A total of 106 eyes of 106 patients with different types of glaucoma were examined by automated light-sense, flicker and resolution perimetry (Humphrey Field Analyzer, program 30-2; flicker perimeter as described by Lachenmayr [16, 18]; resolution perimeter as devised by Frisén [4, 6, 8-11]). The fields were classified in a ...

Static accommodation responses to sinusoidal grating stimuli that displayed temporal modulations in luminance contrast (i.e. contrast flicker) were measured with a laser speckle optometer. The effects of a variety of temporal waveforms were investigated including square-wave modulations, sinusoidal modulations, and band-pass filtered noise. The effects of altering both the amplitude ...

Displacement thresholds of peripheral sites in monocular human vision were obtained. The average of 12 directional thresholds at different visual field sites was used to define isometric lines of average displacement threshold about central vision. Isometric lines extended further into the temporal visual fields along the horizontal meridian than along ...

The purpose of this paper is to better characterize changes over time that occurred in psychophysical detection thresholds for electrical stimulation of the cochlea. Threshold changes observed in nonhuman primates implanted with cochlear electrode arrays can be divided into at least three types based on the patterns of change over ...

Estimates of vibratory detection threshold may be used to detect, characterize, and follow the course of sensory abnormality in neurologic disease. The approach is especially useful in epidemiologic and controlled clinical trials. We studied which algorithm of testing and finding threshold should be used in automatic systems by comparing among ...

It has been reported that psychophysical flicker sensitivity, electroretinogram (ERG), pattern electroretinogram (P-ERG), and visual evoked cortical potential (VECP) responses are affected by ocular hypertension and glaucoma. Moreover, it has also been revealed that artificially augmented intraocular pressure (IOP) impairs electrophysiologic responses. In this investigation the authors varied the levels ...

Detection thresholds were measured for sinusoidal vibrations applied to the thenar eminence and volar forearm. Stimuli were applied via a 0.72-cm2 circular contactor, with and without a rigid surround. At low frequencies, below about 40 Hz, the thresholds were higher without the surround than with the surround. However, in contrast ...

Quoted values of cavitation thresholds reported in the literature vary over several orders of magnitude. This paper describes an investigation of the threshold in a chamber with acoustically transparent windows, situated around the last axial maximum of a 0.75 MHz standing wave field. The chamber, the transducer and the reflector ...

We used Gaussian blurred stimuli to explore the effect of blur on three tasks: (i) 2-line "resolution"; (ii) line detection; and (iii) spatial interval discrimination, in both central and peripheral vision. The results of our experiments can be summarized as follows. (i) 2-Line "resolution": thresholds for pairs of unblurred, low ...

Human observers have different thresholds for flicker detection and color detection of a rapidly flickering spectral stimulus presented on a steady white background. A flickering surround, which did not overlap the stimulus or background, reduced flicker sensitivity but not color sensitivity for both monocular and binocular viewing. However, a flickering ...

We used Gaussian blurred stimuli to explore the effect of blur on three tasks: (i) 2-line resolution; (ii) line detection; and (iii) spatial interval discrimination, in observers with amblyopia due to anisometropia, strabismus, or both. The results of our experiments can be summarized as follows. (i) 2-Line resolution: in normal ...

Exposure duration was found to have a different effect on bisection thresholds than on separation-discrimination thresholds. Bisection thresholds were higher than separation discrimination thresholds between 33 and 150 msec but equal to or lower than them at longer durations. Experiments in which stimulus contrast was manipulated showed that the effect ...

We measured two- and three-line spatial interval and alignment thresholds for a wide range of separations and eccentricities. In order to avoid confounding the role of separation and eccentricity, the test lines were presented on iso-eccentric arcs, with radii between 0.625 and 10 deg. The iso-eccentric paradigm allows separation to ...

The relationship between the amount of light and the amount of response for any photobiological process can be based on the number of incident quanta per unit time (fluence rate-response) or on the number of incident quanta during a given period of irradiation (fluence-response). Fluence-response and fluence rate-response relationships have ...

1. The femoral tactile spine of the cockroach is innervated by a single sensory neuron with its cell body in the spine. A step deflection of the spine produces a burst of action potentials which decays to zero in approximately 1 s. This rapid adaptation occurs during encoding of action ...

The defocus levels required for normal observers to notice the first perceptible blur of a clear test target (blur threshold) and the least perceptible change in the degree of blurriness of an already blurry target (threshold of perceived change in blur) were measured using both the source and observer methods. ...

The purpose of the present study was to determine whether threshold shifts occurred during magnitude-estimation scaling of suprathreshold stimuli presented to the thenar eminence of the right hand. Possible relationships of the vibrotactile threshold shifts to suprathreshold stimulus intensity, magnitude-estimation responses, and over-all scaling behavior were explored. A single group ...

