Space Constancy Research Articles

Can we maintain space constancy in virtual environments?

Can we maintain space constancy in virtual environments?

The experience of using psychosemantic technique “color-associative experiment” in psychological counseling of students

This article presents a qualitative and quantitative study of personality based on psychosemantic technique “color-associative experiment”. The subject of this research is the theoretical framework, procedure for psychosemantic technique “color-associative experiment”, and the possibilities of its application in psychological counseling of students. For quality data processing and interpretation, the author employs the techniques of free and axial coding (the categories correspond to the axes: conditions, phenomenon, its characteristics, strategy of interaction with the phenomenon, and outcome), which allow the psychologist to acquire a holistic representation on the current state of the respondent. The article provides the materials of empirical study, which involved 15 people; describes the results diagnostics of the bachelor's degree students conducted in terms of distance learning at the Academy for the Humanities and Pedagogy  (branch) of the Crimean Federal University in Yalta (April 2020). The obtained results indicate that the verbal space and perceptive-semantic space are not identical, but mutually complementary, forming a holistic picture of the individual semantic space of personality. On the example of implementation of “color-associative experiment” technique, the respondent (bachelor's degree graduate) is characterized by a neurotic structure of personality. The intrapersonal conflict and resulting emotional tension are accompanied by the pursuit of orderliness and freedom (the verbal component of semantic space), but also indicate the prevalence of variability and lack of constancy in the perceptive semantic space of personality. For comparing the results of perceptive and verbal semantic space, the author offers the schematic image of the coordinate system formed by these two axes and saturated with individual meanings of the respondent. Thus, in the dialogue with the respondent, the psychologist forms a map of the individual semantic space of the latter. The application of the method of “color-associative experiment” indicated the instance of the development of reflection among students.

Sounds are remapped across saccades

To achieve visual space constancy, our brain remaps eye-centered projections of visual objects across saccades. Here, we measured saccade trajectory curvature following the presentation of visual, auditory, and audiovisual distractors in a double-step saccade task to investigate if this stability mechanism also accounts for localized sounds. We found that saccade trajectories systematically curved away from the position at which either a light or a sound was presented, suggesting that both modalities are represented in eye-centered oculomotor centers. Importantly, the same effect was observed when the distractor preceded the execution of the first saccade. These results suggest that oculomotor centers keep track of visual, auditory and audiovisual objects by remapping their eye-centered representations across saccades. Furthermore, they argue for the existence of a supra-modal map which keeps track of multi-sensory object locations across our movements to create an impression of space constancy.

Reduction of certain crystalline representations and local constancy in the weight space

We study the mod $p$ reduction of crystalline local Galois representations of dimension 2 under certain conditions on its weight and slope. Berger showed that for a fixed non-zero trace of the Frobenius, the reduction process is locally constant for varying weights. By explicit computation we obtain an upper bound that is a linear function of the slope, for the radius of this local constancy around some special points in the weight space.

Ancient solutions of superlinear heat equations on Riemannian manifolds

We study some qualitative properties of ancient solutions of superlinear heat equations on a Riemannian manifold, with particular interest in positivity and constancy in space.

Bridgemanian space constancy as a precursor to extended cognition.

A few decades ago, cognitive psychologists generally took for granted that the reason we perceive our visual environment as one contiguous stable whole (i.e., space constancy) is because we have an internal mental representation of the visual environment as one contiguous stable whole. They supposed that the non-contiguous visual images that are gathered during the brief fixations that intervene between pairs of saccadic eye movements (a few times every second) are somehow stitched together to construct this contiguous internal mental representation. Determining how exactly the brain does this proved to be a vexing puzzle for vision researchers. Bruce Bridgeman's research career is the story of how meticulous psychophysical experimentation, and a genius theoretical insight, eventually solved this puzzle. The reason that it was so difficult for researchers to figure out how the brain stitches together these visual snapshots into one accurately-rendered mental representation of the visual environment is that it doesn't do that. Bruce discovered that the brain couldn't do that if it tried. The neural information that codes for saccade amplitude and direction is simply too inaccurate to determine exact relative locations of each fixation. Rather than the perception of space constancy being the result of an internal representation, Bruce determined that it is the result of a brain that simply assumes that external space remains constant, and it rarely checks to verify this assumption. In our extension of Bridgeman's formulation, we suggest that objects in the world often serve as their own representations, and cognitive operations can be performed on those objects themselves, rather than on mental representations of them.

