Infants code the direction of chromatic quadrature motion.
The present experiment uses a quadrature motion paradigm to investigate the motion correspondence cues used by young infants for coding the direction of motion of red/green isoluminant gratings. Three-month-old infants and adults were tested with 0.25 c/d luminance-modulated or red/green isoluminant gratings, either moving continuously or shifted in spatial quadrature. Both direction-of-motion and detection thresholds were measured, and motion:detection (M:D) threshold ratios were examined. Infants, like adults, could code the direction of motion of red/green quadrature-shifted gratings. In adults, M:D ratios were similar for continuous and quadrature motion. In infants, M:D ratios were higher for quadrature than for continuous motion, but elevations of similar magnitude were seen for both luminance-modulated and red/green gratings. The results suggest that frequency-doubled signals, such as those often seen in the magnocellular (M-cell) pathway, are not necessary for coding the direction of motion of isoluminant gratings in infant subjects. Two other theoretical options--mediation by the scatter of isoluminance points in the M-cell population, and parvocellular (P-cell) mediation--are discussed.
Lia
B
B
Department of Psychology, University of Washington, Seattle, USA.
Dobkins
K R
KR
Palmer
J
J
Teller
D Y
DY
D000328:Adult; D003118:Color Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology