Time-to-Passage Judgments in Nonconstant Optical Flow Fields

Kaiser, Mary K.; Hecht, Heiko

The time until an approaching object will pass an observer (time to passage, or TTP) is optically specified by a global flow field even in the absence of local expansion or size cues. Kaiser and Mowafy have demonstrated that observers are in fact sensitive to this global flow information. The present studies investigate two factors that are usually ignored in work related to TTP: (1) non-constant motion functions and (2) concomitant eye rotation. Non-constant velocities violate an assumption of some TTP derivations, and eye rotations may complicate heading extraction. Such factors have practical significance, for example, in the case of a pilot accelerating an aircraft or executing a roll. In our studies, a flow field of constant-sized stars was presented monocularly on a large screen. TIP judgments had to be made on the basis of one target star. The flow field varied in its acceleration pattern and its roll component. Observers did not appear to utilize acceleration information. In particular, TTP with decelerating motion were consistently underestimated. TTP judgments were fairly robust with respect to roll, even when roll axis and track vector were decoupled. However, substantial decoupling between heading and track vector led to a decrement in performance, in both the presence and the absence of roll.

Document ID

19970010712

Acquisition Source

Ames Research Center

Document Type

Reprint (Version printed in journal)

Authors

Date Acquired

September 6, 2013

Publication Date

January 1, 1995

Publication Information

Publication: Perception and Psychophysics

Publisher: Psychonomic Society, Inc.

Volume: 57

Issue: 6

Subject Category

Report/Patent Number

Accession Number

97N15885

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Public

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