The truth-telling motor cortex: Response competition in M1 discloses deceptive behaviour

Aviad A. Hadar, Stergios Makris, Kielan Yarrow

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Neural circuits associated with response conflict are active during deception. Here we use transcranial magnetic stimulation to examine for the first time whether competing responses in primary motor cortex can be used to detect lies. Participants used their little finger or thumb to respond either truthfully or deceitfully regarding facial familiarity. Motor-evoked-potentials (MEPs) from muscles associated with both digits tracked the development of each motor plan. When preparing to deceive, the MEP of the non-responding digit (i.e. the plan corresponding to the truth) exceeds the MEP of the responding digit (i.e. the lie), whereas a mirror-reversed pattern occurs when telling the truth. This give away response conflict interacts with the time of stimulation during a speeded reaction period. Lies can even activate digit-specific cortical representations when only verbal responses are made. Our findings support neurobiological models which blend cognitive decision-making with motor programming, and suggest a novel index for discriminating between honest and intentionally false facial recognition.

Original languageEnglish
Pages (from-to)495-502
Number of pages8
JournalBiological Psychology
Issue number2
StatePublished - 1 Feb 2012
Externally publishedYes


  • Deception
  • Lie detection
  • Motor evoked potential (MEP)
  • Response competition
  • Response inhibition
  • Response selection
  • Transcranial magnetic stimulation (TMS)

ASJC Scopus subject areas

  • Neuroscience (all)
  • Neuropsychology and Physiological Psychology


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