Effect of Combined Integrated Learning Programme (CILP) for Learning Disability in Adolescence-A Case Report

This paper reports the benefits of combined integrated learning programme (CILP) in the early rehabilitation of learning disability child. Learning disability is coined by Samuel kirk in 1963 to describe children who have significant difficulties in understanding various language, reading, writing and other mathematical problems. An intervention of 60 days (6 days per week for 10 weeks) was given to the child and prognosis was observed on various outcome variables like Eye hand coordination (EHC), Figure ground perception (FGP), Figure constancy (FC) and Position in space (PIS) before and after the interventions. Considerable improvement was seen by applying CiLP programme in child with learning disability.

Neural Correlates underlying Size Constancy in Virtual Three-Dimensional Space

The perceived size of an object remains relatively constant although its retinal size keeps decreasing as the object moves away along the depth dimension of the 3D space, i.e. size constancy. Neural mechanisms generating size constancy in virtual 3D space, however, remain poorly understood. By constructing a virtual 3D world in the MR scanner, we positioned the same 3D objects either near or far from the observers so that the near and far objects were perceived as having the same physical size despite their differences in retinal size. To control for the effect of differential retinal size, an additional 2D condition was introduced: a large and a small object, with matched retinal images as the near and far objects in the 3D condition, respectively, were presented on a 2D screen. Differences in retinal size activated overlapped areas in bilateral inferior occipital gyrus (IOG) in both experiments. The overlapped areas in IOG, however, showed different patterns of functional connectivity with different neural networks, depending on the perceived size of objects. In particular, IOG showed enhanced connectivity with bilateral superior parietal cortex in the 2D condition, but with inferior temporal and prefrontal cortex in the virtual 3D condition, i.e., size constancy.

Ancient solutions of semilinear heat equations on Riemannian manifolds

We study the qualitative properties of ancient solutions of linear and semilinear heat equations in a Riemannian manifold, with particular attention to positivity and constancy in space.

Rich afterimage illusion and inflow on-screen mechanisms for visual field constancy and visual orientation in space

Rich afterimage illusion and inflow on-screen mechanisms for visual field constancy and visual orientation in space

Active sensing without efference copy: referent control of perception.

Although action and perception are different behaviors, they are likely to be interrelated, as implied by the notions of perception-action coupling and active sensing. Traditionally, it has been assumed that the nervous system directly preprograms motor commands required for actions and uses a copy of them called efference copy (EC) to also influence our senses. This review offers a critical analysis of the EC concept by identifying its limitations. An alternative to the EC concept is based on the experimentally confirmed notion that sensory signals from receptors are perceived relative to referent signals specified by the brain. These referents also underlie the control of motor actions by predetermining where, in the spatial domain, muscles can work without preprogramming how they should work in terms of motor commands or EC. This approach helps solve several problems of action and explain several sensory experiences, including position sense and the sense that the world remains stationary despite changes in its retinal image during eye or body motion (visual space constancy). The phantom limb phenomenon and other kinesthetic illusions are also explained within this framework.

Constancy in Functional Space across a Species Richness Anomaly.

The relationship between large-scale gradients in species richness and functional diversity provides important information regarding the mechanisms driving patterns of biodiversity. A classic hypothesis in ecology is that strong interspecific interactions should result in an increase in the functional volume of assemblages as the species richness increases, whereas climatic constraints may result in no change in functional volume. Most research of this kind examines latitudinal gradients in species richness, but the results are likely confounded by underlying gradients in climate and phylogenetic composition. We take an alternative approach that examines functional richness across a tree species richness anomaly where species richness doubles from Europe to eastern North America. The results demonstrate that the functional richness on both continents saturates at a similar point as species richness increases and that the packing of functional space becomes tighter. Further, the species richness anomaly is driven primarily by genera unique to North America, but those genera contribute less than expected functional richness to the region, indicating a high level of redundancy with genera shared between the continents. Taken together, the results indicate that the species richness anomaly is associated with diversification within a climatically constrained trait space. More generally, the work demonstrates the power of utilizing species richness anomalies in biodiversity research, particularly when they are coupled with information regarding organismal function.

