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Imaging implicit perception: promise and pitfalls

Abstract

The study of implicit perception — perception in the absence of awareness — has a long history. Decades of behavioural work have identified crucial theoretical and methodological issues that must be considered when evaluating claims of implicit perception. Neuroimaging methods provide an important new avenue for illuminating our understanding of perception both with and without awareness, but most imaging experiments have not met the rigorous conditions that the behavioural work has shown are necessary for inferring implicit perception. Here, we review the literature of both behavioural and neuroimaging studies, and note the pitfalls of studying implicit perception as well as the promise that neuroimaging studies have for providing insights about implicit perception when combined with appropriately rigorous behavioural measures of awareness.

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Figure 1: The regression approach.
Figure 2: Visible words and masked words.
Figure 3: Lateralized readiness potential to masked words.
Figure 4: Subcortical visual pathway.
Figure 5: Masking face stimuli.

References

  1. Reingold, E. M. & Merikle, P. M. Using direct and indirect measures to study perception without awareness. Percept. Psychophys. 44, 563–575 (1988).

    CAS  PubMed  Google Scholar 

  2. Reingold, E. M. & Merikle, P. M. On the inter-relatedness of theory and measurement in the study of unconscious processes. Mind Lang. 5, 9–28 (1990).

    Google Scholar 

  3. Erdelyi, M. H. Subliminal perception and its cognates: theory, indeterminacy, and time. Conscious. Cogn. 13, 73–91 (2004).

    PubMed  Google Scholar 

  4. Bachmann, T. Inaptitude of the signal detection theory, useful vexation from the microgenetic view, and inevitability of neurobiological signatures in understanding perceptual (un)awareness. Conscious. Cogn. 13, 101–106 (2004).

    PubMed  Google Scholar 

  5. Bornstein, R. F. Subliminality, consciousness, and temporal shifts in awareness: implications within and beyond the laboratory. Conscious. Cogn. 13, 613–618 (2004).

    PubMed  Google Scholar 

  6. Erdelyi, M. H. Comments on commentaries: Kihlstrom, Bachmann, Reingold, and Snodgrass. Conscious. Cogn. 13, 430–433 (2004).

    PubMed  Google Scholar 

  7. Kihlstrom, J. F. Availability, accessibility, and subliminal perception. Conscious. Cogn. 13, 92–100 (2004).

    PubMed  Google Scholar 

  8. Reingold, E. M. Unconscious perception: assumptions and interpretive difficulties. Conscious. Cogn. 13, 117–122 (2004).

    PubMed  Google Scholar 

  9. Snodgrass, M. The dissociation paradigm and its discontents: how can unconscious perception or memory be inferred? Conscious. Cogn. 13, 107–116 (2004).

    PubMed  Google Scholar 

  10. Snodgrass, M., Bernat, E. & Shevrin, H. Unconscious perception: a model-based approach to method and evidence. Percept. Psychophys. 66, 846–867 (2004).

    PubMed  Google Scholar 

  11. Haase, S. J. & Fiske, G. D. Valid distinctions between conscious and unconscious perception. Percept. Psychophys. 66, 868–871 (2004).

    PubMed  Google Scholar 

  12. Holender, D. & Duscherer, K. Unconscious perception: the need for a paradigm shift. Percept. Psychophys. 66, 872–881 (2004).

    PubMed  Google Scholar 

  13. Reingold, E. M. Unconscious perception and the classic dissociation paradigm: a new angle? Percept. Psychophys. 66, 882–887 (2004).

    PubMed  Google Scholar 

  14. Snodgrass, M., Bernat, E. & Shevrin, H. Unconscious perception: a model-based approach to method and evidence. Percept. Psychophys. 66, 846–867 (2004).

    PubMed  Google Scholar 

  15. Holdender, D. Semantic activation without conscious identification in dichotic listening, parafoveal vision, and visual masking: a survey and appraisal. Behav. Brain Sci. 9, 1–66 (1986).

    Google Scholar 

  16. Poppel, E., Held, R. & Frost, D. Residual visual function after brain wounds involving the central visual pathways in man. Nature 243, 295–296 (1973).

