Biomedical subjects

Lester C Loschky

Publications and source records attributed to Lester C Loschky.

5 recordsLinked to original sources

PubMed2005

Eye movements serialize memory for objects in scenes.

A gaze-contingent short-term memory paradigm was used to obtain forgetting functions for realistic objects in scenes. Experiment 1 had observers freely view nine-item scenes. After observers' gaze left a predetermined target, they could fixate from 1-7 intervening nontargets before the scene was replaced by a spatial probe at the target location. The task was then to select the target from four alternatives. A steep recency benefit was found over the 1-2 intervening object range that declined into an above-chance prerecency asymptote over the remainder of the forgetting function. In Experiment 2, we used sequential presentation and variable delays to explore the contributions of decay and extrafoveal processes to these behaviors. We conclude that memory for objects in scenes, when serialized by fixation sequence, shows recency and prerecency effects that are similar to isolated objects presented sequentially over time. We discuss these patterns in the context of the serial order memory literature and object file theory.

Eye Movements↗

PubMed2003

Gaze-contingent multiresolutional displays: an integrative review.

Gaze-contingent multiresolutional displays (GCMRDs) center high-resolution information on the user's gaze position, matching the user's area of interest (AOI). Image resolution and details outside the AOI are reduced, lowering the requirements for processing resources and transmission bandwidth in demanding display and imaging applications. This review provides a general framework within which GCMRD research can be integrated, evaluated, and guided. GCMRDs (or "moving windows") are analyzed in terms of (a) the nature of their images (i.e., "multiresolution," "variable resolution," "space variant," or "level of detail"), and (b) the movement of the AOI (i.e., "gaze contingent," "foveated," or "eye slaved"). We also synthesize the known human factors research on GCMRDs and point out important questions for future research and development. Actual or potential applications of this research include flight, medical, and driving simulators; virtual reality; remote piloting and teleoperation; infrared and indirect vision; image transmission and retrieval; telemedicine; video teleconferencing; and artificial vision systems.

Data Display↗

PubMed2002

Perception onset time during fixations in free viewing.

In this study, we investigated when visual perception begins in fixations. During picture viewing, the picture was degraded at the beginning of selected saccades and changed back to the original after varying intervals. Participants manually responded whenever they detected changes. The change-backs were undetected when they occurred <6 msec after the end of the saccade, marked by the peak of the overshoot in dual Purkinje image eyetracker data, and detection reached asymptote 32 msec after that marker. Eye velocity at the change-back time also affected detection likelihood. Apparently, perception begins around the time at which the eyes stop rotating at the end of a saccade, giving a psychological justification for measuring fixation durations from then. This also specifies the deadline for gaze-contingent display changes to occur without detectable image motion. Investigators using the dual Purkinje image eyetracker should consider the peak of the overshoot as the fixation onset time and measure intrafixational presentation times from then.

Fixation, Ocular↗

PubMed2002

Saliency of peripheral targets in gaze-contingent multiresolutional displays.

Gaze-contingent multiresolutional displays (GCMRDs) have been proposed to solve the processing and bandwidth bottleneck in many single-user displays, by dynamically placing high-resolution in a window at the center of gaze, with lower resolution everywhere else. The three experiments reported here document aslowing of peripheral target acquisition associated with the presence of a gaze-contingent window. This window effect was shown for displays using either moving video or still images. The window effect was similar across a resolution-defined window condition and a luminance-defined window condition, suggesting that peripheral image degradation is not a prerequisite of this effect. The window effect was also unaffected by the type of window boundary used (sharp or blended). These results are interpreted in terms of an attentional bias resulting in a reduced saliency of peripheral targets due to increased competition from items within the window. We discuss the implications of the window effect for the study of natural scene perception and for human factors research related to GCMRDs.

Fixation, Ocular↗

PubMed2002

Investigating spatial vision and dynamic attentional selection using a gaze-contingent multiresolutional display.

This study examined spatial vision and attentional selection using a gaze-contingent multiresolutional display, with a dynamic, gaze-centered, high-resolution window and lower resolution periphery. Visual search times and eye movements from 15 participants in a 3 x 3 design (Window Radius x Peripheral Resolution) suggest that contrast sensitivity as a function of retinal eccentricity affects attentional selection and visual processing. Smaller windows led to longer search times and shorter saccades; lower peripheral resolution also shortened saccades (all ps < .05) as a result of avoiding fixating degraded areas. Fixation durations, although longer for smaller windows (p < .05), were unaffected by whether the next saccade went within or outside the window. These results are explained through (a) competition among potential saccade targets where above-threshold filtering reduces an object's relative salience and (b) generally disrupted visual processing.

Adult↗