The Bernstein Center Freiburg

Informal Seminar
Jürgen Kornmeier

Institut for Frontier Areas of Psychology and Mental Health
Freiburg Univ.-Augenklinik, Freiburg

When our brain is impressed but we do not notice it – Evidence for an unconscious reliability estimation of the perceptual outcome
Monday, January 18, 2010
16:00 h sharp
Library, first floor
BCCN Building
Hansastr. 9a
Normally, we perceive the world as visually stable. However, a stable conscious percept has to be constructed out of limited and ambiguous information. In the case of ambiguous figures, our perceptual system creates only temporarily stable percepts that suddenly switch to alternative interpretations.
We investigated whether and how the ERP (“event related potential”) to ambiguous figures, evoking such instable percepts, differ from ERPs to unambiguous figure variants, evoking stable percepts.
Results: (1) Tiny figural changes, rendering an ambiguous figure unambiguous, cause a sizable positivity at about 400 ms after stimulus onset (“P400”).
(2) This P400 was found for two different categories of ambiguous figures (Necker cube and Old/Young woman). (3) This strong ERP difference was only found with attended stimuli.
Our results suggest the existence of an unconscious neural instance that evaluates the reliability of the perceptual outcome, given limited and ambiguous visual input. High reliability may have been evolutionary advantageous for action planning, low reliability may have been a trigger for invention and cognition.
The talk is open to the public. Guests are cordially invited!