To investigate the nature of false-negative and false-positive errors in endocrine signal detection, we used a multiparameter convolution procedure to create random hormone secretory bursts. We observed that 1) data containing high signal frequency, amplitude, and/or duration can be analyzed at less stringent peak-detection thresholds; 2) for any given secretory ...

Thresholds for detecting change of angular size were determined for a range of angular separations in young and elderly observers. We found no differences in thresholds between these subjects groups. Thresholds for detection of change of visual angle increased with angular separation in a power function relationship. Angular size change ...

In animals with pre-existing N1 threshold losses of unknown etiology, transection of the crossed olivocochlear bundle (COCB) at the floor of the fourth ventricle resulted in a marked improvement in thresholds in the region of the loss but not at adjacent frequencies with normal thresholds or increased threshold sensitivities. There ...

Thresholds for the detection (at p = 0.75 correct) of the direction of discrete angular movements about a vertical Z axis, having a cosine bell velocity trajectory and a duration of 3.3 s, were determined using an adaptive psychophysical procedure. In 30 subjects the mean threshold for the detection of ...

In acute uremia the auditory brainstem response thresholds in the rat (n = 10) became primarily affected in the low-frequency area. As time elapsed in uremia, even the high-frequency thresholds became impaired. In most animals the latencies for wave 2 at the threshold level increased during the first 48 h ...

The influence of uniform field flicker (UFF) on the contrast threshold for stationary sinusoidal gratings was measured as a function of flicker depth. Changing from no flicker to a flicker depth of 10% produces reliable differences in threshold. Further increases in flicker depth to 60% had little additional influence. The ...

The threshold intensity for detection of an AC electric field was studied in human subjects at several different temperatures and humidities. The dorsum and palm of the hand were exposed to fields, representing hairy and hairless skin, in order to clarify whether hair movement is critical for field detection. Experiments ...

Sixty-three normal subjects and 94 abnormal patients, most of whom had glaucoma, were tested in the central visual field using a threshold-related, eccentricity-compensated, spatially adaptive suprathreshold screening program and a full-threshold program on the Humphrey field analyzer. The initial stimulus locations on the screening test were identical to those of ...

1. Heterochromatic flicker photometry is a way of measuring the spectral sensitivity of the human eye. Two lights of different colour are sinusoidally alternated at, typically, 10-20 Hz, and their relative intensities adjusted by the observer until the sensation of flicker is minimized. This technique has been used to define ...

We have obtained new insights into the behavior of a class of excitable systems when a stimulus, or parameter, is slowly tuned through a threshold value. Such systems do not accommodate no matter how slowly a stimulus ramp is applied, and the stimulus value at onset of repetitive activity shows ...

The CooperVision Dicon AP 2000 does not project the stimulus onto an existing background, but produces the test stimuli with light emitting diodes (LEDs) recessed in a dark cavity in the perimetric bowl. Nearly everywhere in the visual field, the visibility threshold with the Dicon instrument seems equivalent to that ...

Measurements of peripheral visual acuity allow quantitative estimations of retino-cortical neural channels. Analysis of results from high-pass resolution perimetry revealed that about 2/3 of all channels are contained within 30 degrees of visual field eccentricity and that loss of 1/3 raises the average threshold level about 1 decibel. The analytical ...

The 500 Hz tone burst thresholds were obtained by four independent judges from recorded middle latency responses (MLR) and 40 Hz event related potentials (40 Hz ERP) in a group of children ranging in age from 5-12 years old. The thresholds obtained from the two electrophysiological methods were compared to ...

The characteristics of vibrotactile stimulation and an experimental device for the transmission of rhythm information contained in music and similar sounds by means of vibrotactile stimulation are described. The actuator and input/output behavior of the device are examined. Measurement of the intensity discrimination threshold and beat frequency perception threshold is ...

Vibratory detection thresholds were measured at a number of frequencies between 5 and 320 Hz following a lesion of the lateral digital nerve innervating the terminal phalanx of the left index finger. Thresholds measurements began approximately 4 weeks after the nerve was repaired. A staircase method was used to determine ...

Phase discrimination thresholds were measured for yellow/green isoluminant and non-isoluminant compound gratings in which the amplitude of the two components (f and 3f) was twice the detection threshold. The phase discrimination threshold at isoluminance was worse than in all the other conditions, which gave broadly similar threshold data. It is ...

The present study was undertaken in order to study the rate of maturation of the cochlear action potential sensitivity, latency, and tuning curves for various stimulus frequencies and to correlate the development of latency and frequency selectivity with threshold development. This study showed a two-stage model of maturation in which ...

