title: Timing and awareness of movement decisions: does consciousness really come too late?
abstract: Since Libet's seminal observation that a brain potential related to movement preparation occurs before participants report to be aware of their movement intention, it has been debated whether consciousness has causal influence on movement decisions. Here we review recent advances that provide new insights into the dynamics of human decision-making and question the validity of different markers used for determining the onset of neural and conscious events. Motor decisions involve multiple stages of goal evaluation, intention formation, and action execution. While the validity of the Bereitschaftspotential (BP) as index of neural movement preparation is controversial, improved neural markers are able to predict decision outcome even at early stages. Participants report being conscious of their decisions only at the time of final intention formation, just before the primary motor cortex starts executing the chosen action. However, accumulating evidence suggests that this is an artifact of Libet's clock method used for assessing consciousness. More refined methods suggest that intention consciousness does not appear instantaneously but builds up progressively. In this view, early neural markers of decision outcome are not unconscious but simply reflect conscious goal evaluation stages which are not final yet and therefore not reported with the clock method. Alternatives to the Libet clock are discussed that might allow for assessment of consciousness during decision making with improved sensitivity to early decision stages and with less influence from meta-conscious and perceptual inferences.
authors: Division of Neurorehabilitation, Department of Clinical Neurosciences, University Hospital of Geneva Geneva, Switzerland.
authors: Adrian G
authors: AG
authors: Guggisberg
authors: Anaïs
authors: A
authors: Mottaz
keywords: Libet; decision-making; free will; introspection; volition
references: Neuroimage. 2012 Oct 15;63(1):392-402
references: 22776456
references: Proc Natl Acad Sci U S A. 2012 Oct 16;109(42):E2904-13
references: 22869750
references: Clin Neurophysiol. 2006 Nov;117(11):2341-56
references: 16876476
references: Mov Disord. 2000 Nov;15(6):1173-83
references: 11104202
references: Brain. 1998 Aug;121 ( Pt 8):1513-31
references: 9712013
references: Nat Neurosci. 2008 May;11(5):543-5
references: 18408715
references: Psychol Bull. 2011 Mar;137(2):316-44
references: 21090887
references: Nat Neurosci. 2004 Jan;7(1):80-4
references: 14647290
references: Cortex. 2011 Nov-Dec;47(10):1160-5
references: 21752362
references: Science. 2000 Mar 17;287(5460):2036-8
references: 10720334
references: Neuroimage. 2013 Jan 15;65:456-65
references: 23041528
references: Exp Brain Res. 1995;103(3):429-39
references: 7789449
references: Psychol Sci. 2008 Nov;19(11):1110-7
references: 19076482
references: Exp Brain Res. 2006 Sep;173(4):637-49
references: 16544136
references: J Neurophysiol. 1996 Jan;75(1):233-47
references: 8822554
references: Brain. 2000 Jun;123 ( Pt 6):1216-28
references: 10825359
references: Front Hum Neurosci. 2011 Oct 21;5:120
references: 22025912
references: Electroencephalogr Clin Neurophysiol. 1985 May;62(3):209-18
references: 2581761
references: Biol Psychol. 1988 Jun;26(1-3):165-78
references: 3061478
references: Conscious Cogn. 2008 Sep;17(3):616-27
references: 17983768
references: Electroencephalogr Clin Neurophysiol. 1982 Sep;54(3):322-35
references: 6179759
references: Science. 2009 May 8;324(5928):811-3
references: 19423830
references: Neuroscientist. 2008 Aug;14(4):319-25
references: 18660462
references: Front Hum Neurosci. 2008 Mar 28;1:14
references: 18958227
references: Proc Biol Sci. 1997 Oct 22;264(1387):1407-14
references: 9364780
references: Science. 2005 Aug 5;309(5736):948-51
references: 16081740
references: Psychol Sci. 2011 May;22(5):613-8
references: 21515737
references: Electroencephalogr Clin Neurophysiol. 1993 Mar;86(3):176-82
references: 7680993
references: J Neurol Neurosurg Psychiatry. 1996 Jul;61(1):103-6
references: 8676135
references: J Neurophysiol. 2008 Mar;99(3):1461-76
references: 18160425
references: Psychol Sci. 2011 Jan;22(1):103-9
references: 21123855
