Figure and Ground in Space and Time: 2. Frequency, Velocity, and Perceptual Organization

Perception ◽  
1989 ◽  
Vol 18 (5) ◽  
pp. 639-648 ◽  
Author(s):  
Victor Klymenko ◽  
Naomi Weisstein
Keyword(s):  
Spatial Frequency ◽  
Temporal Frequency ◽  
Sine Wave ◽  
Stationary Condition ◽  
Velocity Difference ◽  
Lower Spatial Frequency ◽  
Spatial Frequencies ◽  
Spatiotemporal Tuning ◽  
Sine Wave Gratings ◽  
Ground Organization

The figure – ground organization of an ambiguous bipartite pattern in which the two regions of the pattern contained sine-wave gratings which differed in spatial frequency was examined for two pairs of spatial frequencies: 1 and 4 cycles deg−1, and 1 and 8 cycles deg−1. The region of higher spatial frequency underwent contrast reversal at one of four rates: 0, 3.75, 7.5, or 15 Hz. The region of lower spatial frequency was equated with either the temporal frequency or the velocity of the grating of higher spatial frequency in three sets of conditions: one stationary condition, three in which temporal frequency was equated, and three in which velocity was equated. For the 1 and 4 cycles deg−1 pair, the region of lower spatial frequency tended to be seen as the background a higher percentage of the time. There were significant linear trends for the appearance as background of the region of lower spatial frequency with respect to the magnitude of the velocity difference between the two regions of the pattern. The faster the 1 cycle deg−1 grating moved with respect to the 4 cycles deg−1 grating, the higher the percentage of the time it was seen as the ground. The results for the 1 and 8 cycles deg−1 pair were in some cases unexpected in that the 8 cycles deg−1 grating was seen as the ground behind the 1 cycle deg−1 grating even though it was of a higher spatial frequency and moved at a slower velocity. The spatiotemporal tuning of the visual system is discussed.

Figure and Ground in Space and Time: 1. Temporal Response Surfaces of Perceptual Organization

Perception ◽  
1989 ◽  
Vol 18 (5) ◽  
pp. 627-637 ◽  
Author(s):  
Victor Klymenko ◽  
Naomi Weisstein
Keyword(s):  
Spatial Frequency ◽  
Temporal Frequency ◽  
Sine Wave ◽  
Response Surfaces ◽  
Viewing Time ◽  
Temporal Response ◽  
Frequency Condition ◽  
Spatial Frequencies ◽  
Sine Wave Gratings ◽  
Ground Organization

The figure – ground organization of an ambiguous bipartite pattern can be manipulated by altering the temporal-frequency content of the two regions of the pattern. Ambiguous patterns in which the two regions of each pattern contained sine-wave gratings of either 8, 4, 1, or 0.5 cycles deg−1 undergoing contrast reversal at rates of 0, 3.75, 7.5, or 15 Hz were tested for figure–ground organization under conditions of equated space-averaged and time-averaged luminance and perceived contrast. All combinations of temporal-frequency differences between the two regions were tested at each spatial frequency. The data are reported for two levels of temporal resolution (15 and 30 s). The pattern region with the relatively higher temporal frequency tended to be seen as the background a higher percentage of the viewing time. There were significant linear trends for the appearance as background of the region of higher temporal frequency with respect to the magnitude of the temporal-frequency difference between the two regions of each pattern for all spatial frequencies and data intervals except the final 15 s interval of the lowest (0.5 cycle deg−1) spatial-frequency condition.

Temporal and Spatial Frequency Tuning of the Flicker Motion Aftereffect

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 12-12
Author(s):  
P J Bex ◽  
F A J Verstraten ◽  
I Mareschal
Keyword(s):  
Spatial Frequency ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Motion Aftereffect ◽  
Sine Wave ◽  
Test Grating ◽  
Spatial Frequency Tuning ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Sine Wave Gratings

The motion aftereffect (MAE) was used to study the temporal-frequency and spatial-frequency selectivity of the visual system at suprathreshold contrasts. Observers adapted to drifting sine-wave gratings of a range of spatial and temporal frequencies. The magnitude of the MAE induced by the adaptation was measured with counterphasing test gratings of a variety of spatial and temporal frequencies. Independently of the spatial or temporal frequency of the adapting grating, the largest MAE was found with slowly counterphasing test gratings (∼0.125 – 0.25 Hz). For slowly counterphasing test gratings (<∼2 Hz), the largest MAEs were found when the test grating was of similar spatial frequency to that of the adapting grating, even at very low spatial frequencies (0.125 cycle deg−1). However, such narrow spatial frequency tuning was lost when the temporal frequency of the test grating was increased. The data suggest that MAEs are dominated by a single, low-pass temporal-frequency mechanism and by a series of band-pass spatial-frequency mechanisms at low temporal frequencies. At higher test temporal frequencies, the loss of spatial-frequency tuning implicates separate mechanisms with broader spatial frequency tuning.

