Visual Information and Skill Level in Time-To-Collision Estimation

Perception ◽  
1988 ◽  
Vol 17 (5) ◽  
pp. 623-632 ◽  
Author(s):  
Viola Cavallo ◽  
Michel Laurent
Keyword(s):  
Visual Field ◽  
Visual Information ◽  
Peripheral Vision ◽  
Skill Level ◽  
Viewing Time ◽  
Distance Information ◽  
Driving Experience ◽  
Time To Collision ◽  
The Subject ◽  
The Moment

Previous studies on the visual origin of time-to-collision ( Tc) information have demonstrated that Tc estimates can be based solely on the processing of target expansion rate (optic variable τ). But in the simulated situations used (film clips), there was little reliable information on speed (owing to reduced peripheral vision) and distance (owing to the absence of binocular distance cues) available. In order to determine whether these kinds of information are also taken into account, it is necessary to take an approach where the subject receives a more complete visual input. Thus, an experiment conducted on a circuit under actual driving conditions is reported. Experienced drivers and beginners, who were passengers in a car, had to indicate the moment they expected a collision with a stationary obstacle to take place. Subjects were blindfolded after a viewing time of 3 s. The conditions for speed evaluation (normal versus restricted visual field) and distance evaluation (binocular versus monocular vision) by subjects were varied. The approach speed (30 and 90 km h−1) and actual Tc (3 and 6 s) were also varied. The results show that accuracy of Tc estimation increased with (i) normal visual field, (ii) binocular vision, (iii) higher speeds, and (iv) driving experience. These findings have been interpreted as indicating that both speed and distance information are taken into account in Tc estimation. They suggest furthermore that these two kinds of information may be used differently depending on the skill level of the subject. The results are discussed in terms of the complementarity of the various potentially usable visual means of obtaining Tc information.

Spatial Localization under Conflict Conditions: Is There a Single Explanation?

Perception ◽  
1979 ◽  
Vol 8 (3) ◽  
pp. 323-337 ◽  
Author(s):  
David H Warren
Keyword(s):  
Visual Field ◽  
Visual Information ◽  
Spatial Localization ◽  
Visual Dominance ◽  
Auditory Target ◽  
Proprioceptive Information ◽  
Target Information ◽  
Conflict Situations ◽  
The Subject

Visual–auditory (VA) and visual–proprioceptive (VP) localization conflict paradigms were varied to explore the comparability of the conflict situations. In experiment 1 various attempts were made to decrease the dominance of visual information over proprioceptive and auditory target information. Pairing auditory with proprioceptive information against conflicting visual information did not lessen the visual dominance, nor did dimming the visual field. A ‘cognitive’ manipulation, in which the subject was led to doubt the reliability of the visual information, reduced visual dominance over audition but not visual dominance over proprioception. This difference between the two conflict situations was further explored and corroborated in experiment 2. In experiment 3 no attempt was made to lead the subject to believe that paired discrepant targets were related, and the visual dominance of audition was strong while the visual dominance of proprioception did not occur. The apparent differences between the VA and the VP conflict situations are discussed with regard to the feasibility of generating a unitary explanation of localization conflict results. Several further factors are discussed that must be explored before undertaking such a unitary formulation.

Estimation of Time to Vehicle Arrival—Effects of Age on Use of Available Visual Information

Perception ◽  
1994 ◽  
Vol 23 (8) ◽  
pp. 947-955 ◽  
Author(s):  
Errol R Hoffmann
Keyword(s):  
Visual Information ◽  
Age Groups ◽  
Time Estimation ◽  
Threshold Value ◽  
Viewing Time ◽  
Fully Integrated ◽  
Vehicle Velocity ◽  
Significant Difference ◽  
Movement Distance ◽  
The Subject

Subjects estimated time of vehicle arrival while viewing twenty-four film clips of an approaching vehicle, half with a constant viewing time of 4.2 s and half with a constant vehicle-movement distance of 40 m. The distances from the subject at which the film ended were 20, 60, and 100 m. Speeds of approach varied between 7.45 and 15.44 ms−1. Performance was strongly dependent on age of the subject. Subjects in the 5-6-year-old group made estimates based on the distance of the vehicle; at 7 – 8 years an interaction between the effects of distance and velocity appeared and for 9–10-year-olds there was a main effect of the vehicle velocity. Only for adults was the information from distance and velocity fully integrated. There was no significant difference between males and females for any of the age groups. Performance of adults was very similar to that reported by other authors in that subjects underestimated the time to arrival of the vehicle, with estimated times about 60% of the actual times. Standard deviations of the estimated times were such that a small percentage of subjects overestimated times and hence would have caused a collision if they had proceeded with a crossing. The mechanism of time estimation was strongly dependent on the angular velocity of the vehicle subtended at the eye of the observer. This must exceed a threshold value of about 0.002 rad s_1 (adults) if a linear relationship between estimated and actual times is to be obtained.

