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1.
Nat Commun ; 10(1): 4250, 2019 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-31534122

RESUMO

Sense of agency (SoA) refers to the experience or belief that one's own actions caused an external event. Here we present a model of SoA in the framework of optimal Bayesian cue integration with mutually involved principles, namely reliability of action and outcome sensory signals, their consistency with the causation of the outcome by the action, and the prior belief in causation. We used our Bayesian model to explain the intentional binding effect, which is regarded as a reliable indicator of SoA. Our model explains temporal binding in both self-intended and unintentional actions, suggesting that intentionality is not strictly necessary given high confidence in the action causing the outcome. Our Bayesian model also explains that if the sensory cues are reliable, SoA can emerge even for unintended actions. Our formal model therefore posits a precision-dependent causal agency.


Assuntos
Causalidade , Intenção , Controle Interno-Externo , Modelos Psicológicos , Teorema de Bayes , Humanos , Psicofísica , Reprodutibilidade dos Testes
2.
Nat Neurosci ; 22(10): 1669-1676, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31477898

RESUMO

Visual attention dramatically improves individuals' ability to see and modulates the responses of neurons in every known visual and oculomotor area, but whether such modulations can account for perceptual improvements is unclear. We measured the relationship between populations of visual neurons, oculomotor neurons and behavior during detection and discrimination tasks. We found that neither of the two prominent hypothesized neuronal mechanisms underlying attention (which concern changes in information coding and the way sensory information is read out) provide a satisfying account of the observed behavioral improvements. Instead, our results are more consistent with the hypothesis that attention reshapes the representation of attended stimuli to more effectively influence behavior. Our results suggest a path toward understanding the neural underpinnings of perception and cognition in health and disease by analyzing neuronal responses in ways that are constrained by behavior and interactions between brain areas.


Assuntos
Atenção/fisiologia , Neurônios/fisiologia , Animais , Tomada de Decisões/fisiologia , Macaca mulatta , Masculino , Neurônios Motores/fisiologia , Rede Nervosa/fisiologia , Desempenho Psicomotor/fisiologia , Psicofísica
3.
Doc Ophthalmol ; 139(3): 207-219, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31414313

RESUMO

PURPOSE: Several previous studies have demonstrated that for normal adult subjects the optotype acuity measured with charts is better than the acuity determined with the sweep visual evoked potential (sVEP) using gratings or checks. However, there is no difference in psychophysical measures of acuity with optotype or grating charts. Thus, it is unclear whether the acuity discrepancy between optotype charts and the sVEP result from the stimulus design or other methodological differences. The purpose of this experiment is to determine the relationship between acuities extrapolated from a contrast sensitivity function (CSF) that uses optotypes and the sVEP. METHODS: Normal subjects (N = 10) with acuity of 0.00 logMAR or better (ETDRS chart) were recruited for this study. Two commercially available systems were used to measure CSFs [i.e., the Beethoven System (Ryklin Software, NY) and the qCSF system (Adaptive Sensory Tech, CA)]. The stimuli for the Beethoven were sine wave gratings (0.75-18.50 cpd), and thresholds were determined with a 2-alternative forced choice (2-AFC) procedure combined with a staircase. The stimuli for the qCSF system were spatially filtered letters (10 possible letters, 10-AFC) with the letter sizes and contrasts determined by a Bayesian adaptive procedure. Visual acuity was determined by fitting the data with a double exponential equation and extrapolating the fit to a contrast sensitivity of one. The sVEP was obtained with the PowerDiva (Digital Instrumentation for Visual Assessment, version 3.5, CA). The stimuli were sine wave gratings (80% contrast, 3-36 cpd) counterphased at 7.5 Hz. The final acuity was the average of two estimates each derived from the average of 10 sweeps. RESULTS: The average logMAR chart (acuity converted to cpd), sVEP, Beethoven, and qCSF acuities were 36.6 ± 4.62 cpd (mean ± SD), 31.2 ± 4.59 cpd, 27.3 ± 7.38 cpd, and 27.6 ± 6.36 cpd, respectively. The logMAR chart acuity was significantly different from the other acuity estimates (all p values < 0.05). The sVEP, Beethoven, and qCSF acuities were not different from one another (all p values > 0.05). The Beethoven and the qCSF acuities had a good intraclass correlation coefficient (ICC = 0.85). CONCLUSIONS: Similar to previous publications, the sVEP acuity estimate was less than the optotype chart acuity. The acuity determined with the sVEP and the CSFs with letter and grating stimuli were not statistically different, suggesting that the difference in acuity with the sVEP and optotype charts does not result from stimulus differences. Other methodological differences must account for the discrepancy in sVEP and optotype chart acuity.