    CAS  PubMed  Google Scholar 

  17. Weiskrantz, L., Warrington, E. K., Sanders, M. D. & Marshall, J. Visual capacity in the hemianopic field following a restricted occipital ablation. Brain 97, 709–728 (1972).

    Google Scholar 

  18. Blythe, I. M., Kennard, C. & Ruddock, K. H. Residual vision in patients with retrogeniculate lesions of the visual pathways. Brain 110, 887–905 (1987).

    PubMed  Google Scholar 

  19. Eriksen, C. W. in Nebraska Symposium on Motivation Vol. 6 (ed. Jones, M. R.) 169–227 (Univ. Nebraska Press, Lincoln, Nebraska, 1958).

    Google Scholar 

  20. Eriksen, C. W. Discrimination and learning without awareness: a methodological survey and evaluation. Psychol. Rev. 67, 279–300 (1960).

    CAS  PubMed  Google Scholar 

  21. Bjorkman, M., Juslin, P. & Winman, A. Realism of confidence in sensory discrimination: the underconfidence phenomenon. Percept. Psychophys. 54, 75–81 (1993).

    CAS  PubMed  Google Scholar 

  22. Tversky, A. & Kahneman, D. Judgment under uncertainty: heuristics and biases. Science 185, 1124–1131 (1974).

    CAS  PubMed  Google Scholar 

  23. Kunimoto, C. Miller, J. & Pashler, H. Confidence and accuracy of near-threshold discrimination responses. Conscious. Cogn. 10, 294–340 (2001).

    CAS  PubMed  Google Scholar 

  24. Azzopardi, P. & Cowey, A. Blindsight and visual awareness. Conscious. Cogn. 7, 292–311 (1998).

    CAS  PubMed  Google Scholar 

  25. Wolfe, J. M. in Fleeting Memories: Cognition of Brief Visual Stimuli (ed. Coltheart, V.) 71–94 (MIT Press, Cambridge, Massachusetts, 1999).

    Google Scholar 

  26. Macmillan, N. A. The psychophysics of subliminal perception. Behav. Brain Sci. 9, 38–39 (1986).

    Google Scholar 

  27. Snodgrass, M., Shevrin, H. & Kopka, M. The mediation of intentional judgments by unconscious perceptions: the influence of task strategy, task preference, word meaning, and motivation. Conscious. Cogn. 2, 169–193 (1993).

    Google Scholar 

  28. Draine, S. C. & Greenwald, A. G. Replicable unconscious semantic priming. J. Exp. Psychol. Gen. 127, 286–303 (1998).

    CAS  PubMed  Google Scholar 

  29. Greenwald, A. G., Klinger, M. R. & Schuh, E. S. Activation by marginally perceptible ('subliminal') stimuli: dissociation of unconscious from conscious cognition. J. Exp. Psychol. Gen. 124, 22–42 (1995).

    CAS  PubMed  Google Scholar 

  30. Klauer, K. C., Greenwald, A. G. & Draine, S. C. Correcting for measurement error in detecting unconscious cognition: comment on Draine & Greenwald. J. Exp. Psychol. Gen. 127, 318–319 (1998).

    CAS  PubMed  Google Scholar 

  31. Dosher, B. A. The response-window regression method — some problematic assumptions: comment on Draine and Greenwald (1998). J. Exp. Psychol. Gen. 127, 311–317 (1998).

    Google Scholar 

  32. Merikle, P. M. & Reingold, E. M. On demonstrating unconscious perception: comments on Draine and Greenwald. J. Exp. Psychol. Gen. 127, 304–310 (1998).

    CAS  PubMed  Google Scholar 

  33. Miller, J. Measurement error in subliminal perception experiments: simulation analyses of two regression methods. J. Exp. Psychol. Hum. Percept. Perform. 26, 1461–1477 (2000).

    CAS  PubMed  Google Scholar 

  34. Kunst-Wilson, W. R. & Zajonc, R. B. Affective discrimination of stimuli that cannot be recognized. Science 207, 557–558 (1980).

    CAS  PubMed  Google Scholar 

  35. Merikle, P. M. & Reingold, E. M. Comparing direct (explicit) and indirect (implicit) measures to study unconscious memory. J. Exp. Psychol. Learn. Mem. Cogn. 17, 224–233 (1991).

