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1.
PLoS Comput Biol ; 16(8): e1007920, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32780741

RESUMO

Standard neuroeconomic decision theory assumes that choice is based on a value comparison process, independent from how information about alternative options is collected. Here, we investigate the opposite intuition that preferences are dynamically shaped as options are sampled, through iterative covert pairwise comparisons. Our model builds on two lines of research, one suggesting that a natural frame of comparison for the brain is between default and alternative options, the other suggesting that comparisons spread preferences between options. We therefore assumed that during sequential option sampling, people would 1) covertly compare every new alternative to the current best and 2) update their values such that the winning (losing) option receives a positive (negative) bonus. We confronted this "covert pairwise comparison" model to models derived from standard decision theory and from known memory effects. Our model provided the best account of human choice behavior in a novel task where participants (n = 92 in total) had to browse through a sequence of items (food, music or movie) of variable length and ultimately select their favorite option. Consistently, the order of option presentation, which was manipulated by design, had a significant influence on the eventual choice: the best option was more likely to be chosen when it came earlier in the sequence, because it won more covert comparisons (hence a greater total bonus). Our study provides a mechanistic understanding of how the option sampling process shapes economic preference, which should be integrated into decision theory.


Assuntos
Comportamento de Escolha/fisiologia , Modelos Psicológicos , Adulto , Biologia Computacional , Simulação por Computador , Comportamento do Consumidor , Teoria da Decisão , Feminino , Humanos , Masculino , Motivação , Psicofísica , Adulto Jovem
2.
Nat Commun ; 11(1): 3925, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764538

RESUMO

Adaptation is a ubiquitous property of sensory systems. It is typically considered that neurons adapt to dominant energy in the ambient environment to function optimally. However, perceptual representation of the stimulus, often modulated by feedback signals, sometimes do not correspond to the input state of the stimulus, which tends to be more linked with feedforward signals. Here we investigated the relative contributions to cortical adaptation from feedforward and feedback signals, taking advantage of a visual illusion, the Flash-Grab Effect, to disassociate the feedforward and feedback representation of an adaptor. Results reveal that orientation adaptation is exclusively dependent on the perceived rather than the retinal orientation of the adaptor. Combined fMRI and EEG measurements demonstrate that the perceived orientation of the Flash-Grab Effect is indeed supported by feedback signals in the cortex. These findings highlight the important contribution of feedback signals for cortical neurons to recalibrate their sensitivity.


Assuntos
Adaptação Fisiológica , Ilusões/fisiologia , Orientação Espacial/fisiologia , Adulto , Eletroencefalografia , Potenciais Evocados Visuais , Retroalimentação Fisiológica , Feminino , Neuroimagem Funcional , Humanos , Imagem por Ressonância Magnética , Masculino , Ilusões Ópticas/fisiologia , Estimulação Luminosa , Psicofísica , Retina/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adulto Jovem
3.
PLoS One ; 15(8): e0236321, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32776987

RESUMO

The widely known hue-heat effect, a multisensory phenomenon between vision and thermal sensing, is a hypothesis based on the idea that light and colors affect perceived temperature. However, the application of this effect has not been prevalent in our daily lives. To work towards developing more practical use of the hue-heat effect, we conducted a series of psychophysical experiments to investigate the relationship between perceived temperature and illumination in a well-controlled experimental environment. The results showed that illumination had three types of effects to change our sense of coolness/warmness: creating, eliminating, and exchanging effects. Furthermore, we confirmed the existence of two distinctive time courses for the three effects: creating effect started immediately, but the eliminating effect takes time. These findings provide us with a better understanding of the hue-heat effect and enable us to apply it in everyday life. Paired with the new technologies it can also help with energy conservation.


Assuntos
Percepção de Cores/fisiologia , Iluminação , Sensação Térmica/fisiologia , Feminino , Temperatura Alta , Humanos , Masculino , Estimulação Luminosa/métodos , Psicofísica , Adulto Jovem
4.
PLoS One ; 15(8): e0237854, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853262

