Binocular Utilization of Monocular Cues That are Undetectable Monocularly

Perception ◽  
1978 ◽  
Vol 7 (3) ◽  
pp. 315-322 ◽  
Author(s):  
Bela Julesz ◽  
Hans-Peter Oswald
Keyword(s):  
Eye Movements ◽  
Binocular Disparity ◽  
Detection Threshold ◽  
Density Difference ◽  
Latency Time ◽  
Wide Range ◽  
Random Dot Stereograms ◽  
Perception Time ◽  
Dot Density ◽  
Random Dot Stereogram

The latency time of tracking dynamic random-dot stereograms can be shortened by as much as 100 ms when monocular cues are added by introducing a difference in dot density between target and surround. It has been tacitly assumed that perception time will be reduced only if the added monocular cues are above the detection threshold for each eye. However, the experiments reported here clearly show that stereoscopic performance as measured by an eye tracking task can be greatly enhanced by added monocular cues that cannot be detected. Observers were instructed to track a suddenly displaced vertical bar (portrayed as a dynamic random-dot stereogram) while their eye movements were recorded by EOG. The bar had either a given binocular disparity or zero binocular disparity with respect to its surround. For the target with a disparity (in a wide range), the latency time of tracking decreased by more than 30 ms (10%) as density difference increased from 0 to 4%, whereas in the control conditions with no stereoscopic cues (zero disparity) subjects were unable to track the bar at all within that range of density difference. Thus stereopsis is greatly aided by minimal monocular cues that by themselves elude monocular detection.

scholarly journals First- and second-order contributions to depth perception in anti-correlated random dot stereograms

2018 ◽  
Author(s):  
Jordi M. Asher ◽  
Paul B. Hibbard
Keyword(s):  
Binocular Disparity ◽  
Second Order ◽  
Gap Size ◽  
Neural Responses ◽  
Random Dot Stereograms ◽  
Coarse Spatial Resolution ◽  
Correct Direction ◽  
Random Dot Stereogram ◽  
Circular Target ◽  
Detection Mechanisms

ABSTRACTThe binocular energy model of neural responses predicts that depth from binocular disparity might be perceived in the reversed direction when the contrast of dots presented to one eye is reversed. While reversed depth has been found using anti-correlated random-dot stereogram (ACRDS) the findings are inconsistent across studies. The mixed findings may be accounted for by the presence of a gap between the target and surround, or as a result of overlap of dots around the vertical edges of the stimuli. To test this, we assessed whether (1) the gap size (0, 19.2 or 38.4 arc min) (2) the correlation of dots or (3) the border orientation (circular target, or horizontal or vertical edge) affected the perception of depth. Reversed depth from ACRDS (circular no-gap condition) was seen by a minority of participants, but this effect reduced as the gap size increased. Depth was mostly perceived in the correct direction for ACRDS edge stimuli, with the effect increasing with the gap size. The inconsistency across conditions can be accounted for by the relative reliability of first- and second-order depth detection mechanisms, and the coarse spatial resolution of the latter.

A Nonspecific Learning Effect in the Perception of Random-Dot Stereograms?

Perception ◽  
1982 ◽  
Vol 11 (1) ◽  
pp. 93-95 ◽  
Author(s):  
John Weinman ◽  
Vicky Cooke
Keyword(s):  
Learning Effect ◽  
Prior Experience ◽  
Naive Group ◽  
Random Dot Stereograms ◽  
Perception Time ◽  
The Mean

An experiment is reported the object of which was to check whether a small amount of nonspecific experience in perceiving random-dot stereograms could facilitate the perception of a previously unseen stereogram. The mean stereopsis perception time of a group of totally naive subjects was found to be significantly slower than that of a group who had previously been shown two different stereograms. Closer inspection of the data showed that this difference was primarily due to approximately one third of the naive group who were much slower than the ‘experienced’ group. It is therefore suggested that nonspecific experience provides most initial help for relatively slow perceivers, since many naive subjects can perform as well as those with prior experience of other stereograms.

