title: Conditions for young infants' perception of object trajectories.
abstract: When an object moves behind an occluder and re-emerges, 4-month-old infants perceive trajectory continuity only when the occluder is narrow, raising the question of whether time or distance out of sight is the important constraining variable. One hundred and forty 4-month-olds were tested in five experiments aimed to disambiguate time and distance out of sight. Manipulating the object's visible speed had no effect on infants' responses, but reducing occlusion time by increasing object speed while occluded induced perception of trajectory continuity. In contrast, slowing the ball while it was behind a narrow or intermediate screen did not modify performance. It is concluded that 4-month-olds perceive trajectory continuity when time or distance out of sight is short.
authors.affiliation: Psychology Department, Lancaster University, Lancaster LA1 4YF, UK. j.g.bremner@lancaster.ac.uk
authors.forename: J Gavin
authors.initials: JG
authors.lastname: Bremner
authors.forename: Scott P
authors.initials: SP
authors.lastname: Johnson
authors.forename: Alan
authors.initials: A
authors.lastname: Slater
authors.forename: Uschi
authors.initials: U
authors.lastname: Mason
authors.forename: Kirsty
authors.initials: K
authors.lastname: Foster
authors.forename: Andrea
authors.initials: A
authors.lastname: Cheshire
authors.forename: Joanne
authors.initials: J
authors.lastname: Spring
mesh_terms: D002657:Child Development; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009039:Motion Perception; D013028:Space Perception; D013998:Time Perception; D014796:Visual Perception