Stimuli that cannot be perceived (i.e., that are subliminal) can still elicit neural responses in an observer, but can such stimuli influence behavior and higher-order cognition? Empirical evidence for such effects has periodically been accepted and rejected over the last six decades. Today, many psychologists seem to consider such effects well-established and recent studies have extended the power of subliminal processing to new limits. In my thesis, I examined whether this shift in zeitgeist is matched by a shift in evidential strength for the phenomenon. My conclusion is that several methodological, statistical, and theoretical issues remain in studies of subliminal processing. These issues mean that claimed subliminal effects might be caused by occasional or weak percepts and that it is still unclear what evidence there is for the cognitive processing of subliminal stimuli.
I have previously been involved in projects on perceptual learning, sound-localization, and emotion-attention interactions and worked with EEG and eyetracking.
Sand, A. (2016). Subliminal or not? An appraisal of semantic processing in the near absence of visual awareness. Department of Psychology, Stockholm University (Doctoral dissertation). Full info in DiVA.
Sand, A., & Nilsson, M. E. (2016). Subliminal or not? Comparing null-hypothesis and Bayesian methods for testing subliminal priming. Consciousness and Cognition, 44, 29-40. 10.1016/j.concog.2016.06.012
Sand, A. (2016). Reversed priming effects may be driven by misperception rather than subliminal processing. Frontiers in Psychology, 7, 198. 10.3389/fpsyg.2016.00198
Sand, A., & Nilsson, M. E. (2014). Asymmetric transfer of sound localization learning between indistinguishable interaural cues. Experimental Brain Research, 232(6), 1707-1716. 10.1007/s00221-014-3863-7
Wiens, S., Molapour, T., Overfeld, J., & Sand, A. (2012). High negative valence does not protect emotional event-related potentials from spatial inattention and perceptual load. Cognitive, Affective, & Behavioral Neuroscience, 12(1), 151-160. 10.3758/s13415-011-0072-8
Sand, A., & Wiens, S. (2011). Processing of unattended, simple negative pictures resists perceptual load. NeuroReport, 22(7), 348-352. 10.1097/WNR.0b013e3283463cb1
Wiens, S., Sand, A., & Olofsson, J. K. (2011). Nonemotional features suppress early and enhance late emotional electrocortical responses to negative pictures. Biological Psychology, 86(1), 83-89. 10.1016/j.biopsycho.2010.11.001
Wiens, S., Sand, A., Norberg, J., & Andersson, P. (2011). Emotional event-related potentials are reduced if negative pictures presented at fixation are unattended. Neuroscience Letters, 495(3), 178-182. 10.1016/j.neulet.2011.03.042