    Google Scholar 

  36. Whittlesea, B. & Price, J. Implicit/explicit memory versus analytic/nonanalytic processing: rethinking the mere exposure effect. Mem. Cogn. 29, 234–246 (2001).

    CAS  Google Scholar 

  37. Jacoby, L. L. A process dissociation framework: separating automatic and intentional uses of memory. J. Mem. Lang. 30, 513–541 (1991).

    Google Scholar 

  38. Debner, J. & Jacoby, L. L. Unconscious perception: attention, awareness and control. J. Exp. Psychol. Learn. Mem. Cogn. 20, 304–317 (1994).

    CAS  PubMed  Google Scholar 

  39. Visser, T. A. W. & Merikle, P. M. Conscious and unconscious processes: the effects of motivation. Conscious. Cogn. 8, 94–113 (1999).

    CAS  PubMed  Google Scholar 

  40. Baars, B. J. A Cognitive Theory of Consciousness (Cambridge Univ. Press, Cambridge, 1988).

    Google Scholar 

  41. Baars, B. J. The conscious access hypothesis: origins and recent evidence. Trends Cogn. Sci. 6, 47–52 (2002).

    PubMed  Google Scholar 

  42. Dehaene, S., Kerszberg, M. & Changeux, J. P. A neuronal model of a global workspace in effortful cognitive tasks. Proc. Natl Acad. Sci. USA 95, 14529–14534 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  43. Dehaene, S. & Naccache, L. Towards a cognitive neuroscience of consciousness: basic evidence and workspace framework. Cognition 79, 1–37 (2001).

    CAS  PubMed  Google Scholar 

  44. Dehaene, S. et al. Cerebral mechanisms of word masking and unconscious repetition priming. Nature Neurosci. 4, 752–758 (2001).

    CAS  PubMed  Google Scholar 

  45. Coles, M. G., Gratton, G. & Donchin, E. Detecting early communication: using measures of movement-related potentials to illuminate human information processing. Biol. Psychol. 26, 69–89 (1988).

    CAS  PubMed  Google Scholar 

  46. Dehaene, S. et al. Imaging unconscious semantic priming. Nature 395, 597–600 (1998).

    CAS  PubMed  Google Scholar 

  47. Eimer, M. & Schlaghecken, F. Response facilitation and inhibition in subliminal priming. Biol. Psychol. 64, 7–26 (2003).

    PubMed  Google Scholar 

  48. Naccache, L. & Dehaene, S. The priming method: imaging unconscious repetition priming reveals an abstract representation of number in the parietal lobes. Cereb. Cortex 11, 966–974 (2001).

    CAS  PubMed  Google Scholar 

  49. Dehaene, S. et al. Letter binding and invariant recognition of masked words. Psychol. Sci. 15, 307–313 (2004).

    CAS  PubMed  Google Scholar 

  50. Deacon, D., Hewitt, S., Yang, C. & Nagata, M. Event-related potential indices of semantic priming using masked and unmasked words: evidence that the N400 does not reflect a post-lexical process. Cogn. Brain Res. 9, 137–146 (2000).

    CAS  Google Scholar 

  51. Stenberg, G., Lindgren, M., Johansson, M., Olsson, A. & Rosen, I. Semantic processing without conscious identification: evidence from event-related potentials. J. Exp. Psychol. Learn. Mem. Cogn. 26, 973–1004 (2000).

    CAS  PubMed  Google Scholar 

  52. Kiefer, M. & Spitzer, M. Time course of conscious and unconscious semantic brain activation. Neuroreport 11, 2401–2407 (2000).

    CAS  PubMed  Google Scholar 

  53. Kiefer, M. The N400 is modulated by unconsciously perceived masked words: further evidence for an automatic spreading activation account of N400 priming effects. Cogn. Brain Res. 13, 27–39 (2002).

    Google Scholar 

  54. Kutas, M. & Hillyard, S. A. Reading senseless sentences: brain potentials reflect semantic incongruity. Science 207, 203–205 (1980).

