Comparison of sensitivity to first- and second-order local motion in 5-year-olds and adults.
We compared sensitivity to first- versus second-order motion in 5-year-olds and adults tested with stimuli moving at slower (1.5 degrees s(-1)) and faster (6 degrees s(-1)) velocities. Amplitude modulation thresholds were measured for the discrimination of the direction of motion (up vs. down) for luminance-modulated (first-order) and contrast-modulated (second-order) horizontal sine-wave gratings. At the slower velocity (1.5 degrees s(-1)), the differences in threshold between 5-year-olds and adults were small but significant for both first- and second-order stimuli (0.02 and 0.05 log units worse than adults' thresholds, respectively). However, at the faster velocity (6 degrees s(-1)), the differences in threshold between the children and adults were 8 times greater for second-order motion than for first-order motion. Specifically, children's thresholds were 0.16 log units worse than those of adults for second-order motion compared to only 0.02 log units worse for first-order motion. The different pattern of results for first-order and second-order motion at the faster velocity (6 degrees s(-1)) is consistent with models positing different mechanisms for the two types of motion and suggests that those mechanisms mature at different rates.
Ellemberg
Dave
D
Groupe de Recherche En Neuropsychologie Expérimentale, Université de Montréal, Montréal, Quebec, Canada. dave.ellemberg@staff.mcgill.ca
Lewis
Terri L
TL
Meghji
Karim S
KS
Maurer
Daphne
D
Guillemot
Jean-Paul
JP
Lepore
Franco
F
D000328:Adult; D002675:Child, Preschool; D015350:Contrast Sensitivity; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation / Q000379:methods; D012684:Sensory Thresholds / Q000502:physiology; D014792:Visual Acuity