Stimulus Orientation Research Articles

Sensory perception is a holistic inference process.

Sensory perception is widely considered an inference process that reflects the best guess of a stimulus feature based on uncertain sensory information. Here we challenge this reductionist view and propose that perception is rather a holistic inference process that operates not only at the feature but jointly across all levels of the representational hierarchy. We test this hypothesis in the context of a commonly used psychophysical matching task in which subjects are asked to report their perceived orientation of a test stimulus by adjusting a probe stimulus (method-of-adjustment). We introduce a holistic matching model that assumes that subjects' reports reflect an optimal match between the test and probe stimulus, both in terms of their inferred feature (orientation) and also their higher level representation (orientation category). Validation against several existing data sets demonstrates that the model accurately and comprehensively predicts subjects' response behavior and outperforms previous models both qualitatively and quantitatively. Moreover, the model generalizes to other feature domains and offers an alternative account for categorical color perception. Our results suggest that categorical effects in sensory perception are ubiquitous and can be parsimoniously explained as optimal behavior based on holistic sensory representations. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Bounded contribution of human early visual cortex to the topographic anisotropy in spatial extent perception

To interact successfully with objects, it is crucial to accurately perceive their spatial extent, an enclosed region they occupy in space. Although the topographic representation of space in the early visual cortex (EVC) has been favored as a neural correlate of spatial extent perception, its exact nature and contribution to perception remain unclear. Here, we inspect the topographic representations of human individuals’ EVC and perception in terms of how much their anisotropy is influenced by the orientation (co-axiality) and radial position (radiality) of stimuli. We report that while the anisotropy is influenced by both factors, its direction is primarily determined by radiality in EVC but by co-axiality in perception. Despite this mismatch, the individual differences in both radial and co-axial anisotropy are substantially shared between EVC and perception. Our findings suggest that spatial extent perception builds on EVC’s spatial representation but requires an additional mechanism to transform its topographic bias.

Searching near and far: The attentional template incorporates viewing distance.

According to theories of visual search, observers generate a visual representation of the search target (the "attentional template") that guides spatial attention toward target-like visual input. In real-world vision, however, objects produce vastly different visual input depending on their location: your car produces a retinal image that is 10 times smaller when it is parked 50 compared to 5 m away. Across four experiments, we investigated whether the attentional template incorporates viewing distance when observers search for familiar object categories. On each trial, participants were precued to search for a car or person in the near or far plane of an outdoor scene. In "search trials," the scene reappeared and participants had to indicate whether the search target was present or absent. In intermixed "catch-trials," two silhouettes were briefly presented on either side of fixation (matching the shape and/or predicted size of the search target), one of which was followed by a probe-stimulus. We found that participants were more accurate at reporting the location (Experiments 1 and 2) and orientation (Experiment 3) of probe stimuli when they were presented at the location of size-matching silhouettes. Thus, attentional templates incorporate the predicted size of an object based on the current viewing distance. This was only the case, however, when silhouettes also matched the shape of the search target (Experiment 2). We conclude that attentional templates for finding objects in scenes are shaped by a combination of category-specific attributes (shape) and context-dependent expectations about the likely appearance (size) of these objects at the current viewing location. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Investigating the Roles of the Visual and Parietal Cortex in Representing Content versus Context in Visual Working Memory.

