scholarly journals Monovision and the Misperception of Motion

2019 ◽  
Author(s):  
Johannes Burge ◽  
Victor Rodriguez-Lopez ◽  
Carlos Dorronsoro
Keyword(s):  
Processing Speed ◽  
High Frequency ◽  
Low Frequency ◽  
The United States ◽  
Illusory Motion ◽  
Apparent Paradox ◽  
System A ◽  
Spatial Frequencies ◽  
Stereo Motion ◽  
Pulfrich Effect

Monovision corrections are a common treatment for presbyopia. Each eye is fit with a lens that sharply focuses light from a different distance, causing the image in one eye to be blurrier than the other. Millions of people in the United States and Europe have monovision corrections, but little is known about how differential blur affects motion perception. We investigated by measuring the Pulfrich effect, a stereo-motion phenomenon first reported nearly 100 years ago. When a moving target is viewed with unequal retinal illuminance or contrast in the two eyes, the target appears to be closer or further in depth than it actually is, depending on its frontoparallel direction. The effect occurs because the image with lower illuminance or contrast is processed more slowly. The mismatch in processing speed causes a neural disparity, which results in the illusory motion in depth. What happens with differential blur? Remarkably, differential blur causes a reverse Pulfrich effect, an apparent paradox. Blur reduces contrast and should therefore cause processing delays. But the reverse Pulfrich effect implies that the blurry image is processed more quickly. The paradox is resolved by recognizing that: i) blur reduces the contrast of high-frequency image components more than low-frequency image components, and ii) high spatial frequencies are processed more slowly than low spatial frequencies, all else equal. Thus, this new illusion—the reverse Pulfrich effect—can be explained by known properties of the early visual system. A quantitative analysis shows that the associated misperceptions are large enough to impact public safety.

Disparity Modulation Sensitivity for Narrow-Band-Filtered Stereograms Viewed out of the Plane of Fixation

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 94-94
Author(s):  
B Lee ◽  
B J Rogers
Keyword(s):  
Spatial Frequency ◽  
High Frequency ◽  
Significant Interaction ◽  
Narrow Band ◽  
Low Frequency ◽  
Frequency Pattern ◽  
Spatial Frequencies ◽  
Size Disparity ◽  
Random Dot Stereograms

Narrow-band-filtered random-dot stereograms were used to determine stereo thresholds for detecting sinusoidal disparity modulations. These stereograms were designed to stimulate selectively channels tuned to luminance and corrugation spatial frequencies (Schumer and Ganz, 1979 Vision Research19 1303 – 1314). Thresholds were determined for corrugation frequencies ranging from 0.125 to 1 cycle deg−1, luminance centre spatial frequencies ranging from 1 to 8 cycles deg−1 and disparity pedestal sizes ranging from −32 to +32 min arc. For small disparity pedestals, lowest modulation thresholds were found around 0.5 cycle deg−1 corrugation frequency and 4 cycles deg−1 luminance centre spatial frequency. For large disparity pedestals (±32 arc min), lowest thresholds were shifted towards the lower corrugation frequencies (0.125 cycle deg−1) and lower luminance frequencies (2 cycles deg−1). There was a significant interaction between luminance spatial frequency and disparity pedestal size. For small pedestals, lowest thresholds were found with the highest luminance frequency pattern (4 cycles deg−1). For large pedestals, best performance shifted towards the low-frequency patterns (1 cycle deg−1). This effect demonstrates a massive reduction in stereo-efficiency for high-frequency patterns in the luminance domain at large disparity pedestals which is consistent with the ‘size-disparity relation’ proposed by previous researchers.

