Decision ambiguity is mediated by a late positive potential originating from cingulate cortex

Sai Sun, Shanshan Zhen, Zhongzheng Fu, Daw An Wu, Shinsuke Shimojo, Ralph Adolphs, Rongjun Yu, Shuo Wang

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


People often make decisions in the face of ambiguous information, but it remains unclear how ambiguity is represented in the brain. We used three types of ambiguous stimuli and combined EEG and fMRI to examine the neural representation of perceptual decisions under ambiguity. We identified a late positive potential, the LPP, which differentiated levels of ambiguity, and which was specifically associated with behavioral judgments about choices that were ambiguous, rather than passive perception of ambiguous stimuli. Mediation analyses together with two further control experiments confirmed that the LPP was generated only when decisions are made (not during mere perception of ambiguous stimuli), and only when those decisions involved choices on a dimension that is ambiguous. A further control experiment showed that a stronger LPP arose in the presence of ambiguous stimuli compared to when only unambiguous stimuli were present. Source modeling suggested that the LPP originated from multiple loci in cingulate cortex, a finding we further confirmed using fMRI and fMRI-guided ERP source prediction. Taken together, our findings argue for a role of an LPP originating from cingulate cortex in encoding decisions based on task-relevant perceptual ambiguity, a process that may in turn influence confidence judgment, response conflict, and error correction.

Original languageEnglish
Pages (from-to)400-414
Number of pages15
StatePublished - Aug 15 2017


  • Cingulate cortex
  • Decision
  • Face
  • Late positive potential
  • Perceptual ambiguity


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