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Perceptual bistability as a tool for studying unconscious visual processing

Perceptual bistability as a tool for studying unconscious visual processing. Pieter Moors. Perceptual bistability. Despite constant retinal input, perceptual experience changes continuously

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Perceptual bistability as a tool for studying unconscious visual processing

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  1. Perceptualbistability as a tool forstudyingunconsciousvisual processing Pieter Moors

  2. Perceptualbistability • Despite constant retinal input, perceptualexperience changes continuously • The processing of the suppressed stimulus cangiveinsightinto the neuralcorrelates of visual awareness.

  3. Paradigms • Motion-inducedblindness

  4. Paradigms • Motion-inducedblindness • Binocularrivalryandcontinuous flash suppression • See also the session on binocularrivalry

  5. Paradigms • Motion-inducedblindness • Binocularrivalryandcontinuous flash suppression • See also the session on binocularrivalry • (Visual masking, inattentionalblindness, change blindness, visualcrowding, attentional blink, object substitutionmasking, …)

  6. Measures • Adaptation to the suppressedstimulus • Primingby the suppressed stimulus • Dominance/suppressiondurations • Breakingsuppression (CFS)

  7. Overview • Discussfindings on “low-level”, “mid-level”, and “high-level” aspects of suppressed stimuli • End withdiscussion on the convergenceanddivergencebetween these findings

  8. “Low-level” features • The representation of verysimple features seemstobepreservedduringsuppression • Orientation(Blake & Fox, 1974; Blake et al., 2005; Montaser-Kouhsari et al., 2004; Moradi & Koch, 2005, …) • Spatialfrequency(Yang & Blake, 2012, …) • Color(Hofstoetter et al., 2004, Hong & Blake, 2009) • Motion (Lehmkuhle& Fox, 1975; O’Shea & Crassini, 1981, …)

  9. “Mid-level” features • Gestaltgrouping cues caninfluencedominancedurationsin • MIB (Bonneh et al., 2001; Mitroff & Scholl, 2005)

  10. Bonneh et al. (2001)

  11. Mitroff & Scholl (2005)

  12. “Mid-level” features • Gestaltgrouping cues caninfluencedominancedurationsin • MIB (Bonneh et al., 2001; Mitroff & Scholl, 2005) • Binocularrivalry (Alais & Blake, 1999) • Common fate • Parallelism • Goodcontinuation

  13. “Mid-level” features • Mixed evidencefor more complex Gestalts • E.g., Kanizsa stimulus • Yes: Masking (Poscoliero et al., 2013); CFS (Wang et al., 2013) • No: BR (Sobel & Blake, 2003), CFS (Harris et al., 2011)

  14. Poscolieri et al. (2013)

  15. Wang et al. (2012)

  16. Sobel & Blake (2003)

  17. Harris et al. (2011)

  18. Moors et al. (in prep.) • Divergencebetween direct and indirect measures in rivalryand CFS. • Collinearcontours of the pacmencouldstill drive the effect

  19. Moors et al. (in prep.) • Collinearcontours of the pacmencouldstill drive the effect • Extracting the surface is criticalfor the illusion • Goal: Replicate effect from Wang et al. (2012) anduse control stimuli forsurfaceandcollinearcontours

  20. Stimulus set Kanizsa Cross Kanizsa Surface Regular Regular Irregular Irregular

  21. b-CFS experiment Non dominant eye Dominant eye

  22. Results N = 20 Main effect Stimulus andRegularity (BF = 48)

  23. “High-level” features • Faces • Adaptation in CFS • Face shapeonly (Stein & Sterzer, 2011) • Notidentity (Moradi & Koch, 2005) • Not gender or race (Amihai et al., 2011) • b-CFS findings • Inversioneffects (Jiang et al., 2007) • Familiarityeffects (Gobbini et al., 2013)

  24. “High-level” features • Emotionalfaces • Adaptation toemotionalexpressions(Adams et al., 2010) • Fearfulfaces break suppressionfaster (Yang et al., 2007) • Potentialspatialfrequencyconfound? (Stein & Sterzer, 2011; Gray et al., 2013)

  25. “High-level” features • Semantic processing • In CFS • Scene congruencybiasessuppression (Mudrik et al., 2010, 2011) • For word stimuli • Prime – target congruency(Costello et al., 2009) • Emotional vs. neutralwords(Yang & Yeh, 2011; Sklar et al., 2012)

  26. “High-level” features • Semantic processing • No studyaddressedwhetherwords per se break suppressionfasterthan pseudo/non-words • Ifwords are processed, a word frequency effect is expectedtobeobserved

  27. Heyman and Moors (2014) • Experiment 1 • Word type (word vs. pseudo-word) • Word frequency • Experiment 2 • Pseudo wordsstillreadable • Words vs. non-words • Letter familiarity • Upright vs. inverted

  28. Heyman and Moors (2014) Null model (BF = 26) Null model (BF = 11) N = 18

  29. Heyman and Moors (2014) Null model (BF = 15) Null model (BF = 10) N = 20

  30. Discussion • Unconsciousvisual processing? • Findingsoftendepend on the paradigm • Paradigmsdiffer in theirsuppressionmechanisms • What does thisimplyfor “unconscious” visual processing in general?

  31. Discussion • Are we learningsomethingaboutunconsciousvisual processing? • Or are we learningsomethingabout the level at which a suppressionmethod acts and the representation of the stimulus at that level? • Example: Kanizsa stimulus • CFS vs. masking vs. MIB

  32. Discussion • This point is increasinglybeingrecognized • Breitmeyer (2014) • “Much of brain imaging research relies on the use of one or another of the many noninvasive ways of rendering stimuli invisible. Without knowing at which cortical level of processing these blinding techniques exert their effects, one cannot make unequivocal claims as to what are or are not NCoCs and NCoUs.”

  33. Discussion

  34. Discussion • Fogelson et al. (2014) • Continuous flash suppression versus Chromaticflickerfusion:

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