Reduction Methods of Structure Models for Control System Purposes

2016 ◽  
Vol 248 ◽  
pp. 119-126 ◽  
Author(s):  
Andrzej Koszewnik ◽  
Zdzisław Gosiewski
Keyword(s):  
Control System ◽  
High Frequency ◽  
Closed Loop ◽  
Flexible Structures ◽  
Low Frequency ◽  
Point Of View ◽  
Closed Loop Systems ◽  
System A ◽  
Reduction Methods ◽  
The Stability

To design vibration control system for flexible structures their mathematical model should be reduced. In the paper we consider the influence of the model reduction on the dynamics of the real closed-loop system. A simply cantilever beam is an object of consideration since we are able to formulate the exact analytical model of such structure. As a result of reduction the model with low frequency resonances is usually separated from the high frequency dynamics because high frequency part of the model is naturally strong damped. In order to estimate dynamical system for control purposes in the paper we applied a few orthogonal methods such as: modal, Rayleigh-Ritz and Schur decompositions. As it is shown all methods well calculate resonances frequencies but generate different anti-resonances frequencies. From control strategy in point of view of the flexible structures these anti-resonances have significantly influence on the stability and dynamics of the closed-loop systems.

DIELECTRIC EVIDENCE FOR ACETONE HYDRATE

1963 ◽  
Vol 41 (2) ◽  
pp. 264-273 ◽  
Author(s):  
G. J. Wilson ◽  
D. W. Davidson
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
High Frequency ◽  
Water System ◽  
Low Frequency ◽  
Water Molecules ◽  
Incongruent Melting ◽  
High Frequency Dielectric Constant ◽  
System A ◽  
Acetone Water

The phase diagram of the acetone–water system shows that acetone hydrate decomposes at an incongruent melting point. The existence of acetone hydrate is confirmed by a study of the low-frequency dielectric properties of this system. A dispersion region, related to the relaxation of water molecules in the clathrate structure, is characterized by a "static" dielectric constant and an activation energy about half as large as the corresponding values for ice, and by a limiting high-frequency dielectric constant of about 7 at 200° K. The magnitude of the latter is attributed to orientation of acetone molecules within the larger cavities of the hydrate structure.

Spatial Scale Interactions and Visual-Tracking Performance

Perception ◽  
1997 ◽  
Vol 26 (8) ◽  
pp. 1047-1058 ◽  
Author(s):  
Howard C Hughes ◽  
David M Aronchick ◽  
Michael D Nelson
Keyword(s):  
Spatial Frequency ◽  
High Frequency ◽  
Visual Information ◽  
Low Frequency ◽  
High Spatial Frequency ◽  
Performance Measure ◽  
High Frequency Component ◽  
Stimulus Velocity ◽  
Spatial Frequencies ◽  
Wide Range

It has previously been observed that low spatial frequencies (≤ 1.0 cycles deg−1) tend to dominate high spatial frequencies (≥ 5.0 cycles deg−1) in several types of visual-information-processing tasks. This earlier work employed reaction times as the primary performance measure and the present experiments address the possibility of low-frequency dominance by evaluating visually guided performance of a completely different response system: the control of slow-pursuit eye movements. Slow-pursuit gains (eye velocity/stimulus velocity) were obtained while observers attempted to track the motion of a sine-wave grating. The drifting gratings were presented on three types of background: a uniform background, a background consisting of a stationary grating, or a flickering background. Low-frequency dominance was evident over a wide range of velocities, in that a stationary high-frequency component produced little disruption in the pursuit of a drifting low spatial frequency, but a stationary low frequency interfered substantially with the tracking of a moving high spatial frequency. Pursuit was unaffected by temporal modulation of the background, suggesting that these effects are due to the spatial characteristics of the stationary grating. Similar asymmetries were observed with respect to the stability of fixation: active fixation was less stable in the presence of a drifting low frequency than in the presence of a drifting high frequency.

Required Data Collection Times for Steady and Quasi-steady Experiments

2017 ◽  
Author(s):  
Robert F. Roddy ◽  
David E. Hess
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Frequency Noise ◽  
Surface Ship ◽  
System A ◽  
Low Pass ◽  
Collection Period ◽  
Almost All ◽  
Low Pass Filters

One of the requirements in performing steady or quasi-steady experiments is the determination of adequate collection times so that the data will not be biased due to low frequency energy in the data stream. Since virtually all steady experiments run at DTMB have low pass filters in line with the signal conditioning, high frequency noise is not a consideration in determining the required collection times. At both EMB and DTMB almost all of the surface ship drag measurements were made using gravity type balances until about 1970. These balances used both springs and dampers to modify the natural frequency of the system so that a good average model drag could be determined in a 5-6 sec collection period. Submarine model experiments began using block gages to measure drag beginning in the late 1950's. For these experiments crude methods were used to damp the output data but, to the author’s knowledge, no methods were ever put into place that was analogous to the springs and damper system. A method for determining the required collection times for any steady or quasi-steady experiment is presented along with sample cases showing the necessity for, and the utility of, using such a method.

