Academic journal article Perception and Psychophysics

Detection of Collision Events on Curved Trajectories: Optical Information from Invariant Rate-of-Bearing Change

Academic journal article Perception and Psychophysics

Detection of Collision Events on Curved Trajectories: Optical Information from Invariant Rate-of-Bearing Change

Article excerpt

Previous research (Andersen & Kim, 2001) has shown that a linear trajectory collision event (i.e., a collision between a moving object and an observer) is specified by objects that expand and maintain a constant bearing (the object location remains constant in the visual field). In the present study, we examined the optical information for detecting a collision event when the trajectory was of constant curvature. Under these conditions, a collision event is specified by expansion of an object and a constant rate-of-bearing change. Three experiments were conducted in which trajectory curvature and display duration were varied while time to contact, speed, and initial image position of the collision objects were maintained. The results indicated that collision detection performance decreased with an increase in trajectory curvature and decreased with a decrease in display duration, especially for highly curved trajectories. In Experiment 3, we found that the presentation of a constant rate-of-bearing change in noncollision stimuli resulted in an increase in the false alarm rate. These results demonstrate that observers can detect collision events on curved trajectories and that observers utilize bearing change information.

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Successfully detecting and avoiding collisions is an important task for the safety of an observer. Failure to perform this task can have serious consequences for a moving observer, as well as for other individuals in the environment (i.e., pedestrians, bicyclists, or other drivers). Consider findings from the fatal analysis reporting system of the National Highway Traffic Safety Administration. Of the 25,840 fatal crashes in 2001, 42.7% involved two moving vehicles (Evans, 2004). In addition, a decreased ability to detect and avoid collisions has been shown to be a central factor in the high incidence of falls among the elderly (Weerdesteyn, Nienhuis, & Duysens, 2005; see also Northridge, Nevitt, Kelsey, & Link, 1995; Salgado & Greenberg, 1994).

The conditions that define a collision event are quite varied. Consider the motion of an object or observer that defines a collision event. The direction of object motion can be linear or curved, and the speed of motion can be constant or varying (accelerating or decelerating). Similarly, the direction of observer motion can be linear or curved, and the speed can be constant or varying. All possible combinations of object motion and observer motion would thus yield 16 different combinations of trajectories (straight trajectory/constant speed, curved trajectory/constant speed, straight trajectory/variable speed, and curved trajectory/variable speed, for object and observer motion; see Andersen & Sauer, 2004, for a detailed discussion). In addition, there are eight other trajectory conditions for a static object and a moving observer or a static observer and a moving object. As will be evident from the literature review below, many of these conditions have not been examined.

A considerable number of studies have investigated a related but different issue than collision detection: the time to contact (TTC) of an impending collision event. Lee (1976) provided one of the earliest analyses, showing that TTC (referred to as ô) is specified by the inverse rate of relative optical expansion (i.e., the rate of expansion divided by the image size; see Tresilian [1991] and Wann [1996] for variations of this analysis). The utility of ô has been examined in several contexts, including interceptive judgments in sports (Bootsma & van Wieringen, 1990; Lee, Young, Reddish, Lough, & Clayton, 1983; Savelsbergh & Bootsma, 1994; Zaal & Bootsma, 2004), aviation (Flach & Warren, 1995), reaching (Bingham & Zaal, 2004), and driving (Andersen & Enriquez, 2006; Kiefer, Flannagan, & Jerome, 2006; Schiff, Oldak, & Shah, 1992; Vogel, 2003). Other studies (DeLucia, 2004a, 2004b, 2005; DeLucia, Kaiser, Bush, Meyer, & Sweet, 2003; Kim & Grocki, 2006) have yielded evidence that observers utilize other sources of information (e. …

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