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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Selective attention and the auditory vertex potential. I - Effects of stimulus delivery rate. II - Effects of signal intensity and masking noise

The effects of varying the rate of delivery of dichotic tone pip stimuli on selective attention measured by evoked-potential amplitudes and signal detectability scores were studied. The subjects attended to one channel (ear) of tones, ignored the other, and pressed a button whenever occasional targets - tones of a slightly higher pitch were detected in the attended ear. Under separate conditions, randomized interstimulus intervals were short, medium, and long. Another study compared the effects of attention on the N1 component of the auditory evoked potential for tone pips presented alone and when white noise was added to make the tones barely above detectability threshold in a three-channel listening task. Major conclusions are that (1) N1 is enlarged to stimuli in an attended channel only in the short interstimulus interval condition (averaging 350 msec), (2) N1 and P3 are related to different modes of selective attention, and (3) attention selectivity in multichannel listening task is greater when tones are faint and/or difficult to detect.

Schwent, V. L.↗
NASA NTRS1986

Effects of stimulus characteristics and task demands on pilots' perception of dichotic messages

The experiment is an initial investigation of pilot performance when auditory advisory messages are presented dichotically, either with or without a concurrent pursuit task requiring visual/motor dexterity. The dependent measures were percent correct and correct reaction times for manual responses to the auditory messages. Two stimulus variables which show facilitory effects in traditional dichotic-listening paradigms, differences in pitch and semantic content of the messages, were examined to determine their effectiveness during the functional simulation of helicopter pursuit. In an effort to accumulate points for the advisory messages for accuracy alone or for both accuracy and reaction times which were faster than their opponent's. In general, the combined effects of the stimulus and task variables are additive. When interactions do occur they suggest that an increase in task demands can sometimes mitigate, but usually does not remove, any processing advantages accrued from stimulus characteristics. The implications of these results for cockpit displays are discussed.

Wenzel, Elizabeth M.↗
NASA NTRS1987

Vestibulo-ocular and vestibulospinal function before and after cochlear implant surgery

Vestibular function in cochlear implant candidates varies from normal to total absence of function. In patients with intact vestibular function preoperatively, invasion of the otic capsule places residual vestibular function at risk. Speech-processing strategies that result in large amplitude electrical transients or strategies that employ high amplitude broad frequency carrier signals have the potential for disrupting vestibular function. Five patients were tested with and without electrical stimulation via cochlear electrodes. Two patients experienced subjective vestibular effects that were quickly resolved. No long-term vestibular effects were noted for the two types of second generation cochlear implants evaluated. Histopathological findings from another patient, who had electrically generated vestibular reflex responses to intramodiolar electrodes, indicated that responses elicited were a function of several variables including electrode location, stimulus intensity, stimulus amplitude, and stimulus frequency. Differential auditory, vestibulocolic, and vestibulospinal reflexes were demonstrated from the same electrode as a function of stimulus amplitude, frequency, and duration.

Case Reports↗
NASA NTRS1987

Cross-modal interference and task integration - Resources or preemption switching?

Data are reviewed from experiments that have contrasted intra-modal (visual-visual) information presentation with cross-modal (visual-auditory) presentation. Five different processing mechanisms that are operating in dual stimulus tasks are described, and it is concluded that in studies where visual scanning is not required, cross-modal effects are of two classes. When the visual task is continuous (tracking), a discrete auditory stimulus will preempt tracking performance relative to a discrete visual stimulus, leading to an effective shift in allocation bias. When both tasks are discrete, the data regarding the relative advantages of cross- vs. intra-modal interference are ambivalent.