Spatial cognition, body representation and affective processes: the role of vestibular information beyond ocular reflexes and control of posture.

A growing number of studies in humans demonstrate the involvement of vestibular information in tasks that are seemingly remote from well-known functions such as space constancy or postural control. In this review article we point out three emerging streams of research highlighting the importance of vestibular input: (1) Spatial Cognition: Modulation of vestibular signals can induce specific changes in spatial cognitive tasks like mental imagery and the processing of numbers. This has been shown in studies manipulating body orientation (changing the input from the otoliths), body rotation (changing the input from the semicircular canals), in clinical findings with vestibular patients, and in studies carried out in microgravity. There is also an effect in the reverse direction; top-down processes can affect perception of vestibular stimuli. (2) Body Representation: Numerous studies demonstrate that vestibular stimulation changes the representation of body parts, and sensitivity to tactile input or pain. Thus, the vestibular system plays an integral role in multisensory coordination of body representation. (3) Affective Processes and Disorders: Studies in psychiatric patients and patients with a vestibular disorder report a high comorbidity of vestibular dysfunctions and psychiatric symptoms. Recent studies investigated the beneficial effect of vestibular stimulation on psychiatric disorders, and how vestibular input can change mood and affect. These three emerging streams of research in vestibular science are—at least in part—associated with different neuronal core mechanisms. Spatial transformations draw on parietal areas, body representation is associated with somatosensory areas, and affective processes involve insular and cingulate cortices, all of which receive vestibular input. Even though a wide range of different vestibular cortical projection areas has been ascertained, their functionality still is scarcely understood.

Constancy of local spread rates for buffelgrass (Pennisetum ciliare L.) in the Arizona Upland of the Sonoran Desert

In North American deserts, grass invasions threaten native vegetation via competition and altered fire regimes. Accurate prediction and successful mitigation of these invasions hinge on estimation of spread rates and their degree of constancy in time and space. We used high-resolution aerial photographs from 11 sites in the Santa Catalina Mountains, southern Arizona to reconstruct the spread of buffelgrass (Pennisetum ciliare), a C4 perennial bunchgrass, since 1980. The total area infested was fit to a logistic model and residuals of the model were compared to climatic factors of the corresponding and lagged time periods. Infestations grew from small colonizing patches in the 1980s to 66 ha in 2008, doubling every 2.26–7.04 years since 1988. Although buffelgrass germination, establishment and distribution are favored by wet summers and warm winters, climate variables did not predict spread rates. Buffelgrass has grown at a constant rate, at least since 1988, when much of its expansion took place. In the study area, minimum requirements are met almost every year for germination and reproduction, establishing a consistent baseline for spread that manifests as a constant spread rate.

Temporal dynamics of remapping captured by peri-saccadic continuous motion

Different attention and saccade control areas contribute to space constancy by remapping target activity onto their expected post-saccadic locations. To visualize this dynamic remapping, we used a technique developed by Honda (2006) where a probe moved vertically while participants made a saccade across the motion path. Observers do not report any large excursions of the trace at the time of the saccade that would correspond to the classical peri-saccadic mislocalization effect. Instead, they reported that the motion trace appeared to be broken into two separate segments with a shift of approximately one-fifth of the saccade amplitude representing an overcompensation of the expected retinal displacement caused by the saccade. To measure the timing of this break in the trace, we introduced a second, physical shift that was the same size but opposite in direction to the saccade-induced shift. The trace appeared continuous most frequently when the physical shift was introduced at the midpoint of the saccade, suggesting that the compensation is in place when the saccade lands. Moreover, this simple linear shift made the combined traces appear continuous and linear, with no curvature. In contrast, Honda (2006) had reported that the pre- and post-saccadic portion of the trace appeared aligned and that there was often a small, visible excursion of the trace at the time of the saccade. To compare our results more directly, we increased the contrast of our moving probe in a third experiment. Now some observers reported seeing a deviation in the motion path but the misalignment remained present. We conclude that the large deviations at the time of saccade are generally masked for a continuously moving target but that there is nevertheless a residual misalignment between pre- and post-saccadic coordinates of approximately 20% of the saccade amplitude that normally goes unnoticed.