The Effect of a Central Task on Luminance Thresholds for Peripherally Presented Stimuli

1969 ◽  
Vol 11 (4) ◽  
pp. 387-391 ◽  
Author(s):  
H. W. Leibowitz ◽  
Stuart Appelle
Keyword(s):  
Visual Field ◽  
Peripheral Vision ◽  
Control Group ◽  
Threshold Values ◽  
Fixation Light ◽  
Central Task ◽  
Steady Fixation ◽  
Luminance Threshold ◽  
The Subject

The effect of a central task on peripheral vision was investigated by obtaining luminance thresholds for stimuli presented from 20° to 90° in the periphery. A control group observed a steady foveal fixation light. For the two experimental groups, the fixation light was interrupted periodically and the subject was required to maintain illumination of the light by pressing a button. Interruption rates of 15 and 53 times per minute were investigated. The control condition with the steady fixation light produced the lowest thresholds. For the interrupted conditions, thresholds were higher for the near periphery but differences disappeared in the far periphery. Luminance threshold values were generally highest for the 15-per-minute interrupted group. The results are interpreted as reflecting the effect of an attention-demanding central task on the size of the functional visual field.

Crimes against marriage and family before Criminal Code 1968

2020 ◽  
Vol 15 (1-3) ◽  
pp. 44-59
Author(s):  
Lidia Peneva
Keyword(s):  
Criminal Code ◽  
Point Of View ◽  
Marriage And Family ◽  
Historical Method ◽  
Legal Method ◽  
The Subject ◽  
The Republic ◽  
Criminal Groups ◽  
The Moment ◽  
Structural Point

Crimes against marriage and family are a particular group of social relation­ships that the law has defended properly in view of the high public significance and value they enjoy. At the moment they are regulated in Chapter VI, Section I, of the specific part of the Penal Code the Repub­lic of Bulgaria. The subject matter of this Statement will, however, be the legisla­tive provisions concerning these criminal­ized acts in retrospect. The purpose of the study is to show by historical method and through the comparatively legal method the development of these criminal groups during the periods of various criminal laws in Bulgaria. This will also provide a basis for reflection on possible de lege ferenda proposals. This report from a structural point of view will be divided into three distinct points, marking each of the penal laws in the Republic of Bulgaria, which were in force before 1968.

scholarly journals Cartilage Injuries and Posttraumatic Osteoarthritis in the Wrist: A Review

Cartilage ◽  
2021 ◽  
pp. 194760352110219
Author(s):  
Jonny K. Andersson ◽  
Elisabet Hagert ◽  
Mats Brittberg
Keyword(s):  
Literature Review ◽  
Radius Fractures ◽  
Osteochondral Autograft ◽  
Posttraumatic Osteoarthritis ◽  
Osteochondral Repair ◽  
Chondrocyte Implantation ◽  
Cartilage Injuries ◽  
The Subject ◽  
The Moment ◽  
And Cartilage

Objective: Focal cartilage injuries, and posttraumatic osteoarthritis (OA) in the wrist are likely common and a cause of wrist pain. To estimate the incidence of cartilage lesions and to understand the pathomechanisms leading to wrist cartilage injuries and OA, a literature review on the subject was performed combined with a presentation of one of the authors’ own experience. Design: This study includes a literature review of the topic. As a comparison to the review findings, the observations of one of the authors’ consecutive 48 wrist arthroscopies, were assessed. PubMed, Scholar, and Cochrane databases were searched using the keywords “cartilage injury AND wrist AND treatment” and “wrist AND cartilage AND chondral AND osteochondral AND degenerative OA.” :Result A total of 11 articles, including 9 concerning chondral and osteochondral repair and treatment and 2 regarding posttraumatic OA, were retrieved. The cartilage repair treatments used in these articles were drilling, osteochondral autograft, juvenile articular cartilage allograft, and chondrocyte implantation. One article displayed concomitant cartilage injuries in displaced distal radius fractures in 32% of the patients. The review of our findings from a 1-year cohort of wrist arthroscopies showed 17% cartilage injuries. Conclusion: There is a lack of knowledge in current literature on cartilage injuries and treatment, as well as posttraumatic OA in the wrist. Cartilage injuries appear to be common, being found in 17% to 32% of all wrist arthroscopies after trauma, but no guidelines regarding conservative or surgical treatment can be recommended at the moment. Larger prospective comparative studies are needed.

