scholarly journals Vision is superior to touch in shape perception even with equivalent peripheral input

2016 ◽  
Vol 115 (1) ◽  
pp. 92-99 ◽  
Author(s):  
Yoonju Cho ◽  
J. C. Craig ◽  
S. S. Hsiao ◽  
S. J. Bensmaia
Keyword(s):  
Spatial Patterns ◽  
Visual Processing ◽  
Visual Stimuli ◽  
Spatial Filtering ◽  
Effective Size ◽  
Perceptual Task ◽  
Two Dimensional ◽  
Form Processing ◽  
Visual Patterns ◽  
Equivalent Number

Results from previous studies suggest that two-dimensional spatial patterns are processed similarly in vision and touch when the patterns are equated for effective size or when visual stimuli are blurred to mimic the spatial filtering of the skin. In the present study, we measured subjects' ability to perceive the shape of familiar and unfamiliar visual and tactile patterns to compare form processing in the two modalities. As had been previously done, the two-dimensional tactile and visual patterns were adjusted in size to stimulate an equivalent number of receptors in the two modalities. We also distorted the visual patterns, using a filter that accurately mimics the spatial filtering effected by the skin to further equate the peripheral images in the two modalities. We found that vision consistently outperformed touch regardless of the precise perceptual task and of how familiar the patterns were. Based on an examination of both the earlier and present data, we conclude that visual processing of both familiar and unfamiliar two-dimensional patterns is superior to its tactile counterpart except under very restricted conditions.

scholarly journals Neurophysiology of grapheme decoding

2019 ◽  
pp. 402-433
Author(s):  
Marije SOTO ◽  
Juliana Novo GOMES ◽  
Aniela Improta FRANÇA ◽  
Aniela Gesualdi MANHÃES
Keyword(s):  
Reading Fluency ◽  
Visual Processing ◽  
Individual Performance ◽  
Word Form ◽  
Test Results ◽  
Predictive Tool ◽  
Form Processing ◽  
N170 Component ◽  
8Th Graders ◽  
Electrophysiological Experiment

This study zooms in on the specialization of visual processing that underlies grapheme and word form processing, and presents an electrophysiological experiment performed with 8th graders in a public state elementary school. The methodology of Event Related Brain Potential (EEG-ERP) was used to collect and analyze the N170 component, a neurophysiological signature sensitive to grapheme and word form processing. The test results indicated that, in this group, higher performance in grapheme recognition was not associated to a reduced difference between ERP wave amplitudes in response to word and false font stimuli, but instead to a clear left lateralization of print sensitive N170 responses. Differently from most ERP studies that uses the grand-averaging of all participants’ ERP responses, the current analysis also investigated individual performance of participants. In this modality, the varying levels of intensity and lateralization of the neurophysiological response indicate that a large portion of the participants remain in the process of obtaining reading fluency long after having started to learn how to read. The qualitative correlation between performance and the degree of lateralization is, thus, a novel and promising measurement involving the N170 component as a descriptive and predictive tool in the monitoring of reading acquisition stages.

scholarly journals Spatial Filtering in DCT Domain-Based Frameworks for Hyperspectral Imagery Classification

2019 ◽  
Vol 11 (12) ◽  
pp. 1405 ◽  
Author(s):  
Razika Bazine ◽  
Huayi Wu ◽  
Kamel Boukhechba
Keyword(s):  
Hyperspectral Imagery ◽  
Wiener Filter ◽  
Spatial Filtering ◽  
Spatial Filter ◽  
Computational Time ◽  
Support Vector ◽  
Two Dimensional ◽  
Significant Information ◽  
Dct Domain ◽  
Frequency Components

In this article, we propose two effective frameworks for hyperspectral imagery classification based on spatial filtering in Discrete Cosine Transform (DCT) domain. In the proposed approaches, spectral DCT is performed on the hyperspectral image to obtain a spectral profile representation, where the most significant information in the transform domain is concentrated in a few low-frequency components. The high-frequency components that generally represent noisy data are further processed using a spatial filter to extract the remaining useful information. For the spatial filtering step, both two-dimensional DCT (2D-DCT) and two-dimensional adaptive Wiener filter (2D-AWF) are explored. After performing the spatial filter, an inverse spectral DCT is applied on all transformed bands including the filtered bands to obtain the final preprocessed hyperspectral data, which is subsequently fed into a linear Support Vector Machine (SVM) classifier. Experimental results using three hyperspectral datasets show that the proposed framework Cascade Spectral DCT Spatial Wiener Filter (CDCT-WF_SVM) outperforms several state-of-the-art methods in terms of classification accuracy, the sensitivity regarding different sizes of the training samples, and computational time.