Content-to-context binding is crucial for working memory performance. Using a dual-serial retrocueing (DSR) task on oriented gratings, Yu et al. (2020) found that content (orientation) of both prioritized and unprioritized memory items (PMI; UMI) was represented simultaneously in visual cortex, while their context (location) was represented in intraparietal sulcus (IPS), with a priority-based remapping of the representation of content and context of the UMI in each region, respectively. This registered report acquired fMRI of 24 healthy adults while they performed a DSR task with location as the to-be-reported content and orientation as the task-relevant context. We contrasted three accounts: domain-dependent, the engagement of visual and parietal regions depends on the feature domain (orientation vs location); functional, the engagement of these regions depends on their function (content vs context); and hybrid-a combination of the domain-dependent account and the additional stipulation that IPS encodes context regardless of domain. Delay-period activity in early visual cortex conformed most closely with functional predictions: robust priority-sensitive representation of stimulus location (content), but no evidence for the active representation of stimulus orientation (context). Delay-period activity in IPS, in contrast, conformed most closely to predictions of the hybrid account: active representation of content (location) and of prioritized context (orientation). Exploratory analyses further supported the hybrid account of IPS, revealing univariate sensitivity to variation in both content and context load, the latter in a manner that predicted individual differences in behavior. The representation of visual information in working memory is highly dependent on behavioral context.

Energy harvesting using magnetostrictive materials: Effects of material anisotropy and stress multiaxiality

Low-frequency vibrations are common as background noise in urban and industrial environments. They originate from natural or artificial sources: road vehicles, industrial machinery, wind, etc., and constitute a ubiquitous energy source. In the framework of energy harvesting, magnetostrictive materials are an attractive alternative solution to the brittleness and geometrical limitations of piezoelectric materials. While numerous previous works dealt with uniaxial stress on selected materials, the exploration of the effects of multiaxial loadings and material anisotropy has not yet been investigated as a way to improve the performance of low-frequency vibration energy harvesting systems. In this work, we investigated the capability of grain-oriented electrical steel in an energy-harvesting context. This material has been selected as a model material, notably as it is abundant and cost-effective. It shows limited magnetostriction but significant elastic, magnetic, and magnetostrictive anisotropy. We combined experimental and predictive simulation results to discuss the possibility of increasing the levels of harvested energy by playing with the orientation of magnetic and mechanical stimuli. Various orientations of magnetic field and mechanical stress were considered with regard to the rolling direction of the material. Unexpectedly high energy density amounts, up to 10 mJ·cm−3, were obtained, competing with giant magnetostrictive materials like Terfenol-D or Galfenol.

О корректности математической модели вызванной активности первичной зрительной коры

We propose a mathematical model that formalizes the macro- and meso-level dynamics of electrical potentials in the primary visual cortex of subjects, which corresponds to the presentation of visual stimuli to them. The mathematical framework is based on a twolayer neural field model, represented by a system of integro-differential equations, where the deep layer of the neural field models electrical activity that does not depend directly on the spatial orientation of the visual stimuli, whereas the activity of the superficial layer is sensitive to spatially oriented stimuli. The experimental design of presenting a series of visual stimuli is formalised in the present study in terms of an impulse control problem for the aforementioned two-layer neural field model. We propose a special metric space for construction of a unique solution to the control problem under standard assumptions for mathematical neurobiology regarding the functions involved in the modeling equations. We formulate sufficient conditions for continuous dependence of the solutions on the impulse control.

Healthy aging does not alter centre surround orientation effects in foveal intraocular and interocular contrast suppression

Aims/Purpose: Healthy aging alters how the perceived contrast of a pattern is influenced by its surround. Neural mechanisms underlying this aging effect can be disentangled by manipulating stimulus orientation, duration, and by using dichoptic viewing. Here, we tested whether intraocular and interocular center surround contrast suppression demonstrate distinct effects of surround orientation, and if so, whether they are altered by healthy aging.Methods: We measured the perceived contrast of a circular, vertically oriented sine grating (0.67° diameter, 20% contrast) alone and in the presence of annular sinusoidal surround (6° diameter, 40% contrast) in 18 younger (19–32 years) and 18 older adults (61–78 years). Factors explored were: intraocular versus interocular viewing, parallel versus orthogonal surround orientation, and 40 ms versus 200 ms stimulus duration. Surround orientation effect (SOE) was calculated as 1‐ (contrast suppression by orthogonal surround/ contrast suppression by parallel surround). SOE was 0 if contrast suppression was equal between both surround orientations, and the value increased if parallel surround produced stronger suppression than orthogonal surround.Results: The interocular SOE was not influenced by stimulus duration, whereas, intraocular SOE was stronger at 40 ms compared to 200 ms (viewing condition x stimulus duration: F(1,34) = 24.38, p < 0.01). Older and younger adults showed similar SOE under all test conditions (main effect of age: F(1,34) = 0.02, p = 0.89). Age did not affect how stimulus duration influenced intraocular and interocular SOE (age x viewing condition x stimulus duration: F(1,34) = 0.41, p = 0.52).Conclusions: Our results suggest that centre surround orientation effects on intraocular and interocular contrast suppression is dependent on stimulus duration and this relationship is unaltered by healthy aging.