scholarly journals What do patients with glaucoma see: a novel iPad app to improve glaucoma patient awareness of visual field loss

2020 ◽  
pp. bjophthalmol-2020-317034
Author(s):  
Meghal Gagrani ◽  
Jideofor Ndulue ◽  
David Anderson ◽  
Sachin Kedar ◽  
Vikas Gulati ◽  
...  
Keyword(s):  
Visual Field ◽  
Vision Loss ◽  
Peripheral Vision ◽  
Glaucoma Patient ◽  
Visual Field Loss ◽  
Sensitivity Threshold ◽  
Roc Curve Analysis ◽  
The Mean ◽  
Ipad App ◽  
Field Defects

PurposeGlaucoma patients with peripheral vision loss have in the past subjectively described their field loss as ‘blurred’ or ‘no vision compromise’. We developed an iPad app for patients to self-characterise perception within areas of glaucomatous visual field loss.MethodsTwelve glaucoma patients with visual acuity ≥20/40 in each eye, stable and reliable Humphrey Visual Field (HVF) over 2 years were enrolled. An iPad app (held at 33 cm) allowed subjects to modify ‘blur’ or ‘dimness’ to match their perception of a 2×2 m wall-mounted poster at 1 m distance. Subjects fixated at the centre of the poster (spanning 45° of field from centre). The output was degree of blur/dim: normal, mild and severe noted on the iPad image at the 54 retinal loci tested by the HVF 24-2 and was compared to threshold sensitivity values at these loci. Monocular (Right eye (OD), left eye (OS)) HVF responses were used to calculate an integrated binocular (OU) visual field index (VFI). All three data sets were analysed separately.Results36 HVF and iPad responses from 12 subjects (mean age 71±8.2y) were analysed. The mean VFI was 77% OD, 76% OS, 83% OU. The most common iPad response reported was normal followed by blur. No subject reported dim response. The mean HVF sensitivity threshold was significantly associated with the iPad response at the corresponding retinal loci (For OD, OS and OU, respectively (dB): normal: 23, 25, 27; mild blur: 18, 16, 22; severe blur: 9, 9, 11). On receiver operative characteristic (ROC) curve analysis, the HVF retinal sensitivity cut-off at which subjects reported blur was 23.4 OD, 23 OS and 23.3 OU (dB).ConclusionsGlaucoma subjects self-pictorialised their field defects as blur; never dim or black. Our innovation allows translation of HVF data to quantitatively characterise visual perception in patients with glaucomatous field defects.

Computerized color perimetry in multiple sclerosis

1998 ◽  
Vol 4 (2) ◽  
pp. 79-84 ◽  
Author(s):  
N Accornero ◽  
S Rinalduzzi ◽  
M Capozza ◽  
E Millefiorini ◽  
G C Filligoi ◽  
...  
Keyword(s):  
Visual Field ◽  
Statistical Difference ◽  
Cost Effective ◽  
Quantitative Information ◽  
Field Analysis ◽  
Visual Field Defects ◽  
Highly Sensitive ◽  
The Subject ◽  
Color Perimetry ◽  
Field Defects

Color visual field analysis has proven highly sensitive for early visual impairments diagnosis in MS, yet it has never attained widespread popularity usually because the procedure is difficult to standardize, the devices are costly, and the test is fatiguing. We propose a computerized procedure running on standard PC, cost effective, clonable, and easy handled. Two hundred and sixty-four colored patches subtending 18 angle of vision, with selected hues and low saturation levels are sequentially and randomly displayed on gray equiluminous background of the PC screen subtending 2486408 angle of vision. The subject is requested to press a switch at the perception of the stimulus. The output provides colored maps with quantitative information. Comparison between normals and a selected population of MS patients with no actual luminance visual field defects, showed high statistical difference.

