The Role of ON- and OFF-Channel Processing in the Detection of Bilateral Symmetry

Perception ◽  
10.1068/p3387 ◽  
2002 ◽  
Vol 31 (9) ◽  
pp. 1061-1072 ◽  
Author(s):  
Anna Brooks ◽  
Rick van der Zwan
Keyword(s):  
Bilateral Symmetry ◽  
Limited Range ◽  
Visual Scene ◽  
Performance Decrement ◽  
Symmetry Detection ◽  
Axis Orientation ◽  
Present Evidence ◽  
Detection Mechanisms

We present evidence that grouping for luminance does not take precedence over the detection of bilaterally symmetrical patterns. Using single-axis and double-axis images, we found that element pairs within which luminance is held constant drive symmetry-detection mechanisms more effectively than pairs within which luminance varies. Moreover, the performance decrement observed for patterns defined by element pairs within which luminance varies is not specific to interchannel variation. Luminance variation within the ON and OFF channels has the same effect as variation between the channels on the performance of axis-orientation identification tasks. It is argued that this constitutes possible evidence for subchannels within the ON and OFF channels. One of the characteristics of the subchannels is that each processes only a limited range of luminance steps. The implications of this type of luminance processing for the detection of symmetry in the visual scene are discussed.

The Differential Effects of Simultaneous and Successive Cueing on the Detection of Bilateral Symmetry in Dot Patterns

2000 ◽  
Vol 53 (1) ◽  
pp. 165-190 ◽  
Author(s):  
Peter Wenderoth
Keyword(s):  
Visual Processing ◽  
Processing Time ◽  
Reaction Times ◽  
Vertical Axis ◽  
Bilateral Symmetry ◽  
Frame Of Reference ◽  
Symmetry Detection ◽  
Axis Orientation ◽  
Differential Effects ◽  
Orientation Ordering

Corballis and Roldan (1975) obtained speeded judgements of whether dot patterns were bilaterally symmetrical about, or translated across, a line. Reaction times (RTs) were ordered V (vertical) > D (diagonal) > H (horizontal) where “>” means faster than. Similar results occurred with blocked axis orientations, suggesting subjects cannot prepare by rotating a mental frame of reference. Blocking trials may have been ineffective because blocking cannot provide incremental benefits over those already provided by axis lines. Four experiments show that the usual axis orientation ordering of V > H > D is markedly attentuated by simultaneous but not successive axis lines. Also, axis cue lines and axis blocking are not equivalent treatments. Instead, unblocked line cues require finite processing time whereas, under blocking, subjects can prepare for the expected orientation. There was no suggestion anywhere of the V > D > H axis ordering that Corballis and Roldan reported. Successive axis line cues may only direct attention to the orientation being cued, but simultaneous line cues may change the stimulus itself, thus providing an additional means of visual processing that facilitates symmetry detection at non-vertical axis orientations.

The Effects on Bilateral-Symmetry Detection of Multiple Symmetry, near Symmetry, and Axis Orientation

Perception ◽  
1997 ◽  
Vol 26 (7) ◽  
pp. 891-904 ◽  
Author(s):  
Peter Wenderoth
Keyword(s):  
Response Bias ◽  
Human Perception ◽  
Negative Stimulus ◽  
Bilateral Symmetry ◽  
Symmetry Detection ◽  
Axis Orientation ◽  
Second Stage ◽  
Asymmetrical Pattern ◽  
Stage Process ◽  
Axes Of Symmetry

Palmer and Hemenway (1978 Journal of Experimental Psychology: Human Perception and Performance4 691–702) reported that shapes with multiple axes of symmetry are processed faster than those with single symmetry even when trials are blocked so that the subject knows that any symmetry axis will be vertical. Because their model of symmetry detection postulated a two-stage process in which all orientations are searched crudely at first, in no particular order, followed by second-stage scrutiny, the continued salience of multiple over single symmetry with blocking could not be explained. They claimed that stimuli with multiple axes of symmetry have an additional ‘goodness’. Four experiments are reported in which it is demonstrated that both sensitivity ( d′) and response bias ( β) vary considerably in symmetry detection, not just as a function of the positive (symmetrical) stimuli used but also as a function of the negative or conjugate instances selected. Although stimuli with multiple axes of symmetry may well have extra salience due to pattern ‘goodness’, this factor may have been confounded with response bias in Palmer and Hemenway's experiments. It is suggested that several of their—as well as other researchers—results could be due to some combination of the effects of type of positive stimulus, type of negative stimulus, and response bias directed towards responding positively to highly symmetrical stimuli in a mix of less symmetrical stimuli. Palmer and Hemenway appear to have been correct in suggesting that subjects are more sensitive to quadruple than single symmetry, but the experiments indicate that subjects are also more willing to respond “symmetrical” to stimuli with quadruple symmetry when trials are not blocked, as in Palmer and Hemenway's experiment 1. However, it is demonstrated that the latter effect can be removed by blocking trials so that only one class of symmetrical pattern and one class of asymmetrical pattern occur in any block.

