Continuous flash suppression and monocular pattern masking impact subjective awareness similarly
- 198 Downloads
Peters and Lau (eLife, 4, e09651, 2015) found that when criterion bias is controlled for, there is no evidence for unconscious visual perception in normal observers, in the sense that they cannot directly discriminate a target above chance without knowing it. One criticism of that study is that the visual suppression method used, forward and backward masking (FBM), may be too blunt in the way it interferes with visual processing to allow for unconscious forced-choice discrimination. To investigate this question, we compared FBM directly to continuous flash suppression (CFS) in a two-interval forced-choice task. Although CFS is popular, and may be thought of as a more powerful visual suppression technique, we found no difference in the degree of perceptual impairment between the two suppression types. To the extent that CFS impairs perception, both objective discrimination and subjective awareness are impaired to similar degrees under FBM. This pattern was consistently observed across three experiments in which various experimental parameters were varied. These findings provide evidence for an ongoing debate about unconscious perception: normal observers cannot perform forced-choice discrimination tasks unconsciously.
KeywordsVisual awareness Binocular vision: Rivalry/ Bistable Perception visual perception
This work was supported by a grant from the National Institutes of Health (U.S.) to H.L. (Grant No. R01NS088628), and a National Science Foundation Graduate Research Fellowship to J.D.K.
- Almeida, J., Mahon, B. Z., Nakayama, K., & Caramazza, A. (2008). Unconscious processing dissociates along categorical lines. Proceedings of the National Academy of Sciences of the United States of America, 105, 15214–15218. https://doi.org/10.1073/pnas.0805867105 CrossRefPubMedPubMedCentralGoogle Scholar
- Green, D. M., & Swets, J. A. (1966). Signal detection theory and psychophysics. New York, NY: Wiley.Google Scholar
- Hesselmann, G., Hebart, M., & Malach, R. (2011). Differential BOLD activity associated with subjective and objective reports during “blindsight” in normal observers. The Journal of Neuroscience: The Official Journal of the Society for Neuroscience, 31(36), 12936–12944. https://doi.org/10.1523/JNEUROSCI.1556-11.2011 CrossRefGoogle Scholar
- Kingdom, F. A. A., & Prins, N. (2010). Psychophysics: A practical introduction. London, UK: Academic Press.Google Scholar
- Lakens, D., McLatchie, N., Isager, P. M., Scheel, A. M., & Dienes, Z. (2018). Improving Inferences about null effects with Bayes factors and equivalence tests. Journals of Gerontology Series B: Psychological Sciences. https://doi.org/10.1093/geronb/gby065.
- Lau, H. (2008). Are we studying consciousness yet? Frontiers of Consciousness: Chichele Lectures, 340. https://doi.org/10.1093/acprof:oso/9780199233151.001.0001 CrossRefGoogle Scholar
- Lau, H., & Passingham, R. (2006). Relative blindsight in normal observers and the neural correlate of visual consciousness. Proceedings of the National Academy of Sciences of the United States of America, 103(49), 18763–18768. https://doi.org/10.1073/pnas.0607716103 CrossRefPubMedPubMedCentralGoogle Scholar
- Peters, M. A., & Lau, H. (2015). Human observers have optimal introspective access to perceptual processes even for visually masked stimuli. eLife, 4, e09651. https://doi.org/10.7554/eLife.09651
- Phillips, I. (2017). Unconscious perception reconsidered. Retrieved from http://www.ianbphillips.com/uploads/2/2/9/4/22946642/antwerp.pdf.
- Phillips, I., & Block, N. (2016). Debate on unconscious perception. In B. Nanay (Ed.), Current controversies in philosophy of perception (pp. 165–92). New York, NY: Routledge. Retrieved from http://www.nyu.edu/gsas/dept/philo/faculty/block/papers/2016.debate.pdf Google Scholar
- Weiskrantz, L. (1986). Blindsight: A case study and implications. Oxford, UK: Oxford University Press.Google Scholar