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Post-decision wagering objectively measures awareness


The lack of an accepted measure of awareness has made claims that accurate decisions can be made without awareness controversial. Here we introduce a new objective measure of awareness, post-decision wagering. We show that participants fail to maximize cash earnings by wagering high following correct decisions in blindsight, the Iowa gambling task and an artificial grammar task. This demonstrates, without the uncertainties associated with the conventional subjective measures of awareness (verbal reports and confidence ratings), that the participants were not aware that their decisions were correct. Post-decision wagering may be used to study the neural correlates of consciousness.

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Figure 1: Performance and wagering in the modified Iowa gambling task.

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N.P. was supported by a Rhodes Scholarship and A.C. by the UK Medical Research Council.

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Authors and Affiliations



All three authors contributed to the execution of the experiments and the writing of this manuscript.

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Correspondence to Navindra Persaud.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Fig. 1

Wagering versus performance in aware and unaware conditions by GY. (PDF 77 kb)

Supplementary Fig. 2

Wagering versus performance in aware and unaware conditions in the artificial grammar task. (PDF 192 kb)

Supplementary Fig. 3

Wagering versus performance in the Iowa gambling task. (PDF 218 kb)

Supplementary Table 1

Localization task with subthreshold stimuli in the scotoma (right hemifield). (PDF 39 kb)

Supplementary Table 2

Pooled data for subthreshold stimuli presented in the scotoma (right hemifield) during yes-no and localization tasks. (PDF 52 kb)

Supplementary Table 3

Localization task with suprathreshold stimuli presented in the scotoma (right hemifield). (PDF 6 kb)

Supplementary Table 4

Localization task with suprathreshold stimuli presented in the normal (left) hemifield. (PDF 39 kb)

Supplementary Table 5

Localization task with a mix of suprathreshold and subthreshold stimuli presented in both hemifields. (PDF 40 kb)

Supplementary Table 6

d' values for blindsight and artificial grammar. (PDF 40 kb)

Supplementary Methods (PDF 169 kb)

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Persaud, N., McLeod, P. & Cowey, A. Post-decision wagering objectively measures awareness. Nat Neurosci 10, 257–261 (2007).

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