Assuntos
Sensibilidades de Contraste/fisiologia , Potenciais Evocados Visuais/fisiologia , Acuidade Visual/fisiologia , Adulto , Teorema de Bayes , Biometria , Eletrorretinografia , Feminino , Voluntários Saudáveis , Humanos , Masculino , Psicofísica/métodos , Testes Visuais , Adulto Jovem
4.
Doc Ophthalmol ; 139(3): 235-245, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31338649

RESUMO

BACKGROUND: Sellar region tumor growth represents an important cause of visual loss due to mechanical compression of the optic nerve apparatus. Many investigations have used non-invasive tools to evaluate the visual field consequences of this damage, and good associations have been reported between psychophysical and electrophysiological perimetries. Few reports have considered the tumor size as a predictor of visual field loss. AIMS: In the present study, we evaluated the association between the visual perimetry measured by Humphrey visual field analyzer and multifocal visual evoked cortical potential (mfVECP) and the tumor size. METHODS: Our sample was composed of 14 patients diagnosed with sellar tumors by magnetic resonance imaging. We accounted the number of sectors with negative visual responses for both methods. A simple logistic regression analysis was used to evaluate the association between the tumor dimensions and the visual field features RESULTS: Three patients had preserved visual fields, three patients showed hemianopic defects, and eight patients had generalized visual field losses at both evaluations. We observed that the three maximum diameters of the tumor and total tumor volume had different predictive abilities regarding the extent of visual field loss when using psychophysical and mfVECP data. The maximum craniocaudal diameter of the tumor was the better predictor of the psychophysical measurements, whereas for the mfVECP results, all tumor dimensions and volumes had similar values that predict visual field losses. CONCLUSION: Tumor size as a predictor of visual loss has potential to assist in the clinical intervention and to prevent the irreversible visual impairment caused by tumors of the sellar region.


Assuntos
Adenoma/patologia , Potenciais Evocados Visuais/fisiologia , Neoplasias Hipofisárias/patologia , Retina/fisiopatologia , Transtornos da Visão/fisiopatologia , Testes de Campo Visual/métodos , Campos Visuais/fisiologia , Adenoma/diagnóstico por imagem , Adulto , Idoso , Eletrorretinografia , Feminino , Humanos , Modelos Logísticos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Neoplasias Hipofisárias/diagnóstico por imagem , Psicofísica , Adulto Jovem
5.
Work ; 63(2): 231-241, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31156203

RESUMO

BACKGROUND: Obesity prevalence in the workforce is clearly increasing. Simultaneously, manual lifting/lowering loads, referred to as Vertical Handling Tasks (VHT) in this paper, are common in industries and services. Performing VHT exposes workers to physical overload, which can be measured using a psychophysical approach. Various risk factors can increase this overload, including individual factors such as workers' Body Mass Index (BMI). OBJECTIVE: To study the possible effects of workers' BMI and some task conditions on physical overload during VHT. METHODS: Psychophysical data were collected from 51 participants having different body constitutions (including non-obese, overweight and obese). The participants performed 6 VHT (3 different loads ×2 workstation configurations), during which they lifted and lowered a test-box between their knees and shoulders. For each task, they reported their perceived exertion using the Borg Category Ratio-10 (CR-10) scale. RESULTS: The results showed that the CR-10 scale is sensitive to the variation of the task conditions tested. However, the psychophysical data pointed to a tendency to decrease the perception of physical overload as workers' BMI increases. CONCLUSIONS: This may compromise the validity of the application of psychophysical data as an ergonomic approach for Work-Related Musculoskeletal Disorders (WRMSD) prevention in obese workers.


