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All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Psychophysical Evaluation of Three-Dimensional Auditory Displays

This report describes the progress made during the second year of a three-year Cooperative Research Agreement. The CRA proposed a program of applied psychophysical research designed to determine the requirements and limitations of three-dimensional (3-D) auditory display systems. These displays present synthesized stimuli to a pilot or virtual workstation operator that evoke auditory images at predetermined positions in space. The images can be either stationary or moving. In previous years, we completed a number of studies that provided data on listeners' abilities to localize stationary sound sources with 3-D displays. The current focus is on the use of 3-D displays in 'natural' listening conditions, which include listeners'head movements, moving sources, multiple sources and 'echoic' sources. The results of our research on one of these topics, the localization of multiple sources, was reported in the most recent Semi-Annual Progress Report (Appendix A). That same progress report described work on two related topics, the influence of a listener's a-priori knowledge of source characteristics and the discriminability of real and virtual sources. In the period since the last Progress Report we have conducted several new studies to evaluate the effectiveness of a new and simpler method for measuring the HRTF's that are used to synthesize virtual sources and have expanded our studies of multiple sources. The results of this research are described below.

Wightman, Frederic L.↗
NASA NTRS1995

Psychophysical Evaluation of Three-Dimensional Auditory Displays

This report describes the process made during the first year of a three-year Cooperative Research Agreement (CRA NCC2-542). The CRA proposed a program of applied of psychophysical research designed to determine the requirements and limitations of three-dimensional (3-D) auditory display systems. These displays present synthesized stimuli to a pilot or virtual workstation operator that evoke auditory images at predetermined positions in space. The images can be either stationary or moving. In previous years. we completed a number of studies that provided data on listeners' abilities to localize stationary sound sources with 3-D displays. The current focus is on the use of 3-D displays in 'natural' listening conditions, which include listeners' head movements, moving sources, multiple sources and 'echoic' sources. The results of our research on two of these topics, the role of head movements and the role of echoes and reflections, were reported in the most recent Semi-Annual Pro-ress Report (Appendix A). In the period since the last Progress Report we have been studying a third topic, the localizability of moving sources. The results of this research are described. The fidelity of a virtual auditory display is critically dependent on precise measurement of the listener''s Head-Related Transfer Functions (HRTFs), which are used to produce the virtual auditory images. We continue to explore methods for improving our HRTF measurement technique. During this reporting period we compared HRTFs measured using our standard open-canal probe tube technique and HRTFs measured with the closed-canal insert microphones from the Crystal River Engineering Snapshot system.

Wightman, Frederic L.↗
NASA NTRS2015

Psychophysical Calibration of Mobile Touch-Screens for Vision Testing in the Field

The now ubiquitous nature of touch-screen displays in cell phones and tablet computers makes them an attractive option for vision testing outside of the laboratory or clinic. Accurate measurement of parameters such as contrast sensitivity, however, requires precise control of absolute and relative screen luminances. The nonlinearity of the display response (gamma) can be measured or checked using a minimum motion technique similar to that developed by Anstis and Cavanagh (1983) for the determination of isoluminance. While the relative luminances of the color primaries vary between subjects (due to factors such as individual differences in pre-retinal pigment densities), the gamma nonlinearity can be checked in the lab using a photometer. Here we compare results obtained using the psychophysical method with physical measurements for a number of different devices. In addition, we present a novel physical method using the device's built-in front-facing camera in conjunction with a mirror to jointly calibrate the camera and display. A high degree of consistency between devices is found, but some departures from ideal performance are observed. In spite of this, the effects of calibration errors and display artifacts on estimates of contrast sensitivity are found to be small.

gamma correction↗
NASA NTRS1997

Uncertain responses by humans and rhesus monkeys (Macaca mulatta) in a psychophysical same-different task

The authors asked whether animals, like humans, use an uncertain response adaptively to escape indeterminate stimulus relations. Humans and monkeys were placed in a same-different task, known to be challenging for animals. Its difficulty was increased further by reducing the size of the stimulus differences, thereby making many same and different trials difficult to tell apart. Monkeys do escape selectively from these threshold trials, even while coping with 7 absolute stimulus levels concurrently. Monkeys even adjust their response strategies on short time scales according to the local task conditions. Signal-detection and optimality analyses confirm the similarity of humans' and animals' performances. Whereas associative interpretations account poorly for these results, an intuitive uncertainty construct does so easily. The authors discuss the cognitive processes that allow uncertainty's adaptive use and recommend further comparative studies of metacognition.

NASA Discipline Space Human Factors↗
NASA NTRS1967

Attention and psychophysical time.

Intermittency hypothesis suggesting temporal integration of data processing of human central nervous system achieved through control of clock generating time points

CENTRAL NERVOUS SYSTEM↗
NASA NTRS1972

Concurrent variation of response bias and sensitivity in an operant-psychophysical test.

