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Journal of Vision Jun 2024The watercolor effect (WCE) is a striking visual illusion elicited by a bichromatic double contour, such as a light orange and a dark purple, hugging each other on a... (Review)
Review
The watercolor effect (WCE) is a striking visual illusion elicited by a bichromatic double contour, such as a light orange and a dark purple, hugging each other on a white background. Color assimilation, emanating from the lighter contour, spreads onto the enclosed surface area, thereby tinting it with a chromatic veil, not unlike a weak but real color. Map makers in the 17th century utilized the WCE to better demarcate the shape of adjoining states, while 20th-century artist Bridget Riley created illusory watercolor as part of her op-art. Today's visual scientists study the WCE for its filling-in properties and strong figure-ground segregation. This review emphasizes the superior strength of the WCE for grouping and figure-ground organization vis-à-vis the classical Gestalt factors of Max Wertheimer (1923), thereby inspiring a notion of form from induced color. It also demonstrates that a thin chromatic line, flanking the inside of a black Mondrian-type pattern, induces the WCE across a large white surface area. Phenomenological, psychophysical, and neurophysiological approaches are reviewed.
Topics: Humans; Color Perception; History, 20th Century; Optical Illusions; Form Perception; History, 17th Century; History, 19th Century; History, 18th Century
PubMed: 38913017
DOI: 10.1167/jov.24.6.15 -
Cortex; a Journal Devoted To the Study... Jun 2024Our brains are constantly adapting to changes in our visual environments. Neural adaptation exerts a persistent influence on the activity of sensory neurons and our... (Review)
Review
Our brains are constantly adapting to changes in our visual environments. Neural adaptation exerts a persistent influence on the activity of sensory neurons and our perceptual experience, however there is a lack of consensus regarding how adaptation is implemented in the visual system. One account describes fatigue-based mechanisms embedded within local networks of stimulus-selective neurons (networked fatigue models). Another depicts adaptation as a product of stimulus expectations (predictive coding models). In this review, I evaluate neuroimaging and psychophysical evidence that poses fundamental problems for predictive coding models of neural adaptation. Specifically, I discuss observations of distinct repetition and expectation effects, as well as incorrect predictions of repulsive adaptation aftereffects made by predictive coding accounts. Based on this evidence, I argue that networked fatigue models provide a more parsimonious account of adaptation effects in the visual system. Although stimulus expectations can be formed based on recent stimulation history, any consequences of these expectations are likely to co-occur (or interact) with effects of fatigue-based adaptation. I conclude by proposing novel, testable hypotheses relating to interactions between fatigue-based adaptation and other predictive processes, focusing on stimulus feature extrapolation phenomena.
PubMed: 38905873
DOI: 10.1016/j.cortex.2024.06.003 -
Frontiers in Pain Research (Lausanne,... 2024Pain is a complex and multifaced sensory and emotional experience. Virtual reality (VR) has shown promise in reducing experimental pain and chronic pain. This study...
BACKGROUND
Pain is a complex and multifaced sensory and emotional experience. Virtual reality (VR) has shown promise in reducing experimental pain and chronic pain. This study examines an immersive VR environment initially designed for endometriosis patients, which demonstrated short-term analgesic effects. The research aims to determine the impact of the VR environment on experimental pain intensity and unpleasantness both during and after VR exposure (3D with binaural beats), while using an active control condition (2D with no binaural beats). Additionally, a secondary objective of the study was to identify the psychological and psychophysical factors that predict the analgesic effects of the immersive digital therapeutic tool.
METHODS
The study involved twenty-one healthy individuals and used a within-subject design, comparing a VR treatment with an active control condition. Continuous heat stimulation was applied to the left forearm with a Peltier thermode. Pain ratings were collected for immediate and short-term effects.
