Adults with dyslexia show deficits on spatial frequency doubling and visual attention tasks

Dyslexia ◽  
2004 ◽  
Vol 10 (1) ◽  
pp. 24-43 ◽  
Author(s):  
Judy Buchholz ◽  
Elinor McKone
Keyword(s):  
Visual Attention ◽  
Spatial Frequency ◽  
Frequency Doubling ◽  
Attention Tasks

scholarly journals Sustained Splits of Attention within versus across Visual Hemifields Produce Distinct Spatial Gain Profiles

2016 ◽  
Vol 28 (1) ◽  
pp. 111-124 ◽  
Author(s):  
Sabrina Walter ◽  
Christian Keitel ◽  
Matthias M. Müller
Keyword(s):  
Visual Attention ◽  
Visual Processing ◽  
Behavioral Performance ◽  
Lower Visual Field ◽  
Light Emitting ◽  
Visual Hemifield ◽  
Attention Tasks ◽  
Visual Cortices ◽  
Cortical Visual Processing ◽  
Visual Hemifields

Visual attention can be focused concurrently on two stimuli at noncontiguous locations while intermediate stimuli remain ignored. Nevertheless, behavioral performance in multifocal attention tasks falters when attended stimuli fall within one visual hemifield as opposed to when they are distributed across left and right hemifields. This “different-hemifield advantage” has been ascribed to largely independent processing capacities of each cerebral hemisphere in early visual cortices. Here, we investigated how this advantage influences the sustained division of spatial attention. We presented six isoeccentric light-emitting diodes (LEDs) in the lower visual field, each flickering at a different frequency. Participants attended to two LEDs that were spatially separated by an intermediate LED and responded to synchronous events at to-be-attended LEDs. Task-relevant pairs of LEDs were either located in the same hemifield (“within-hemifield” conditions) or separated by the vertical meridian (“across-hemifield” conditions). Flicker-driven brain oscillations, steady-state visual evoked potentials (SSVEPs), indexed the allocation of attention to individual LEDs. Both behavioral performance and SSVEPs indicated enhanced processing of attended LED pairs during “across-hemifield” relative to “within-hemifield” conditions. Moreover, SSVEPs demonstrated effective filtering of intermediate stimuli in “across-hemifield” condition only. Thus, despite identical physical distances between LEDs of attended pairs, the spatial profiles of gain effects differed profoundly between “across-hemifield” and “within-hemifield” conditions. These findings corroborate that early cortical visual processing stages rely on hemisphere-specific processing capacities and highlight their limiting role in the concurrent allocation of visual attention to multiple locations.

Telephone Conversations Affect the Executive but not the Alerting or Orienting Network

2021 ◽  
Author(s):  
Melina Kunar ◽  
Derrick Watson ◽  
Rhiannon Richards ◽  
Daniel Gunnell
Keyword(s):  
Visual Attention ◽  
Selective Attention ◽  
Mobile Phone ◽  
Dual Task ◽  
Response Times ◽  
Amount Of Information ◽  
Attentional Networks ◽  
Attention Tasks ◽  
Conflict Effect ◽  
The Individual

Previous work has shown that talking on a mobile phone leads to an impairment of visual attention. Gunnell et al. (2020) investigated the locus of these dual-task impairments and found that although phone conversations led to cognitive delays in response times, other mechanisms underlying particular selective attention tasks were unaffected. Here we investigated which attentional networks, if any, were impaired by having a phone conversation. We used the Attentional Network Task (ANT) to evaluate performance of the alerting, orienting and executive attentional networks, both in conditions where people were engaged in a conversation and where they were silent. Two experiments showed that there was a robust delay in response across all three networks. However, at the individual network level, holding a conversation did not influence the size of the alerting or orienting effects but it did reduce the size of the conflict effect within the executive network. The findings suggest that holding a conversation can reduce the overall speed of responding and, via its influence on the executive network, can reduce the amount of information that can be processed from the environment.

Observations on Spatial-Frequency Doubling

Perception ◽  
1974 ◽  
Vol 3 (1) ◽  
pp. 81-86 ◽  
Author(s):  
C W Tyler
Keyword(s):  
Spatial Frequency ◽  
Transient Response ◽  
Frequency Doubling ◽  
Amacrine Cells ◽  
Distortion Model ◽  
Detection Model ◽  
Disparity Detection

The involvement of disparity detectors in the perception of spatial-frequency doubling in a flickering grating was tested by viewing the grating horizontally. Frequency doubling was unimpaired, and must therefore occur independently of disparity detection. A distortion model of frequency doubling was compared with a flicker-detection model, in predicting the appearance of nonsinusoidal gratings. The results support the flicker-detection model but not the distortion model. Physiological considerations suggest that spatial-frequency doubling may be mediated by the transient response of the amacrine cells in the retina.