The yes-no signal detection procedure was applied to a single-response operant paradigm in which rats discriminated between a standard auditory intensity and attenuated comparison values. The payoff matrix was symmetrical (with reinforcing brain stimulation for correct detections and brief time-out for errors), but signal probability and intensity differences were varied to generate a family of isobias and isosensitivity functions. The d' parameter remained fairly constant across a wide range of bias levels. Isobias functions deviated from a strict matching strategy as discrimination difficulty increased, although an orderly relation was maintained between signal probability value and the degree and direction of response bias.

Terman, M.↗
NASA NTRS1975

An elementary psychophysical model to predict ride comfort in the combined stress of multiple degrees of freedom

The quality of airplane rides probably will become increasingly important to passengers, particularly in terminal area operations and on short haul trips. The development of models to predict ride comfort is considered. An elementary model concept is presented herein and compared with subjective ride comfort response ratings measured on actual scheduled airline flights and simulated flights.

Stone, R. W., Jr.↗
NASA NTRS1984

Psychophysical Research in Development of a Fiber-optic Helmet Mounted Display

The Fiber Optic Helmet Mounted Display (FOHMD) was conceived as an innovative solution to existing flight simulator display deficiencies. An initial (breadboard) version of the system was fabricated to permit experimentation which would help define design requirements for a more refined engineering prototype. A series of visual/human factors studies are being conducted at the USAF Human Resources Laboratory (AFHRL) Operations Training Division, Williams AFB, Arizona to determine the optimum fit of human observer operating characteristics and fiber optic helmet mounted display technology. Pilot performance within a variety of high resolution insert/binocular overlap combinations is being assessed in two classes of environment. The first two of four studies planned incorporate an air-to-air combat environment, whereas the second two studies will use a low level environment with air to ground weapons delivery.

Kruk, R. V.↗
NASA NTRS1984

Measurement of Workload: Physics, Psychophysics, and Metaphysics

The present paper reviews the results of two experiments in which workload analysis was conducted based upon performance measures, brain evoked potentials and magnitude estimations of subjective load. The three types of measures were jointly applied to the description of the behavior of subjects in a wide battery of experimental tasks. Data analysis shows both instances of association and dissociation between types of measures. A general conceptual framework and methodological guidelines are proposed to account for these findings.

Gopher, D.↗
NASA NTRS1986

Window of visibility - A psychophysical theory of fidelity in time-sampled visual motion displays

A film of an object in motion presents on the screen a sequence of static views, while the human observer sees the object moving smoothly across the screen. Questions related to the perceptual identity of continuous and stroboscopic displays are examined. Time-sampled moving images are considered along with the contrast distribution of continuous motion, the contrast distribution of stroboscopic motion, the frequency spectrum of continuous motion, the frequency spectrum of stroboscopic motion, the approximation of the limits of human visual sensitivity to spatial and temporal frequencies by a window of visibility, the critical sampling frequency, the contrast distribution of staircase motion and the frequency spectrum of this motion, and the spatial dependence of the critical sampling frequency. Attention is given to apparent motion, models of motion, image recording, and computer-generated imagery.

Watson, A. B.↗
NASA NTRS1985

The psychophysics of workload - A second look at the relationship between subjective measures and performance

Load estimates based upon subjective and performance indices were compared for subjects performing size matching and letter typing tasks under 6 levels of priorities, in single and dual task conditions. Each half of the group used a different task as reference in their subjective judgement. The results are interpreted to indicate that subjective measures are especially sensitive to voluntary allocation of attention and to the load on working memory. Association with performance is expected whenever these two factors are main determinants of performance efficiency, otherwise the two are likely to dissociate.

Gopher, D.↗
NASA NTRS1989

Application of visual psychophysics to the design of video systems for use in space

A series of two-alternative forced choice experiments was conducted to compare the sharpness of televised moving images sampled using cardinal or diagonal patterns with reference images of varying resolution. The results indicate that both image sampling and resolution orientation play an important role in determining apparent sharpness of the images. If an image has better cardinal than diagonal resolution, the apparent sharpness is significantly greater. Thus, if the polar distribution of resolution is limited by the sampling process, diagonal sampling can be expected to yield a sharper image than cardinal sampling with the same number of pixels.

Glenn, William E.↗
NASA NTRS1991

Psychophysical evaluation of three-dimensional auditory displays

Work during this reporting period included the completion of our research on the use of principal components analysis (PCA) to model the acoustical head related transfer functions (HRTFs) that are used to synthesize virtual sources for three dimensional auditory displays. In addition, a series of studies was initiated on the perceptual errors made by listeners when localizing free-field and virtual sources. Previous research has revealed that under certain conditions these perceptual errors, often called 'confusions' or 'reversals', are both large and frequent, thus seriously comprising the utility of a 3-D virtual auditory display. The long-range goal of our work in this area is to elucidate the sources of the confusions and to develop signal-processing strategies to reduce or eliminate them.

Wightman, Frederic L.↗