Assuntos
Índice de Massa Corporal , Percepção , Esforço Físico/fisiologia , Adulto , Ergonomia/instrumentação , Ergonomia/métodos , Feminino , Humanos , Remoção/efeitos adversos , Masculino , Projetos Piloto , Psicofísica/métodos , Psicofísica/tendências , Fatores de Risco , Trabalho/fisiologia , Trabalho/psicologia
6.
J Vis ; 19(6): 7, 2019 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-31173632

RESUMO

Early vision proceeds through distinct ON and OFF channels, which encode luminance increments and decrements respectively. It has been argued that these channels also contribute separately to stereoscopic vision. This is based on the fact that observers perform better on a noisy disparity discrimination task when the stimulus is a random-dot pattern consisting of equal numbers of black and white dots (a "mixed-polarity stimulus," argued to activate both ON and OFF stereo channels), than when it consists of all-white or all-black dots ("same-polarity," argued to activate only one). However, it is not clear how this theory can be reconciled with our current understanding of disparity encoding. Recently, a binocular convolutional neural network was able to replicate the mixed-polarity advantage shown by human observers, even though it was based on linear filters and contained no mechanisms which would respond separately to black or white dots. Here, we show that a subtle feature of the way the stimuli were constructed in all these experiments can explain the results. The interocular correlation between left and right images is actually lower for the same-polarity stimuli than for mixed-polarity stimuli with the same amount of disparity noise applied to the dots. Because our current theories suggest stereopsis is based on a correlation-like computation in primary visual cortex, this postulate can explain why performance was better for the mixed-polarity stimuli. We conclude that there is currently no evidence supporting separate ON and OFF channels in stereopsis.


Assuntos
Percepção de Profundidade/fisiologia , Psicofísica , Células Ganglionares da Retina/fisiologia , Visão Binocular/fisiologia , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Humanos
7.
Doc Ophthalmol ; 139(2): 123-136, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31214918

RESUMO

PURPOSE: The traditional assessment of visual acuity and contrast sensitivity depends more on subjective judgments. Steady-state motion visual evoked potentials (SSMVEPs) can provide an objective and quantitative method to evaluate visual functions such as visual acuity and contrast sensitivity. Here, we explored the possibility of objective SSMVEP visual acuity and contrast sensitivity testing, and compared its performance with that of psychophysical methods. METHODS: In this study, we designed a specific concentric ring with oscillating expansion and contraction SSMVEP paradigm to assess visual acuity and contrast sensitivity. By changing the parameters of the paradigm, the SSMVEP paradigm with different contrasts and spatial frequencies corresponding to different visual acuity and contrast sensitivity was designed. Moreover, we proposed a threshold determination criterion to define the corresponding objective SSMVEP visual acuity and contrast sensitivity. RESULTS: We tested visual acuity and contrast sensitivity of sixteen healthy adults utilizing this paradigm with an electroencephalography system. Our data suggested that there was no significant difference between objective visual acuity and contrast sensitivity measurements based on the SSMVEPs and subjective psychophysical ones. CONCLUSION: Our study proved that SSMVEPs can be an objective and quantitative method to measure visual acuity and contrast sensitivity.


Assuntos
Sensibilidades de Contraste/fisiologia , Potenciais Evocados Visuais/fisiologia , Percepção de Movimento/fisiologia , Acuidade Visual/fisiologia , Adulto , Eletroencefalografia , Eletrorretinografia , Feminino , Humanos , Masculino , Psicofísica , Limiar Sensorial , Testes Visuais , Adulto Jovem
8.
J Opt Soc Am A Opt Image Sci Vis ; 36(4): B97-B102, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31044967

RESUMO

Starbursts seen around small bright lights at night have been attributed to optical scatter, diffraction, or aberrations. We manipulated pupil aperture and aberrations to investigate the entopic appearance of perceived starbursts. The impact of circular, annular, and wedge-shaped pupil apertures, and spherical aberration sign and magnitude were used to identify pupil sub-apertures responsible for each radial perceived starburst line. Local intensity distributions within the starbursts mapped onto unique sub-regions of the pupil of both phakic and pseudophakic eyes, consistent with the hypothesis that ocular aberrations are the cause of starbursts. In paraxially focused eyes, the size of starbursts is predicted by the amount of spherical aberration, and starburst orientation is either the same or 180 deg rotated from the pupil region that creates each starburst line. No starbursts are seen when the pupil diameter is smaller than 3 mm. Replacing the eye's natural lens with a radially symmetric and optically homogeneous intraocular lens reduced the observed number of starbursts by 50%. Geometrical optics modeling including the measured aberrations of an individual eye can reveal point spread function structure that captures some of the key elements of the entopic perceptions.