    CAS  PubMed  Google Scholar 

  55. Brown, C. & Hagoort, P. The processing nature of the N400: evidence from masked priming. J. Cogn. Neurosci. 5, 34–44 (1993).

    CAS  PubMed  Google Scholar 

  56. Ruz, M., Madrid, E., Lupianez, J. & Tudela, P. High density ERP indices of conscious and unconscious semantic priming. Cogn. Brain Res. 17, 719–731 (2003).

    Google Scholar 

  57. LeDoux, J. The Emotional Brain: The Mysterious Underpinnings of Emotional Life (Simon & Schuster, New York, 1996).

    Google Scholar 

  58. Linke, R., De Lima, A. D., Schwegler, H. & Pape, H. C. Direct synaptic connections of axons from superior colliculus with identified thalamo-amygdaloid projection neurons in the rat: possible substrates of a subcortical visual pathway to the amygdala. J. Comp. Neurol. 403, 158–170 (1999).

    CAS  PubMed  Google Scholar 

  59. Whalen, P. J. et al. Masked presentations of emotional facial expressions modulate amygdala activity without explicit knowledge. J. Neurosci. 18, 411–418 (1998).

    CAS  PubMed  PubMed Central  Google Scholar 

  60. Morris, J. S., Ohman, A. & Dolan, R. J. Conscious and unconscious emotional learning in the human amygdala. Nature 393, 467–470 (1998).

    CAS  PubMed  Google Scholar 

  61. Nomura, M. et al. Functional association of the amygdala and ventral prefrontal cortex during cognitive evaluation of facial expressions primed by masked angry faces: an event-related fMRI study. Neuroimage 21, 352–363 (2004).

    PubMed  Google Scholar 

  62. Phillips, M. L. et al. Differential neural responses to overt and covert presentations of facial expressions of fear and disgust. Neuroimage 21, 1484–1496 (2004).

    PubMed  Google Scholar 

  63. Morris, J. S., Ohman, A. & Dolan, R. J. A subcortical pathway to the right amygdala mediating 'unseen' fear. Proc. Natl Acad. Sci. USA 96, 1680–1685 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  64. Morris, J. S., DeGelder, B., Weiskrantz, L. & Dolan, R. J. Differential extrageniculostriate and amygdala responses to presentation of emotional faces in a cortically blind field. Brain 124, 1241–1252 (2001).

    CAS  PubMed  Google Scholar 

  65. Vuilleumier, P. et al. Neural response to emotional faces with and without awareness: event-related fMRI in a parietal patient with visual extinction and spatial neglect. Neuropsychologia 40, 2156–2166 (2002).

    CAS  PubMed  Google Scholar 

  66. Driver, J. & Vuilleumier, P. Perceptual awareness and its loss in unilateral neglect and extinction. Cognition 79, 39–88 (2001).

    CAS  PubMed  Google Scholar 

  67. Pasley, B. N., Mayes, L. C. & Schultz, R. T. Subcortical discrimination of unperceived objects during binocular rivalry. Neuron 42, 163–172 (2004).

    CAS  PubMed  Google Scholar 

  68. Williams, L. M. et al. Mapping the time course of nonconscious and conscious perception of fear: an integration of central and peripheral measures. Hum. Brain Mapp. 21, 64–74 (2004).

    PubMed  Google Scholar 

  69. Liddell, B. J., Williams, L. M., Rathjen, J., Shevrin, H. & Gordon, E. A temporal dissociation of subliminal versus supraliminal fear perception: an event-related potential study. J. Cogn. Neurosci. 16, 479–486 (2004).

    PubMed  Google Scholar 

  70. Krolak-Salmon, P., Henaff, M. A., Vighetto, A., Bertrand, O. & Mauguiere, F. Early amygdala reaction to fear spreading in occipital, temporal, and frontal cortex: a depth electrode ERP study in human. Neuron 42, 665–676 (2004).

    CAS  PubMed  Google Scholar 

  71. Vuilleumier, P., Armony, J. L., Driver, J. & Dolan, R. J. Distinct spatial frequency sensitivities for processing faces and emotional expressions. Nature Neurosci. 6, 624–631 (2003).