RESUMO

Drug-induced long QT syndrome (diLQTS), characterized by a prolongation of the QT-interval on the electrocardiogram (ECG), is a serious adverse drug reaction that can cause the life-threatening arrhythmia Torsade de Points (TdP). Self-monitoring for diLQTS could therefore save lives, but detecting it on the ECG is difficult, particularly at high and low heart rates. In this paper, we evaluate whether using a pseudo-colouring visualisation technique and changing the coordinate system (Cartesian vs. Polar) can support lay people in identifying QT-prolongation at varying heart rates. Four visualisation techniques were evaluated using a counterbalanced repeated measures design including Cartesian no-colouring, Cartesian pseudo-colouring, Polar no-colouring and Polar pseudo-colouring. We used a multi-reader, multi-case (MRMC) receiver operating characteristic (ROC) study design within a psychophysical paradigm, along with eye-tracking technology. Forty-three lay participants read forty ECGs (TdP risk n = 20, no risk n = 20), classifying each QT-interval as normal/abnormal, and rating their confidence on a 6-point scale. The results show that introducing pseudo-colouring to the ECG significantly increased accurate detection of QT-interval prolongation regardless of heart rate, T-wave morphology and coordinate system. Pseudo-colour also helped to reduce reaction times and increased satisfaction when reading the ECGs. Eye movement analysis indicated that pseudo-colour helped to focus visual attention on the areas of the ECG crucial to detecting QT-prolongation. The study indicates that pseudo-colouring enables lay people to visually identify drug-induced QT-prolongation regardless of heart rate, with implications for the more rapid identification and management of diLQTS.


Assuntos
Eletrocardiografia , Frequência Cardíaca , Síndrome do QT Longo/diagnóstico por imagem , Síndrome do QT Longo/fisiopatologia , Adulto , Cor , Movimentos Oculares/fisiologia , Feminino , Fixação Ocular/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Satisfação Pessoal , Estimulação Luminosa , Psicofísica , Curva ROC , Tempo de Reação , Fatores de Risco , Sensibilidade e Especificidade , Adulto Jovem
5.
PLoS One ; 15(5): e0233568, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32470031

RESUMO

Studies on natural and social vision often need to quantify subjective intensity along a particular dimension for a large number of stimuli whose perceptual ordering is unknown. Here, we introduce an easy experimental protocol of comparative judgments that can rank and scale subjective stimulus intensity using a comparatively small number of trials. On each trial in our protocol, the observer initially views M stimuli sampled from a space of N stimuli and selects the stimulus that elicits maximum subjective response along a given dimension (e.g., the most attractive). The selected stimulus is subsequently discarded, the observer then performs a judgment on the remaining stimuli, and the process is iterated until the last stimulus remains and a new trial begins. The method relies on sorting perceived stimulus order in the N x N comparison matrix via logistic regression and sampling the next set of M stimuli such that responses will be collected only for stimulus pairs whose expected response ratio is most informative. Numerical simulations demonstrate that this method can estimate psychological scale with a small number of responses. Psychophysical experiments confirm that the method can quickly estimate the contrast response function for gratings and the perceived glossiness of naturalistic objects. This protocol would be useful for characterizing human judgments along various dimensions, especially those with no physical image correlates such as emotional and social attributes.


Assuntos
Julgamento , Psicologia/métodos , Emoções , Humanos , Psicofísica
6.
PLoS One ; 15(4): e0231959, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32352993

RESUMO

We measured psychophysical thresholds for discriminating the speeds of two arrays of moving dots. The arrays could be juxtaposed or could be spatially separated by up to 10 degrees of visual angle, eccentricity being held constant. We found that the precision of the judgments varied little with separation. Moreover, the function relating threshold to separation was similar whether the arrays moved in the same, in opposite or in orthogonal directions. And there was no significant difference in threshold whether the two stimuli were initially presented to the same cerebral hemisphere or to opposite ones. How are human observers able to compare stimuli that fall at well separated positions in the visual field? We consider two classes of explanation: (i) Observers' judgments might be based directly on the signals of dedicated 'comparator neurons', i.e. neurons drawing inputs of opposite sign from local regions of the visual field. (ii) Signals about local features might be transmitted to the site of comparison by a shared 'cerebral bus', where the same physical substrate carries different information from moment to moment. The minimal effects of proximity and direction (which might be expected to influence local detectors of relative motion), and the combinatorial explosion in the number of comparator neurons that would be required by (i), lead us to favor models of type (ii).


