title: Is judging time-to-contact based on 'tau'?
abstract: An investigation was undertaken into whether judgments of time-to-contact between a laterally moving object and a bar are based on the direct perception of an optical variable (tau), or on the ratio between the perceived distance and perceived velocity of the object. A moving background was used to induce changes in the perceived velocities without changing the optical variables that specify time-to-contact. Background motion induced large systematic errors in the estimated time-to-contact. It is concluded that the judgment of time-to-contact is primarily based on the ratio between the perceived distance and the perceived velocity, and not on tau.
authors.affiliation: Vakgroep Fysiologie, Erasmus Universiteit Rotterdam, The Netherlands. smeets@fys1.fgg.eur.nl
authors.forename: J B
authors.initials: JB
authors.lastname: Smeets
authors.forename: E
authors.initials: E
authors.lastname: Brenner
authors.forename: S
authors.initials: S
authors.lastname: Trébuchet
authors.forename: D R
authors.initials: DR
authors.lastname: Mestre
mesh_terms: D000054:Acceleration; D001288:Attention; D004215:Distance Perception; D005364:Field Dependence-Independence; D006801:Humans; D007600:Judgment; D009039:Motion Perception; D009949:Orientation; D010364:Pattern Recognition, Visual; D011601:Psychophysics; D013998:Time Perception