Characteristics of changes in the level of resistance of mixed martial arts athletes to a stress stimulus in the conditions of different force load regimes

The presented article is devoted to the study of the problem of developing effective strength training regimens for mixed martial arts athletes, taking into account the specifics of this sport and determining the level of resistance of their body and the manifestation of processes of long-term adaptation to a stressful stimulus of the appropriate nature. The purpose of the study was to study the characteristics of the change in the level of resistance of the body of mixed martial arts athletes under the conditions of the use of power load regimes with different parameters of volume and intensity. 75 athletes aged 19±0.7 years, who were divided into 3 groups, took part in the research. The following research methods were used: theoretical and methodological analysis of data from scientific and methodological literature, control testing of the development of maximum muscle strength of athletes, a method of quantitative assessment of the level of physical exertion in power sports, biochemical methods of controlling the concentration of cortisol in the blood serum of participants, a pedagogical experiment, mathematics - statistical methods of processing results. The results of the study indicate that mainly in the athletes of group 3, who during the 12 weeks of the study used a regime of high-intensity loads (Rа=0.72) under the conditions of anaerobic-lactate type of energy supply of muscle activity, we observe the most accelerated growth rates of the power capabilities of the pectoral m muscles on the background of the lowest load volume indicators in a separate set among the groups. At the same time, under the given conditions of training activity, the level of the body's resistance to such a stress stimulus of a force orientation is maximally increased in such a short period of time among athletes of the 3rd group. At the same time, in the athletes of the first group under the conditions of using the mode of low-intensity power loads (Rа=0.53), not only a minimal shift in relation to the investigated problem was detected, but also a fixed manifestation of compensatory reactions to the stressful stimulus.

Geometry of visuospatial working memory information in miniature gaze patterns.

Stimulus-dependent eye movements have been recognized as a potential confound in decoding visual working memory information from neural signals. Here we combined eye-tracking with representational geometry analyses to uncover the information in miniature gaze patterns while participants (n = 41) were cued to maintain visual object orientations. Although participants were discouraged from breaking fixation by means of real-time feedback, small gaze shifts (<1°) robustly encoded the to-be-maintained stimulus orientation, with evidence for encoding two sequentially presented orientations at the same time. The orientation encoding on stimulus presentation was object-specific, but it changed to a more object-independent format during cued maintenance, particularly when attention had been temporarily withdrawn from the memorandum. Finally, categorical reporting biases increased after unattended storage, with indications of biased gaze geometries already emerging during the maintenance periods before behavioural reporting. These findings disclose a wealth of information in gaze patterns during visuospatial working memory and indicate systematic changes in representational format when memory contents have been unattended.

Dynamic alpha power modulations and slow negative potentials track natural shifts of spatio-temporal attention.