Assuntos
Fenômenos Ópticos , Pupila/fisiologia , Humanos , Psicofísica
9.
Invest Ophthalmol Vis Sci ; 60(6): 1906-1913, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31042798

RESUMO

Purpose: We investigated the pattern of meridional anisotropies, if any, for pattern onset-offset visual evoked potential (POVEPs) responses and psychophysical grating acuity (GA) in children with normal letter visual acuity (20/20 or better). Methods: A total of 29 children (aged 3-9 years), nine of whom were astigmatic (AS), were recruited. Orientation-specific monocular POVEPs were recorded in response to sinewave grating stimuli oriented along the subjects' principal AS meridians. Horizontal and vertical gratings were designated Meridians 1 and 2, respectively, for nonastigmatic patients (Non-AS). Binocular POVEPs in response to the same stimuli, but oriented at 45°, 90°, 135°, and 180°, were recorded. Psychophysical GAs were assessed monocularly and binocularly along the same meridians using the same stimuli by a 2-alternative-forced-choice staircase technique. The C3 amplitudes and peak latencies of the POVEP and GAs were compared across meridians using linear mixed models (monocular) and ANOVA (binocular). Results: There were significant meridional anisotropies in monocular C3 amplitudes regardless of astigmatism status (P = 0.001): Meridian 2 (mean ± SE Non-AS, 30.13 ± 2.07 µV; AS, 26.53 ± 2.98 µV) was significantly higher than Meridian 1 (Non-AS, 26.14 ± 1.87 µV; AS, 21.68 ± 2.73 µV; P = 0.019), but no meridional anisotropies were found for GA or C3 latency. Binocular C3 amplitude in response to horizontally oriented stimuli (180°, 29.71 ± 3.06 µV) was significantly lower than the oblique (45°, 36.62 ± 3 .05 µV; P = 0.03 and 135°, 35.95 ± 2.92 µV; P = 0.04) and vertical (90°, 37.82 ± 3.65 µV; P = 0.02) meridians, and binocular C3 latency was significantly shorter in response to vertical than oblique gratings (P ≤ 0.001). Conclusions: Meridional anisotropy was observed in children with normal vision. The findings suggest that horizontal gratings result in a small, but significantly lower POVEP amplitude than for vertical and oblique gratings.


Assuntos
Astigmatismo/fisiopatologia , Potenciais Evocados Visuais/fisiologia , Orientação/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Psicofísica/métodos , Visão Binocular/fisiologia , Acuidade Visual , Anisotropia , Astigmatismo/diagnóstico , Criança , Pré-Escolar , Feminino , Humanos , Masculino
10.
Acta Neurobiol Exp (Wars) ; 79(1): 39-52, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31038484

RESUMO

In the present study, we tested the ability of our computational model of the filled­space illusion to account for data collected in experiments with stimuli comprising single­dot distractors. In three sets of experiments, we investigated this illusory effect as a function of distance between the distractor and lateral terminator of the reference spatial interval of the three­dot stimulus. We found that the model calculations properly predicted all of the observed changes in magnitude of the illusion for stimuli with a single distracting dot placed both within and outside the interval, as well as, for stimuli with two distractors arranged symmetrically relative to the lateral terminator. To additionally test the model, in a fourth set of experiments we performed psychophysical examination of the conventional Oppel­Kundt stimulus with a different number of equally spaced dots subdividing the filled part. Adequate correspondence between the computational and experimental data supports our assumptions concerning the origin of the filled­space illusion.


Assuntos
Percepção de Forma/fisiologia , Ilusões Ópticas/fisiologia , Percepção Espacial/fisiologia , Simulação por Computador , Feminino , Humanos , Masculino , Modelos Psicológicos , Estimulação Luminosa , Psicofísica , Adulto Jovem
11.
Trends Hear ; 23: 2331216519841980, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31081487

RESUMO

It is widely believed that the frequency selectivity of the auditory system is largely determined by processes occurring in the cochlea. If so, musical training would not be expected to influence frequency selectivity. Consistent with this, auditory filter shapes for low center frequencies do not differ for musicians and nonmusicians. However, it has been reported that psychophysical tuning curves (PTCs) at 4000 Hz were sharper for musicians than for nonmusicians. This study explored the origin of the discrepancy across studies. Frequency selectivity was estimated for musicians and nonmusicians using three methods: fast PTCs with a masker that swept in frequency, "traditional" PTCs obtained using several fixed masker center frequencies, and the notched-noise method. The signal frequency was 4000 Hz. The data were fitted assuming that each side of the auditory filter had the shape of a rounded-exponential function. The sharpness of the auditory filters, estimated as the Q10 values, did not differ significantly between musicians and nonmusicians for any of the methods, but detection efficiency tended to be higher for the musicians. This is consistent with the idea that musicianship influences auditory proficiency but does not influence the peripheral processes that determine the frequency selectivity of the auditory system.