scholarly journals Higher-level mechanisms detect facial symmetry

2005 ◽  
Vol 272 (1570) ◽  
pp. 1379-1384 ◽  
Author(s):  
Gillian Rhodes ◽  
Marianne Peters ◽  
Kieran Lee ◽  
M. Concetta Morrone ◽  
David Burr
Keyword(s):  
Visual Processing ◽  
Symmetry Detection ◽  
Extensive Experience ◽  
Facial Symmetry ◽  
Evolutionary Selection ◽  
Low Level ◽  
Wide Range ◽  
High Level ◽  
Detection Mechanisms

The role of symmetry detection in early visual processing and the sensitivity of biological visual systems to symmetry across a wide range of organisms suggest that symmetry can be detected by low-level visual mechanisms. However, computational and functional considerations suggest that higher-level mechanisms may also play a role in facial symmetry detection. We tested this hypothesis by examining whether symmetry detection is better for faces than comparable patterns, which share low-level properties with faces. Symmetry detection was better for upright faces than for inverted faces (experiment 1) and contrast-reversed faces (experiment 2), implicating high-level mechanisms in facial symmetry detection. In addition, facial symmetry detection was sensitive to spatial scale, unlike low-level symmetry detection mechanisms (experiment 3), and showed greater sensitivity to a 45° deviation from vertical than is found for other aspects of face perception (experiment 4). These results implicate specialized, higher-level mechanisms in the detection of facial symmetry. This specialization may reflect perceptual learning resulting from extensive experience detecting symmetry in faces or evolutionary selection pressures associated with the important role of facial symmetry in mate choice and ‘mind-reading’ or both.

scholarly journals ATSPINDŽIO SIMETRIJOS DETEKCIJOS YPATUMAI

Psichologija ◽  
2001 ◽  
Vol 24 ◽  
pp. 69-82
Author(s):  
Alvydas Šoliūnas ◽  
Ona Gurčinienė
Keyword(s):  
Experimental Data ◽  
Bilateral Symmetry ◽  
Detection Accuracy ◽  
Symmetry Detection ◽  
Experimental Procedure ◽  
Line Segments ◽  
Experimental Part ◽  
Horizontal Symmetry ◽  
Symmetry Number

Nors simetrija suvokiama iš pirmo žvilgsnio greitai ir be pastangų, nėra aišku, kaip vyksta šis procesas, kokie yra simetrijos detekcijos mechanizmai? Straipsnyje apžvelgiami įvairių simetrijos rūšių ypatumai, didžiausią dėmesį skiriant atspindžio simetrijai. Aptartos pagrindinės simetrijos detekcijos teorijos ir modeliai. Eksperimentinė straipsnio dalis skirta siekimui pagilinti turimas žinias eksperimentiniais rezultatais, gautais su kitokio tipo stimulais ir kitokia užduotimi, nei naudota kitų tyrinėtojų. Testo stimulai buvo 4, 6, 7, arba 8 vertikalių ir horizontalių linijos atkarpų figūros, o užduotis reikalavo nurodyti stimulų simetrijos tipą - vertikalios simetrijos, horizontalios simetrijos ar nesimetrinis. Figūra rodoma 10 ms, o maskuojantis stimulas pateikiamas po 20-95 ms, priklausomai nuo tiriamojo. Rezultatai patvirtino vertikalios atspindžio simetrijos dominavimą horizontalios atžvilgiu. Stimulo atkarpų skaičius neturėjo įtakos nei vertikalios, nei horizontalios simetrijos detekcijos tikslumui, o nesimetriniai stimulai daugumos tiriamųjų buvo detektuojami taip pat tiksliai, kaip ir vertikalios simetrijos stimulai. Autorių pasiūlyta eksperimentinė metodika, leisianti išaiškinti dėmesio dalyvavimą simetrijos detekcijoje. CHARACTERISTICS OF BILATERAL SYMMETRY DETECTION Alvydas Šoliūnas, Ona Gurčinienė SummaryAlthough the symmetry is detected very fast and without efforts, it is not known how this process is going on and what mechanisms make the detection of symmetry possible. This paper reviews the characteristics of the detection of various symmetry types giving the majority of attention to bilateral symmetry. The main theories and models of symmetry detection are discussed as well. Experimental part of the paper is devoted to extend the existing knowledge with experimental data which were obtained with the stimuli and procedure that differ from that used by other investigators. Test stimuli were figures consisting of four, six, seven, or eight horizontal and vertical line-segments, and the task for subjects was to answer what kind of stimulus was presented - vertically symmetrical, horizontally symmetrical, or asymmetrical. Test stimuli were presented very briefly (10 ms) followed by masking after 20-95 ms. Experimental results confirmed the advantage of vertical over horizontal symmetry. Number of line-segments did not influence the detection accuracy nor for vertical, nor for horizontal symmetry. Majority of subjects detected asymmetrical stimuli with the same accuracy as vertically symmetrical stimuli. Authors offer an experimental procedure that would enable to explain the role of attention in symmetry detection.

