title: Sensitivity to first- and second-order drifting gratings in 3-month-old infants.
abstract: In two experiments, we investigated 3-month-old infants' sensitivity to first- and second-order drifting gratings. In Experiment 1 we used forced-choice preferential looking with drifting versus stationary gratings to estimate depth modulation thresholds for 3-month-old infants and a similar task for a comparison group of adults. Thresholds for infants were more adult-like for second-order than first-order gratings. In Experiment 2, 3-month-olds dishabituated to a change in first-order orientation, but not to a change in direction of first- or second-order motion. Hence, results from Experiment 1 were likely driven by the perception of flicker rather than motion. Thus, infants' sensitivity to uniform motion is slow to develop and appears to be driven initially by flicker-sensitive mechanisms. The underlying mechanisms have more mature tuning for second-order than for first-order information.
authors.affiliation: Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, ON, Canada, L8S 4K1; e-mail:  vickiearmstrong@gmail.com.
authors.forename: Vickie
authors.initials: V
authors.lastname: Armstrong
authors.forename: Daphne
authors.initials: D
authors.lastname: Maurer
authors.forename: Dave
authors.initials: D
authors.lastname: Ellemberg
authors.forename: Terri L
authors.initials: TL
authors.lastname: Lewis
keywords: Development; first-order; flicker; infants; motion; second-order