The monaural speech-reception threshold of sentences in noise, here defined as the 50% correct-syllables threshold, was measured for a female speaker with and without speechreading via a video monitor. The additional visual information resulted in a 4.6-dB lower threshold for a group of 12 young subjects and in a 4.0-dB ...

The effect of refraction accuracy on the differential light threshold of a Goldmann size III (0.43 degrees diameter) stimulus was evaluated in the right eyes of five normal subjects with randomly ordered sequence of plano, +1.00-, +2.00-, +3.00-, +4.00-, +5.00-, and +6.00-diopter (D) spherical overcorrections. Threshold measurements were performed at ...

Measurement of cutaneous thermal thresholds is a valuable technique for detecting small fibre neuropathy. A robust and portable microcomputer controlled system, which separately measures thresholds for warming and cooling, is described. Thresholds at three sites have been measured; the cheek, the dorsum of the hand and the sole of the ...

Five semiobjective devices for testing sensory perception thresholds were concomitantly used on 36 normal subjects to determine normal threshold values, intersubject variability, and their correlation with age. The five devices include the Semmes-Weinstein monofilament (touch); three-point esthesiometer (two-point discrimination); Pfizer thermal tester (temperature); biothesiometer (vibration); and Optacon tactile tester (vibration). ...

Resolution thresholds were determined for a configuration of two blobs with overlapping Gaussian spatial and temporal envelopes presented near detection-threshold luminance contrast. The resolution thresholds are a constant fraction of the blur parameter of the stimuli over a range of at least two decades. There is no indication for a ...

At 1, 10, and 50 Hz, photopic flicker sensitivity to a nonpatterned stimulus of constant area and luminance with a small equiluminous surround tended to decrease when eccentricity increased from 0 to 70 deg. The decrease was steeper for lower flicker frequencies. When the stimulus and surround were M scaled ...

Thresholds for detection of change of size and for detection of change of velocity were measured in young and elderly observers. No differences in thresholds between these subject groups were found at the fovea or in more peripheral retina. The results indicate a degree of functional redundancy in the peripheral ...

Psychophysical luminance thresholds were taken from dark-adaptation curves representing two-hour intervals around the clock to identify diurnal changes in photopic and scotopic luminance sensitivity. Dark adaptation curves were obtained by tracking thresholds for a 2 deg achromatic stimulus located 10 deg temporal to the fovea of the left eye following ...

With strict fixation, a flickering light spot smaller than 3 deg presented to the peripheral retina will rapidly appear to lose contrast and stop flickering within 35 s, before fading away completely. The time required for this adaptation to occur decreases with: decreasing depth of modulation (97-9%); decreasing stimulus diameter ...

Foveal increment thresholds were measured in young, middle-aged, and older observers. These thresholds, which involved the detection of a small test flash as a function of the intensity of a larger background adapting field (AF), were measured at the instant of onset of the AF (transient condition) and when the ...

Thresholds for the detection (at p = 0.67 correct) of the direction of discrete linear movements in the horizontal plane, having a cosine bell velocity trajectory and duration of 3 s, were determined in 24 subjects. Thresholds in the Z body axis (mean 0.154 m X s-2) were significantly higher ...

A comparison has been made of air conduction thresholds after myringoplasty and stapes surgery for otosclerosis in both the conventional (0.25 to 8 kHz) and high frequency (8 to 20 kHz) ranges. Significant threshold losses occurred in the high frequencies following both procedures. Threshold improvement was significantly greater at the ...

Vibratory perception thresholds were determined for 90 subjects working at a shipyard with industrial solvents. The duration of exposure varied from 1 to 44 years (mean 19.6 years). Four of the men but none of women had bilaterally significantly increased thresholds in the lower limbs. In addition, seven subjects had ...

The distribution of lowest tone-response thresholds was examined within 3 different isofrequency planes (10, 20 and 30 kHz) of the inferior colliculus (IC) of the house mouse. Lowest thresholds are located in, or slightly rostrolateral to the center of each isofrequency plane. Thresholds increase centrifugally, although in the rostrolateral direction ...

To determine the relationship of foveal absolute thresholds to visual acuity in retinitis pigmentosa, we measured thresholds in 40 patients with various forms of retinitis pigmentosa (including Usher's syndrome) whose Snellen visual acuities were 20/30 or better. At all visual acuity levels, the patients' foveal thresholds were significantly higher than ...

A perimeter was constructed, using red light-emitting diodes by remodeling a Foerster's perimeter, to test three time-dependent visual functions, ie, double flash resolution (DFR), which is the time threshold of double flash separation, critical flicker fusion frequency (CFF), which is the threshold of flicker separation and perceptual delay (PD), which ...