Skip to main content
NCBI home page
Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1992 Dec 1;89(23):11113–11117. doi: 10.1073/pnas.89.23.11113

Implicit knowledge: new perspectives on unconscious processes.

D L Schacter 1
PMCID: PMC50499  PMID: 1454787

Abstract

Recent evidence from cognitive science and neuroscience indicates that brain-damaged patients and normal subjects can exhibit nonconscious or implicit knowledge of stimuli that they fail to recollect consciously or perceive explicitly. Dissociations between implicit and explicit knowledge, which have been observed across a variety of domains, tasks, and materials, raise fundamental questions about the nature of perception, memory, and consciousness. This article provides a selective review of relevant evidence and considers such phenomena as priming and implicit memory in amnesic patients and normal subjects, perception without awareness and "blindsight" in patients with damage to visual cortex, and nonconscious recognition of familiar faces in patients with facial-recognition deficits (prosopagnosia). A variety of theoretical approaches to implicit/explicit dissociations are considered. One view is that all of the various dissociations can be attributed to disruption or disconnection of a common mechanism underlying conscious experience; an alternative possibility is that each dissociation requires a separate explanation in terms of domain-specific processes and systems. More generally, it is concluded that rather than reflecting the operation of affectively charged unconscious processes of the kind invoked by psychodynamic or Freudian theorists, dissociations between implicit and explicit knowledge are a natural consequence of the ordinary computations of the brain.