Enhancing the Weak Signal With Arbitrary High-Frequency by Vibrational Resonance in Fractional-Order Duffing Oscillators

2017 ◽  
Vol 12 (5) ◽  
Author(s):  
J. H. Yang ◽  
Miguel A. F. Sanjuán ◽  
H. G. Liu
Keyword(s):  
Fractional Order ◽  
High Frequency ◽  
Low Frequency ◽  
Original System ◽  
Scale Transformation ◽  
Weak Signal ◽  
Vibrational Resonance ◽  
High Frequency Signal ◽  
System A ◽  
Auxiliary Signal

When the traditional vibrational resonance (VR) occurs in a nonlinear system, a weak character signal is enhanced by an appropriate high-frequency auxiliary signal. Here, for the harmonic character signal case, the frequency of the character signal is usually smaller than 1 rad/s. The frequency of the auxiliary signal is dozens of times of the frequency of the character signal. Moreover, in the real world, the characteristic information is usually indicated by a weak signal with a frequency in the range from several to thousands rad/s. For this case, the weak high-frequency signal cannot be enhanced by the traditional mechanism of VR, and as such, the application of VR in the engineering field could be restricted. In this work, by introducing a scale transformation, we transform high-frequency excitations in the original system to low-frequency excitations in a rescaled system. Then, we make VR to occur at the low frequency in the rescaled system, as usual. Meanwhile, the VR also occurs at the frequency of the character signal in the original system. As a result, the weak character signal with arbitrary high-frequency can be enhanced. To make the rescaled system in a general form, the VR is investigated in fractional-order Duffing oscillators. The form of the potential function, the fractional order, and the reduction scale are important factors for the strength of VR.

Effect of repetitive visual stimuli on behaviour and plasma corticosterone of European starlings

2005 ◽  
Vol 55 (3) ◽  
pp. 245-258 ◽  
Author(s):  
◽  
◽  
◽  
Keyword(s):  
Spatial Frequency ◽  
High Frequency ◽  
Temporal Frequency ◽  
Low Frequency ◽  
High Spatial Frequency ◽  
Plasma Corticosterone ◽  
European Starlings ◽  
Fluorescent Lamps ◽  
Spatial Frequencies ◽  
Temporal And Spatial

AbstractFlickering light can cause adverse effects in some humans, as can rhythmic spatial patterns of particular frequencies. We investigated whether birds react to the temporal frequency of standard 100 Hz fluorescent lamps and the spatial frequency of the visual surround in the manner predicted by the human literature, by examining their effects on the preferences, behaviour and plasma corticosterone of European starlings (Sturnus vulgaris). We predicted that high frequency lighting (> 30 kHz) and a relatively low spatial frequency on the walls of their cages (0.1 cycle cm−1) would be less aversive than low frequency lighting (100 Hz) and a relatively high spatial frequency (2.5 cycle cm−1). Birds had strong preferences for both temporal and spatial frequencies. These preferences did not always fit with predictions, although there was evidence that 100 Hz was more stressful than 30 kHz lighting, as birds were less active and basal corticosterone levels were higher under 100 Hz lighting. Our chosen spatial frequencies had no overall significant effect on corticosterone levels. Although there are clearly effects of, and interactions between, the frequency of the light and the visual surround on the behaviour and physiology of birds, the pattern of results is not straightforward.