Visual Anticipatory Information Modulates Multisensory Interactions of Artificial Audiovisual Stimuli

2010 ◽  
Vol 22 (7) ◽  
pp. 1583-1596 ◽  
Author(s):  
Jean Vroomen ◽  
Jeroen J. Stekelenburg
Keyword(s):  
Visual Information ◽  
Speech Sound ◽  
Human Action ◽  
Visual Signal ◽  
Multisensory Interactions ◽  
Temporal Occurrence ◽  
Audiovisual Stimuli ◽  
The Moment ◽  
Integrative Processing ◽  
Audiovisual Interaction

The neural activity of speech sound processing (the N1 component of the auditory ERP) can be suppressed if a speech sound is accompanied by concordant lip movements. Here we demonstrate that this audiovisual interaction is neither speech specific nor linked to humanlike actions but can be observed with artificial stimuli if their timing is made predictable. In Experiment 1, a pure tone synchronized with a deformation of a rectangle induced a smaller auditory N1 than auditory-only presentations if the temporal occurrence of this audiovisual event was made predictable by two moving disks that touched the rectangle. Local autoregressive average source estimation indicated that this audiovisual interaction may be related to integrative processing in auditory areas. When the moving disks did not precede the audiovisual stimulus—making the onset unpredictable—there was no N1 reduction. In Experiment 2, the predictability of the leading visual signal was manipulated by introducing a temporal asynchrony between the audiovisual event and the collision of moving disks. Audiovisual events occurred either at the moment, before (too “early”), or after (too “late”) the disks collided on the rectangle. When asynchronies varied from trial to trial—rendering the moving disks unreliable temporal predictors of the audiovisual event—the N1 reduction was abolished. These results demonstrate that the N1 suppression is induced by visual information that both precedes and reliably predicts audiovisual onset, without a necessary link to human action-related neural mechanisms.

Apparent Velocity of Motion Aftereffects in Central and Peripheral Vision

Perception ◽  
1986 ◽  
Vol 15 (5) ◽  
pp. 603-612 ◽  
Author(s):  
Michael J Wright
Keyword(s):  
Visual Field ◽  
Time Course ◽  
Peripheral Vision ◽  
Temporal Frequency ◽  
Motion Aftereffect ◽  
Apparent Velocity ◽  
Real Motion ◽  
Temporal Decay ◽  
Spatial Grain ◽  
Motion Aftereffects

Adapting to a drifting grating (temporal frequency 4 Hz, contrast 0.4) in the periphery gave rise to a motion aftereffect (MAE) when the grating was stopped. A standard unadapted foveal grating was matched to the apparent velocity of the MAE, and the matching velocity was approximately constant regardless of the visual field position and spatial frequency of the adapting grating. On the other hand, when the MAE was measured by nulling with real motion of the test grating, nulling velocity was found to increase with eccentricity. The nulling velocity was constant when scaled to compensate for changes in the spatial ‘grain’ of the visual field. Thus apparent velocity of MAE is constant across the visual field, but requires a greater velocity of real motion to cancel it in the periphery. This confirms that the mechanism underlying MAE is spatially-scaled with eccentricity, but temporally homogeneous. A further indication of temporal homogeneity is that when MAE is tracked, by matching or by nulling, the time course of temporal decay of the aftereffect is similar for central and for peripheral stimuli.

Emulsion Stability Evaluation Using Fractal Dimensions Approach

2007 ◽  
Vol 555 ◽  
pp. 177-182 ◽  
Author(s):  
Snezana Pašalić ◽  
P.B. Jovanić ◽  
B. Bugarski
Keyword(s):  
Visual Information ◽  
Emulsion Stability ◽  
Fractal Dimensions ◽  
Ccd Camera ◽  
Point Of View ◽  
Stable Region ◽  
Stability Evaluation ◽  
Water Emulsion ◽  
The Moment ◽  
Oil In Water Emulsion

There are many developed strategies for evaluating emulsion stability, aimed at determining the life circle of emulsions. Most of them are based on rheological properties of emulsions. There are, however, very few based on direct emulsion observations. In this paper we present a developed method for the emulsion stability evaluation by direct observation of optical emulsion properties. We propose the fractal dimension approach as a stability quantification measure. The method is based on the measure of emulsion transmittance properties, which are directly dependent on the emulsion stability at the moment of measurement. The oil in water emulsion was used as a test emulsion. The system is classified as stable emulsion and our intention was to find the moment when it starts to break. Emulsion transmittance properties were measure applying a system for acquisition of visual information, which is based on a CCD camera and a fast PC configuration equipped with the capturing software. The acquired sets of visual information were analyzed by the OZARIA software package. The fractal dimensions were determined by the box counting method. For these experiments, 100 boxes of different sizes were used. Experimental emulsions were measured after 7, 14, 21 and 28 days from the moment of creation. A slight increase in fractal dimensions was observed, which indicates that the emulsions are still in the stable region, or from the fractal point of view emulsion are still regular and no significant irregularities were observed. From the first experiments the applied methodology proved to be sensitive enough to be used for emulsions stability evaluation.

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