RESULTS
In both the VR and Control conditions, there were no significant differences in pain intensity before, during, and after exposure. However, during VR exposure, there was a significant decrease in pain unpleasantness as compared to before exposure ( < 0.001), with a 27.2% pain reduction. In the Control condition, there were no significant differences in pain unpleasantness during and after exposure. Furthermore, no psychological and psychophysical factors predicted the analgesic effects.
DISCUSSION
The study investigated how a VR environment affected experimentally induced pain in healthy volunteers. It showed that VR reduced pain unpleasantness during exposure but had no lasting impact. The VR environment mainly influenced the emotional aspect of pain, possibly due to its inclusion of binaural beats and natural stimuli. The study suggests that the VR environment should be tested in chronic pain population with high distress levels.
REGISTRATION NUMBER CLINICALTRIALSGOV
NCT06130267.
PubMed: 38903416
DOI: 10.3389/fpain.2024.1366892 -
Vision Research Jun 2024It is important to understand the development of meridional anisotropies in neurotypical children since those with poor visual development, such as amblyopia, can have...
It is important to understand the development of meridional anisotropies in neurotypical children since those with poor visual development, such as amblyopia, can have different patterns of meridional anisotropies. While the oblique effect is usually observed in adults, neurotypical children who have normal 20/20 visual acuity tend to demonstrate a horizontal effect electrophysiologically. In this longitudinal study, orientation-specific visual evoked potentials (osVEPs) and psychophysical grating acuity were used to investigate the changes in the meridional anisotropies in children aged 3.8 to 9.2 years over two visits averaging four months apart. While it was hypothesized that the electrophysiological horizontal effect may shift towards an oblique effect, it was found that the electrophysiological horizontal effect persisted to be present in response to the suprathreshold moderate contrast 4 cycles-per-degree grating stimuli. Psychophysical grating acuity, however, demonstrated an oblique effect when assessed binocularly. In addition, a significant effect of visit, representing an increase in the average age over this period, was observed in the average osVEP C3 amplitudes (4.5 μV) and psychophysical grating acuity (0.28 octaves or approximately 1-line on the logMAR chart). These findings are relevant when evaluating amblyopia treatments and interventions, as it confirms the necessity to take into account of the effect of normal maturation and learning effects when evaluating young children. Special attention should also be given to children with early-onset myopia and high astigmatism even when their visual acuity is 20/20 as the electrophysiological findings are suggestive of poor visual development, which warrants further investigation.
PubMed: 38896923
DOI: 10.1016/j.visres.2024.108439 -
BioRxiv : the Preprint Server For... Jun 2024Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the striatum, predominantly associated with motor symptoms. However, non-motor...
Parkinson's disease (PD) is characterized by the degeneration of dopaminergic neurons in the striatum, predominantly associated with motor symptoms. However, non-motor deficits, particularly sensory symptoms, often precede motor manifestations, offering a potential early diagnostic window. The impact of non-motor deficits on sensation behavior and the underlying mechanisms remains poorly understood. In this study, we examined changes in tactile sensation within a Parkinsonian state by employing a mouse model of PD induced by 6-hydroxydopamine (6-OHDA) to deplete striatal dopamine (DA). Leveraging the conserved mouse whisker system as a model for tactile-sensory stimulation, we conducted psychophysical experiments to assess sensory-driven behavioral performance during a tactile detection task in both the healthy and Parkinson-like states. Our findings reveal that DA depletion induces pronounced alterations in tactile sensation behavior, extending beyond expected motor impairments. We observed diverse behavioral deficits, spanning detection performance, task engagement, and reward accumulation, among lesioned individuals. While subjects with extreme DA depletion consistently showed severe sensory behavioral deficits, others with substantial DA depletion displayed minimal changes in sensory behavior performance. Moreover, some exhibited moderate degradation of behavioral performance, likely stemming from sensory signaling loss rather than motor impairment. The implementation of a sensory detection task is a promising approach to quantify the extent of impairments associated with DA depletion in the animal model. This facilitates the exploration of early non-motor deficits in PD, emphasizing the importance of incorporating sensory assessments in understanding the diverse spectrum of PD symptoms.
