Individual Differences in Perceived Elevation and Verticality: Evidence of a Common Visual Process

2013 ◽  
Vol 26 (3) ◽  
pp. 205-239 ◽  
Author(s):  
Adam Y. Shavit ◽  
Wenxun Li ◽  
Leonard Matin
Keyword(s):  
Individual Differences ◽  
Visual Perception ◽  
Median Plane ◽  
The Body ◽  
Visual Orientation ◽  
Frontoparallel Plane ◽  
Individual Subject ◽  
Orientation Process ◽  
Egocentric Bias ◽  
Integration Rules

The frontoparallel orientation of a long peripheral line influences two visual norms, elevation, also called the visual perception of eye level (VPEL), and orientation in the frontoparallel plane, called visually perceived vertical (VPV). However, VPEL and VPV are distinct in that different integration rules describe the combinatorial effects of two lines symmetrically located on opposite sides of the median plane. Nevertheless, we propose that the same orientation-sensitive process underlies the two discriminations. We measured the two norms while we manipulated visual orientation with 1-line and 2-line stimuli (on opposite sides of the median plane), then modeled the large and significant effect of line orientation on VPEL and VPV settings as linear averages of signals from vision and from non-visual, body-referenced, vestibular and proprioceptive mechanisms. Significant correlations are evident between observers () in the effect of visual orientation on both VPEL and VPV, and in the baseline measures (dark value, intercept) on both norms. The latter egocentric bias is further discussed in the context of the operation of the body-referenced mechanism across different egocentric discriminations for an individual subject. Given the evidence for different integration rules, the pattern of individual co-variation implies the existence of a single, shared visual orientation process that feeds to separate integration processes.

Individual Differences in the Flexibility of Peripersonal Space

2017 ◽  
Vol 64 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Samuel B. Hunley ◽  
Arwen M. Marker ◽  
Stella F. Lourenco
Keyword(s):  
Individual Differences ◽  
Peripersonal Space ◽  
The Body ◽  
Laser Pointer ◽  
Baseline Measure ◽  
Bisection Task ◽  
Defensive Function ◽  
Representational Space ◽  
Laser Condition ◽  
Line Bisection Task

Abstract. The current study investigated individual differences in the flexibility of peripersonal space (i.e., representational space near the body), specifically in relation to trait claustrophobic fear (i.e., fear of suffocating or being physically restricted). Participants completed a line bisection task with either a laser pointer (Laser condition), allowing for a baseline measure of the size of one’s peripersonal space, or a stick (Stick condition), which produces expansion of one’s peripersonal space. Our results revealed that individuals high in claustrophobic fear had larger peripersonal spaces than those lower in claustrophobic fear, replicating previous research. We also found that, whereas individuals low in claustrophobic fear demonstrated the expected expansion of peripersonal space in the Stick condition, individuals high in claustrophobic fear showed less expansion, suggesting decreased flexibility. We discuss these findings in relation to the defensive function of peripersonal space and reduced attentional flexibility associated with trait anxieties.

scholarly journals Correlated individual differences suggest a common mechanism underlying metacognition in visual perception and visual short-term memory

2017 ◽  
Vol 284 (1867) ◽  
pp. 20172035 ◽  
Author(s):  
Jason Samaha ◽  
Bradley R. Postle
Keyword(s):  
Individual Differences ◽  
Visual Perception ◽  
Short Term Memory ◽  
Adaptive Behaviour ◽  
Common Mechanism ◽  
Stimulus Feature ◽  
Relevant Stimulus ◽  
Short Term ◽  
Term Memory ◽  
Visual Short Term Memory