Global Precedence, Spatial Frequency Channels, and the Statistics of Natural Images

1996 ◽  
Vol 8 (3) ◽  
pp. 197-230 ◽  
Author(s):  
Howard C. Hughes ◽  
George Nozawa ◽  
Frederick Kitterle
Keyword(s):  
Spatial Frequency ◽  
High Frequency ◽  
Reaction Times ◽  
Low Frequency ◽  
Natural Images ◽  
Visual Pattern ◽  
Pattern Perception ◽  
Global Precedence ◽  
Processing Times ◽  
Spatial Frequencies

A great deal of evidence suggests that early in processing, retinal images are filtered by parallel, spatial frequency selective channels. We attempt to incorporate this view of early vision with the principle of global precedence, which holds that Gestalt-like processes sensitive to global image configurations tend to dominate local feature processing in human pattern perception. Global precedence is inferred from the pattern of reaction times observed when visual patterns contain multiple cues at different levels of spatial scale. Specifically, it is frequently observed that global processing times are largely unaffected by conflicting local cues, but local processing times are substantially lengthened by conflicting global cues. The asymmetry of these effects suggests the dominant role of global configurations. Since global spatial information is effectively represented by low spatial frequencies, global precedence potentially implies a low frequency dominance. The thesis is that low spatial frequencies tend to be available before information carried by higher frequency bands, producing a coarse-to-fine temporal order in visual spatial perception. It is suggested that a variety of factors contribute to the “prior entry” of low frequency information, including the high contrast gain of the magnocellular pathway, the amplitude spectra typical of natural images, and inhibitory interactions between the parallel frequency-tuned channels. Evidence suggesting a close relationship between global precedence and spatial frequency channels is provided by observations that the essential features of the global precedence effect are obtained using patterns consisting of low and high frequency sinusoids. The hypothesis that these asymmetric interference effects are due to interactions between parallel spatial channels is supported by an analysis of reaction times (RTs), which shows that RTs to redundant low and high frequency cues produce less facilitation than predictions that assume the channels are independent. In view of previous work showing that global precedence depends upon the low frequency content of the stimuli, we suggest that low spatial frequencies represent the sine qua non for the dominance of configurational cues in human pattern perception, and that this configurational dominance reflects the microgenesis of visual pattern perception. This general view of the temporal dynamics of visual pattern recognition is discussed, is considered from an evolutionary perspective, and is related to certain statistical regularities in natural scenes. Potential adaptive advantages of an interactive parallel architecture that confers an initial processing advantage to low resolution information are explored.

scholarly journals Psychophysical evidence for distinct contributions in processing low and high spatial frequencies of fearful facial expressions in backward masking task

2012 ◽  
Vol 43 (3) ◽  
pp. 167-172
Author(s):  
Remigiusz Szczepanowski ◽  
Agata Sobków
Keyword(s):  
Facial Expressions ◽  
High Frequency ◽  
Present Report ◽  
Low Frequency ◽  
Conscious Awareness ◽  
Backward Masking ◽  
Emotional Faces ◽  
Fearful Faces ◽  
Spatial Frequencies ◽  
Conscious Processing

The present report examined the hypothesis that two distinct visual routes contribute in processing low and high spatial frequencies of fearful facial expressions. Having the participants presented with a backwardly masked task, we analyzed conscious processing of spatial frequency contents of emotional faces according to both objective and subjective taskrelevant criteria. It was shown that fear perception in the presence of the low-frequency faces can be supported by stronger automaticity leading to less false positives. In contrary, the detection of high-frequency fearful faces was more likely supported by conscious awareness leading to more true positives.

scholarly journals Electric and Acoustic Stimulation in Cochlear Implant Recipients with Hearing Preservation

2018 ◽  
Vol 39 (04) ◽  
pp. 414-427 ◽  
Author(s):  
Christopher Welch ◽  
Margaret Dillon ◽  
Harold Pillsbury
Keyword(s):  
Hearing Loss ◽  
Speech Perception ◽  
Cochlear Implant ◽  
Hearing Aids ◽  
High Frequency ◽  
Low Frequency ◽  
Hearing Preservation ◽  
The United States ◽  
Acoustic Stimulation ◽  
Electric Hearing

AbstractHearing loss affects 30 million people in the United States, and a subset of these patients have normal low-frequency hearing and ski-sloped high-frequency hearing loss. For these patients, hearing aids alone may not provide adequate benefit. Cochlear implantation alone has been utilized to improve speech perception. The addition of high-frequency electric hearing to low-frequency acoustic hearing in these patients is beneficial. Technical improvements have allowed preservation of low-frequency hearing in cochlear implant recipients, allowing for electric and acoustic stimulation in the same ear with significant improvements in speech perception, sound localization, music appreciation, and quality of life.

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