Shelf‐basin exchange times of Arctic surface waters estimated from 228Th/228Ra disequilibrium

The transpolar drift is strongly enriched in 228Ra accumulated on the wide Arctic shelves with subsequent rapid offshore transport. We present new data of Polarstern expeditions to the central Arctic and to the Kara and Laptev seas. Because 226Ra activities in Pacific waters are 30% higher than in Atlantic waters, we correct 226Ra for the Pacific admixture when normalizing 228Ra with 226Ra. The use of 228Ra decay as age marker critically depends on the constancy in space and time of the source activity, a condition that has not yet adequately been tested. While 228Ra decays during transit over the central basin, ingrowth of 228Th could provide an alternative age marker. The high 228Th/228Ra activity ratio (AR = 0.8–1.0) in the central basins is incompatible with a mixing model based on horizontal eddy diffusion. An advective model predicts that 228Th grows to an equilibrium AR, the value of which depends on the scavenging regime. The low AR over the Lomonosov Ridge (AR = 0.5) can be due to either rapid transport (minimum age without scavenging 1.1 year) or enhanced scavenging. Suspended particulate matter load (derived from beam transmission and particulate 234Th) and total 234Th depletion data show that scavenging, although extremely low in the central Arctic, is enhanced over the Lomonosov Ridge, making an age of 3 years more likely. The combined data of 228Ra decay and 228Th ingrowth confirm the existence of a recirculating gyre in the surface water of the eastern Eurasian Basin with a river water residence time of at least 3 years.

Training of attention functions in children with attention deficit hyperactivity disorder

Pharmacological treatment of children with ADHD has been shown to be successful; however, medication may not normalize attention functions. The present study was based on a neuropsychological model of attention and assessed the effect of an attention training program on attentional functioning of children with ADHD. Thirty-two children with ADHD and 16 healthy children participated in the study. Children with ADHD were randomly assigned to one of the two conditions, i.e., an attention training program which trained aspects of vigilance, selective attention and divided attention, or a visual perception training which trained perceptual skills, such as perception of figure and ground, form constancy and position in space. The training programs were applied in individual sessions, twice a week, for a period of four consecutive weeks. Healthy children did not receive any training. Alertness, vigilance, selective attention, divided attention, and flexibility were examined prior to and following the interventions. Children with ADHD were assessed and trained while on ADHD medications. Data analysis revealed that the attention training used in the present study led to significant improvements of various aspects of attention, including vigilance, divided attention, and flexibility, while the visual perception training had no specific effects. The findings indicate that attention training programs have the potential to facilitate attentional functioning in children with ADHD treated with ADHD drugs.

Spatiotopic apparent motion reveals local variations in space constancy

While participants made 10° horizontal saccades, two dots were presented, one before and one after the saccade. Each dot was presented for 400 ms, the first turned off about 100 ms before, while the second turned on about 100 ms after the saccade. The two dots were separated vertically by 3°, but because of the intervening eye movement, they were also separated horizontally on the retina by an additional 10°. Participants nevertheless reported that the perceived motion was much more vertical than horizontal, suggesting that the trans-saccadic displacement was corrected, at least to some extent, for the retinal displacement caused by the eye movement. The corrections were not exact, however, showing significant biases that corresponded to about 5% of the saccade amplitude. The perceived motion between the probes was tested at 9 different locations and the biases, the deviations from accurate correction, varied significantly across locations. Two control experiments for judgments of position and of verticality of motion without eye movement confirmed that these biases are specific to the correction for the saccade. The local variations in the correction for saccades are consistent with physiological "remapping" proposals for space constancy that individually correct only a few attended targets but are not consistent with global mechanisms that predict the same correction at all locations.

The timing of space constancy during smooth pursuit eye movements

The timing of space constancy during smooth pursuit eye movements

How the Brain Makes the World Appear Stable

Space constancy, the appearance of a stable visual world despite shifts of all visual input with each eye movement, has been explained historically with a compensatory signal (efference copy or corollary discharge) that subtracts the eye movement signal from the retinal image shift accompanying each eye movement. Quantitative measures have shown the signal to be too small and too slow to mediate space constancy unaided. Newer theories discard the compensation idea, instead calibrating vision to each saccadic target.