Wickens, Christopher D.↗
NASA NTRS1975

Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

Short latency (under 10 msec) responses elicited by bursts of white noise were recorded from the scalps of human subjects. Response alterations produced by changes in the noise burst duration (on-time), inter-burst interval (off-time), and onset and offset shapes were analyzed. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise time but was unaffected by changes in fall time. Increases in stimulus duration, and therefore in loudness, resulted in a systematic increase in latency. This was probably due to response recovery processes, since the effect was eliminated with increases in stimulus off-time. The amplitude of wave V was insensitive to changes in signal rise and fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It was concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

Hecox, K.↗
NASA NTRS1975

Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

Short latency (under 10 msec) evoked responses elicited by bursts of white noise were recorded from the scalp of human subjects. Response alterations produced by changes in the noise burst duration (on-time) inter-burst interval (off-time), and onset and offset shapes are reported and evaluated. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise-time but was unaffected by changes in fall-time. The amplitude of wave V was insensitive to changes in signal rise-and-fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It is concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

Hecox, K.↗
NASA NTRS1975

Electrophysiological measurement of human auditory function

Knowledge of the human auditory evoked response is reviewed, including methods of determining this response, the way particular changes in the stimulus are coupled to specific changes in the response, and how the state of mind of the listener will influence the response. Important practical applications of this basic knowledge are discussed. Measurement of the brainstem evoked response, for instance, can state unequivocally how well the peripheral auditory apparatus functions. It might then be developed into a useful hearing test, especially for infants and preverbal or nonverbal children. Clinical applications of measuring the brain waves evoked 100 msec and later after the auditory stimulus are undetermined. These waves are clearly related to brain events associated with cognitive processing of acoustic signals, since their properties depend upon where the listener directs his attention and whether how long he expects the signal.

Galambos, R.↗
NASA NTRS1971

Investigation of the neurological correlates of information reception

Animals trained to respond to a given pattern of electrical stimuli applied to pathways or centers of the auditory nervous system respond also to certain patterns of acoustic stimuli without additional training. Likewise, only certain electrical stimuli elicit responses after training to a given acoustic signal. In most instances, if a response has been learned to a given electrical stimulus applied to one center of the auditory nervous system, the same stimulus applied to another auditory center at either a higher or lower level will also elicit the response. This kind of transfer of response does not take place when a stimulus is applied through electrodes implanted in neural tissue outside of the auditory system.

Source record↗
NASA NTRS1975

Clinical applications of the human brainstem responses to auditory stimuli

A technique utilizing the frequency following response (FFR) (obtained by auditory stimulation, whereby the stimulus frequency and duration are mirror-imaged in the resulting brainwaves) as a clinical tool for hearing disorders in humans of all ages is presented. Various medical studies are discussed to support the clinical value of the technique. The discovery and origin of the FFR and another significant brainstem auditory response involved in studying the eighth nerve is also discussed.

Galambos, R.↗
NASA NTRS1995

Auditory Spatial Layout

All auditory sensory information is packaged in a pair of acoustical pressure waveforms, one at each ear. While there is obvious structure in these waveforms, that structure (temporal and spectral patterns) bears no simple relationship to the structure of the environmental objects that produced them. The properties of auditory objects and their layout in space must be derived completely from higher level processing of the peripheral input. This chapter begins with a discussion of the peculiarities of acoustical stimuli and how they are received by the human auditory system. A distinction is made between the ambient sound field and the effective stimulus to differentiate the perceptual distinctions among various simple classes of sound sources (ambient field) from the known perceptual consequences of the linear transformations of the sound wave from source to receiver (effective stimulus). Next, the definition of an auditory object is dealt with, specifically the question of how the various components of a sound stream become segregated into distinct auditory objects. The remainder of the chapter focuses on issues related to the spatial layout of auditory objects, both stationary and moving.

Wightman, Frederic L.↗
NASA NTRS1974

Human auditory evoked potentials. II - Effects of attention

Attention directed toward auditory stimuli, in order to detect an occasional fainter 'signal' stimulus, caused a substantial increase in the N1 (83 msec) and P2 (161 msec) components of the auditory evoked potential without any change in preceding components. This evidence shows that human auditory attention is not mediated by a peripheral gating mechanism. The evoked response to the detected signal stimulus also contained a large P3 (450 msec) wave that was topographically distinct from the preceding components. This late positive wave could also be recorded in response to a detected omitted stimulus in a regular train and therefore seemed to index a stimulus-independent perceptual decision process.

