Talk by Christian Valuch (Göttingen): "Exploring the (un)concious using continous flash suppression"

Affective Neuroscience and Psychophysiology  

Colloquium

Dr. Christian Valuch (University of Goettingen)

21.05.2019 18:00 - 20:00 — GEMI, Raum 1.134

Exploring the (un)concious using continous flash suppression

To which extent can sensory stimuli influence human behavior without conscious awareness? This question has occupied psychologists for decades and has been recently investigated using an experimental technique called Continuous Flash Suppression (CFS). CFS reduces conscious awareness of a stimulus presented to one eye by simultaneously presenting a sequence of contrast-intensive visual patterns to the other eye of the same observer. CFS is often used to investigate to what extent certain categories of stimuli (e.g., emotional stimuli) gain access to awareness more rapidly, and which levels of stimulus processing occur unconsciously. Several studies suggested that CFS permits high-level (e.g., semantic) processing without conscious awareness. I will present findings from our experiments that challenge this view. We found that action priming – as a behavioral marker of (un)conscious processing – is closely related to conscious perception during CFS. In addition, using steady-state visually evoked potentials as an electrophysiological marker of stimulus processing, we found that increasing suppression strength leads to a reduction in the neural signature of suppressed stimuli. Our results suggest that CFS interferes with stimulus processing at early cortical processing stages, making high-level cognitive processing without awareness rather unlikely. I will conclude by giving a perspective on how CFS could broaden our understanding of the contributions of stimulus properties and  perceptual expertise to conscious experience. I will argue that while CFS might not be the best-suited method to study unconscious processing, it is a very potent method for determining the perceptual salience of certain stimulus categories, as well as the strength of top-down influences (attention, expectations, and learning) on early visual processing stages.