Contradiction in universal and particular reasoning

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A wide range of essential reasoning tasks rely on contradiction identification, a cornerstone of human rationality, communication and debate founded on the inversion of the logical operators "Every" and "Some." A high-density electroencephalographic (EEG) study was performed in 11 normal young adults. The cerebral network involved in the identification of contradiction included the orbito-frontal and anterior-cingulate cortices and the temporo-polar cortices. The event-related dynamic of this network showed an early negative deflection lasting 500 ms after sentence presentation. This was followed by a positive deflection lasting 1.5 s, which was different for the two logical operators. A lesser degree of network activation (either in neuron number or their level of phase locking or both) occurred while processing statements with "Some," suggesting that this was a relatively simpler scenario with one example to be figured out, instead of the many examples or the absence of a counterexample searched for while processing statements with "Every." A self-generated reward system seemed to resonate the recruited circuitry when the contradictory task is successfully completed.


Original languageEnglish
Pages (from-to)4187-4197
Number of pages11
JournalHuman Brain Mapping
Issue number12
Early online date24 Jun 2009
Publication statusPublished - Dec 2009


  • adult, algorithms, brain, brain mapping, cognition, electroencephalography, female, humans, intelligence, male, neural pathways, reward, computer-assisted signal processing, contradictory reasoning, independent component analysis, logical operators


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