Picton, T. W.↗
NASA NTRS1998

Testing Models for Perceptual Discrimination Using Repeatable Noise

Adding noise to stimuli to be discriminated allows estimation of observer classification functions based on the correlation between observer responses and relevant features of the noisy stimuli. Examples will be presented of stimulus features that are found in auditory tone detection and visual Vernier acuity. Using the standard signal detection model (Thurstone scaling), we derive formulas to estimate the proportion of the observer's decision variable variance that is controlled by the added noise. One is based on the probability of agreement of the observer with him/herself on trials with the same noise sample. Another is based on the relative performance of the observer and the model. When these do not agree, the model can be rejected. A second derivation gives the probability of agreement of observer and model when the observer follows the model except for internal noise. Agreement significantly less than this amount allows rejection of the model.

Ahumada, Albert J., Jr.↗
NASA NTRS1998

Masking by Gratings Predicted by an Image Sequence Discriminating Model: Testing Models for Perceptual Discrimination Using Repeatable Noise

Adding noise to stimuli to be discriminated allows estimation of observer classification functions based on the correlation between observer responses and relevant features of the noisy stimuli. Examples will be presented of stimulus features that are found in auditory tone detection and visual vernier acuity. using the standard signal detection model (Thurstone scaling), we derive formulas to estimate the proportion of the observers decision variable variance that is controlled by the added noise. one is based on the probability of agreement of the observer with him/herself on trials with the same noise sample. Another is based on the relative performance of the observer and the model. When these do not agree, the model can be rejected. A second derivation gives the probability of agreement of observer and model when the observer follows the model except for internal noise. Agreement significantly less than this amount allows rejection of the model.

Ahumada, Albert J., Jr.↗
NASA NTRS2002

Ideomotor compatibility in the psychological refractory period effect: 29 years of oversimplification

Four experiments examined whether the psychological refractory period (PRP) effect can be eliminated with ideomotor compatible (IM) but not stimulus-response compatible (SR) tasks, as reported by A. G. Greenwald and H. G. Shulman (1973). Their tasks were used: a left or right movement to a left- or right-pointing arrow (IM) or to the word left or right (SR) for Task 1; saying "A" or "B" (IM) or "1" or "2" (SR) to an auditory A or B for Task 2. The stimulus onset asynchronies were 0, 100, 200, 300, 500, and 1,000 ms in Experiment 1, and only 0, 100, 200, and 1,000 ms in Experiments 2-4. The arrow was in the center of the screen in Experiments 1-3 and to the left or right in Experiment 4. As in Greenwald and Shulman's Experiment 2, the instructions stated that most often the 2 stimuli would be presented simultaneously. A PRP effect was obtained in all conditions, most likely because response-selection decisions are required even for IM tasks.

Refractory Period, Psychological↗
NASA NTRS1984

Objective measure of pilot workload

Timesharing behavior in a data-entry task, similar to a pilot entering navigation data into an on-board computer is investigated. Auditory reaction time as a function of stimulus information and dimensionality is examined. This study has direct implications for stimulus selection for secondary tasks used in the GAT flight simulator at Ames Research Center. Attenuation effects of heat and cold stress in a psychological refractory period task were studied. The focus of interest is the general effects of stress on attention rather than upon specific temperature related phenomena.

Kantowitz, B. H.↗
NASA NTRS1976

Neural coding of high-frequency tones

Available evidence was presented indicating that neural discharges in the auditory nerve display characteristic periodicities in response to any tonal stimulus including high-frequency stimuli, and that this periodicity corresponds to the subjective pitch.

Howes, W. L.↗
NASA NTRS1980

Comparative assessment of prognosis of the stop stimulus and trapezoidal rotation programs

For prognosis of the diagnostic possibilities of the stop stimulus and trapezoidal rotation programs with respect to the nystagmus response, 24 healthy young persons with normal auditory and vestibular analysers were studied experimentally. The trapezoidal program more accurately reflects the function and tone balance of the vestibular system than the stop stimulus program and causes the subject no unpleasant sensations during the study. Some optimum couples, acceleration and armchair rotation rate, necessary for effective deviation of the cupuloendolymphatic system were determined. The maximum angular velocity of the slow nystagmus component was more informative than nystagmus duration. The trapezoidal program is recommended for otoneurological practice and the maximum angular velocity of the slow nystagmus component as the basic index.

Grigorova, V. K.↗