Assuntos
Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Humanos , Percepção de Movimento/fisiologia , Psicofísica , Fatores de Tempo
7.
Invest Ophthalmol Vis Sci ; 61(5): 5, 2020 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-32392311

RESUMO

Purpose: We investigated and characterized the patterns of meridional anisotropies in newly diagnosed refractive amblyopes using pattern onset-offset visual evoked potentials (POVEPs) and psychophysical grating acuity (GA). Methods: Twenty-five refractive amblyopes were recruited and compared with non-amblyopic controls from our previous study. Monocular POVEPs were recorded in response to sinewave 4 cycles per degree (cpd) grating stimuli oriented along each individual participants' principal astigmatic meridians, which were approximately horizontal (meridian 1) and vertical (meridian 2). Binocular POVEPs in response to the same stimuli, but oriented at 45°, 90°, 135°, and 180°, were recorded. Psychophysical GAs were assessed along the same meridians using a two-alternative non-forced-choice technique. The C3 amplitudes and peak latencies of the POVEPs and GAs were compared across meridians for both groups (refractive amblyopes and controls) using linear mixed models (monocular) and ANOVA (binocular), and post hoc analysis was conducted to determine if meridional anisotropies in this cohort of amblyopes were related to low (≤1.50 diopters [D]), moderate (1.75-2.75 D) and high (≥3.00 D) astigmatism. Results: In the newly diagnosed refractive amblyopes, there were no significant meridional anisotropies across all outcome measures, but the post hoc analysis demonstrated that C3 amplitude was significantly higher in those with low (P = 0.02) and moderate (P = 0.004) astigmatism compared to those with high astigmatism. Refractive amblyopes had poorer GA and C3 amplitudes compared to controls by approximately two lines on the logMAR chart (monocular: P = 0.013; binocular: P = 0.014) and approximately 6 µV (monocular: P = 0.009; binocular: P = 0.027), respectively. Conclusions: Deleterious effects of high astigmatism was evident in newly diagnosed refractive amblyopes, but the neural deficits do not seem to be orientation-specific for the stimulus parameters investigated.


Assuntos
Ambliopia/fisiopatologia , Potenciais Evocados Visuais/fisiologia , Orientação/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Anisotropia , Astigmatismo/fisiopatologia , Estudos de Casos e Controles , Criança , Pré-Escolar , Humanos , Psicofísica
8.
Atten Percept Psychophys ; 82(6): 2963-2984, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32346824

RESUMO

Means and standard deviations of psychophysical measurements are first and second statistical moments that reflect neural mechanisms underlying the measured sensation: for example, standard deviations of hue matches are difference-thresholds that reflect the color pathways' spectral response. Might memory psychophysics yield similar insight into neural mechanisms underlying recognition? Five experiments measured memory means and difference-thresholds: Means of monochromatic hue matches made from memory hardly changed with memory time. Hue memory remained consistent even though the variability of those matches increased exponentially as memory time increased to 14 s. This indicates the loss of accuracy in the memory resulted from a random decay of the stored information. Nevertheless, the hue memory difference-thresholds as a function of wavelength continued to resemble sensory difference-threshold functions as memory time increased. Similar results obtained by dichoptic matches indicated this resemblance was not a retinal effect. Line and grating orientation memory difference-thresholds also retained their similarity to sensory difference-threshold functions as memory time increased. The similarity was not some artifact of measuring difference-thresholds by matching because such results were also obtained using a forced-choice method. Similarity of memory discrimination functions to sensory functions is quantitative evidence that, despite decay, activity retrieved from memory resembles the sensory responses used when two stimuli are compared simultaneously. Feasibility of this conclusion was tested by modeling the memory-matching procedure. It produced difference-thresholds resembling those obtained with simultaneous matches when the stored signal had decayed to 10%. Together these results provide "inside" evidence that cortical activity resembling sensory responses underlie recognition.


Assuntos
Percepção de Cores , Memória , Limiar Diferencial , Humanos , Psicofísica , Limiar Sensorial
9.
Work ; 65(3): 497-507, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32116269

