Results of Using Different Modes of Presentation of Stereostimuli in the Study of Stereo Vision in Normal Children and in Children with Non-Paralytic Strabismus without Functional Scotoma

The work is devoted to one of the actual problems of current ophthalmology — creating effective methods of studying stereovision.The purpose — comparative analysis of the capability of stereoperception under conditions of using different regimes of alternating presentation of stereo stimuli with different characteristics in children with strabismus and in children without ophthalmopathology.Patients and methods. 294 school children — 167 children of the control group (without ophthalmopathology) and 127 children with non-paralytic strabismus without functional scotoma (FSS) were observed. We used stereostimuli with different characteristics in the following regimes of presentation: 1) the regime of simple monocular alternating (alternate presentation of an image for the right and left eye); 2) the regime having an “empty” interval (black background) between monocular phases; 3) the regime having a binocular phase (a binocular image containing details corresponding to the stimuli for the right eye and the left eye) between monocular phases.Results. It was found that the majority of children with non-paralytic strabismus, who are incapable of stereoperception with the classic Fly-test and Lang-test, can perceive the stereoeffect with alternating presentation of stereostimuli within individual ranges of durations of monocular phases, a binocular phase and an “empty” interval. In children of the control group when switching from the simple alternation regime to the “empty” interval regime the maximal durations of monocular phases, which preserved the stereoeffect, decreased and when switching to the binocular phase regime they significantly increased. In children with strabismus linear images are simpler for stereoperception than random-dot images as well as in children of the control group (p < 0.001); stimuli creating the effect of the frontoparallel separation of details get perceived better than those creating the decline effect or the turning effect (p < 0.001); stimuli creating the effect of the vertical stripes decline get perceived better than those creating the effect of the horizontal stripes turning (p < 0.001). However, as opposed to the children of the control group, in children with strabismus the stereoeffect gets formed better under conditions of the peripheral localization of linear details than under conditions of the central one.Conclusion. Using computer programs with different regimes of alternating presentation of stereostimuli with certain characteristics allows to effectively evaluate individual capability of stereoperception which is necessary for the personalized approach to the selection of visual stimuli and stimuli presentation regimes in functional treatment of patients with non-paralytic strabismus.

Results of Using Alternating Presentation of Stereostimuli in Children with Functional Scotoma in Non-Paralytic Strabismus

The work is devoted to one of the actual problems of modern strabismology — the study of the ability to stereo perception in children with non-paralytic strabismus.Purpose: to study the capability to stereovision with alternating presentation of stereostimuli in children with functional scotoma in non-paralytic strabismus.Patients and methods. 113 children with functional scotoma (FS) in non-paralytic strabismus were observed. We used stereostimuli with different characteristics in the following regimes of presentation: 1) the regime of simple monocular alternating (alternate presentation of an image for the right eye and the left eye); 2) the regime having an “empty” interval (black background) between monocular phases; 3) the regime having a binocular phase (a binocular image containing details corresponding to the stimuli for the right eye and the left eye) between monocular phases.Results. It was found that in 23 (20,3 %) children, the ability to stereo perception was completely absent. All these children had stable total FS (monocular vision). In the remaining 90 children (with unstable or regional FS), the ability to stereo perception was shown with some stimuli in some modes of their alternating presentation. For stimuli with a central arrangement of linear parts, the stereo effect was possible when they were presented in an alternating mode with an “empty” interval lasting from 20 to 70 ms in combination with the duration of monocular phases from 30 to 90 ms. For stimuli with a peripheral arrangement of linear elements, 22.1 % of children were able to stereo perception not only in the “empty” interval mode, but also in the simple alternation mode. At the same time, the greatest number of children capable of stereo perception was detected when using the mode with an “empty” interval of 30–60 ms and a duration of monocular phases of 40–60 ms. With random-dot stimuli, none of the children in this group were capable of stereo perception.Conclusion. Our results suggest that even in patients with FS in non-paralytic strabismus, stereo perception is possible under the conditions of alternating presentation of stimuli with certain characteristics. In this case, the most likely appearance of a stereo effect with stimuli containing peripheral linear elements that create a stereo effect when presented in an alternating mode with an empty interval between monocular phases.

