Perceptual ranking versus visual evoked potentials for different local features in texture segregation.
OBJECTIVE
To validate recent reports of specific visual evoked potentials associated with preattentive texture segregation (tsVEPs) and to quantitatively compare perceptual segregation strength and tsVEP amplitudes across different local features.


METHODS
Four local features were selected: crossed vs noncrossed, line segments differing in orientation by 90 degrees, U-shapes differing in orientation by 90 degrees, and U-shapes differing in orientation by 180 degrees. The two variants of each local feature were spatially arranged in a checkerboard pattern; for the first three features this led to pop-out of a "preattentive checkerboard." In seven subjects, perceptual segregation strength was assessed using ranking, and tsVEPs were recorded in these and three additional subjects.


RESULTS
Statistically significant tsVEPs were obtained for the features crossed vs noncrossed and 90 degrees-line segments. Ranking results and tsVEP amplitudes were highly correlated (P < 0.001); the order of perceptual ranking and the order of tsVEP amplitudes were identical; 180 degrees-U-shapes had lowest ranking, mean tsVEP amplitude was 0.1 microV, close to noise. Line segments had maximal ranking, tsVEP amplitude was 1.5 microV.


CONCLUSIONS
The results suggest that tsVEPs quantitatively reflect the activity of cortical mechanisms involved in texture segregation across various features.
Meigen
T
T
Elektrophysiologisches Labor, Universitäts-Augenklinik, Freiburg, Germany.
Bach
M
M
D000328:Adult; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005556:Form Perception / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D010775:Photic Stimulation; D011601:Psychophysics; D014793:Visual Cortex / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*