Full text

PDF
11113

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bauer R. M. Autonomic recognition of names and faces in prosopagnosia: a neuropsychological application of the Guilty Knowledge Test. Neuropsychologia. 1984;22(4):457–469. doi: 10.1016/0028-3932(84)90040-x. [DOI] [PubMed] [Google Scholar]
  2. Cave C. B., Squire L. R. Intact and long-lasting repetition priming in amnesia. J Exp Psychol Learn Mem Cogn. 1992 May;18(3):509–520. doi: 10.1037//0278-7393.18.3.509. [DOI] [PubMed] [Google Scholar]
  3. Cermak L. S., Blackford S. P., O'Connor M., Bleich R. P. The implicit memory ability of a patient with amnesia due to encephalitis. Brain Cogn. 1988 Apr;7(2):145–156. doi: 10.1016/0278-2626(88)90026-7. [DOI] [PubMed] [Google Scholar]
  4. Cermak L. S., Talbot N., Chandler K., Wolbarst L. R. The perceptual priming phenomenon in amnesia. Neuropsychologia. 1985;23(5):615–622. doi: 10.1016/0028-3932(85)90063-6. [DOI] [PubMed] [Google Scholar]
  5. Cheesman J., Merikle P. M. Distinguishing conscious from unconscious perceptual processes. Can J Psychol. 1986 Dec;40(4):343–367. doi: 10.1037/h0080103. [DOI] [PubMed] [Google Scholar]
  6. Cohen N. J., Squire L. R. Preserved learning and retention of pattern-analyzing skill in amnesia: dissociation of knowing how and knowing that. Science. 1980 Oct 10;210(4466):207–210. doi: 10.1126/science.7414331. [DOI] [PubMed] [Google Scholar]
  7. Daum I., Channon S., Canavan A. G. Classical conditioning in patients with severe memory problems. J Neurol Neurosurg Psychiatry. 1989 Jan;52(1):47–51. doi: 10.1136/jnnp.52.1.47. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Gabrieli J. D., Milberg W., Keane M. M., Corkin S. Intact priming of patterns despite impaired memory. Neuropsychologia. 1990;28(5):417–427. doi: 10.1016/0028-3932(90)90069-z. [DOI] [PubMed] [Google Scholar]
  9. Glisky E. L., Schacter D. L. Extending the limits of complex learning in organic amnesia: computer training in a vocational domain. Neuropsychologia. 1989;27(1):107–120. doi: 10.1016/0028-3932(89)90093-6. [DOI] [PubMed] [Google Scholar]
  10. Glisky E. L., Schacter D. L. Long-term retention of computer learning by patients with memory disorders. Neuropsychologia. 1988;26(1):173–178. doi: 10.1016/0028-3932(88)90041-3. [DOI] [PubMed] [Google Scholar]
  11. Goodale M. A., Milner A. D., Jakobson L. S., Carey D. P. A neurological dissociation between perceiving objects and grasping them. Nature. 1991 Jan 10;349(6305):154–156. doi: 10.1038/349154a0. [DOI] [PubMed] [Google Scholar]
  12. Graf P., Mandler G., Haden P. E. Simulating amnesic symptoms in normal subjects. Science. 1982 Dec 17;218(4578):1243–1244. doi: 10.1126/science.7146909. [DOI] [PubMed] [Google Scholar]
  13. Graf P., Squire L. R., Mandler G. The information that amnesic patients do not forget. J Exp Psychol Learn Mem Cogn. 1984 Jan;10(1):164–178. doi: 10.1037//0278-7393.10.1.164. [DOI] [PubMed] [Google Scholar]
  14. Greenwald A. G. New look 3. Unconscious cognition reclaimed. Am Psychol. 1992 Jun;47(6):766–779. doi: 10.1037/0003-066x.47.6.766. [DOI] [PubMed] [Google Scholar]
  15. Jacoby L. L., Dallas M. On the relationship between autobiographical memory and perceptual learning. J Exp Psychol Gen. 1981 Sep;110(3):306–340. doi: 10.1037//0096-3445.110.3.306. [DOI] [PubMed] [Google Scholar]
  16. Kihlstrom J. F. The cognitive unconscious. Science. 1987 Sep 18;237(4821):1445–1452. doi: 10.1126/science.3629249. [DOI] [PubMed] [Google Scholar]
  17. Lewicki P., Hill T., Czyzewska M. Nonconscious acquisition of information. Am Psychol. 1992 Jun;47(6):796–801. doi: 10.1037//0003-066x.47.6.796. [DOI] [PubMed] [Google Scholar]
  18. Marcel A. J. Conscious and unconscious perception: experiments on visual masking and word recognition. Cogn Psychol. 1983 Apr;15(2):197–237. doi: 10.1016/0010-0285(83)90009-9. [DOI] [PubMed] [Google Scholar]
  19. Marsolek C. J., Kosslyn S. M., Squire L. R. Form-specific visual priming in the right cerebral hemisphere. J Exp Psychol Learn Mem Cogn. 1992 May;18(3):492–508. doi: 10.1037//0278-7393.18.3.492. [DOI] [PubMed] [Google Scholar]
  20. McAndrews M. P., Glisky E. L., Schacter D. L. When priming persists: long-lasting implicit memory for a single episode in amnesic patients. Neuropsychologia. 1987;25(3):497–506. doi: 10.1016/0028-3932(87)90074-1. [DOI] [PubMed] [Google Scholar]
  21. Merikle P. M. Perception without awareness. Critical issues. Am Psychol. 1992 Jun;47(6):792–795. doi: 10.1037//0003-066x.47.6.792. [DOI] [PubMed] [Google Scholar]
  22. Milberg W., Blumstein S. E. Lexical decision and aphasia: evidence for semantic processing. Brain Lang. 1981 Nov;14(2):371–385. doi: 10.1016/0093-934x(81)90086-9. [DOI] [PubMed] [Google Scholar]