RESUMO

BACKGROUND: One-handed lifting commonly occurs in the industry. Specific guidelines of proper heights during one-handed lifting could be valuable information to design or to assess the risk of work environment. OBJECTIVE: The objective of this study was to determine the maximum acceptable height and comfortable height during one-handed vertical lifting by gender, participant height, hand, and object weight. METHODS: Based on the psychophysical method, 72 males and 50 females, divided into four different height groups, determined their maximum acceptable and comfortable heights by each hand (left and right) and various object weights (1 kg, 3 kg, 5 kg, and 8 kg). RESULTS: Males revealed significantly greater maximum acceptable heights (males: 157 cm; females: 135 cm) and higher comfortable heights (males: 104 cm; females: 96 cm) compared to females. The participants' heights, which hand was used to lift, and the object weight were significant factors in determining the maximum acceptable height for both males and females. The multiple linear regression model of the maximum acceptable height showed more robust predictive power (R2 = 0.55) compared to the comfortable height (R2 = 0.20) as a function of gender, participant height, hand, and object weight. CONCLUSIONS: Results suggest that gender, participant height, hand, and object weight are important variables to consider when determining the proper surface height of one-handed vertical lifting. Using the robust predictive model, an appropriate maximum acceptable height could be suggested based on the material handler's anthropometric information and object weight.


Assuntos
Ergonomia , Remoção , Adulto , Estatura , Feminino , Lateralidade Funcional , Mãos , Humanos , Coreia (Geográfico) , Masculino , Psicofísica , Fatores Sexuais , Análise e Desempenho de Tarefas
10.
J Vis ; 20(3): 3, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32181859

RESUMO

In paradigms of visual search where the search feature (say color) can change from trial to trials, responses are faster for trials where the search color is repeated than when it changes. This is a clear example of "priming" of attention. Here we test whether the priming effects can be revealed by pupillometry, and also whether they are related to autistic-like personality traits, as measured by the Autism-Spectrum Quotient (AQ). We repeated Maljkovic and Nakayama's (1994) classic priming experiment, asking subjects to identify rapidly the shape of a singleton target defined by color. As expected, reaction times were faster when target color repeated, and the effect accumulated over several trials; but the magnitude of the effect did not correlate with AQ. Reaction times were also faster when target position was repeated, again independent of AQ. Presentation of stimuli caused the pupil to dilate, and the magnitude of dilation was greater for switched than repeated trials. This effect did not accumulate over trials, and did not correlate with the reaction times difference, suggesting that the two indexes measure independent aspects of the priming phenomenon. Importantly, the amplitude of pupil modulation correlated negatively with AQ, and was significant only for those participants with low AQ. The results confirm that pupillometry can track perceptual and attentional processes, and furnish useful information unobtainable from standard psychophysics, including interesting dependencies on personality traits.


Assuntos
Transtorno Autístico/fisiopatologia , Percepção de Cores/fisiologia , Percepção de Forma/fisiologia , Pupila/fisiologia , Priming de Repetição/fisiologia , Adulto , Feminino , Humanos , Masculino , Psicofísica , Tempo de Reação , Inquéritos e Questionários , Adulto Jovem
11.
J Vis ; 20(3): 6, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32207770

RESUMO

While visual size preferences regarding still objects have been investigated and linked to the "canonical size" effect-where preferred on-screen size was significantly related to objects' real-world size-the visual size preferences related to moving images of natural scenes has not been researched. In this study, we measured the preferred size of moving images of natural scenes and short duration and investigated the effect of viewing distance on size preferences. Our results showed that the preferred size varied strongly depending on content, and we found moving images' canonical size effect. The preferred size in images of scenery was significantly larger than in images of persons, and there was a positive correlation between the preferred size and the real-world physical size of the main subjects in the images. When the viewing distance was doubled, the preferred size increased about 10% as a ratio to screen size-in contrast to the findings of a previous study. While the rationale for these findings is not yet clear, our analysis suggests that neither the motion component in the images nor the nature of their background area are contributing factors. We suggest that environment, viewing distance, and screen size may contribute to this effect.


Assuntos
Percepção de Distância/fisiologia , Percepção de Movimento/fisiologia , Percepção de Tamanho/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psicofísica , Adulto Jovem
12.
PLoS One ; 15(2): e0229139, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32092081