Improving the questions we ask, with Psychology and Cognitive Conflict.

2018 ◽  
Author(s):  
Brett Buttliere
Keyword(s):  
Problem Solving ◽  
Scientific Method ◽  
Meaning Making ◽  
Cognitive Conflict ◽  
Empirical Literature ◽  
Present Evidence ◽  
Scientific Papers ◽  
Science In Society

Over the last decade, there have been many suggestions to improve how scientists answer their questions, but far fewer attempt to improve the questions scientists are asking in the first place. The goal of the paper is then to examine and summarize synthesize the evidence on how to ask the best questions possible. First is a brief review of the philosophical and empirical literature on how the best science is done, which implicitly but not explicitly mentions the role of psychology and especially cognitive conflict. Then we more closely focus on the psychology of the scientist, finding that they are humans, engaged in a meaning making process, and that cognitive conflict is a necessary input for any learning or change in the system. The scientific method is, of course, a specialized meaning making process. We present evidence for this central role of cognitive conflict in science by examining the most discussed scientific papers between 2013 and 2017, which are, in general, controversial and about big problems (e.g., whether vaccines cause autism, how often doctors kill us with their mistakes). Toward the end we discuss the role of science in society, suggesting science itself is an uncertainty reducing and problem solving enterprise. From this basis we encourage scientists to take riskier stances on bigger topics, for the good of themselves and society generally.

Role of Reynolds and Archimedes numbers in particle-fluid flows

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Haim Kalman
Keyword(s):  
Flow Regime ◽  
Power Function ◽  
Fluid Flows ◽  
Limited Range ◽  
Operating Conditions ◽  
Pneumatic Conveying ◽  
Particulate Materials ◽  
Simple Power ◽  
Simple Power Function

AbstractAny scientific behavior is best represented by nondimensional numbers. However, in many cases, for pneumatic conveying systems, dimensional equations are developed and used. In some cases, many of the nondimensional equations include Reynolds (Re) and Froude (Fr) numbers; they are usually defined for a limited range of materials and operating conditions. This study demonstrates that most of the relevant flow types, whether in horizontal or vertical pipes, can be better described by Re and Archimedes (Ar) numbers. Ar can also be used in hydraulic conveying systems. This paper presents many threshold velocities that are accurately defined by Re as a simple power function of Ar. Many particulate materials are considered by Ar, thereby linking them to a common behavior. Using various threshold velocities, a flow regime chart for horizontal conveying is presented in this paper.

scholarly journals Recent Advancements in the Mechanisms Underlying Resistance to PD-1/PD-L1 Blockade Immunotherapy

Cancers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 663
Author(s):  
Yu Yuan ◽  
Abdalla Adam ◽  
Chen Zhao ◽  
Honglei Chen
Keyword(s):  
Immune Evasion ◽  
Immune Checkpoint ◽  
Poor Prognosis ◽  
Target Therapy ◽  
Acquired Resistance ◽  
Immune Checkpoint Blockade ◽  
Therapeutic Strategies ◽  
Present Evidence ◽  
Immunosuppressive Factor

Release of immunoreactive negative regulatory factors such as immune checkpoint limits antitumor responses. PD-L1 as a significant immunosuppressive factor has been involved in resistance to therapies such as chemotherapy and target therapy in various cancers. Via interacting with PD-1, PD-L1 can regulate other factors or lead to immune evasion of cancer cells. Besides, immune checkpoint blockade targeting PD-1/PD-L1 has promising therapeutic efficacy in the different tumors, but a significant percentage of patients cannot benefit from this therapy due to primary and acquired resistance during treatment. In this review, we described the utility of PD-L1 expression levels for predicting poor prognosis in some tumors and present evidence for a role of PD-L1 in resistance to therapies through PD-1/PD-L1 pathway and other correlating signaling pathways. Afterwards, we elaborate the key mechanisms underlying resistance to PD-1/PD-L1 blockade in cancer immunotherapy. Furthermore, promising combination of therapeutic strategies for patients resistant to PD-1/PD-L1 blockade therapy or other therapies associated with PD-L1 expression was also summarized.

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