Assuntos
Percepção Auditiva , Música , Psicofísica , Adulto , Limiar Auditivo , Cóclea , Humanos , Ruído , Mascaramento Perceptivo , Psicofísica/métodos
12.
PLoS Comput Biol ; 15(5): e1007063, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31125331

RESUMO

Visual performance depends on polar angle, even when eccentricity is held constant; on many psychophysical tasks observers perform best when stimuli are presented on the horizontal meridian, worst on the upper vertical, and intermediate on the lower vertical meridian. This variation in performance 'around' the visual field can be as pronounced as that of doubling the stimulus eccentricity. The causes of these asymmetries in performance are largely unknown. Some factors in the eye, e.g. cone density, are positively correlated with the reported variations in visual performance with polar angle. However, the question remains whether these correlations can quantitatively explain the perceptual differences observed 'around' the visual field. To investigate the extent to which the earliest stages of vision-optical quality and cone density-contribute to performance differences with polar angle, we created a computational observer model. The model uses the open-source software package ISETBIO to simulate an orientation discrimination task for which visual performance differs with polar angle. The model starts from the photons emitted by a display, which pass through simulated human optics with fixational eye movements, followed by cone isomerizations in the retina. Finally, we classify stimulus orientation using a support vector machine to learn a linear classifier on the photon absorptions. To account for the 30% increase in contrast thresholds for upper vertical compared to horizontal meridian, as observed psychophysically on the same task, our computational observer model would require either an increase of ~7 diopters of defocus or a reduction of 500% in cone density. These values far exceed the actual variations as a function of polar angle observed in human eyes. Therefore, we conclude that these factors in the eye only account for a small fraction of differences in visual performance with polar angle. Substantial additional asymmetries must arise in later retinal and/or cortical processing.


Assuntos
Modelos Neurológicos , Modelos Psicológicos , Campos Visuais/fisiologia , Algoritmos , Biologia Computacional , Movimentos Oculares/fisiologia , Humanos , Fenômenos Fisiológicos Oculares , Orientação/fisiologia , Estimulação Luminosa , Psicofísica , Células Fotorreceptoras Retinianas Cones/fisiologia , Software , Máquina de Vetores de Suporte , Visão Ocular/fisiologia
13.
Atten Percept Psychophys ; 81(5): 1189-1196, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31089976

RESUMO

This paper considers how to identify statistical outliers in psychophysical datasets where the underlying sampling distributions are unknown. Eight methods are described, and each is evaluated using Monte Carlo simulations of a typical psychophysical experiment. The best method is shown to be one based on a measure of spread known as Sn. This is shown to be more sensitive than popular heuristics based on standard deviations from the mean, and more robust than non-parametric methods based on percentiles or interquartile range. MATLAB code for computing Sn is included.


Assuntos
Conjuntos de Dados como Assunto/estatística & dados numéricos , Modelos Estatísticos , Psicofísica/estatística & dados numéricos , Heurística , Humanos , Método de Monte Carlo
14.
J Vis ; 19(4): 19, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30998829

RESUMO

Estimation of the orientation of the head relative to the earth's vertical is thought to rely on the integration of vestibular and visual cues. The role of visual cues can be tested using a rod-and-frame task in which a global visual scene, typically a square frame, is displayed at different orientations together with a rod whose perceived direction is a proxy for the head-in-space estimate. While it is known that the frame biases this percept, and hence the subjective visual vertical, the possible role of the rod itself in this processing has not been examined. Current models about spatial orientation assume that the visual orientation of the rod and its uncertainty play no role in the visual-vestibular integration process, but are only involved in the transformation that yields rod orientation in space, thereby contributing additive noise to the subjective visual vertical. Here we tested the validity of this assumption in the rod-and-frame task by replacing the rod with an ellipse whose orientation uncertainty was manipulated by varying its eccentricity (i.e., making the ellipse more or less rounded). Using a psychophysical approach, subjects performed this ellipse-and-frame task for three different eccentricities of the ellipse (0.74, 0.82, 0.99) and three frame orientations (-17.5°, 0°, 17.5°). Results show that ellipse eccentricity affects the uncertainty but not the bias of the subjective visual vertical, suggesting that the ellipse does not interact with the frame in global visual processing but contributes additive noise in computing its orientation in world coordinates.