Short-Term Memory for Speed

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 156-156
Author(s):  
P Thompson ◽  
R Stone ◽  
E Walton
Keyword(s):  
Spatial Frequency ◽  
Short Term Memory ◽  
Temporal Frequency ◽  
Frequency Discrimination ◽  
Sine Wave ◽  
Short Term ◽  
Term Memory ◽  
Visual Short Term Memory ◽  
Speed Discrimination ◽  
Sine Wave Gratings

We have measured the retention of information about stimulus speed in visual short-term memory by measuring speed discrimination in a two-interval forced-choice task. We have also measured such discrimination in conditions where a ‘memory masker’ is presented during the interstimulus interval (ISI) in a fashion analogous to the experiment of Magnussen et al (1991 Vision Research31 1213 – 1219). Magnussen et al found that spatial frequency discrimination was disrupted when the mask had a spatial frequency that differed from the test spatial frequency by an octave or more. We have investigated the speed discrimination of 8 Hz, 1 cycle deg−1 drifting sine-wave gratings with the following drifting masks presented in the ISI: (i) 8 Hz 1 cycle deg−1, same direction as the test; (ii) 8 Hz, 8 cycles deg−1, opposite direction to the test; (iii) 8 Hz, 8 cycles deg−1, same direction as the test; (iv) 24 Hz, 3 cycles deg−1, same direction as the test. These masks were chosen to investigate whether the temporal frequency, the spatial frequency, the speed, or the direction of motion of the mask affected retention. We found that in none of these conditions was the discrimination of the test gratings impaired significantly. This pattern of results is therefore different from that found with spatial frequency discrimination and suggests that, whatever mechanism is responsible for the retention of information about speed, it is different from that responsible for the retention of information about spatial frequency.

scholarly journals Is the DeVries-Rose to Weber Transition Empirically Possible with Sine-Wave Gratings?

2005 ◽  
Vol 8 (2) ◽  
pp. 113-118
Author(s):  
Miguel A. García-Pérez
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Light Level ◽  
Sine Wave ◽  
Retinal Illuminance ◽  
Visual Functioning ◽  
Photopic Vision ◽  
Spatial Frequencies ◽  
Grating Acuity ◽  
Sine Wave Gratings

Visual functioning at various retinal illuminance levels is usually measured either by determining grating acuity as a function of light level or by determining how sensitivity to sine-wave gratings changes with retinal illuminance. The former line of research has shown that grating acuity follows a two-branch relationship with retinal illuminance, with the point of discontinuity occurring at the transition from scotopic to photopic vision. Results of the latter line of research have summarily been described as a transition from the DeVries-Rose law to Weber's law, according to which log sensitivity increases linearly with log illuminance with a slope of 0.5 over a range of low illuminances (the DeVries-Rose range) and then levels off and does not increase with further increases of illuminance (the Weber range). This paper aims at determining the compatibility of the results of these two lines of research. We consider empirical constraints from data bearing on the shape of the surface describing contrast sensitivity to sine-wave gratings as a function of spatial frequency and illuminance simultaneously, in order to determine whether they are consistent with a summary description in terms of DeVries-Rose and Weber's laws. Our analysis indicates that, with sine-wave gratings, the DeVries-Rose law can only hold empirically at low spatial frequencies.

Pretectal Neurons Optimized for the Detection of Saccade-Like Movements of the Visual Image

2001 ◽  
Vol 85 (4) ◽  
pp. 1512-1521 ◽  
Author(s):  
N.S.C. Price ◽  
M. R. Ibbotson
Keyword(s):  
Spatial Frequency ◽  
Second Harmonic ◽  
Temporal Frequency ◽  
Receptive Fields ◽  
High Spatial Frequency ◽  
Sine Wave ◽  
Wide Field ◽  
Visual Response ◽  
High Contrast ◽  
Sine Wave Gratings

