Spatial Frequency and Selective Attention to Spatial Location

Perception ◽  
1987 ◽  
Vol 16 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Gordon L Shulman ◽  
James Wilson
Keyword(s):  
Visual Field ◽  
Selective Attention ◽  
Spatial Frequency ◽  
Spatial Attention ◽  
Spatial Location ◽  
Peripheral Visual Field ◽  
Low Frequencies ◽  
Full Field ◽  
High Frequencies ◽  
Probe Technique

The effect of spatial attention on the detectability of gratings of different spatial frequency was measured using a probe technique. Three experiments are reported in which the detectability of full-field probe gratings was measured while subjects analyzed stimuli presented in either the central or the peripheral visual field. Selective attention to peripheral stimuli produced a facilitation at low frequencies and a decrement at high frequencies. These effects disappeared under forced-choice presentation.

Spatial Frequency and Selective Attention to Local and Global Information

Perception ◽  
1987 ◽  
Vol 16 (1) ◽  
pp. 89-101 ◽  
Author(s):  
Gordon L Shulman ◽  
James Wilson
Keyword(s):  
Selective Attention ◽  
Spatial Frequency ◽  
Global Structure ◽  
Global Processing ◽  
Local Processing ◽  
Global Information ◽  
Low Frequencies ◽  
High Frequencies ◽  
Relative Shift ◽  
Spatial Frequencies

Probe methods were used to investigate whether the distribution of attention to the local or the global structure of a stimulus affects the detectability of different spatial frequencies. Four experiments are reported in which the detectability of threshold probe gratings of different spatial frequencies was measured while subjects analyzed either the local or the global information from a display. A relative shift in the detectability of low and high frequencies was observed. Low frequencies were facilitated during global processing and/or high frequencies were facilitated during local processing.

scholarly journals Pre-saccadic remapping relies on dynamics of spatial attention

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Martin Szinte ◽  
Donatas Jonikaitis ◽  
Dragan Rangelov ◽  
Heiner Deubel
Keyword(s):  
Visual Field ◽  
Spatial Attention ◽  
Temporal Dynamics ◽  
Receptive Fields ◽  
Spatial Location ◽  
Visual Scene ◽  
Attentional Allocation ◽  
Attentional Resources ◽  
Spatial And Temporal Dynamics ◽  
Saccadic Remapping

Each saccade shifts the projections of the visual scene on the retina. It has been proposed that the receptive fields of neurons in oculomotor areas are predictively remapped to account for these shifts. While remapping of the whole visual scene seems prohibitively complex, selection by attention may limit these processes to a subset of attended locations. Because attentional selection consumes time, remapping of attended locations should evolve in time, too. In our study, we cued a spatial location by presenting an attention-capturing cue at different times before a saccade and constructed maps of attentional allocation across the visual field. We observed no remapping of attention when the cue appeared shortly before saccade. In contrast, when the cue appeared sufficiently early before saccade, attentional resources were reallocated precisely to the remapped location. Our results show that pre-saccadic remapping takes time to develop suggesting that it relies on the spatial and temporal dynamics of spatial attention.

scholarly journals A Prospective Study on Algorithms Adapted to the Spatial Frequency in Tomography

2006 ◽  
Vol 2006 ◽  
pp. 1-6 ◽  
Author(s):  
Vincent Israel-Jost ◽  
Philippe Choquet ◽  
André Constantinesco
Keyword(s):  
Spatial Frequency ◽  
Tomographic Reconstruction ◽  
Iterative Algorithms ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Low Frequencies ◽  
Reconstruction Process ◽  
High Frequencies ◽  
A Prospective Study ◽  
Simultaneous Algebraic Reconstruction Technique

The use of iterative algorithms in tomographic reconstruction always leads to a frequency adapted rate of convergence in that low frequencies are accurately reconstructed after a few iterations, while high frequencies sometimes require many more computations. In this paper, we propose to buildfrequency adapted(FA) algorithms based on a condition of incomplete backprojection and propose an FAsimultaneous algebraic reconstruction technique(FA-SART) algorithm as an example. The results obtained with the FA-SART algorithm demonstrate a very fast convergence on a highly detailed phantom when compared to the original SART algorithm. Though the use of such an FA algorithm may seem difficult, we specify in which case it is relevant and propose several ways to improve the reconstruction process with FA algorithms.