Adaptive behaviour depends on the ability to introspect accurately about one's own performance. Whether this metacognitive ability is supported by the same mechanisms across different tasks is unclear. We investigated the relationship between metacognition of visual perception and metacognition of visual short-term memory (VSTM). Experiments 1 and 2 required subjects to estimate the perceived or remembered orientation of a grating stimulus and rate their confidence. We observed strong positive correlations between individual differences in metacognitive accuracy between the two tasks. This relationship was not accounted for by individual differences in task performance or average confidence, and was present across two different metrics of metacognition and in both experiments. A model-based analysis of data from a third experiment showed that a cross-domain correlation only emerged when both tasks shared the same task-relevant stimulus feature. That is, metacognition for perception and VSTM were correlated when both tasks required orientation judgements, but not when the perceptual task was switched to require contrast judgements. In contrast with previous results comparing perception and long-term memory, which have largely provided evidence for domain-specific metacognitive processes, the current findings suggest that metacognition of visual perception and VSTM is supported by a domain-general metacognitive architecture, but only when both domains share the same task-relevant stimulus feature.

scholarly journals Latent Factors Limiting the Performance of sEMG-Interfaces

2018 ◽  
Author(s):  
Sergey Lobov ◽  
Nadia Krilova ◽  
Innokentiy Kastalskiy ◽  
Victor Kazantsev ◽  
Valeri A. Makarov
Keyword(s):  
The Body ◽  
Fine Tuning ◽  
Fatty Tissue ◽  
Latent Factors ◽  
Individual Subject ◽  
Training Strategy ◽  
Real Time Analysis ◽  
Signal Processing Algorithms ◽  
Gaming Environment

Recent advances in recording and real-time analysis of surface electromyographic signals (sEMG) have fostered the use of sEMG human-machine interfaces for controlling personal computers, prostheses of upper limbs, and exoskeletons among others. Despite a relatively high mean performance, sEMG-interfaces still exhibit strong variance in the fidelity of gesture recognition among different users. Here we systematically study the latent factors determining the performance of sEMG-interfaces in synthetic tests and in an arcade game. We show that the degree of muscle cooperation and the amount of the body fatty tissue are the decisive factors in synthetic tests. Our data suggest that these factors can only be adjusted by a long-term training, which promotes fine-tuning of low-level neural circuits driving the muscles. A short-term training has no effect on synthetic tests, but significantly increases the game scoring. This implies that it works at a higher decision-making level, not relevant for synthetic gestures. We propose a procedure that enables quantification of the gestures’ fidelity in a dynamic gaming environment. For each individual subject the approach allows identifying “problematic” gestures that decrease gaming performance. This information can be used for optimizing the training strategy and for adapting the signal processing algorithms to individual users, which could be a way for a qualitative leap in the development of future sEMG-interfaces.

Visual Perception in Specific Learning Difficulties

2021 ◽  
Vol 1 (1) ◽  
pp. 25-40
Author(s):  
Neriman Aral
Keyword(s):  
Individual Differences ◽  
Visual Perception ◽  
Learning Difficulties ◽  
Learning Difficulty ◽  
The Family ◽  
Mental Problems ◽  
The Moment ◽  
The Individual ◽  
The Brain ◽  
Specific Learning

From the moment the child is born, learning becomes meaningful and it is interpreted as a result of the experiences first in the family and then in school. However, it is sometimes not possible to talk about the fact that learning takes place in all children although the process has taken place in this direction. Sometimes the individual differences that exist in children and the inability to get the necessary support in structuring their learning experiences can be effective in the failure of learning, while sometimes the type of congenital difficulty can be effective. One of these types of difficulty is a specific learning difficulty. It is not always possible for children with specific learning difficulties to learn, even if they do not have any mental problems. In this case, many factors can be effective, especially the problems that children experience in their visual perception can become effective. Since visual perception is the processing of symbols received from the environment in the brain, the problem that may be experienced in this process can also make it difficult to learn this situation. In line with these considerations, it is aimed to focus on the importance of visual perception in specific learning difficulties.

Queer Structures of Religious Feeling: What Time Is Now?

