scholarly journals Improvement in line orientation discrimination is retinally local but dependent on cognitive set

1992 ◽  
Vol 52 (5) ◽  
pp. 582-588 ◽  
Author(s):  
Ling-Po Shiu ◽  
Harold Pashler
Keyword(s):  
Line Orientation ◽  
Orientation Discrimination ◽  
Cognitive Set

scholarly journals Effects of Feedback-Based Visual Line-Orientation Discrimination Training for Visuospatial Disorders After Stroke

2012 ◽  
Vol 27 (2) ◽  
pp. 142-152 ◽  
Author(s):  
Johanna Funk ◽  
Kathrin Finke ◽  
Stefan Reinhart ◽  
Mareike Kardinal ◽  
Kathrin S. Utz ◽  
...  
Keyword(s):  
Discrimination Training ◽  
Line Orientation ◽  
Orientation Discrimination ◽  
Effects Of Feedback

Does Attention Have Different Effects on Line Orientation and Line Arrangement Discrimination?

1991 ◽  
Vol 43 (4) ◽  
pp. 825-857 ◽  
Author(s):  
MaryLou Cheal ◽  
Don R. Lyon ◽  
David C. Hubbard
Keyword(s):  
Target Location ◽  
Spatial Location ◽  
Forced Choice ◽  
Line Orientation ◽  
Orientation Discrimination ◽  
Choice Test ◽  
Line Segments ◽  
Line Arrangement ◽  
Focal Attention ◽  
Component Line

Visual search and texture segregation studies have led to the inference that stimuli differing in the orientation of their component line segments can be distinguished without focal attention, whereas stimuli that differ only in the arrangement of line segments cannot. In most of this research, the locus of attention has not been explicitly manipulated. In the first experiment presented here, attention was directed to a relevant peripheral target by a cue presented near the target location or at the fovea. Effects of attention on orientation discrimination were assessed in a two-alternative forced-choice task with targets that were either: (1) lines that slanted obliquely to the right or left, or were horizontal or vertical, or (2) Y-like targets that had a short arm leading obliquely right or left of a vertical line. In some groups, a four-alternative forced-choice test with lines at 0°, 45°, 90°, and 135° orientations was used. Discrimination of these targets (i.e. targets that differ in the orientation of component line segments) was only minimally facilitated as the time between the onset of the valid cue and the onset of the target (cue-target stimulus onset asynchrony, SOA) was increased from 0 or 17 msec to 267 msec. In contrast, discrimination of targets that did not differ in the orientation of component line segments but differed in line arrangement (T-like characters), was greatly facilitated by longer cue-target SOAs. In Experiment 2, a cue misdirected attention on 20% of the trials. A decrement occurred on incorrectly cued trials in comparison to correctly cued trials for both types of stimuli used (lines and Ts). The results from these experiments suggest that discrimination of line orientation benefits less from focal attention than does discrimination of line arrangement, but that both discriminations suffer when attention must be disengaged from an irrelevant spatial location.

scholarly journals Spatial and Temporal Integration of Signals in Foveal Line Orientation

1997 ◽  
Vol 77 (5) ◽  
pp. 2677-2684 ◽  
Author(s):  
Gerald Westheimer ◽  
Eric J. Ley
Keyword(s):  
Time Window ◽  
Temporal Integration ◽  
Receptive Fields ◽  
Spatial Summation ◽  
Line Length ◽  
Line Orientation ◽  
Orientation Discrimination ◽  
Middle Segment ◽  
Line Segments ◽  
Black And White

Westheimer, Gerald and Eric J. Ley. Spatial and temporal integration of signals in foveal line orientation. J. Neurophysiol. 77: 2677–2684, 1997. The discrimination of the orientation of a line improves with line length, reaching an optimum when a foveal line is ∼0.5° long. We studied the effect of eliminating sections of the line, of displacing them out of alignment, and of delaying them. Orientation discrimination thresholds are only a little elevated when a 25-arcmin line is replaced by three equally spaced collinear 5-arcmin segments. Two collinear 5-arcmin segments show better thresholds than a single one when they are separated by as much as 20 arcmin. But thresholds are impaired by bringing line segments out of collinearity by as little as 1 arcmin. Asynchrony of up to 50 ms can be tolerated, but when the middle segment of a three-line pattern is delayed by ∼100 ms there is active inhibition, thresholds being now higher than when the middle segment is absent. It is concluded that for signals to address the orientation discrimination mechanism optimally, they have to be contained inside a narrow spatial corridor and be presented within a time window of ∼50 ms, but that some spatial summation can take place over a length of ≥0.5° in the fovea. Because short lines made of black and white collinear segments do not have good orientation thresholds, whereas longer and interrupted lines do, it is concluded that what is involved is potentiating interaction between collinearly arranged neurons with identical orientation selectivity rather than summation of signals within the receptive fields of single neurons.

Orienting and Focusing in Voluntary and Involuntary Visuospatial Attention Conditions

2010 ◽  
Vol 24 (3) ◽  
pp. 198-209 ◽  
Author(s):  
Yan Wang ◽  
Jianhui Wu ◽  
Shimin Fu ◽  
Yuejia Luo
Keyword(s):  
Gain Control ◽  
Event Related Potentials ◽  
Stimulus Onset ◽  
Orientation Discrimination ◽  
Involuntary Attention ◽  
Attention Condition ◽  
Voluntary Attention ◽  
Visual Spatial ◽  
Related Potentials ◽  
Underlying Mechanisms

In the present study, we used event-related potentials (ERPs) and behavioral measurements in a peripherally cued line-orientation discrimination task to investigate the underlying mechanisms of orienting and focusing in voluntary and involuntary attention conditions. Informative peripheral cue (75% valid) with long stimulus onset asynchrony (SOA) was used in the voluntary attention condition; uninformative peripheral cue (50% valid) with short SOA was used in the involuntary attention condition. Both orienting and focusing were affected by attention type. Results for attention orienting in the voluntary attention condition confirmed the “sensory gain control theory,” as attention enhanced the amplitude of the early ERP components, P1 and N1, without latency changes. In the involuntary attention condition, compared with invalid trials, targets in the valid trials elicited larger and later contralateral P1 components, and smaller and later contralateral N1 components. Furthermore, but only in the voluntary attention condition, targets in the valid trials elicited larger N2 and P3 components than in the invalid trials. Attention focusing in the involuntary attention condition resulted in larger P1 components elicited by targets in small-cue trials compared to large-cue trials, whereas in the voluntary attention condition, larger P1 components were elicited by targets in large-cue trials than in small-cue trials. There was no interaction between orienting and focusing. These results suggest that orienting and focusing of visual-spatial attention are deployed independently regardless of attention type. In addition, the present results provide evidence of dissociation between voluntary and involuntary attention during the same task.

Judgment of Line Orientation

1975 ◽  
Author(s):  
A. L. Benton ◽  
N. R. Varney ◽  
K. deS. Hamsher
Keyword(s):  
Line Orientation

Palmprint Verification Based On Competitive Coding and Robust Line Orientation Coding Schemes

2013 ◽  
Vol 8 (2) ◽  
pp. 26-31
Author(s):  
R. M. J. Priya ◽  
◽  
S Gayathri ◽  
C. Lakshmipriya ◽  
M. Arunkumar ◽  
...  
Keyword(s):  
Line Orientation ◽  
Coding Schemes
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