RESUMO

OBJECTIVE: The purpose of this study was to assess the relationship between an embodied sensory experience and the ability to translate the perception of this experience visually using modifiable motion graphics. METHODS: A custom-designed software was developed to enable users to modify a motion graphic in real-time. The motion graphics were designed to depict realistic visualizations of pain quality descriptors, such as tingling and burning. Participants (N = 34) received an electrical stimulation protocol known to elicit sensations of tingling. The protocol consisted of eight stimulation intensities ranging from 2-6mA delivered, in a randomized fashion and repeated three times, to the index finger. Immediately after each stimulus, participants drew the area of the evoked sensation on a digital body chart of the hand. Participants then modified the motion graphic of tingling by adjusting two parameters, namely the speed (rate of dots disappearing and re-appearing) and density of these dots in the drawn area. Then, participants rated the perceived intensity and selected the most appropriate pain quality descriptor. RESULTS: There was an increase in the area, density, and perceived intensity ratings as the electrical stimulation intensity increased (P<0.001). The density of the motion graphic, but not speed, correlated with perceived intensity ratings (0.69, P<0.001) and electrical stimulation intensities (0.63, P<0.01). The descriptor 'tingling' was predominantly selected in the range of 3-4.5mA and was often followed by 'stabbing' as the electrical intensity increased. DISCUSSION: The motion graphic tested was perceived to reflect a tingling sensation, the stimulation protocol elicited a tingling sensation, and participants adjusted one of the two motion graphic features systematically. In conclusion, an embodied sensation, such as tingling, maybe visually represented similarly between individuals. These findings create research, clinical, and commercial opportunities that utilize psychophysics to explore, visualize, and quantify changes in embodied sensory experiences in response to known stimuli.


Assuntos
Estimulação Elétrica , Histórias em Quadrinhos como Assunto , Sensação , Humanos , Medição da Dor , Psicofísica , Software
13.
Doc Ophthalmol ; 141(1): 45-55, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32034583

RESUMO

PURPOSE: To compare two forms of perimetry that use large contrast-modulated grating stimuli in terms of: their relative diagnostic power, their independent diagnostic information about glaucoma and their utility for mfVEPs. We evaluated a contrast-threshold mfVEP in normal controls using the same stimuli as one of the tests. METHODS: We measured psychophysical contrast thresholds in one eye of 16 control subjects and 19 patients aged 67.8 ± 5.65 and 71.9 ± 7.15, respectively, (mean ± SD). Patients ranged in disease severity from suspects to severe glaucoma. We used the 17-region FDT-perimeter C20-threshold program and a custom 9-region test (R9) with similar visual field coverage. The R9 stimuli scaled their spatial frequencies with eccentricity and were modulated at lower temporal frequencies than C20 and thus did not display a clear spatial frequency-doubling (FD) appearance. Based on the overlapping areas of the stimuli, we transformed the C20 results to 9 measures for direct comparison with R9. We also compared mfVEP-based and psychophysical contrast thresholds in 26 younger (26.6 ± 7.3 y, mean ± SD) and 20 older normal control subjects (66.5 ± 7.3 y) control subjects using the R9 stimuli. RESULTS: The best intraclass correlations between R9/C20 thresholds were for the central and outer regions: 0.82 ± 0.05 (mean ± SD, p ≤ 0.0001). The areas under receiver operator characteristic plots for C20 and R9 were as high as 0.99 ± 0.012 (mean ± SE). Canonical correlation analysis (CCA) showed significant correlation (r = 0.638, p = 0.029) with 1 dimension of the C20 and R9 data, suggesting that the lower and higher temporal frequency tests probed the same neural mechanism(s). Low signal quality made the contrast-threshold mfVEPs non-viable. The resulting mfVEP thresholds were limited by noise to artificially high contrasts, which unlike the psychophysical versions, were not correlated with age. CONCLUSION: The lower temporal frequency R9 stimuli had similar diagnostic power to the FDT-C20 stimuli. CCA indicated the both stimuli drove similar neural mechanisms, possibly suggesting no advantage of FD stimuli for mfVEPs. Given that the contrast-threshold mfVEPs were non-viable, we used the present and published results to make recommendations for future mfVEP tests.


Assuntos
Potenciais Evocados Visuais/fisiologia , Glaucoma de Ângulo Aberto/fisiopatologia , Campos Visuais/fisiologia , Adulto , Idoso , Eletrorretinografia , Feminino , Humanos , Pressão Intraocular/fisiologia , Masculino , Pessoa de Meia-Idade , Hipertensão Ocular/fisiopatologia , Psicofísica , Curva ROC , Tonometria Ocular , Acuidade Visual/fisiologia , Testes de Campo Visual
14.
PLoS One ; 15(2): e0228861, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084146

