Constance S. Royden

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In eight experiments, we examined the ability to judge heading during tracking eye movements. To assess the use of retinal-image and extra-retinal information in this task, we compared heading judgments with executed as opposed to simulated eye movements. In general, judgments were much more accurate during executed eye movements. Observers in the simulated(More)
In experiments testing the accuracy of human heading judgments, subjects often misperceive their motion when viewing a display that simulates motion along a straight line path accompanied by an eye movement. Rather than perceiving motion on a straight line, observers often reported that they seemed to be moving along a curved path. This paper presents a(More)
When a person walks through a rigid environment while holding eyes and head fixed, the pattern of retinal motion flows radially away from a point, the focus of expansion (Fig. 1a). Under such conditions of translation, heading corresponds to the focus of expansion and people identify it readily. But when making an eye/head movement to track an object off to(More)
A mathematical analysis is presented of a model that uses motion-opponent operators similar to neurons found in the primate middle temporal visual area, to determine observer heading and depth from optical flow information. The response of these operators to depth changes in the form of a slanted plane or a step edge is analyzed, and the outputs of(More)
Experienced drivers performed simple steering maneuvers in the absence of continuous visual input. Experiments conducted in a driving simulator assessed drivers' performance of lane corrections during brief visual occlusion and examined the visual cues that guide steering. The dependence of steering behavior on heading, speed, and lateral position at the(More)
When moving toward a stationary scene, people judge their heading quite well from visual information alone. Much experimental and modeling work has been presented to analyze how people judge their heading for stationary scenes. However, in everyday life, we often move through scenes that contain moving objects. Most models have difficulty computing heading(More)
In visual search, items defined by a unique feature are found easily and efficiently. Search for a moving target among stationary distractors is one such efficient search. Search for a stationary target among moving distractors is markedly more difficult. In the experiments reported here, we confirm this finding and further show that searches for a(More)
The tko (technical knockout) mutation is one of a family of behavioral mutations that cause "bang sensitivity" in D. melanogaster. Using P-element-mediated transformation, we show that a 3.1 kb piece of genomic DNA complements tko. This fragment contains only one complete transcript, 0.68 kb in length. This transcript is abundantly expressed through all(More)
Psychophysical experiments have shown that human heading judgments can be biased by the presence of moving objects. Here we present a theoretical argument that motion differences can account for the direction of bias seen in humans. We further examine the responses of a computer simulation of a model for computing heading that uses motion-opponent operators(More)
Previous studies have shown that a physiologically based model using motion-opponent operators to compute heading performs accurately for simulated observer translations. Here we show how this model can explain an illusory shift in the perceived focus of expansion of a radial flow field that occurs when a field of laterally moving dots is superimposed on a(More)