2017 ◽  
Author(s):  
Ann Pellegrini
Keyword(s):  
The Body ◽  
The Other ◽  
Individual Subject ◽  
Psychoanalysis And Religion ◽  
Time Out ◽  
Religious Feeling ◽  
The Times ◽  
The One ◽  
The Individual ◽  
Queer Temporality

This essay asks what psychoanalysis and religion might have to say to each other in view of Freud’s secular aspirations and queer theory’s temporal turn. Both queer temporality and psychoanalysis offer resources for understanding the multiple ways time coats, codes, and disciplines the body in secular modernity. This is so even though psychoanalysis is one of these disciplines. Nevertheless, the times of psychoanalysis are multiple. On the one hand, psychoanalysis quite frequently lays down a teleology in which the individual subject matures along a set pathway. On the other hand, this developmental imperative is at profound odds with psychoanalysis’s capacity to make room for the co-existence of past and present in ways that confound secular time’s forward march. This latter recognition—co-temporality—may even lay down routes for the cultivation of “counter-codes” (Foucault’s term), ways of living and experiencing and telling time out of sync with the linear logics of what José Muñoz has called “straight time.”

Dynamic Embodiment and the Graphic Illness Narrative Genre

2019 ◽  
pp. 47-80
Author(s):  
Elisabeth El Refaie
Keyword(s):  
Visual Perception ◽  
Illness Narratives ◽  
The Body ◽  
Illness Narrative ◽  
Abstract Concepts ◽  
Social And Emotional ◽  
Words And Images

This chapter argues that some genres are more centrally concerned with the body than others, and that each genre exploits the affordances of its modes and media in unique ways. Thus, graphic illness narratives are characterized not only by their focus on the physical, social, and emotional impacts of disease, but also by their innovative use of the tools and materials of the comics medium, including inherent tensions between words and images, and between sequence and layout. These features impose particular constraints and offer unique opportunities to artists, influencing their choice of metaphors and the shape these metaphors take. For example, in many such works the expected direction of metaphorical transfer from sensorimotor experience to more abstract concepts is reversed, as the diseased body and the nature of visual perception are foregrounded in the artist’s consciousness.

scholarly journals Age-related reweighting of visual and vestibular cues for vertical perception

2019 ◽  
Vol 121 (4) ◽  
pp. 1279-1288 ◽  
Author(s):  
Bart B. G. T. Alberts ◽  
Luc P. J. Selen ◽  
W. Pieter Medendorp
Keyword(s):  
Spatial Orientation ◽  
Contextual Information ◽  
Sensory Information ◽  
The Body ◽  
Individual Subject ◽  
Noise Characteristics ◽  
Age Related ◽  
Vestibular Cues ◽  
Age Dependent ◽  
Visual Frame

As we age, the acuity of our sensory organs declines, which may affect our lifestyle. Sensory deterioration in the vestibular system is typically bilateral and gradual, and could lead to problems with balance and spatial orientation. To compensate for the sensory deterioration, it has been suggested that the brain reweights the sensory information sources according to their relative noise characteristics. For rehabilitation and training programs, it is important to understand the consequences of this reweighting, preferably at the individual subject level. We psychometrically examined the age-dependent reweighting of visual and vestibular cues used in spatial orientation in a group of 32 subjects (age range: 19–76 yr). We asked subjects to indicate the orientation of a line (clockwise or counterclockwise relative to the gravitational vertical) presented within an oriented square visual frame when seated upright or with their head tilted 30° relative to the body. Results show that subjects’ vertical perception is biased by the orientation of the visual frame. Both the magnitude of this bias and response variability become larger with increasing age. Deducing the underlying sensory noise characteristics, using Bayesian inference, suggests an age-dependent reweighting of sensory information, with an increasing weight of the visual contextual information. Further scrutiny of the model suggests that this shift in sensory weights is the result of an increase in the noise of the vestibular signal. Our approach quantifies how noise properties of visual and vestibular systems change over the life span, which helps to understand the aging process at the neurocomputational level. NEW & NOTEWORTHY Perception of visual vertical involves a weighted fusion of visual and vestibular tilt cues. Using a Bayesian approach and experimental psychophysics, we quantify how this fusion process changes with age. We show that, with age, the vestibular information is down-weighted whereas the visual weight is increased. This shift in sensory reweighting is primarily due to an age-related increase of the noise of vestibular signals.