Assuntos
Ilusões/fisiologia , Orientação Espacial/fisiologia , Adulto , Sinais (Psicologia) , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psicofísica , Percepção Espacial/fisiologia , Incerteza , Adulto Jovem
15.
J Vis ; 19(4): 21, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30998831

RESUMO

In a selective centroid task, the participant views a brief cloud of items of different types-some of which are targets, the others distractors-and strives to mouse-click the centroid of the target items, ignoring the distractors. Advantages of the centroid task are that multiple target types can appear in the same display and that influence functions, which estimate the weight of each stimulus type in the cloud on the perceived centroid for each participant, can be obtained easily and efficiently. Here we document the strong, negative impact on performance that results when the participant is instructed to attend to target dots that consist of two or more levels of a single feature dimension, even when those levels differ categorically from those of the distractor dots. The results also show a smaller, but still observable decrement in performance that results when there is heterogeneity in the distractor dots.


Assuntos
Atenção/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Adulto , Feminino , Humanos , Masculino , Mascaramento Perceptivo/fisiologia , Psicofísica , Tempo de Reação/fisiologia , Adulto Jovem
16.
J Vis ; 19(4): 26, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-31009527

RESUMO

An important phenomenon in the study of human perception is the ability of observers to identify different types of surface materials. The present article will consider a wide range of factors that can influence the perceptual identification of glass, including the structural complexity of an object, whether it is hollow or solid, and the pattern of illumination. Several illumination techniques used in the field of photography are described, and examples are provided to show how they interact with structural complexity. A single psychophysical experiment is reported to evaluate the perceptions of naïve observers using a novel categorization task designed to assess potential confusions among multiple material categories. Finally, the paper will enumerate a number of specific image features that are potentially diagnostic for the identification of glass, and it will evaluate their relative importance for human perception.


Assuntos
Vidro , Óptica e Fotônica , Propriedades de Superfície , Percepção Visual/fisiologia , Humanos , Imagem Tridimensional , Iluminação , Psicofísica , Refração Ocular/fisiologia
17.
Neuroimage ; 197: 120-132, 2019 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-31028922

RESUMO

Distinguishing animate from inanimate objects is fundamental for social perception in humans and animals. Visual motion cues indicative of self-propelled object motion are useful for animacy perception: they can be detected over a wide expanse of visual field, at distance and in low visibility conditions, can attract attention and provide clues about object behaviour. However, the neural correlates of animacy perception evoked exclusively by visual motion cues, i.e. not relying on form, background or visual context, are unclear. We aimed to address this question in four psychophysical experiments in humans, two of which performed during neuroimaging. The stimulus was a single dot with constant form that moved on a blank background and evoked controlled degrees of perceived animacy through parametric variations of self-propelled motion cues. BOLD signals reflecting perceived animacy in a graded manner irrespective of eye movements were found in one intraparietal region. Additional whole-brain and region-of-interest analyses revealed no comparable effects in brain regions associated with social processing or other areas. Our study shows that animacy perception evoked solely by visual motion cues, a basic perceptual process in social cognition, engages brain regions not primarily associated with social cognition.


Assuntos
Sinais (Psicologia) , Percepção de Movimento/fisiologia , Lobo Parietal/fisiologia , Adulto , Atenção/fisiologia , Mapeamento Encefálico , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Estimulação Luminosa , Psicofísica , Adulto Jovem
18.
Nat Commun ; 10(1): 1719, 2019 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-30979880

RESUMO

Humans typically make near-optimal sensorimotor judgements but show systematic biases when making more cognitive judgements. Here we test the hypothesis that, while humans are sensitive to the noise present during early sensory encoding, the "optimality gap" arises because they are blind to noise introduced by later cognitive integration of variable or discordant pieces of information. In six psychophysical experiments, human observers judged the average orientation of an array of contrast gratings. We varied the stimulus contrast (encoding noise) and orientation variability (integration noise) of the array. Participants adapted near-optimally to changes in encoding noise, but, under increased integration noise, displayed a range of suboptimal behaviours: they ignored stimulus base rates, reported excessive confidence in their choices, and refrained from opting out of objectively difficult trials. These overconfident behaviours were captured by a Bayesian model blind to integration noise. Our study provides a computationally grounded explanation of human suboptimal cognitive inference.


