Visual information about time-to-collision between two objects.

Abstract

In a forced-choice paradigm, human observers' sensitivity to visual information specifying a moving object's future time of arrival at a designated position in the field of view was evaluated. A geometrical analysis demonstrated that information specifying a first-order temporal relationship (i.e., without taking changes in velocity into account) is available in the combination of the relative rate of dilation of the optical contour of the moving object and the relative rate of constriction of the optical gap separating the moving object from the target position. Observers were sensitive to information contained in the relative rate of constriction of the optical gap if no contour dilation component was present and to the combination of information contained in the relative rates of dilation of the optical contour of the moving object and constriction of the optical gap if both were present albeit with a differential weighting of the 2 components.

Time-to-Contact Estimation of Accelerated Stimuli Is Based on First-Order Information.

“…If these results are in agreement with those reported within the perspective of Lee's (1976Lee's ( , 1980 work (Bootsma & Oudejans, 1993;Kaiser & Hecht, 1995;Lee et al, 1983Lee et al, , 1997Port et al, 1997;Ripoll & Latiri, 1997), then they underscore the robustness of the quantitative predictions for the use of a TTC1(x) strategy.…”

“…They showed that the angle-time functions of the three different height conditions lie much closer to the TTC1-time function than to the TTC-time function. 2 Generalizing the TTC1 hypothesis to nonradial approaches, Bootsma and colleagues (Bootsma et al, 1997;Bootsma & Oudejans, 1993) proposed that TTC is specified by information combining the relative velocity of the expansion of the optical contour of a moving object (˙) with the relative velocity of the contraction of the visual angle between the object and the point of interception (˙). This information variable, ( , ), specifying TTC1(x) at any point in space, is formalized by 1/ ( , ) ϭ ˙/sin Ϫ ˙/ sin ϭ Ϫ1/TTC1(x), where ˙is the inverse of ( ) as defined by Lee (1976) when is small (when Յ 10°, sin Ϸ ), corresponds to the angle formed at the participant's observation point by the object and the point of interception, and ˙c orresponds to the variation of this angle as a function of time (see Figure 2).…”

Shedding some light on catching in the dark: Perceptual mechanisms for catching fly balls.

“…For instance, time-to-contact information is also often mathematically described as related to the motion on the retina. But just as with AT, in principle these geometrical descriptions of time-to-contact information (see, e.g., Bootsma & Oudejans, 1993, for visual information about time to contact between two objects) leave how this information is picked up (with or without eye and head movements) an open question. In most situations in which time to contact is to be perceived (e.g., one-handed sideward catching, maneuvering through traffic), one probably also tracks the object with which one wants to make or avoid contact (see Tresilian, 1990, for a description of intermodal pickup of time-to-contact information).…”

A vector-integration-to-endpoint model for performance of viapoint movements

“…In contrast to cases of diving or looming toward the eyes, trajectories in reaching often do not lead to optical expansion cues. Bootsma & Oudejans (1993) demonstrated that in many situations information about future time of contact is contained in the relative rate of constriction of the optical gap that separates the moving object from a designated position, or in the ratio of the distance between two objects to the rate of change of this distance. In the terms of our model, we assume that subjects use the ratio of the residual distance between desired position (T,) and present position (PPV) to the hand's perceived velocity towards the target.…”