The visual response properties of nondirectional wide-field sensitive neurons in the wallaby pretectum are described. These neurons are called scintillation detectors (SD-neurons) because they respond vigorously to rapid, high contrast visual changes in any part of their receptive fields. SD-neurons are most densely located within a 1- to 2-mm radius from the nucleus of the optic tract, interspersed with direction-selective retinal slip cells. Receptive fields are monocular and cover large areas of the contralateral visual field (30–120°). Response sizes are equal for motion in all directions, and spontaneous activities are similar for all orientations of static sine-wave gratings. Response magnitude increases near linearly with increasing stimulus diameter and contrast. The mean response latency for wide-field, high-contrast motion stimulation was 43.4 ± 9.4 ms (mean ± SD, n = 28). The optimum visual stimuli for SD-neurons are wide-field, low spatial frequency (<0.2 cpd) scenes moving at high velocities (75–500°/s). These properties match the visual input during saccades, indicating optimal sensitivity to rapid eye movements. Cells respond to brightness increments and decrements, suggesting inputs from on and off channels. Stimulation with high-speed, low spatial frequency gratings produces oscillatory responses at the input temporal frequency. Conversely, high spatial frequency gratings give oscillations predominantly at the second harmonic of the temporal frequency. Contrast reversing sine-wave gratings elicit transient, phase-independent responses. These responses match the properties of Y retinal ganglion cells, suggesting that they provide inputs to SD-neurons. We discuss the possible role of SD-neurons in suppressing ocular following during saccades and in the blink or saccade-locked modulation of lateral geniculate nucleus activity to control retino-cortical information flow.

Spatial-Frequency Characteristics of Different Areas of Human Cortex

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 167-167
Author(s):  
A K Harauzov ◽  
Y E Shelepin ◽  
S V Pronin
Keyword(s):  
Spatial Frequency ◽  
Temporal Frequency ◽  
Receptive Fields ◽  
Occipital Lobe ◽  
Occipital Cortex ◽  
Normal Subjects ◽  
Sine Wave ◽  
Electrode System ◽  
Frequency Characteristics ◽  
Spatial Frequencies

We recorded visual evoked potentials in normal subjects from different areas of the occipital cortex, from the temporal and parietal lobes according to the ‘ten - twenty’ electrode system. Stimuli were black-and-white sine-wave gratings with eight different spatial frequencies in the range 0.45 to 14.4 cycles deg−1, presented at four different temporal frequencies (1, 2, 4, 8 Hz). Stimulation was either contrast-reversal or onset. VEPs were analysed both by component analysis and by Fourier transformation. Spatial characteristics were measured from the dependence of the amplitudes and latencies of the main response components (N1, P1, N2, P2) on the contrast and spatial frequency of the gratings. The characteristics obtained in the occipital lobe are in accordance with earlier experimental data [Regan, 1989 Human Electrophysiology (Amsterdam: Elsevier)]. When the temporal frequency of stimulation was increased, the maximum of the spatial-frequency curves shifted to lower spatial frequencies. However, we found differences in the spatial-frequency characteristics of different cortical areas. The results are discussed in terms of differences in the spatial and temporal tuning of the receptive fields of neurons in these areas.

The Dependence of Monocular Rivalry on Spatial Frequency

Perception ◽  
1973 ◽  
Vol 2 (2) ◽  
pp. 127-133 ◽  
Author(s):  
J Atkinson ◽  
F W Campbell ◽  
A Fiorentini ◽  
L Maffei
Keyword(s):  
Spatial Frequency ◽  
Sine Wave ◽  
Ambiguous Figures ◽  
Alternation Rate ◽  
Higher Harmonics ◽  
Square Wave ◽  
Sharp Edges ◽  
Harmonic Components ◽  
Sine Wave Gratings

The effect of change in spatial frequency on the alternation rate of two crossed gratings was measured. The rate was found to decrease with increase in spatial frequency, but to change only little with contrast. Low alternation rate was observed for crossed square-wave gratings compared to crossed sine-wave gratings; here the rate of rivalry is largely dependent upon the presence or absence of the first three harmonic components rather than the higher harmonics which contribute to the sharp edges of the square wave. The results are compared with those for some ambiguous figures.

