated a task set execution account of unconscious priming. This account has been confirmed by studies of masked evaluative and semantic category priming, in which we observed context and task set effects. In two further series of experiments, we specified the attentional mechanisms, which enhance or attenuate unconscious evaluative and spatial priming. We found that attentional sensitization of unconscious evaluative and spatial priming, which both benefit from perceptual induction similar to visuo-motor priming, is strikingly different from sensitization of semantic priming, which specifically benefits from semantic induction. In line with our ERP and fMRI measurements, this indicates that visuo-motor shape, evaluative (in particular pictorial, to lesser extent verbal priming) and spatial priming depend on visuo-motor processes leading to response execution, whereas semantic priming is exclusively based on semantic processes. The differential mechanisms underlying priming lead to a susceptibility to specific attentional sets. We also established for the first time task cue effects on masked priming: Masked or visible cues, which were associated with a specific task set, modulated subsequent unconscious priming. Unexpectedly, the direction of the effects differed from those obtained with the induction task paradigm suggesting that task sets activated by task cues are rapidly inhibited, when no task has to be performed thereafter. In order to measure a potential attentional right hemisphere bias on unconscious processing, we a developed novel experimental paradigm, in which we presented a subliminally primed lexical decision task within two streams in both visual fields. In line with our predictions, a right hemisphere bias for masked priming was found, but the effect was not particular strong, as it was only seen in the ERP, but not in the behavioral data. The established task cue effects and attentional competition effects during dual visual field stimulation on unconscious processing open entirely new research fields and are interesting for technical applications. The implicit top-down control of unconscious processing by attentional sensitization demonstrated here evidences the adaptability of the cognitive system in optimizing ongoing processing toward the pursuit of an intended goal. The research conducted in this project and the associated research network received much interest from the general public and was featured by several magazine, newspaper, radio and TV reports.
Publications
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(2014). Flexible establishment of functional brain networks supports attentional modulation of unconscious cognition. Human Brain Mapping, 35, 5500-5516
Ulrich, M., Adams, S. C., & Kiefer, M.
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(2014). Unconscious vision and executive control: How unconscious processing and conscious action control interact. Consciousness and Cognition, 27, 268-287
Ansorge, U., Kunde, W., & Kiefer , M.
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(2015) Suggestion-induced modulation of semantic priming during functional magnetic resonance imaging. PLoS One 10(4): e0123686. doi:10.1371/journal.pone.0123686
Ulrich, M., Kiefer, M., Bongartz, W., Grön, G., & Hoenig, K
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(2015). Boundary conditions for the influence of unfamiliar non-target primes in unconscious evaluative priming: The moderating role of attentional task sets. Consciousness and Cognition, 35, 342-356
Kiefer, M., Sim, E. J., & Wentura, D.
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(2016). The neural signature of subliminal visuomotor priming: Brain activity and functional connectivity profiles. Cerebral Cortex, 26, 2471-2482
Ulrich M, Kiefer M
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(2016). The semantic origin of unconscious priming: Behavioral and event-related potential evidence during category congruency priming from strongly and weakly related masked words. Cognition, 146, 143-157
Ortells, J. J., Kiefer, M., Castillo, A., Megias, M., & Morillas, A.