Filled-Duration Illusions

Data relevant to the ‘filled-duration illusion’, the claim that filled intervals appear to last longer than unfilled ones of the same real duration, are reviewed. A distinction is made between divided-time studies (where an empty interval has one or more than one brief dividing stimulus inside it) and filled-duration studies (where the filled intervals are filled with some continuous event). Divided durations appear to last longer than empty ones, and the effect grows with the number of dividers, although it may be restricted to short durations. The best current explanation appears to involve the weighted summation of the different subintervals of which the total duration is composed. When intervals with simple fillers are contrasted with empty ones, they are usually judged as longer, and the effect may grow as the intervals lengthen, at least over short duration ranges. When complex fillers are used, fillers usually have no effect on perceived duration or shorten it. A pacemaker-counter approach can account for some simple filler effects, and division of attention for complex filler effects. Although there are some exceptions, ‘filled-interval illusions’ of all these types are normally found, but some problems, such as questions about the relative perceived variability of filled and unfilled intervals, or stimulus order effects, merit further research.

Some Time Violations Go Less Noticed: Gestalt Grouping? A Brief Report

This brief report is inspired by Bolton’s (1894, Am. J. Psychol., 6, 145–238) tick-tock phenomenon, which describes an illusionary accented grouping of isochronous, non-accented click sequences. It has repeatedly been shown that in stimulus-wise grouped sequences of an XXXOOO character (where X differs from O in terms of intensity, pitch level, or filled or unfilled duration), gap deviations between groups are more prone to go unnoticed compared to deviations within a group (e.g., Fitzgibbons et al., 1974, Percept. Psychophys., 16, 522–528.). Yet, not much is known about whether comparable anisochrony insensitivities might also occur in equal-accented sequences (XXXXX). In a same/different task setting, listeners had to detect isochrony deviations that appeared in different empty-interval locations across 800 trials within a five-pulse sequence of 250 ms interonset intervals. Findings revealed a major location dependency, with least detection accuracy for gap deviations occurring in the last interval, particularly if the 250 ms gap was lengthened rather than shortened. Results are discussed in relation to potential Gestalt grouping and Nakajima et al.’s (2014, Perception, 33, 1061–1079) perceptual assimilation and contrast observations in three-tone sequences.

On topological properties of the set of maldistributed sequences

The real sequence (xn) is maldistributed if for any non-empty interval I, the set {n ∈𝕅 : xn ∈I} has upper asymptotic density 1. The main result of this note is that the set of all maldistributed real sequences is a residual set in the set of all real sequences (i.e., the maldistribution is a typical property in the sense of Baire categories). We also generalize this result.

A DIAGONALLY IMPLICIT RUNGE-KUTTA-NYSTROM (RKN) METHOD FOR SOLVING SECOND ORDER ODES ON PARALLEL COMPUTERS

In this paper, diagonally implicit Runge-Kutta-Nystrom (RKN) method of high-order for the numerical solution of second order ordinary differential equations (ODE) possessing oscillatory solutions to be used on parallel computers is constructed. The method has the properties of minimized local truncation error coefficients as well as possessing non-empty interval of periodicity, thus suitable for oscillatory problems. The method was tested with standard test problems from the literature and numerical results compared with the analytical solution to show the advantage of the algorithm

NEW INSIGHTS FROM THE CANONICAL RAMSEY–CASS–KOOPMANS GROWTH MODEL

The present article presents novel results on the Ramsey–Cass–Koopmans growth model. It is shown that the shadow price of capital goes to infinity as the capital stock goes to zero even if all functions are bounded with finite derivatives and that imposing the Inada condition of infinite derivative of the per capita production function at zero stock is irrelevant. It is also shown that unless marginal utility at zero consumption is infinity, there will be a non-empty interval where the Keynes–Ramsey rule does not hold. The paper also shows that the stable saddle path in a phase diagram with the state variable and the shadow price has an unrecognized economic interpretation that enables us to illustrate the value function as the integral of the stable saddle path.

Integrated Model of Inductive-Deductive Inference Based on Finite Predicates and Implicative Regularities

The theory of Boolean functions, especially in respect to representing these functions in the disjunctive or conjunctive normal forms, is extended in this chapter onto the case of finite predicates. Finite predicates are decomposed by that into some binary units, which will correspond to components of Boolean vectors and matrices and are represented as combinations of these units. Further, the main concepts used for solving pattern recognition problems are defined, namely world model, data, and knowledge. The data presenting information about the existence of some objects with definite combinations of properties is considered, as well as the knowledge presenting information about the existence of regular relationships between attributes. These relationships prohibit some combinations of properties. In this way, the knowledge gives the information about the non-existence of objects with some definite (prohibited) combinations of attribute values. A special form of regularity representation, called implicative regularities, is introduced. Any implicative regularity generates an empty interval in the Boolean space of object descriptions, which do not contradict the data. The problem of plausibility evaluation of induced implicative regularities should be solved by that. The pattern recognition problem is solved by two steps. First, regularities are extracted from the database (inductive inference); second, the obtained knowledge is used for the object recognition (deductive inference).