scholarly journals New particle formation in the sulfuric acid–dimethylamine–water system: reevaluation of CLOUD chamber measurements and comparison to an aerosol nucleation and growth model

2018 ◽  
Vol 18 (2) ◽  
pp. 845-863 ◽  
Author(s):  
Andreas Kürten ◽  
Chenxi Li ◽  
Federico Bianchi ◽  
Joachim Curtius ◽  
António Dias ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Detection Threshold ◽  
Sulfuric Acid Concentration ◽  
Water System ◽  
Particle Formation ◽  
New Particle Formation ◽  
Flow Tube ◽  
Aerosol Model ◽  
Wide Range ◽  
Good Agreement

Abstract. A recent CLOUD (Cosmics Leaving OUtdoor Droplets) chamber study showed that sulfuric acid and dimethylamine produce new aerosols very efficiently and yield particle formation rates that are compatible with boundary layer observations. These previously published new particle formation (NPF) rates are reanalyzed in the present study with an advanced method. The results show that the NPF rates at 1.7 nm are more than a factor of 10 faster than previously published due to earlier approximations in correcting particle measurements made at a larger detection threshold. The revised NPF rates agree almost perfectly with calculated rates from a kinetic aerosol model at different sizes (1.7 and 4.3 nm mobility diameter). In addition, modeled and measured size distributions show good agreement over a wide range of sizes (up to ca. 30 nm). Furthermore, the aerosol model is modified such that evaporation rates for some clusters can be taken into account; these evaporation rates were previously published from a flow tube study. Using this model, the findings from the present study and the flow tube experiment can be brought into good agreement for the high base-to-acid ratios (∼ 100) relevant for this study. This confirms that nucleation proceeds at rates that are compatible with collision-controlled (a.k.a. kinetically controlled) NPF for the conditions during the CLOUD7 experiment (278 K, 38 % relative humidity, sulfuric acid concentration between 1 × 106 and 3 × 107 cm−3, and dimethylamine mixing ratio of ∼ 40 pptv, i.e., 1 × 109 cm−3).

Visual responses of pulvinar and collicular neurons during eye movements of awake, trained macaques

1991 ◽  
Vol 66 (2) ◽  
pp. 485-496 ◽  
Author(s):  
D. L. Robinson ◽  
J. W. McClurkin ◽  
C. Kertzman ◽  
S. E. Petersen
Keyword(s):  
Eye Movements ◽  
Superior Colliculus ◽  
Visual Stimulation ◽  
Receptive Fields ◽  
Visual Responses ◽  
Stimulus Motion ◽  
Stimulus Movement ◽  
Pursuit Eye Movements ◽  
Extraretinal Signal ◽  
Wide Range

1. We recorded from single neurons in awake, trained rhesus monkeys in a lighted environment and compared responses to stimulus movement during periods of fixation with those to motion caused by saccadic or pursuit eye movements. Neurons in the inferior pulvinar (PI), lateral pulvinar (PL), and superior colliculus were tested. 2. Cells in PI and PL respond to stimulus movement over a wide range of speeds. Some of these cells do not respond to comparable stimulus motion, or discharge only weakly, when it is generated by saccadic or pursuit eye movements. Other neurons respond equivalently to both types of motion. Cells in the superficial layers of the superior colliculus have similar properties to those in PI and PL. 3. When tested in the dark to reduce visual stimulation from the background, cells in PI and PL still do not respond to motion generated by eye movements. Some of these cells have a suppression of activity after saccadic eye movements made in total darkness. These data suggest that an extraretinal signal suppresses responses to visual stimuli during eye movements. 4. The suppression of responses to stimuli during eye movements is not an absolute effect. Images brighter than 2.0 log units above background illumination evoke responses from cells in PI and PL. The suppression appears stronger in the superior colliculus than in PI and PL. 5. These experiments demonstrate that many cells in PI and PL have a suppression of their responses to stimuli that cross their receptive fields during eye movements. These cells are probably suppressed by an extraretinal signal. Comparable effects are present in the superficial layers of the superior colliculus. These properties in PI and PL may reflect the function of the ascending tectopulvinar system.