Assuntos
Cognição , Ruído , Psicofísica , Adulto , Teorema de Bayes , Comportamento de Escolha , Transtornos Cognitivos/fisiopatologia , Simulação por Computador , Tomada de Decisões , Feminino , Humanos , Masculino , Orientação , Análise de Regressão , Reprodutibilidade dos Testes , Adulto Jovem
19.
Nat Hum Behav ; 3(4): 393-405, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30971792

RESUMO

The principles underlying functional asymmetries in cortex remain debated. For example, it is accepted that speech is processed bilaterally in auditory cortex, but a left hemisphere dominance emerges when the input is interpreted linguistically. The mechanisms, however, are contested, such as what sound features or processing principles underlie laterality. Recent findings across species (humans, canines and bats) provide converging evidence that spectrotemporal sound features drive asymmetrical responses. Typically, accounts invoke models wherein the hemispheres differ in time-frequency resolution or integration window size. We develop a framework that builds on and unifies prevailing models, using spectrotemporal modulation space. Using signal processing techniques motivated by neural responses, we test this approach, employing behavioural and neurophysiological measures. We show how psychophysical judgements align with spectrotemporal modulations and then characterize the neural sensitivities to temporal and spectral modulations. We demonstrate differential contributions from both hemispheres, with a left lateralization for temporal modulations and a weaker right lateralization for spectral modulations. We argue that representations in the modulation domain provide a more mechanistic basis to account for lateralization in auditory cortex.


Assuntos
Córtex Auditivo/fisiologia , Lateralidade Funcional/fisiologia , Nível de Percepção Sonora/fisiologia , Inteligibilidade da Fala/fisiologia , Percepção da Fala/fisiologia , Estimulação Acústica/métodos , Adolescente , Adulto , Eletrocorticografia/métodos , Feminino , Humanos , Magnetoencefalografia/métodos , Masculino , Psicofísica/métodos , Processamento de Sinais Assistido por Computador , Fatores de Tempo , Adulto Jovem
20.
J Exp Psychol Gen ; 148(4): 713-727, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30973263

RESUMO

Brain plasticity is a key mechanism for learning and recovery. A striking example of plasticity in the adult brain occurs following input loss, for example, following amputation, whereby the deprived zone is "invaded" by new representations. Although it has long been assumed that such reorganization leads to functional benefits for the invading representation, the behavioral evidence is controversial. Here, we investigate whether a temporary period of somatosensory input loss to one finger, induced by anesthetic block, is sufficient to cause improvements in touch perception ("direct" effects of deafferentation). Further, we determine whether this deprivation can improve touch perception by enhancing sensory learning processes, for example, by training ("interactive" effects). Importantly, we explore whether direct and interactive effects of deprivation are dissociable by directly comparing their effects on touch perception. Using psychophysical thresholds, we found brief deprivation alone caused improvements in tactile perception of a finger adjacent to the blocked finger but not to non-neighboring fingers. Two additional groups underwent minimal tactile training to one finger either during anesthetic block of the neighboring finger or a sham block with saline. Deprivation significantly enhanced the effects of tactile perceptual training, causing greater learning transfer compared with sham block. That is, following deafferentation and training, learning gains were seen in fingers normally outside the boundaries of topographic transfer of tactile perceptual learning. Our results demonstrate that sensory deprivation can improve perceptual abilities, both directly and interactively, when combined with sensory learning. This dissociation provides novel opportunities for future clinical interventions to improve sensation. (PsycINFO Database Record (c) 2019 APA, all rights reserved).


Assuntos
Dedos/fisiologia , Aprendizagem/fisiologia , Percepção do Tato/fisiologia , Tato/fisiologia , Adulto , Anestésicos/farmacologia , Feminino , Humanos , Aprendizagem/efeitos dos fármacos , Masculino , Psicofísica/métodos , Tato/efeitos dos fármacos , Percepção do Tato/efeitos dos fármacos , /fisiologia , Adulto Jovem
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