    CAS  PubMed  Google Scholar 

  72. Pessoa, L., McKenna, M., Gutierrez, E. & Ungerleider, L. G. Neural processing of emotional faces requires attention. Proc. Natl Acad. Sci. USA 99, 11458–11463 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  73. Esteves, F. & Ohman, A. Masking the face: recognition of emotional facial expressions as a function of the parameters of backward masking. Scand. J. Psychol. 34, 1–18 (1993).

    CAS  PubMed  Google Scholar 

  74. Broadbent, D. E. Perception and Communication (Oxford Univ. Press, London, 1987).

    Google Scholar 

  75. Deutsch, J. A. & Deutsch, D. Attention: some theoretical considerations. Psychol. Rev. 70, 51–61 (1963).

    Google Scholar 

  76. Treisman, A. M. Strategies and models of selective attention. Psychol. Rev. 76, 282–299 (1969).

    CAS  PubMed  Google Scholar 

  77. Dulany, D. E. in Scientific Approaches to Consciousness (eds Cohen, J. D. & Schooler, J. W.) 179–212 (Carnegie Mellon Symposia on Cognition, Hillsdale, New Jersey 1997).

    Google Scholar 

  78. Di Lollo, V., Enns, J. T. & Rensink, R. A. Competition for consciousness among visual events: the psychophysics of reentrant visual processes. J. Exp. Psychol. Gen. 129, 481–507 (2000).

    CAS  PubMed  Google Scholar 

  79. Lamme, V. A. F., Zipser, K. & Spekreijse, H. Masking interrupts figure-ground signals in V1. J. Cogn. Neurosci. 14, 1044–1053 (2002).

    PubMed  Google Scholar 

  80. Rolls, E. T., Tovee, M. J. & Panzeri, S. The neurophysiology of backward visual masking: information analysis. J. Cogn. Neurosci. 11, 300–311 (1999).

    CAS  PubMed  Google Scholar 

  81. Macknik, S. L. & Livingstone, M. S. Neuronal correlates of visibility and invisibility in the primate visual system. Nature Neurosci. 1, 144–149 (1998).

    CAS  PubMed  Google Scholar 

  82. Marcel, A. J. Conscious and unconscious perception: an approach to the relations between phenomenal experience and perceptual processes. Cogn. Psychol. 15, 283–300 (1983).

    Google Scholar 

  83. Marcel, A. J. in Attention and Performance VIII (ed. Nickerson, R. S.) 435–457 (Erlbaum, Hillsdale, New Jersey, 1980).

    Google Scholar 

  84. Marcel, A. J. Conscious and unconscious perception: experiments on visual masking and word recognition. Cogn. Psychol. 15, 197–237 (1983).

    CAS  PubMed  Google Scholar 

  85. Merikle, P. M. & Reingold, E. M. in Perception Without Awareness: Cognitive, Clinical, and Social Perspectives (eds Bornstein, R. F. & Pittman, T. S.) 55–80 (Guilford, New York, 1992).

    Google Scholar 

  86. Stoerig, P. & Cowey, A. Blindsight in man and monkey. Brain 120, 535–559 (1997).

    PubMed  Google Scholar 

  87. Weiskrantz, L. Roots of blindsight. Prog. Brain Res. 144, 229–241 (2004).

    CAS  PubMed  Google Scholar 

  88. Wiens, S. et al. Keeping it short: a comparison of methods for brief picture presentation. Psychol. Sci. 15, 282–285 (2004).

    PubMed  Google Scholar 

  89. Abrams, R. L. & Greenwald, A. G. Parts outweigh the whole (word) in unconscious analysis of meaning. Psychol. Sci. 11, 118–124 (2000).

    CAS  PubMed  Google Scholar 

  90. Gazaniga, M. S., Ivry, R. B. & Mangun, G. R. Cognitive Neuroscience: the Biology of the Mind 2nd Edn (W. W. Norton & Company, New York, 2002).

    Google Scholar 

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Hannula, D., Simons, D. & Cohen, N. Imaging implicit perception: promise and pitfalls. Nat Rev Neurosci 6, 247–255 (2005). https://doi.org/10.1038/nrn1630

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