The objective of this research project is to check whether awareness of stimulus presence as compared to awareness of stimulus shape is a unitary process or not. By employing event related potentials (ERPs) derived from the EEG, we may check whether visual awareness negativities (VAN) for conditions in which stimulus presence or shape has to be detected are the same or different. It was hypothesized that this process is not likely to be unitary, which would show up in different topographies and underlying sources of the VAN in these different conditions.

Use of the metacontrast masking paradigm enables us to differentiate stimuli into those of which one is aware and those of which one is unaware, which was exploited in several previous studies. (Koivisto & Revonsuo, 2008a; Railo & Koivisto, 2009; Lamy, Salti & Bar-Haim, 2009; Raillo et al, 2011). Railo and Koivisto, (2009) compared masked and pseudomasked stimuli whereas Breitmeyer and Ögmen (2006) presented stimuli at unpredictable locations to check how awareness and spatial attention overlap each other. They concluded that these two processes are very likely to be separate. However, awareness may overlap nonspatial attention. We take it into account and in novelty present identical stimuli only centrally in both conditions: aware versus unaware. Thanks to this the comparison between both conditions is maximally simple and other factors may easily be excluded.

EEG registration and analysis will show if both processes generate the same ERPs and if they come from the same brain regions. By this we will come closer to determining the mechanisms underlying visual awareness and at the same time adding to the general knowledge on human consciousness.  In future it may also help to built more effective brain computer interfaces (BCI) to make life easier for consciousness impaired people.

• Breitmeyer, B. G., & Öğmen, H. (2006). Visual masking: Time slices through conscious and unconscious vision. Spatial Vision (p. 370). Oxford University Press
• Genetti, M., Khateb, A., Heinzer, S., Michel, C. M., & Pegna, A. J. (2009). Temporal dynamics of awareness for facial identity revealed with ERP. Brain and Cognition, 69(2), 296–305. doi:10.1016/j.bandc.2008.08.008
• Koivisto, M, & Revonsuo, A. (2008). The role of selective attention in visual awareness of stimulus features: Electrophysiological studies. Cognitive Affective Behavioral Neuroscience, 8(2), 195–210. doi:10.3758/CABN.8.2.195
• Koivisto, Mika, & Revonsuo, A. (2008). Comparison of event-related potentials in attentional blink and repetition blindness. Brain Research, 1189(16), 115–126. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/18035339
• Lamy, D., Salti, M., & Bar-haim, Y. (2008). Neural Correlates of Subjective Awareness and Unconscious Processing : An ERP Study. Journal of Cognitive Neuroscience, 1435–1446.
• Railo, H., & Koivisto, M. (2009). The electrophysiological correlates of stimulus visibility and metacontrast masking. Consciousness and cognition, 18(3), 794–803. doi:10.1016/j.concog.2009.01.006
• Railo, H., Koivisto, M., & Revonsuo, A. (2011). Tracking the processes behind conscious perception: A review of event-related potential correlates of visual consciousness. Consciousness and Cognition, 20(3), 972–983. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21482150