references: Conscious Cogn. 2007 Jun;16(2):241-54
references: 17049882
references: Psychophysiology. 1989 May;26(3):251-69
references: 2667018
references: Exp Brain Res. 1998 May;120(2):263-72
references: 9629968
references: Electroencephalogr Clin Neurophysiol. 1980 Aug;49(3-4):213-26
references: 6158398
references: Neuroimage. 1999 Dec;10(6):682-94
references: 10600414
references: Psychol Sci. 2008 Jan;19(1):49-54
references: 18181791
references: Clin Neurophysiol. 1999 Jan;110(1):126-32
references: 10348331
references: Science. 2004 Feb 20;303(5661):1208-10
references: 14976320
references: Trends Cogn Sci. 2002 Aug 1;6(8):339-344
references: 12140084
references: Cognition. 2013 May;127(2):264-9
references: 23466640
references: Mov Disord. 1991;6(3):217-24
references: 1922126
references: Hum Neurobiol. 1984;3(4):235-40
references: 6526709
references: Neuroimage. 2008 May 1;40(4):1686-700
references: 18356081
references: Physiol Rev. 1990 Jan;70(1):1-41
references: 2404287
references: Prog Brain Res. 2006;159:275-95
references: 17071238
references: Exp Brain Res. 1999 May;126(1):128-33
references: 10333013
references: Pflugers Arch Gesamte Physiol Menschen Tiere. 1959;270:103-20
references: 13808181
references: Exp Brain Res. 2013 Sep;229(3):347-57
references: 23354661
references: Neuroimage. 2010 Mar;50(1):291-301
references: 20026224
references: Neuroimage. 2006 Feb 15;29(4):1294-302
references: 16246592
references: Brain. 1995 Aug;118 ( Pt 4):913-33
references: 7655888
references: J Neurophysiol. 1999 Jun;81(6):3065-77
references: 10368421
references: J Neurosci. 1991 Nov;11(11):3656-66
references: 1941101
references: Nat Rev Neurosci. 2012 May 18;13(6):407-20
references: 22595786
references: Conscious Cogn. 2011 Dec;20(4):1899-915
references: 21498087
references: Electroencephalogr Clin Neurophysiol. 1993 Apr;89(2):95-103
references: 7683607
references: Electroencephalogr Clin Neurophysiol. 1975 Nov;39(5):455-63
references: 52438
references: Pers Soc Psychol Bull. 2009 Feb;35(2):260-8
references: 19141628
references: Front Hum Neurosci. 2010 May 14;4:38
references: 20508746
references: Neuropsychologia. 2011 Apr;49(5):767-776
references: 21255591
references: Neuron. 2011 Feb 10;69(3):548-62
references: 21315264
references: Exp Brain Res. 2013 Sep;229(3):301-12
references: 23515626
references: J Neurophysiol. 2005 Dec;94(6):4269-80
references: 16093343
references: J Neurophysiol. 2003 Apr;89(4):2208-14
references: 12612037
references: Neuron. 2009 Oct 29;64(2):281-9
references: 19874794
references: Psychol Sci. 2009 Jan;20(1):17-21
references: 19152537
references: Electroencephalogr Clin Neurophysiol. 1990 Oct;76(4):351-61
references: 1699728
references: J Neurol Neurosurg Psychiatry. 1981 Aug;44(8):735-8
references: 6946193
references: Neuroimage. 2005 Oct 15;28(1):154-64
references: 16023374
references: J Neurosci. 2012 Sep 5;32(36):12488-98
references: 22956839
references: Trends Cogn Sci. 2006 Mar;10(3):108-16
references: 16469524
references: Eur J Neurosci. 2008 Dec;28(11):2344-51
references: 19046374
references: Neuron. 2006 Sep 7;51(5):651-9
references: 16950162
references: Front Hum Neurosci. 2011 Feb 28;5:21
references: 21427777
references: Front Neurosci. 2007 Oct 15;1(1):185-96
references: 18982128
references: Pflugers Arch Gesamte Physiol Menschen Tiere. 1965 May 10;284:1-17
references: 14341490
references: Nature. 2001 Jul 12;412(6843):150-7
references: 11449264
references: Nat Neurosci. 2002 Apr;5(4):382-5
references: 11896397
references: Conscious Cogn. 2010 Mar;19(1):447-56
references: 19736023
references: Front Neurosci. 2011 Mar 17;5:33
references: 21441998
references: Science. 2010 Jul 2;329(5987):47-50
references: 20595607
references: Nat Rev Neurosci. 2008 Dec;9(12):934-46
references: 19020512
references: Exp Brain Res. 1995;102(3):445-60
references: 7737391
references: Int J Psychophysiol. 2008 Feb;67(2):151-7
references: 18096261
references: Science. 2004 Jun 18;304(5678):1782-7
references: 15205529
references: Brain. 1983 Sep;106 (Pt 3):623-42
references: 6640273
references: Conscious Cogn. 2012 Sep;21(3):1482-90
references: 22579497
references: Prog Brain Res. 1980;54:3-15
references: 7220930
references: J Cogn Neurosci. 2007 Jan;19(1):81-90
references: 17214565