Passengers in moving vehicles often see an interesting phenomenon when they fixate one of several objects that are at different distances. Looking sideways out the window, they may notice that all objects closer than the fixated object appear to move in a direction opposite to their movement, whereas all objects farther than the fixated object appear to move in the direction in which they are traveling. You can see similar apparent motions by holding your index fingers at different distances while swinging your head back and forth. When you look at the far finger, the near one appears to move against the direction of head movements; when you look at the near finger, the far one appears to move with the direction of head movement. Theterm "motion parallax" is often used in referring to these and other apparent motions that are concomitant with lateral head movements (e.g., Coren, Porac, & Ward, 1979; Gibson, Gibson, Smith, & Flock, 1959; Shebilske & Proffitt, 1981). Gogel, however, prefers the term "apparent concomitant motion." This paper will adopt Gogel's term to avoid clouding issues in an ongoing debate that contends issues much deeper than terminology.