1a, when an observer maintains visual fixation on the traffic light while moving to the right, all of the stationary objects in the scene have an image velocity that is determined by their 3D location and the movement of the observer. Regarding depth perception from motion parallax, stationary objects at varying depths have different retinal image velocities during lateral self-translation. Moreover, the brain can estimate depth with greater precision by integrating disparity and motion parallax cues 9, 10, 11. Robust monocular depth perception can also be attained from motion parallax, the image motion induced by translational self-motion 6, 7, 8. Stereoscopic depth perception relies on slight differences between the retinal images projected onto the two eyes, known as binocular disparity 4, 5. The visual system has evolved multiple mechanisms to judge the depth of objects in a 3D scene 1, 2, 3. To make sense of the 3D structure of the visual scene, the brain must also accurately infer the depths of moving objects. Many situations, some critical to an animal’s survival such as hunting prey, require the brain to correctly identify moving objects in a three-dimensional (3D) scene during self-motion. Our findings establish that scene-relative object motion can confound perceptual judgements of depth during self-motion. These biases were large when the object was viewed monocularly, and were greatly reduced, but not eliminated, when binocular disparity cues were provided. This pattern of biases is expected if subjects confound image motion due to self-motion with that due to scene-relative object motion. Subjects showed a far bias when object and observer moved in the same direction, and a near bias when object and observer moved in opposite directions. A target object could be either stationary or moving laterally at different velocities, and subjects were asked to judge the depth of the object relative to the plane of fixation. Naïve human subjects viewed a virtual 3D scene consisting of a ground plane and stationary background objects, while lateral self-motion was simulated by optic flow. Thus, it is unknown whether perceived depth based on motion parallax is biased by object motion relative to the scene. Previous experimental and theoretical work on perception of depth from motion parallax has assumed that objects are stationary in the world. To correctly compute depth from motion parallax, only the component of image motion caused by self-motion should be used by the brain. However, if an object moves relative to the scene, this complicates the computation of depth from motion parallax since there will be an additional component of image motion related to scene-relative object motion. During observer translation, the relative image motion of stationary objects at different distances (motion parallax) provides potent depth information. Relative binocular parallax See stereoscopic visual acuity.An important function of the visual system is to represent 3D scene structure from a sequence of 2D images projected onto the retinae. Example: when viewing the landscape through the window of a moving train near objects appear to move much more quickly than distant objects. Motion parallax Apparent difference in the direction of movement or speed produced when the subject moves relative to his environment (Fig. Monocular parallax The apparent change in the relative position of an object when the eye is moved from one position to another. See chromostereopsis longitudinal chromatic aberration. This phenomenon is attributed to the chromatic aberration of the eye. The relative displacement of the two images becomes reversed when the pinhole is on the other side of that axis. When the pupil is centred on the achromatic axis (in some people the pinhole may have to be placed away from the centre of the pupil), the two images appear superimposed. a blue object and a red object) when observed through a disc with a pinhole placed near the edge of the pupil. Apparent displacement of an object viewed from two different points not on a straight line with the object.īinocular parallax The difference in angle subtended at each eye by an object that is viewed first with one eye and then with the other.Ĭhromatic parallax Apparent lateral displacement of two monochromatic sources (e.g.

Motion parallax quizzlet