Insights for mfVEPs from perimetry using large spatial frequency-doubling and near frequency-doubling stimuli in glaucoma

2020 ◽  
Vol 141 (1) ◽  
pp. 45-55
Author(s):  
Siti Nurliyana Abdullah ◽  
Gordon F. Sanderson ◽  
Mohd Aziz Husni ◽  
Ted Maddess
Keyword(s):  
Spatial Frequency ◽  
Frequency Doubling

scholarly journals Image Modification Based on Spatial Frequency Components for Visual Attention Retargeting

2017 ◽  
Vol E100.D (6) ◽  
pp. 1339-1349 ◽  
Author(s):  
Hironori TAKIMOTO ◽  
Syuhei HITOMI ◽  
Hitoshi YAMAUCHI ◽  
Mitsuyoshi KISHIHARA ◽  
Kensuke OKUBO
Keyword(s):  
Visual Attention ◽  
Spatial Frequency ◽  
Frequency Components

scholarly journals Constructing an Instrument for Measuring the Selective Visual Attention of Basic-Stage Students in Gaza and Verifying its Psychometric Characteristics

2020 ◽  
Vol 14 (3) ◽  
pp. 503
Author(s):  
Akram M. El-Hujuj ◽  
Zeinab A. Badawy
Keyword(s):  
Visual Attention ◽  
Basic Education ◽  
Validity And Reliability ◽  
Education Students ◽  
Selective Visual Attention ◽  
Attention Tasks ◽  
Potential Factor ◽  
Khan Younis ◽  
Instrument Reliability ◽  
Academic Year

The research aims at constructing an instrument for measuring the selective visual attention of basic education students in Gaza, and verifying its validity and reliability. The research sample consisted of 200   grade ten students in Khan Younis (for the academic year, 2018 -2019). The evidence of constructive validity and the factorial validity of the instrument were  investigated. Results of the predictive factorial analysis showed that the three tasks of the instrument  covered a single  potential factor  namely selective visual attention. All slides of the selective visual attention tasks have achieved statistically significant correlations with the overall scores of the instrument.  The content of the slides was also validated in relation to the instrument. The instrument reliability was also checked with the alpha coefficient for the final form of the instrument as a whole (0,962), and the split–half  reliability coefficients ranged from (0.770 – 0.907). The final form of the instrument  showed three major functions.

Deposition of Cr Atoms Using Switching-Detuning Light Mask for Direct Atom Lithography

2019 ◽  
Vol 15 (6) ◽  
pp. 626-630
Author(s):  
Li Zhu ◽  
Xiao Deng ◽  
Jie Liu ◽  
Xinbin Cheng ◽  
Tongbao Li
Keyword(s):  
Spatial Frequency ◽  
Deposition Time ◽  
Frequency Doubling ◽  
Deposition Process ◽  
Atom Beam ◽  
High Uniformity ◽  
Dipole Force ◽  
Scaling Down ◽  
Pitch Distance ◽  
Atom Lithography

Background: As progress on the nanofabrication has made semiconductor developed rapidly, there is an increasing need in precise pitch standards to calibrate the structure of devices at nanoscale. Nano-gratings fabricated by atom lithography are unique and suitable to act as precise pitch standard because its pitch distance is directly traceable to a natural constant. As the scaling down of nano-devices, it is very challenging to double the spatial frequency of nano-grating while keeping the self-traceability in atom lithography. Methods: In this study, the switching-detuning light mask is utilized for Cr atom lithography. During a single deposition process, the standing wave frequency is switching from positive detuning to negative detuning alternatively. Results: Nano-gratings fabricated using switching-detuning light mask is successfully replicated with double spatial frequency and self-traceability. Non-uniformity between neighboring Cr lines shows up with a corrected pitch of 107.15 Conclusion: Non-uniformity is mainly caused by the dipole force discrepancy between positive and negative detuning light mask. Therefore, to increase the high uniformity of nano-gratings, the deposition time of negative detuning should be at least twice as the positive detuning. On the other hand, to reduce the pitch uncertainty, it is necessary to reduce the distance between the atom beam and reflection mirror as close as possible. These two significant optimization designs are promising to increase the spatial frequency doubling performance with high uniformity and accuracy.

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