PubMed: 38895263
DOI: 10.1101/2024.06.05.597339 -
Frontiers in Neuroscience 2024In neural prostheses, intensity modulation of a single channel (i.e., through a single stimulating electrode) has been achieved by increasing the magnitude or width of...
In neural prostheses, intensity modulation of a single channel (i.e., through a single stimulating electrode) has been achieved by increasing the magnitude or width of each stimulation pulse, which risks eliciting pain or paraesthesia; and by changing the stimulation rate, which leads to concurrent changes in perceived frequency. In this study, we sought to render a perception of tactile intensity and frequency independently, by means of temporal pulse train patterns of fixed magnitude, delivered non-invasively. Our psychophysical study exploits a previously discovered frequency coding mechanism, where the perceived frequency of stimulus pulses grouped into periodic bursts depends on the duration of the inter-burst interval, rather than the mean pulse rate or periodicity. When electrical stimulus pulses were organised into bursts, perceived intensity was influenced by the number of pulses within a burst, while perceived frequency was determined by the time between the end of one burst envelope and the start of the next. The perceived amplitude was modulated by 1.6× while perceived frequency was varied independently by 2× within the tested range (20-40 Hz). Thus, the sensation of intensity might be controlled independently from frequency through a single stimulation channel without having to vary the injected electrical current. This can form the basis for improving strategies in delivering more complex and natural sensations for prosthetic hand users.
PubMed: 38894940
DOI: 10.3389/fnins.2024.1125597 -
Medycyna Pracy Jun 2024Building law regulations determine designing the built environment recognising the needs of users of different ages and psychophysical abilities. Seniors and their...
BACKGROUND
Building law regulations determine designing the built environment recognising the needs of users of different ages and psychophysical abilities. Seniors and their spatial needs are covered there to a limited extent. The benchmark for design are wheelchair users. Their spatial requirements are greater in relation to independent walkers, including most older people. This makes it difficult to adapt the whole built environment to the needs of people with less mobility dysfunction. This can be considered in terms of spatial design and investment costs.
MATERIAL AND METHODS
The paper analyses the building regulations of 3 countries in terms of legal conditions to shape the architectural movement space of older people and disabled people. Analytical and comparative methods are used. Such research is becoming relevant and necessary. The analyses are conducted in the context of ageing populations. They are justified by statistical data on the age groups of Polish society. This is followed by design analyses of the legal requirements in the wheelchair movement space and proposals for alternatives, e.g., people walking with canes (case study). Their aim is to indicate methods to limit excessive communication spaces in buildings while maintaining functional values for all users.
RESULTS
Research may show the possibility of greater diversification of regulations and alternatives to current laws. They are dedicated to participants in investment processes to shape accessible buildings. They can also be used in legislative work on amendments to the construction law.
CONCLUSIONS
Changes in building regulations and a detailed approach to the mobility needs of older and disabled people (walking independently) are proposed. These decisions can provide benefits (spatial and economic savings). They fall into the "design for all" trend and sustainability of the built environment. These demands are based on no longer valid normative regulations. Med Pr Work Health Saf. 2024;75(3).
PubMed: 38873967
DOI: 10.13075/mp.5893.01512 -
Frontiers in Sports and Active Living 2024This article aims to present a new argument on the validity of utilizing karate in youth safety education. First, the important role of safety education and the need to...
This article aims to present a new argument on the validity of utilizing karate in youth safety education. First, the important role of safety education and the need to seek new means of influencing young people is presented and the significant role of sport in this area. The field of Far Eastern combat sports was underlined here as being particularly important because they contain internal codes of moral conduct. Therefore, the new argument is to take the perspective of karate as a combat sport, martial art, and self defence system in one. Karate as a combat sport refers to fighting skills in the following directions: traditional, sport and Olympic; and in the following systems: semi contact, knockdown, full contact, mix fighting. Karate as a martial art has a health-promoting character and emphasises the psycho-physical development of practitioners and the recognition of ethical codes. And karate as a self defence system is concerned with proficiency in out-of-sport confrontations, but also in risk assessment. Karate has been found to be an effective means in educating young people to safety, but in order for it to be effective, it needs to be adopted in its entirety. Because the combat sport perspective activates youth in physical culture, the martial art perspective educates according to norms and rules; and the self defence system perspective teaches how to act in difficult situations.