Visual Persistence as a Function of Spatial Frequency and Age

Perception ◽  
1980 ◽  
Vol 9 (5) ◽  
pp. 529-532 ◽  
Author(s):  
William Lovegrove ◽  
Margaret Heddle
Keyword(s):  
Spatial Frequency ◽  
Age Groups ◽  
Sine Wave ◽  
Visual Persistence ◽  
Sine Wave Gratings

Duration of visual persistence for sine-wave gratings of 1, 2, 4, 8, 12, and 16 cycles deg−1 was determined for seven-year-old, ten-year-old, and thirteen-year-old children. It was found that there was a decrease in persistence duration with age but the slope of this function for the different age groups did not change.

scholarly journals Spatiotemporal Properties of Fast and Slow Neurons in the Pretectal Nucleus Lentiformis Mesencephali in Pigeons

2000 ◽  
Vol 84 (5) ◽  
pp. 2529-2540 ◽  
Author(s):  
Douglas R. W. Wylie ◽  
Nathan A. Crowder
Keyword(s):  
Temporal Frequency ◽  
Receptive Fields ◽  
Sine Wave ◽  
Accessory Optic System ◽  
Stimulus Velocity ◽  
Preferred Direction ◽  
Pretectal Nucleus ◽  
Contralateral Eye ◽  
Sine Wave Gratings ◽  
Self Motion

Neurons in the pretectal nucleus lentiformis mesencephali (LM) are involved in the analysis of optic flow that results from self-motion. Previous studies have shown that LM neurons have large receptive fields in the contralateral eye, are excited in response to largefield stimuli moving in a particular (preferred) direction, and are inhibited in response to motion in the opposite (anti-preferred) direction. We investigated the responses of LM neurons to sine wave gratings of varying spatial and temporal frequency drifting in the preferred and anti-preferred directions. The LM neurons fell into two categories. “Fast” neurons were maximally excited by gratings of low spatial [0.03–0.25 cycles/° (cpd)] and mid-high temporal frequencies (0.5–16 Hz). “Slow” neurons were maximally excited by gratings of high spatial (0.35–2 cpd) and low-mid temporal frequencies (0.125–2 Hz). Of the slow neurons, all but one preferred forward (temporal to nasal) motion. The fast group included neurons that preferred forward, backward, upward, and downward motion. For most cells (81%), the spatial and temporal frequency that elicited maximal excitation to motion in the preferred direction did not coincide with the spatial and temporal frequency that elicited maximal inhibition to gratings moving in the anti-preferred direction. With respect to motion in the anti-preferred direction, a substantial proportion of the LM neurons (32%) showed bi-directional responses. That is, the spatiotemporal plots contained domains of excitation in addition to the region of inhibition. Neurons tuned to stimulus velocity across different spatial frequency were rare (5%), but some neurons (39%) were tuned to temporal frequency. These results are discussed in relation to previous studies of the responses of neurons in the accessory optic system and pretectum to drifting gratings and other largefield stimuli.

Envelope-responsive neurons in areas 17 and 18 of cat

1994 ◽  
Vol 72 (5) ◽  
pp. 2134-2150 ◽  
Author(s):  
Y. X. Zhou ◽  
C. L. Baker
Keyword(s):  
Spatial Frequency ◽  
Cortical Neurons ◽  
Narrow Range ◽  
High Spatial Frequency ◽  
Sine Wave ◽  
Relative Strength ◽  
Visual Responses ◽  
Spatial Frequencies ◽  
Sensitivity Level ◽  
Areas 17 And 18

1. Single cortical neurons are known to respond to visual stimuli containing Fourier components only in a narrow range of spatial frequencies. This investigation demonstrates that some neurons in cat area 17 and 18 can also respond to certain stimuli that have no Fourier components inside the cell's luminance spatial frequency passband. 2. To study such “non-Fourier” responses, we used envelope stimuli that consisted of a high-spatial-frequency sinusoidal luminance grating (carrier) whose contrast was modulated by a low-spatial frequency sine wave (envelope). There was no Fourier component at the apparent periodicity of the envelope spatial frequency. However, some cells responded to such a “phantom” component of the envelope modulation when it fell inside the cell's luminance spatial frequency passband while all the real Fourier components in the stimuli were outside. 3. We conducted extensive control experiments to eliminate the possibility of producing artifactual responses to the envelope stimuli due to any small residual nonlinearity of the z-linearized CRT screen. The control experiments included 1) testing of screen linearity to ensure that the effect from the residual screen nonlinearity was no larger than the sensitivity level of visual responses and 2) comparing the responses to envelope stimuli with the responses to the equivalent contrast of the artifact produced by the screen nonlinearity. All these control experiments indicated that any effect of screen nonlinearity did not contribute significantly to the neural envelope responses. 4. We performed a statistical analysis to obtain an index of relative strength of envelope responses for each cell and to objectively classify cells as “envelope-responsive” or “non-envelope-responsive.”(ABSTRACT TRUNCATED AT 250 WORDS)

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