RESUMO

A wireless photovoltaic retinal prosthesis is currently being studied with the aim of providing prosthetic vision to patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). The major challenge of a photovoltaic device is its limited power efficiency. Our retinal prosthetic design implements a unique divisional power supply scheme (DPSS) system that provides the electrical power generated by all of the solar cells to only a subset of electrodes at any moment in time. The aim of the present study was to systematically characterize the spatiotemporal integration performance of the system under various DPSS conditions using human subjects and a psychophysical approach. A 16x16 pixels LED array controlled by Arduino was used to simulate the output signal of the DPSS design, and human performance under different visual stimulations at various update frequencies was then used to assess the spatiotemporal capability of retinal prostheses. The results showed that the contrast polarity of the image, image brightness, and division number influenced the lower limit of the update frequency of the DPSS system, while, on the other hand, visual angle, ambient light level, and stimulation order did not affect performance significantly. Pattern recognition by visual persistence with spatiotemporal integration of multiple frames of sparse dots is a feasible approach in retinal prosthesis design. These findings provide an insight into how to optimize a photovoltaic retinal prosthesis using a DPSS design with an appropriate update frequency for reliable pattern recognition. This will help the development of a wireless device able to restore vision to RP and AMD patients in the future.


Assuntos
Fontes de Energia Elétrica , Próteses Visuais , Adulto , Sensibilidades de Contraste/fisiologia , Estimulação Elétrica , Eletrodos Implantados , Voluntários Saudáveis , Humanos , Degeneração Macular/fisiopatologia , Degeneração Macular/cirurgia , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa , Psicofísica , Retinite Pigmentosa/fisiopatologia , Retinite Pigmentosa/cirurgia , Energia Solar , Análise Espaço-Temporal , Percepção Visual/fisiologia , Tecnologia sem Fio , Adulto Jovem
16.
IEEE Trans Haptics ; 13(1): 102-108, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31940554

RESUMO

The human hand detects high-frequency vibrations in all directions but cannot distinguish the direction, which suggests a multi-dimensional vibrotactile stimulus is haptically equivalent to some one-dimensional (1D) stimulus. In this article, we explore how a 6D vibrotactile stimulus rendered at the haptic interaction point (HIP) of a kinesthetic haptic interface, with the stylus held in a precision pen-hold grasp, is mapped to an equivalent 1D stimulus normalized by the detection threshold. We gather a large human-subjects data set in which we determine detection thresholds for 45 distinct combinations of three orthogonal forces and three orthogonal torques rendered at the HIP, at a single frequency of 108 Hz corresponding to the peak sensitivity in our prior study. Using this data set, we find a general quadratic weighting function to predict the 1D normalized stimulus for a given 6D vibrotactile stimulus. We find that including just seven (out of a possible 21) independent parameters in the symmetric weighting matrix is sufficient to capture the non-obvious coupling between forces and torques rendered at the HIP for dimensional reduction from 6D to 1D.


Assuntos
Retroalimentação Sensorial , Limiar Sensorial , Percepção do Tato , Adulto , Feminino , Humanos , Masculino , Estimulação Física , Análise de Componente Principal , Psicofísica , Vibração , Adulto Jovem
17.
J Vis ; 20(1): 2, 2020 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-31999821

RESUMO

Saccadic eye movements occur in sequences, gathering new information about the visual environment to support successful task completion. Here, we examine the control of these saccadic sequences and specifically the extent to which the spatial aspects of the saccadic responses are programmed in parallel. We asked participants to saccade to a series of visual targets and, while they shifted their gaze around the display, we displaced select targets. We found that saccade landing position was deviated toward the previous location of the target suggesting that partial parallel programming of target location information was occurring. The saccade landing position was also affected by the new target location, which demonstrates that the saccade landing position was also partially updated following the shift. This pattern was present even for targets that were the subject of the next fixation. Having a greater preview about the sequence path influenced saccade accuracy with saccades being less affected by relocations when there is less preview information. The results demonstrate that landing positions from a saccade sequence are programmed in parallel and combined with more immediate visual signals.


Assuntos
Fixação Ocular/fisiologia , Movimentos Sacádicos/fisiologia , Percepção Visual/fisiologia , Adolescente , Medições dos Movimentos Oculares , Feminino , Humanos , Masculino , Desempenho Psicomotor , Psicofísica , Tempo de Reação , Adulto Jovem
18.
Muscle Nerve ; 62(2): 167-175, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-31943276

RESUMO

Small fiber neuropathy (SFN) is being recognized with increasing frequency in neuromuscular practice due to improved diagnostic techniques. Although there are some common etiologies, up to one-third of cases are considered idiopathic. In recent years, several disorders have unexpectedly been reported in association with SFN, on clinical grounds and complementary investigations, including quantitative sensory testing, intraepidermal nerve fiber density and confocal corneal microscopy. Knowledge of these disorders is important in clinical practice as increased awareness enables prompt diagnosis of SFN in these settings and early optimal therapeutic management of affected patients. Furthermore, these new developments may lead to a better understanding of the pathophysiologic mechanisms underlying SFN in these different disorders as well as, in some cases, an expanded spectrum of affected organs and systems. This article reviews these reported associations, their possible pathophysiologic bases, and the potential resulting management implications.


