Role of awareness and metacognition in audio-visual ventriloquism

Human perceptual experience is inherently multisensory. The brain continuously makes decisions about which sensory signals should be interpreted as common and which as separate events. Basic principles of the processes underlying such decisions have been widely explored over the past few decades. While there is a good understanding of the function of bottom-up binding cues, little is known about how automatic multisensory integration is and what is the role of subjective perceptual experience. This thesis employs the Ventriloquist Effect (VE) to investigate the interplay between awareness, metacognition and audio-visual integration. Chapters 1 and 2 describe the current state of knowledge about relevant aspects of multisensory integration and analytical techniques applied in the empirical chapters. Chapter 3 shows that Ventriloquist Effect can be caused by visual stimuli presented under Continuous Flash Suppression, which are not consciously perceived. Chapter 4 investigates neural mechanisms of the effect for aware and unaware flashes. Chapter 5 shows semantic modulation of VE for unmasked, but not masked images, even though VE is present for unseen stimuli. Chapter 6 investigates the function of spatial and semantic congruency in multisensory causal metacognition. Chapter 7 provides a summary of the main findings and discusses their contribution to the field.