Assessing the Role of Vergence Changes in the Perception of Random-Dot Stereograms by Using Open-Loop Control of Vergence

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 131-131 ◽  
Author(s):  
B J Rogers ◽  
M F Bradshaw
Keyword(s):  
Open Loop ◽  
Open Loop Control ◽  
Complex Surfaces ◽  
Loop Control ◽  
Random Dot Stereograms ◽  
Disparity Range ◽  
The Difference ◽  
Random Dot Stereogram ◽  
University Of Chicago Press

The fact that the 3-D shape of surfaces depicted by random dot stereograms can take several seconds or even tens of seconds to appear has been attributed to the failure to make appropriate vergence changes [B Julesz, 1971 Foundations of Cyclopean Perception (Chicago, IL: University of Chicago Press)]. Alternatively, the long latencies could be a consequence of the processing time needed to match the disparate images. To distinguish between these possibilities we measured perceptual latencies in a situation in which vergence changes had no effect on retinal disparities. To do this, horizontal eye movements were recorded with the aid of close-fitting scleral search coils in both eyes and the difference signal used to shift horizontally the two halves of a random-dot stereogram by equal and opposite amounts. When the amount of shift was equal to the magnitude of the vergence change, changes of vergence had no effect on the pattern of disparities—open-loop vergence. Three observers were presented with a sequence of stereograms depicting both ‘simple’ surfaces (a single square lying in front of the surround) and ‘complex’ surfaces, including spirals, ‘wedding cakes’, and saddle shapes under both normal and open-loop conditions. Under open-loop conditions, the complete 3-D shape was never perceived when the disparity range of the stereogram was large (>40 min arc), demonstrating the necessity of vergence changes, but the 3-D structure of ‘complex’ surfaces did build up over a period of several seconds indicating a separate disparity processing limitation.

Activity of omnipause neurons in alert cats during saccadic eye movements and visual stimuli

1982 ◽  
Vol 47 (5) ◽  
pp. 827-844 ◽  
Author(s):  
C. Evinger ◽  
C. R. Kaneko ◽  
A. F. Fuchs
Keyword(s):  
Eye Movements ◽  
Smooth Pursuit ◽  
Visual Stimuli ◽  
Pause Duration ◽  
Visual Input ◽  
Transient Increase ◽  
Abducens Nucleus ◽  
Wide Range ◽  
Area Centralis ◽  
Omnipause Neurons