Assuntos
Esclerose Amiotrófica Lateral/complicações , Fibromialgia/complicações , Síndrome de Guillain-Barré/complicações , Doença de Parkinson/complicações , Polirradiculoneuropatia Desmielinizante Inflamatória Crônica/complicações , Neuropatia de Pequenas Fibras/complicações , Biópsia , Córnea/inervação , Córnea/patologia , Síndrome de Ehlers-Danlos/complicações , Epiderme/inervação , Epiderme/patologia , Potenciais Evocados , Humanos , Doença por Corpos de Lewy/complicações , Microscopia Confocal , Fibras Nervosas Amielínicas/patologia , Vacinas contra Papillomavirus/efeitos adversos , Psicofísica , Transtorno do Comportamento do Sono REM/complicações , Neuropatia de Pequenas Fibras/induzido quimicamente , Neuropatia de Pequenas Fibras/diagnóstico , Neuropatia de Pequenas Fibras/patologia
19.
Atten Percept Psychophys ; 82(4): 1912-1927, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31898067

RESUMO

We recently showed that motion dynamics greatly enhance the magnitude of certain size contrast illusions, such as the Ebbinghaus and Delboeuf illusions. Here, we extend our study of the effect of motion dynamics on size illusions through a novel dynamic corridor illusion, in which a single target translates along a corridor background. Across three psychophysical experiments, we quantify the effects of stimulus dynamics on the Ebbinghaus and corridor illusions across different viewing conditions. The results revealed that stimulus dynamics had opposite effects on these different classes of size illusions. Whereas dynamic motion enhanced the magnitude of the Ebbinghaus illusion, it attenuated the magnitude the corridor illusion. Our results highlight precision-driven weighting of visual cues by neural circuits computing perceived object size. This hypothesis is consistent with observations beyond size perception and may represent a more general principle of cue integration in the visual system.


Assuntos
Percepção de Movimento/fisiologia , Ilusões Ópticas/fisiologia , Estimulação Luminosa/métodos , Percepção de Tamanho/fisiologia , Adulto , Sinais (Psicologia) , Feminino , Humanos , Masculino , Psicofísica , Distribuição Aleatória , Adulto Jovem
20.
Atten Percept Psychophys ; 82(4): 1613-1631, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31898076

RESUMO

Numerous studies have shown that more visual features can be stored in visual short-term memory (VSTM) when they are encoded from fewer objects (Luck & Vogel, 1997, Nature, 390, 279-281; Olson & Jiang, 2002, Perception & Psychophysics, 64[7], 1055-1067). This finding has been consistent for simple objects with one surface and one boundary contour, but very few experiments have shown a clear performance benefit when features are organized as multipart objects versus spatially dispersed single-feature objects. Some researchers have suggested multipart object integration is not mandatory because of the potential ambiguity of the display (Balaban & Luria, 2015, Cortex, 26(5), 2093-2104; Luria & Vogel, 2014, Journal of Cognitive Neuroscience, 26[8], 1819-1828). For example, a white bar across the middle of a red circle could be interpreted as two objects, a white bar occluding a red circle, or as a single two-colored object. We explore whether an object benefit can be found by disambiguating the figure-ground organization of multipart objects using a luminance gradient and linear perspective to create the appearance of a unified surface. Also, we investigated memory for objects with a visual feature indicated by a hole, rather than an additional surface on the object. Results indicate the organization of multipart objects can influence VSTM performance, but the effect is driven by how the specific organization allows for use of global ensemble statistics of the memory array rather than a memory benefit for local object representations.


Assuntos
Percepção de Forma/fisiologia , Memória de Curto Prazo/fisiologia , Estimulação Luminosa/métodos , Adulto , Neurociência Cognitiva/métodos , Feminino , Humanos , Masculino , Psicofísica , Percepção Visual/fisiologia
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