Perception of Simple and Complex Visual Stimuli: Decision Strategies and Hemispheric Differences in Same—Different Judgments

Perception ◽  
1995 ◽  
Vol 24 (7) ◽  
pp. 787-809 ◽  
Author(s):  
R John Irwin ◽  
Margaret A Francis
Keyword(s):  
Visual Field ◽  
Receiver Operating Characteristic ◽  
Operating Characteristic ◽  
Visual Stimuli ◽  
Optimal Decision ◽  
Hemispheric Differences ◽  
Decision Strategy ◽  
Decision Strategies ◽  
Visual Patterns ◽  
Rating Method

The accuracy with which observers could judge whether two visual stimuli were the same or different was measured with the rating method of detection theory. For judgments of whether two pictures referred to natural or manufactured things, the shape of the obtained receiver operating characteristic (ROC) was consistent with the observers adopting an optimal decision strategy. A similar result was found for judgments of complex but meaningless visual patterns. For judgments of whether two colours that differed along a simple sensory dimension were the same or different, however, the resulting ROC was consistent with the observers adopting a suboptimal differencing strategy. The accuracy of the judgments did not depend on the visual field to which the stimuli were presented.

SPATIOTEMPORAL PATTERNS IN LANGMUIR PLASMAS

1994 ◽  
Vol 08 (24) ◽  
pp. 1503-1510 ◽  
Author(s):  
CANGTAO ZHOU ◽  
X.T. HE
Keyword(s):  
Phase Space ◽  
Schrödinger Equation ◽  
Spatial Patterns ◽  
Schrodinger Equation ◽  
Nonlinear Schrodinger Equation ◽  
Numerical Results ◽  
Spatiotemporal Patterns ◽  
Two Dimensional ◽  
Fourier Space ◽  
Quintic Nonlinear Schrödinger Equation

The constitutions of the phase space, stochasticity, and the complicated patterns of Langmuir fields are investigated in terms of a two-dimensional cubic-quintic nonlinear Schrödinger equation. The numerical results obviously illustrate that the quintic non-linearity leads to the production of the complicated patterns. The mechanism to form these spatial patterns is also analyzed by measuring the spectrum of energy in Fourier space. It is shown that the complicated patterns are associated with the complexity of trajectory in phase space and the stochastic partition of energy in Fourier modes.

Vernier Image Processing: Model and Experiments

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 110-110
Author(s):  
A V Chihman ◽  
V N Chihman ◽  
Y E Shelepin
Keyword(s):  
Fourier Analysis ◽  
Visual Processing ◽  
Fourier Spectrum ◽  
Field Size ◽  
Two Dimensional ◽  
Frequency Range ◽  
Additional Line ◽  
Point Spread ◽  
Model Predictions ◽  
Spread Function

Earlier we proposed a model for visual processing of the optical image of Vernier targets (1996 Perception25 Supplement, 115 – 116) based on Fourier analysis of the image. Our model comprises blurring of the thin Vernier bars by the optical point-spread function followed by calculation of the two-dimensional Fourier spectrum. In our model the processing area for Fourier analysis (the receptive field size) is 5 min arc. For a Vernier target, the contrast energy in the low-spatial-frequency range is different in different orientations, and magnification of the Vernier shift changes the orientation of the oblique Fourier components. To test the model, we carried out experiments in which the stimuli were Vernier lines with additional line distractors orthogonal to the orientation of the oblique Fourier components. Thresholds for detecting Vernier displacements were determined by a 2AFC paradigm and compared with model predictions. The results are consistent with our modelling of Vernier performance as a measurement of oblique components of the 2-D Fourier spectrum.

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