Neurophysiology of subjective confidence in a partial report paradigm

MARTÍN GRAZIANO; LUCAS PARRA; MARIANO SIGMAN

Huerta Grande, Córdoba

Congreso; IRCN Second Joint Meeting of the Argentine Society for Neurosciences (SAN) and the Argentine Workshop in Neurosciences (TAN); 2010

A vast ensemble of stimuli are continuously being processed in parallel by the sensory system, most of which elicit only a brief transient sensory response which fades after few hundreds of milliseconds without reaching working memory or consciousness. This sensory representation is referred as iconic memory. Previously we found a strong dissociation between the objective performance and the subjective confidence in the response in a partial report paradigm,, allowing the understanding of the brain dynamics in the construction of subjective confidence.Here we report a high-density EEG experiment in which we infer elements of the EEG response which are indicative of subjective confidence. We found that an early response during encoding partially correlates with perceived confidence. However, the bulk of the weight of subjective confidence is determined during a late, N400-like waveform, during the retrieval stage. A reconstruction of the cortical source locates the N400 waveform at the occipito-temporal cortex. This experiment shows that we can find markers of access to internal, subjective states, that are uncoupled from objective response and stimulus properties of the task, and we propose that this can be used with decoding methods of EEG to infer subjective mental states.