Alpha power modulations and slow negative potentials have previously been associated with anticipatory processes in spatial and temporal top-down attention. In typical experimental designs, however, neural responses triggered by transient stimulus onsets can interfere with attention-driven activity patterns and our interpretation of such. Here, we investigated these signatures of spatio-temporal attention in a dynamic paradigm free from potentially confounding stimulus-driven activity using electroencephalography. Participants attended the cued side of a bilateral stimulus rotation and mentally counted how often one of two remembered sample orientations (i.e., the target) was displayed while ignoring the uncued side and non-target orientation. Afterwards, participants performed a delayed match-to-sample task, in which they indicated if the orientation of a probe stimulus matched the corresponding sample orientation (previously target or non-target). We observed dynamic alpha power reductions and slow negative waves around task-relevant points in space and time (i.e., onset of the target orientation in the cued hemifield) over posterior electrodes contralateral to the locus of attention. In contrast to static alpha power lateralization, these dynamic signatures correlated with subsequent memory performance (primarily detriments for matching probes of the non-target orientation), suggesting a preferential allocation of attention to task-relevant locations and time points at the expense of reduced resources and impaired performance for information outside the current focus of attention. Our findings suggest that humans can naturally and dynamically focus their attention at relevant points in space and time and that such spatio-temporal attention shifts can be reflected by dynamic alpha power modulations and slow negative potentials.

Visual Environment Aspects of Public Building Design for People with Down Syndrome

Down syndrome is a trisomy genetic disorder resulting in cognitive delays in the fetus. Cognitive impairment in Down syndrome affects short-term memory and motor impairment due to the characteristic hypotonia of the muscles. People with Down syndrome tend to be visual learners. Through visuals, they are easier to remember and repeat. Visual memory in Down syndrome is better than auditory memory in receiving information. Therefore, the visual environment aspect is presented as a facility in architectural element designs to improve cognition, memory, and motor skills in the wayfinding orientation stimulus. Aspects of the visual environment are offered to stimulate the sensory vision repeatedly. Sensory architecture has a role in activating the body in receiving information, exploring the world, providing taste, and forming social relationships. This paper aims to discuss the design of the visual environment in stimulating the sensory vision of people with Down syndrome to facilitate wayfinding orientation. Visual environment design through colours, patterns, materials, and light are presented as tools to activate visual understanding in responding to and remembering wayfinding orientations. Aspects of the visual environment are communication and encouraging physical activity for users.

Category Learning Selectively Enhances Representations of Boundary-Adjacent Exemplars in Early Visual Cortex.

Category learning and visual perception are fundamentally interactive processes, such that successful categorization often depends on the ability to make fine visual discriminations between stimuli that vary on continuously valued dimensions. Research suggests that category learning can improve perceptual discrimination along the stimulus dimensions that predict category membership and that these perceptual enhancements are a byproduct of functional plasticity in the visual system. However, the precise mechanisms underlying learning-dependent sensory modulation in categorization are not well understood. We hypothesized that category learning leads to a representational sharpening of underlying sensory populations tuned to values at or near the category boundary. Furthermore, such sharpening should occur largely during active learning of new categories. These hypotheses were tested using fMRI and a theoretically constrained model of vision to quantify changes in the shape of orientation representations while human adult subjects learned to categorize physically identical stimuli based on either an orientation rule (N = 12) or an orthogonal spatial frequency rule (N = 13). Consistent with our predictions, modeling results revealed relatively enhanced reconstructed representations of stimulus orientation in visual cortex (V1-V3) only for orientation rule learners. Moreover, these reconstructed representations varied as a function of distance from the category boundary, such that representations for challenging stimuli near the boundary were significantly sharper than those for stimuli at the category centers. These results support an efficient model of plasticity wherein only the sensory populations tuned to the most behaviorally relevant regions of feature space are enhanced during category learning.

Human perception of spatial frequency varies with stimulus orientation and location in the visual field

Neuroanatomical variations across the visual field of human observers go along with corresponding variations of the perceived coarseness of visual stimuli. Here we show that horizontal gratings are perceived as having lower spatial frequency than vertical gratings when occurring along the horizontal meridian of the visual field, whereas gratings occurring along the vertical meridian show the exact opposite effect. This finding indicates a new peculiarity of processes operating along the cardinal axes of the visual field.