Automated Spectrophotometry

1971 ◽  
Vol 11 ◽  
pp. 179-182
Author(s):  
G. I. Thompson
Keyword(s):  
Spatial Frequency ◽  
The Other ◽  
Stellar Spectrum ◽  
Low Frequencies ◽  
High Frequencies ◽  
The Past ◽  
Other Hand ◽  
Spatial Frequencies ◽  
Special Cases ◽  
The Continuum

Starting from a digitized and calibrated stellar spectrum—what can we most usefully do with it?Traditionally a spectrum consists of two parts, a continuum and some lines. These have been variously defined in the past, so perhaps another definition may be allowed. Over large ranges the two components can be distinguished quite sharply in the spatial frequency plane. The continuum contains only low frequencies, whereas in the line the information is contained in the high frequencies. In the word “continuum” is included the instrumental absorption functions, emulsion sensitivity, wide interstellar and atmospheric bands, and even the wide wings of very strong lines. From the word “lines”, on the other hand, the strongest lines are excluded; these may contain intermediate spatial frequencies in their core regions. They are relatively infrequent and so may be treated as special cases.

On Why Objects Appear Smaller in the Visual Periphery

2019 ◽  
Vol 31 (1) ◽  
pp. 88-96 ◽  
Author(s):  
Wladimir Kirsch ◽  
Roland Pfister ◽  
Wilfried Kunde
Keyword(s):  
Visual Field ◽  
Visual System ◽  
Structural Properties ◽  
Spatial Attention ◽  
Visuospatial Attention ◽  
Peripheral Target ◽  
Perceptual Distortion ◽  
Visual Periphery ◽  
Peripheral Location ◽  
Exogenous Cue

An object appears smaller in the periphery than in the center of the visual field. In two experiments ( N = 24), we demonstrated that visuospatial attention contributes substantially to this perceptual distortion. Participants judged the size of central and peripheral target objects after a transient, exogenous cue directed their attention to either the central or the peripheral location. Peripheral target objects were judged to be smaller following a central cue, whereas this effect disappeared completely when the peripheral target was cued. This outcome suggests that objects appear smaller in the visual periphery not only because of the structural properties of the visual system but also because of a lack of spatial attention.

Effect of Blowing Agent on Cell Morphology and Acoustic Absorption of Natural Rubber Foam

2015 ◽  
Vol 804 ◽  
pp. 25-29 ◽  
Author(s):  
Wanlop Harnnarongchai ◽  
Kantima Chaochanchaikul
Keyword(s):  
Natural Rubber ◽  
Cell Size ◽  
Cell Morphology ◽  
Foam Cell ◽  
Adsorption Coefficient ◽  
Low Frequencies ◽  
Potassium Oleate ◽  
High Frequencies ◽  
Blowing Agent ◽  
Open Cell Foam

The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO3) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO3 at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO3 addition.

Hearing loss in diabetics

1993 ◽  
Vol 107 (3) ◽  
pp. 179-182 ◽  
Author(s):  
J. R. Cullen ◽  
M. J. Cinnamond
Keyword(s):  
Hearing Loss ◽  
Sensorineural Deafness ◽  
Insulin Dosage ◽  
Speech Discrimination ◽  
Low Frequencies ◽  
High Frequencies ◽  
History Of ◽  
Insulin Dependent ◽  
Stapedial Reflex ◽  
The Relationship

The relationship between diabetes and senbsorineural hearing loss has been disputed. This study compares 44 insulin-dependent diabetics with 38 age and sex matched controls. All had pure tone and speech audiometry performed, with any diabetics showing sensorineural deafness undergoing stapedial reflecx decat tests. In 14 diabetics stapedial reflex tests showed no tone decay in any patient, but seven showed evidence of recruitment. Analysis of vaiance showed the diabetics to be significantly deafer than the control population.The hearing loss affected high frequencies in both sexes, but also low frequencies in the male. Speech discrimination scores showed no differences. Further analysis by sex showed the males to account for most of the differences. Analysys of the audiograms showered mostly a high tone loss. Finally duration of disbetes, insulin dosage and family history of diabtes were not found to have a significant effect on threshold.

Sign in / Sign up

Export Citation Format

Share Document