  23. Musen G., Squire L. R. Nonverbal priming in amnesia. Mem Cognit. 1992 Jul;20(4):441–448. doi: 10.3758/bf03210928. [DOI] [PubMed] [Google Scholar]
  24. Perenin M. T., Jeannerod M. Visual function within the hemianopic field following early cerebral hemidecortication in man--I. Spatial localization. Neuropsychologia. 1978;16(1):1–13. doi: 10.1016/0028-3932(78)90037-4. [DOI] [PubMed] [Google Scholar]
  25. Roediger H. L., 3rd, Blaxton T. A. Effects of varying modality, surface features, and retention interval on priming in word-fragment completion. Mem Cognit. 1987 Sep;15(5):379–388. doi: 10.3758/bf03197728. [DOI] [PubMed] [Google Scholar]
  26. Roediger H. L., 3rd Implicit memory. Retention without remembering. Am Psychol. 1990 Sep;45(9):1043–1056. doi: 10.1037//0003-066x.45.9.1043. [DOI] [PubMed] [Google Scholar]
  27. Saint-Cyr J. A., Taylor A. E., Lang A. E. Procedural learning and neostriatal dysfunction in man. Brain. 1988 Aug;111(Pt 4):941–959. doi: 10.1093/brain/111.4.941. [DOI] [PubMed] [Google Scholar]
  28. Schacter D. L., Church B. A. Auditory priming: implicit and explicit memory for words and voices. J Exp Psychol Learn Mem Cogn. 1992 Sep;18(5):915–930. doi: 10.1037//0278-7393.18.5.915. [DOI] [PubMed] [Google Scholar]
  29. Schacter D. L. Perceptual representation systems and implicit memory. Toward a resolution of the multiple memory systems debate. Ann N Y Acad Sci. 1990;608:543–571. doi: 10.1111/j.1749-6632.1990.tb48909.x. [DOI] [PubMed] [Google Scholar]
  30. Schacter D. L. Priming of old and new knowledge in amnesic patients and normal subjects. Ann N Y Acad Sci. 1985;444:41–53. doi: 10.1111/j.1749-6632.1985.tb37578.x. [DOI] [PubMed] [Google Scholar]
  31. Schacter D. L. Understanding implicit memory. A cognitive neuroscience approach. Am Psychol. 1992 Apr;47(4):559–569. doi: 10.1037//0003-066x.47.4.559. [DOI] [PubMed] [Google Scholar]
  32. Shimamura A. P. Priming effects of amnesia: evidence for a dissociable memory function. Q J Exp Psychol A. 1986 Nov;38(4):619–644. doi: 10.1080/14640748608401617. [DOI] [PubMed] [Google Scholar]
  33. Shimamura A. P., Squire L. R. Paired-associate learning and priming effects in amnesia: a neuropsychological study. J Exp Psychol Gen. 1984 Dec;113(4):556–570. doi: 10.1037//0096-3445.113.4.556. [DOI] [PubMed] [Google Scholar]
  34. Squire L. R. Memory and the hippocampus: a synthesis from findings with rats, monkeys, and humans. Psychol Rev. 1992 Apr;99(2):195–231. doi: 10.1037/0033-295x.99.2.195. [DOI] [PubMed] [Google Scholar]
  35. Squire L. R., Ojemann J. G., Miezin F. M., Petersen S. E., Videen T. O., Raichle M. E. Activation of the hippocampus in normal humans: a functional anatomical study of memory. Proc Natl Acad Sci U S A. 1992 Mar 1;89(5):1837–1841. doi: 10.1073/pnas.89.5.1837. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Torjussen T. Visual processing in cortically blind hemifields. Neuropsychologia. 1978;16(1):15–21. doi: 10.1016/0028-3932(78)90038-6. [DOI] [PubMed] [Google Scholar]
  37. Tranel D., Damasio A. R. Knowledge without awareness: an autonomic index of facial recognition by prosopagnosics. Science. 1985 Jun 21;228(4706):1453–1454. doi: 10.1126/science.4012303. [DOI] [PubMed] [Google Scholar]
  38. Tulving E., Hayman C. A., Macdonald C. A. Long-lasting perceptual priming and semantic learning in amnesia: a case experiment. J Exp Psychol Learn Mem Cogn. 1991 Jul;17(4):595–617. doi: 10.1037//0278-7393.17.4.595. [DOI] [PubMed] [Google Scholar]
  39. Tulving E., Schacter D. L. Priming and human memory systems. Science. 1990 Jan 19;247(4940):301–306. doi: 10.1126/science.2296719. [DOI] [PubMed] [Google Scholar]
  40. Warrington E. K., Weiskrantz L. The effect of prior learning on subsequent retention in amnesic patients. Neuropsychologia. 1974 Oct;12(4):419–428. doi: 10.1016/0028-3932(74)90072-4. [DOI] [PubMed] [Google Scholar]
  41. Weiskrantz L. Varieties of residual experience. Q J Exp Psychol. 1980 Aug;32(3):365–386. doi: 10.1080/14640748008401832. [DOI] [PubMed] [Google Scholar]
  42. Weiskrantz L., Warrington E. K. Conditioning in amnesic patients. Neuropsychologia. 1979;17(2):187–194. doi: 10.1016/0028-3932(79)90009-5. [DOI] [PubMed] [Google Scholar]
  43. Weiskrantz L., Warrington E. K., Sanders M. D., Marshall J. Visual capacity in the hemianopic field following a restricted occipital ablation. Brain. 1974 Dec;97(4):709–728. doi: 10.1093/brain/97.1.709. [DOI] [PubMed] [Google Scholar]
  44. Zihl J. "Blindsight": improvement of visually guided eye movements by systematic practice in patients with cerebral blindness. Neuropsychologia. 1980;18(1):71–77. doi: 10.1016/0028-3932(80)90085-8. [DOI] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES