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S.E. Suter, J.S. Hillman, P.S. Suter, V.J. Everett; Holy Cow! VEPs to a Difficult to Organize Stimulus . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4121.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Do steady-state [SS] and transient VEPs yield complementary information about organization of elements in object perception? VEPs were obtained to the Potishman-Dallenbach-Renshaw image when the cow was not and then was perceived. Methods: The high contrast 8-deg image was contrast reversed at 6.4, 7.1, and 8.0 Hz and presented as a 750-ms appearance-disappearance stimulus. Both upright and inverted images were presented prior to and after instructions pointing out the cow. All observers reported here (n = 22) did not perceive the cow prior to the instruction and perceived it thereafter. VEPs were recorded from Oz, O2, and O2b (midway to T6) referenced to left ear. SS 2nd harmonic amplitude and phase and transient P1, N2, P2, and N3 amplitude and implicit time were scored. Results: Differences are p < .05. SS VEP amplitudes diminished moving away from Oz. Neither P1 amplitude nor implicit time differed across recording sites. Amplitude of the P1-N2 and N2-P2 complexes increased and the P1-N2 duration lengthened away from Oz, suggesting emergence of an N2 component. The cow percept was associated with greater SS amplitude at O2b for the lowest presentation frequency and with greater transient P2-N3 amplitude at Oz. Conclusions: Transient and SS VEPs yield complementary information about organization of elements into a perceived object.
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