PubMed: 38873226
DOI: 10.3389/fspor.2024.1400920 -
Frontiers in Robotics and AI 2024Force is crucial for learning psychomotor skills in laparoscopic tissue manipulation. Fundamental laparoscopic surgery (FLS), on the other hand, only measures time and...
Force is crucial for learning psychomotor skills in laparoscopic tissue manipulation. Fundamental laparoscopic surgery (FLS), on the other hand, only measures time and position accuracy. FLS is a commonly used training program for basic laparoscopic training through part tasks. The FLS is employed in most of the laparoscopic training systems, including box trainers and virtual reality (VR) simulators. However, many laparoscopic VR simulators lack force feedback and measure tissue damage solely through visual feedback based on virtual collisions. Few VR simulators that provide force feedback have subjective force metrics. To provide an objective force assessment for haptic skills training in the VR simulators, we extend the FLS part tasks to haptic-based FLS (HFLS), focusing on controlled force exertion. We interface the simulated HFLS part tasks with a customized bi-manual haptic simulator that offers five degrees of freedom (DOF) for force feedback. The proposed tasks are evaluated through face and content validity among laparoscopic surgeons of varying experience levels. The results show that trainees perform better in HFLS tasks. The average Likert score observed for face and content validity is greater than 4.6 ± 0.3 and 4 ± 0.5 for all the part tasks, which indicates the acceptance of the simulator among subjects for its appearance and functionality. Face and content validations show the need to improve haptic realism, which is also observed in existing simulators. To enhance the accuracy of force rendering, we incorporated a laparoscopic tool force model into the simulation. We study the effectiveness of the model through a psychophysical study that measures just noticeable difference (JND) for the laparoscopic gripping task. The study reveals an insignificant decrease in gripping-force JND. A simple linear model could be sufficient for gripper force feedback, and a non-linear LapTool force model does not affect the force perception for the force range of 0.5-2.5 N. Further study is required to understand the usability of the force model in laparoscopic training at a higher force range. Additionally, the construct validity of HFLS will confirm the applicability of the developed simulator to train surgeons with different levels of experience.
PubMed: 38873121
DOI: 10.3389/frobt.2024.1363952 -
PloS One 2024This body image study tests the viability of transferring a complex psychophysical paradigm from a controlled in-person laboratory task to an online environment. 172...
This body image study tests the viability of transferring a complex psychophysical paradigm from a controlled in-person laboratory task to an online environment. 172 female participants made online judgements about their own body size when viewing images of computer-generated female bodies presented in either in front-view or at 45-degrees in a method of adjustment (MOA) paradigm. The results of these judgements were then compared to the results of two laboratory-based studies (with 96 and 40 female participants respectively) to establish three key findings. Firstly, the results show that the accuracy of online and in-lab estimates of body size are comparable, secondly that the same patterns of visual biases in judgements are shown both in-lab and online, and thirdly online data shows the same view-orientation advantage in accuracy in body size judgements as the laboratory studies. Thus, this study suggests that that online sampling potentially represents a rapid and accurate way of collecting reliable complex behavioural and perceptual data from a more diverse range of participants than is normally sampled in laboratory-based studies. It also offers the potential for designing stratified sampling strategies to construct a truly representative sample of a target population.
Topics: Humans; Female; Body Image; Adult; Psychophysics; Young Adult; Adolescent; Body Size; Visual Perception; Judgment; Internet
PubMed: 38857270
DOI: 10.1371/journal.pone.0302747