scholarly journals Live Fast, Die Young, and Sleep Later: Life History Strategy and Human Sleep Behavior

2020 ◽  
Author(s):  
Vahe Dishakjian ◽  
Daniel M T Fessler ◽  
Adam Maxwell Sparks
Keyword(s):  
Life History ◽  
Individual Differences ◽  
Sleep Duration ◽  
Sleep Onset ◽  
Life History Strategy ◽  
The Body ◽  
Equation Modeling ◽  
Sleep Onset Latency ◽  
Sleep Behaviors

Abstract Background and objectives Life History Theory (LHT) describes trade-offs that organisms make with regard to three investment pathways: growth, maintenance, and reproduction. In light of the reparative functions of sleep, we examine sleep behaviors and corresponding attitudes as proximate manifestations of an individual’s underlying relative prioritization of short-term reproduction versus long-term maintenance. Methodology We collected survey data from 568 participants across two online studies having different participant pools. We use a mixture of segmented and hierarchical regression models, structural equation modeling, and machine learning to infer relationships between sleep duration/quality, attitudes about sleep, and biodemographic/psychometric measures of life history strategy (LHS). Results An age-mediated U- or V-shaped relationship appears when LHS is plotted against habitual sleep duration, with the fastest strategies occupying the sections of the curve with the highest mortality risk: < 6.5 hours (short sleep) and > 8.5 hours (long sleep). LH “fastness” is associated with increased sleepiness and worse overall sleep quality: delayed sleep onset latency, more wakefulness after sleep onset, higher sleep-wake instability, and greater sleep duration variability. Hedonic valuations of sleep may mediate the effects of LHS on certain sleep parameters. Conclusions and implications The costs of deprioritizing maintenance can be parameterized in the domain of sleep, where “life history fastness” corresponds with sleep patterns associated with greater senescence and mortality. Individual differences in sleep having significant health implications can thus be understood as components of lifelong trajectories likely stemming from calibration to developmental circumstances. Relatedly, hedonic valuations of sleep may constitute useful avenues for non-pharmacological management of chronic sleep disorders. LAY Summary Sleep is essential because it allows the body to repair and maintain itself. But time spent sleeping is time that cannot be spent doing other things. People differ in how much they prioritize immediate rewards, including sociosexual opportunities, versus long-term goals. In this research, we show that individual differences in sleep behaviors, and attitudes toward sleep, correspond with psychological and behavioral differences reflecting such differing priorities. Orientation toward sleep can thus be understood as part of the overall lifetime strategies that people pursue.

Switching and Combining Antipsychotics

CNS Spectrums ◽  
2010 ◽  
Vol 15 (S6) ◽  
pp. 8-11 ◽  
Author(s):  
Christoph U. Correll
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Clinical Decision Making ◽  
Clinical Decision ◽  
Individual Variability ◽  
The Body ◽  
Striatal Dopamine ◽  
Caloric Content ◽  
Pharmacokinetic Profiles ◽  
Positron Emission

Pharmacologic knowledge can inform clinical decision-making, particularly the dosing and switching decisions made with antipsychotics. Of relevance are the pharmacokinetic (what does the body do to the drug) and the pharmacodynamic (what does the drug do to the body) properties of antipsychotics.The goal of antipsychotic dosing is to achieve sufficient dopa-mine blockade in areas where dopamine excess can lead to psychosis, mania, or aggression. Using positron emission topography, one investigation showed that response rates were considerably higher in patients who achieved >65% striatal dopamine blockade. Conversely, striatal dopamine blockade >80% predicted the emergence of extrapyramidal symptoms (EPS) or akathisia.There is, however, considerable intra-individual variability in achieving the desired 60% to 80% striatal dopamine blockade. Such variability is likely due to inter-individual differences in the absorption, distribution, metabolism and elimination of medications. At the same time, antipsychotics themselves differ in their general pharmacokinetic profiles. For example, ziprasidone absorption is ~50% less when ingested on an empty stomach than when taken with a meal; the degree of absorption depends on the caloric content, while the fat content is not relevant.

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