1. In the cats trained to follow a target spot with their eyes, activity was recorded from omnipause neurons (OPNs). OPNs discharge at a relatively high steady tonic rate (50-130 spikes/s) during visual fixation and smooth-pursuit eye movements but exhibit a complete cessation of discharge that begins before saccades in any direction. They are located in a compact region of the dorsal pontine tegmentum near the midline, just rostral to the abducens nucleus. 2. The average duration of the horizontal or vertical component of a saccade increases monotonically with pause duration, but a given pause duration is associated with a large range of individual saccade parameters and the timing of the pause, such as the latency from the pause onset to saccade onset or the interval from the maximum saccade velocity to the end of the pause, is no better. However, OPNs can be divided into two distinct groups on the basis of the timing of the pause relative to the parameters of the saccade. One group ceases discharging 32.4 +/- 4.6 ms, on average, before the saccade, while the second pauses 18.2 +/- 3.4 ms before the saccade. 3. Microstimulation at the site of OPNs affects the occurrence and trajectory of saccades but not smooth pursuit or fixation. Sustained electrical stimulation (20 micro A) lasting several seconds prevents the occurrence of saccades while brief trains (10-60 ms), timed to occur early in the saccade, interrupt it in midflight for the duration of the train. The latency to the interruption is about 26 ms. These data support the view that OPNs tonically inhibit the saccadic machinery between saccades and must be turned off to allow a saccade to occur. 4. Almost every (65 of 69) feline OPN exhibited a brief transient increase in activity for visual stimuli moving in any direction with a wide range of velocities. A moving 1 degree spot was generally more effective than a moving full-field, striped background. All units also showed a transient increase in firing when the spot was turned either on or off. Receptive fields plotted with the spot were greater than 250 deg2 and always included the area centralis. Two-thirds of the cells tested also responded to auditory stimuli. 5. Interaction between the excitatory visual input and the saccade-related pause was tested by comparing OPN activity and the saccadic trajectory during eye movements in the dark versus the light and by presenting brief flashes of light during a saccade. During saccades in the dark, the steady firing of OPNs was less than during saccades in the light. Only by stabilizing a flashed spot of light to occur on the area centralis at the beginning of the saccade was it possible to activate an OPN artificially to interrupt the saccade in midflight. Therefore, rather than being instrumental in specifically controlling the saccade trajectory, the visual input, along with the auditory and other sensory inputs, probably serves, under normal visual conditions, to help establish the tonic rate of OPNs. 6...

Reversed Visual Motion and Self-Sustaining Eye Oscillations

Perception ◽  
1997 ◽  
Vol 26 (7) ◽  
pp. 823-830 ◽  
Author(s):  
Lothar Spillmann ◽  
Stuart Anstis ◽  
Anne Kurtenbach ◽  
Ian Howard
Keyword(s):  
Eye Movements ◽  
Flow Field ◽  
Negative Feedback ◽  
Positive Feedback ◽  
Optic Flow ◽  
Visual Motion ◽  
Optokinetic Nystagmus ◽  
Retinal Images ◽  
Wide Range ◽  
Reversed Motion

A random-dot field undergoing counterphase flicker paradoxically appears to move in the same direction as head and eye movements, ie opposite to the optic-flow field. The effect is robust and occurs over a wide range of flicker rates and pixel sizes. The phenomenon can be explained by reversed phi motion caused by apparent pixel movement between successive retinal images. The reversed motion provides a positive feedback control of the display, whereas under normal conditions retinal signals provide a negative feedback. This altered polarity invokes self-sustaining eye movements akin to involuntary optokinetic nystagmus.

scholarly journals Stimulus Dependence of Disparity Coding in Primate Visual Area V4

2005 ◽  
Vol 93 (1) ◽  
pp. 620-626 ◽  
Author(s):  
Jay Hegdé ◽  
David C. Van Essen
Keyword(s):  
Binocular Disparity ◽  
Three Dimensional ◽  
Visual Area ◽  
Tuning Curves ◽  
Depth Cues ◽  
Area V4 ◽  
Random Dot Stereograms ◽  
Dimensional Shape ◽  
Visual Area V4 ◽  
Three Dimensional Shape

Disparity tuning in visual cortex has been shown using a variety of stimulus types that contain stereoscopic depth cues. It is not known whether different stimuli yield similar disparity tuning curves. We studied whether cells in visual area V4 of the macaque show similar disparity tuning profiles when the same set of disparity values were tested using bars or dynamic random dot stereograms, which are among the most commonly used stimuli for this purpose. In a majority of V4 cells (61%), the shape of the disparity tuning profile differed significantly for the two stimulus types. The two sets of stimuli yielded statistically indistinguishable disparity tuning profiles for only a small minority (6%) of V4 cells. These results indicate that disparity tuning in V4 is stimulus-dependent. Given the fact that bar stimuli contain two-dimensional (2-D) shape cues, and the random dot stereograms do not, our results also indicate that V4 cells represent 2-D shape and binocular disparity in an interdependent fashion, revealing an unexpected complexity in the analysis of depth and three-dimensional shape.

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