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Titolo:
CONTRAST RESPONSE OF A MOVEMENT-ENCODING SYSTEM
Autore:
ALLIK J; PULVER A;
Indirizzi:
UNIV TARTU,DEPT PSYCHOL,TIIGI 78 TARTU 2400 EE ESTONIA
Titolo Testata:
Journal of the Optical Society of America. A, Optics, image science,and vision.
fascicolo: 6, volume: 12, anno: 1995,
pagine: 1185 - 1197
SICI:
1084-7529(1995)12:6<1185:CROAMS>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
RANDOM-DOT PATTERNS; MOTION PERCEPTION; APPARENT MOTION; PSYCHOPHYSICAL EVIDENCE; MACAQUE MONKEY; AREA MT; DIRECTION; DISCRIMINATION; MODEL; ADAPTATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
65
Recensione:
Indirizzi per estratti:
Citazione:
J. Allik e A. Pulver, "CONTRAST RESPONSE OF A MOVEMENT-ENCODING SYSTEM", Journal of the Optical Society of America. A, Optics, image science,and vision., 12(6), 1995, pp. 1185-1197

Abstract

The ability to identify the direction of apparent motion in a sequence of two short light pulses of different amplitudes at separate spatial locations was studied. The product of pulse amplitudes is a very poor predictor of such performance when one of the two signals is much higher in amplitude than the other: above a certain amplitude the probability of correct identification becomes virtually independent of the amplitude of the larger pulse. There was no noticeable difference in performance between low-high and high-low contrast sequences. Both the direction identification and the simple contrast-detection probabilities can be represented by the same psychometric function of the luminance increment Delta L, provided that Delta L is normalized by the nth power of the background luminance level, L(b). These results suggest that the general Reichardt-type scheme of movement encoding should be modified in the manner proposed for the fly's visual system [5. Opt. Sec,Am. A 6, 116 (1989)]: (1) the mean luminance is subtracted from the input signal before the signal is subjected to a nonlinear compression and (2) saturation characteristics are inserted into both branches of the two mirror-symmetric motion-detection subunits before multiplication of the input signals. The identical metric of the contrast responsesuggests that movement discrimination and luminance detection are twodifferent special-purpose computations performed on the output of thesame encoding network.

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Documento generato il 26/09/20 alle ore 03:42:51