An Angry, Hopeful, or Efficacious Citizen: Information, Emotion, and Participation in an Emerging Democracy

A growing body of research has examined how access to political information via digital media contributes to democratic participation in new or transitory democracies. Much of this work focuses on cognitive factors, such as political efficacy and civic knowledge, while less attention is paid to the role of emotion. Drawing on insights from the orientation–stimuli–orientation–response (O-S-O-R) and anger activism model (AAM), this study proposes and tests a model of political information seeking and participation using a national survey of adult Nigerians ( N = 600). Findings provide support for the model and highlight potential pathways through which political information may enhance participation.

Tuning perception and decisions to temporal context

Recent work suggests that serial dependence, where perceptual decisions are biased toward previous stimuli, arises from the prior that sensory input is temporally correlated. However, existing studies have mostly used random stimulus sequences that do not involve such temporal consistencies. Here, we manipulated the temporal statistics of visual stimuli to examine the role of true temporal correlations in serial dependence. In two experiments, observers reproduced the orientation of the last stimulus in a sequence, while we varied temporal correlations in the stimulus features at two timescales: stimulus history within the trial and decision history across trials. We found a clear dissociation: increasing temporal correlation in the stimulus history led to adaptation-like repulsive biases, whereas increasing temporal correlation in the decision history reduced attractive biases. Thus, we suggest that temporal correlation enhances the discriminative ability of the visual system, revealing the fundamental role of the broader temporal context.

The basis of S–R learning: associations between individual stimulus features and responses

Three experiments tested the hypothesis that response selection skill involves associations between individual stimulus features and responses. The Orientation group in Experiments 1 and 2 first practiced responding to the orientation of a line stimulus while ignoring its color, and the Color group practiced responding to the color of the line while disregarding its orientation. When in the ensuing test conditions the Orientation group responded to the color of the line, RTs and errors increased when the then irrelevant line orientation was inconsistent with practice. This confirmed that during practice, Orientation participants had developed orientation feature–response associations they could not fully inhibit. Yet, evidence for color feature–response associations was not observed in the Color group. This was attributed to orientation identification being faster than color identification, even after having practiced responding to colors. Experiment 3 involved practicing to three line stimuli with unique orientation and color combinations. It showed evidence for the independent development of orientation feature–response associations and color feature–response associations. Together, these results indicate that the typical RT reduction with practice in response selection tasks is caused in part by the capacity of participants to learn selecting responses on the basis of the stimulus feature that becomes available first.

STUDY OF THE FEATURES OF ACADEMIC PROCRASTINATION OF YOUTH STUDENTS

This article delves into the concept of academic procrastination as a psychological phenomenon that serves as a significant barrier to personal development and lies at the core of the issue of an individual's incapacity to shape a cohesive life vision. This vision encompasses both short-term and long-term planning, goal-setting, and behavior geared toward self-realization. Various approaches to comprehending the essence of this phenomenon, including psychodynamic, behavioral, and cognitive perspectives, are examined. The study reveals that academic procrastination is a considerable issue among student youth, with 75% exhibiting a high level of academic procrastination. Among students in the 3rd and 4th years, a greater inclination towards elevated levels of academic procrastination is observed, whereas 1st and 2nd-year students display higher motivation and less inclination towards procrastination. This could be associated with shifts in study habits and increased workload upon transitioning to higher years. Students in the 3rd and 4th years necessitate the development of time management strategies and overcoming procrastination to attain success. The primary cause of academic procrastination among student youth, according to survey results, is academic perfectionism (76%), while a lack of academic motivation and anxiety are identified as less provocative factors. Approximately half of the respondents are found to be internals, the majority of whom possess a moderate level of internal stimuli orientation. In contrast, 55% of the respondents are classified as externals, relying more on external factors in their academic pursuits.

Invited Session IV: Studies of the visual cortex with sub-millimeter resolution: Imaging the visual brain at high spatiotemporal resolution.

Since the discovery of orientation-selective neurons in the cat primary visual cortex (V1), how the mammalian nervous system computes the orientation of visual stimuli has been a flagship question in neuroscience. With the recent advances in in vivo imaging of neural activity using genetically encoded indicators and two-photon fluorescence microscopy, we can now achieve synapse-resolving functional imaging and kilohertz imaging of membrane voltage in the mouse V1. I will describe our recent advancements in imaging visual processing at high spatiotemporal resolution, as well as two studies on the orientation selectivity of neurons in the mouse visual pathway.

Peri-Saccadic Orientation Identification Performance and Visual Neural Sensitivity Are Higher in the Upper Visual Field.

Visual neural processing is distributed among a multitude of sensory and sensory-motor brain areas exhibiting varying degrees of functional specializations and spatial representational anisotropies. Such diversity raises the question of how perceptual performance is determined, at any one moment in time, during natural active visual behavior. Here, exploiting a known dichotomy between the primary visual cortex (V1) and superior colliculus (SC) in representing either the upper or lower visual fields, we asked whether peri-saccadic orientation identification performance is dominated by one or the other spatial anisotropy. Humans (48 participants, 29 females) reported the orientation of peri-saccadic upper visual field stimuli significantly better than lower visual field stimuli, unlike their performance during steady-state gaze fixation, and contrary to expected perceptual superiority in the lower visual field in the absence of saccades. Consistent with this, peri-saccadic superior colliculus visual neural responses in two male rhesus macaque monkeys were also significantly stronger in the upper visual field than in the lower visual field. Thus, peri-saccadic orientation identification performance is more in line with oculomotor, rather than visual, map spatial anisotropies.SIGNIFICANCE STATEMENT Different brain areas respond to visual stimulation, but they differ in the degrees of functional specializations and spatial anisotropies that they exhibit. For example, the superior colliculus (SC) both responds to visual stimulation, like the primary visual cortex (V1), and controls oculomotor behavior. Compared with the primary visual cortex, the superior colliculus exhibits an opposite pattern of upper/lower visual field anisotropy, being more sensitive to the upper visual field. Here, we show that human peri-saccadic orientation identification performance is better in the upper compared with the lower visual field. Consistent with this, monkey superior colliculus visual neural responses to peri-saccadic stimuli follow a similar pattern. Our results indicate that peri-saccadic perceptual performance reflects oculomotor, rather than visual, map spatial anisotropies.

Widespread and Multifaceted Binocular Integration in the Mouse Primary Visual Cortex.

The brain combines two-dimensional images received from the two eyes to form a percept of three-dimensional surroundings. This process of binocular integration in the primary visual cortex (V1) serves as a useful model for studying how neural circuits generate emergent properties from multiple input signals. Here, we perform a thorough characterization of binocular integration using electrophysiological recordings in the V1 of awake adult male and female mice by systematically varying the orientation and phase disparity of monocular and binocular stimuli. We reveal widespread binocular integration in mouse V1 and demonstrate that the three commonly studied binocular properties-ocular dominance, interocular matching, and disparity selectivity-are independent of each other. For individual neurons, the responses to monocular stimulation can predict the average amplitude of binocular response but not its selectivity. Finally, the extensive and independent binocular integration of monocular inputs is seen across cortical layers in both regular-spiking and fast-spiking neurons, regardless of stimulus design. Our data indicate that the current model of simple feedforward convergence is inadequate to account for binocular integration in mouse V1, thus suggesting an indispensable role played by intracortical circuits in binocular computation.SIGNIFICANCE STATEMENT Binocular integration is an important step of visual processing that takes place in the visual cortex. Studying the process by which V1 neurons become selective for certain binocular disparities is informative about how neural circuits integrate multiple information streams at a more general level. Here, we systematically characterize binocular integration in mice. Our data demonstrate more widespread and complex binocular integration in mouse V1 than previously reported. Binocular responses cannot be explained by a simple convergence of monocular responses, contrary to the prevailing model of binocular integration. These findings thus indicate that intracortical circuits must be involved in the exquisite computation of binocular disparity, which would endow brain circuits with the plasticity needed for binocular development and processing.