Modulation of the Rod-And-Frame Illusion by Additional External Stimuli

Perception ◽  
1995 ◽  
Vol 24 (10) ◽  
pp. 1105-1118 ◽  
Author(s):  
Donatella Spinelli ◽  
Gabriella Antonucci ◽  
Roberta Daini ◽  
Daniela Fanzon ◽  
Pierluigi Zoccolotti
Keyword(s):  
Visual Processing ◽  
Local Processing ◽  
Frame Tilt ◽  
Visual Vestibular Interaction ◽  
Frame Condition ◽  
External Frame ◽  
Global And Local ◽  
External Stimuli ◽  
Rod And Frame

The presence of an additional external upright frame was studied in three experiments to separate the role of visuovestibular, global, and local mechanisms in the rod-and-frame illusion (RFI). In the first experiment, carried out in a dark room, the external frame surrounded a large tilted frame. Rod-setting errors to the vertical were abolished with the additional-frame condition (at 22° inner-frame tilt) confirming earlier findings. However, small, residual direct (at 11° inner-frame tilt) and indirect effects (at 33° inner-frame tilt) were still present, indicating the persistence of global visual processing. In the second experiment, the RFI in the dark was compared with the RFI with the lights on. Turning the light on abolished the effect at 22° and 33° frame tilt; however, a small direct effect was maintained at 11° frame tilt. These two studies indicate that the addition of veridical vertical information abolishes the effect owing to visuovestibular mechanisms. In the third experiment, a small rod and frame was used with the lights on (a condition abolishing visual—vestibular interaction). In the case of a small gap between the rod and the inducing frame (a condition which maximises local processing), the effect of the outer upright frame was negligible; this indicates that the additional frame had no effect on local processing. In the case of a large gap (a condition which minimises local processing), the external square reduced the illusion, indicating its modulating effect on visual global processing. Overall, an upright external frame exerts a differential influence depending on which mechanisms contribute most to the RFI in a given experimental condition.

Large Errors in the Perception of Verticality are Generated by Luminance Borders (Integrated across Space) Not by Subjective Borders

Perception ◽  
10.1068/p3070 ◽  
2001 ◽  
Vol 30 (2) ◽  
pp. 177-184
Author(s):  
Donatella Spinelli ◽  
Gabriella Antonucci ◽  
Maria Luisa Martelli ◽  
Pierluigi Zoccolotti
Keyword(s):  
Opposite Direction ◽  
Subjective Contour ◽  
Standard Condition ◽  
Global Orientation ◽  
Tilted Frame ◽  
Frame Tilt ◽  
Visual Vertical ◽  
Perception Of Verticality ◽  
Rod And Frame

The rod-and-frame illusion shows large errors in the judgment of visual vertical in the dark if the frame is large and there are no other visible cues (Witkin and Asch, 1948 Journal of Experimental Psychology38 762–782). Three experiments were performed to investigate other characteristics of the frame critical for generating these large errors. In the first experiment, the illusion produced by an 11° tilted frame made by luminance borders (standard condition) was considerably larger than that produced by a subjective-contour frame. In the second experiment, with a 33° frame tilt, the illusion was in the direction of frame tilt with a luminance-border frame but in the opposite direction in the subjective-contour condition. In the third experiment, to contrast the role of local and global orientation, the sides of the frame were made of short separate luminous segments. The segments could be oriented in the same direction as the frame sides, in the opposite direction, or could be vertical. The orientation of the global frame dominated the illusion while local orientation produced much smaller effects. Overall, to generate a large rod-and-frame illusion in the dark, the tilted frame must have luminance, not subjective, contours. Luminance borders do not need to be continuous: a frame made of sparse segments is also effective. The mechanism responsible for the large orientation illusion is driven by integrators of orientation across large areas, not by figural operators extracting shape orientation in the absence of oriented contours.

Global Orientation Disrupts the Detection of a Similar Local Orientation

Perception ◽  
1997 ◽  
Vol 26 (10) ◽  
pp. 1259-1270 ◽  
Author(s):  
Johan Lauwereyns ◽  
Géry d'Ydewalle
Keyword(s):  
Visual Search ◽  
Target Letter ◽  
Target Line ◽  
Local Processing ◽  
Local Orientation ◽  
Critical Feature ◽  
Line Segments ◽  
Global Orientation ◽  
Global And Local

Two experiments were carried out with organised displays in order to examine the role of similarity between global and local orientation in visual search. In both experiments, distractors were organised to form a diagonal line of plus or minus 45°. In experiment 1, target displays were presented tachistoscopically. Participants searched for a target letter ‘Q’ among distractor letters ‘O’. In experiment 2, participants performed a heterogeneity task with target line segments that could have an orientation of either plus or minus 45°. The target appeared partly or completely inside a distractor circle. In both experiments, the target was more difficult to detect when the critical feature aligned with the slope of the global diagonal than when the feature did not align. Taken together, the two experiments suggested a sequential global-to-local processing in which the orientation of the global figure disrupts the detection of a similar local orientation.

On the Role of Abstraction in Global and Local Processing Phenomena

2010 ◽  
Vol 21 (3) ◽  
pp. 198-202 ◽  
Author(s):  
Katherine M. Darwent ◽  
Kentaro Fujita ◽  
Cheryl J. Wakslak
Keyword(s):  
Local Processing ◽  
Global And Local ◽  
Global And Local Processing

Visual Factors Affecting the Rod-And-Frame Illusion: Role of Gap Size and Frame Components

Perception ◽  
1995 ◽  
Vol 24 (10) ◽  
pp. 1119-1130 ◽  
Author(s):  
Gabriella Antonucci ◽  
Daniela Fanzon ◽  
Donatella Spinelli ◽  
Pierluigi Zoccolotti
Keyword(s):  
Small Degree ◽  
Gap Size ◽  
Illusory Effect ◽  
Superiority Effect ◽  
Actual Length ◽  
Vertical Meridian ◽  
Factors Affecting ◽  
Frame Tilt ◽  
Rod And Frame

In two studies the effect of the distance between the tip of the rod and the frame sides (gap) in the rod-and-frame (RF) illusion was examined and the effect of a full-square condition was compared with that of two different frame amputations. In both studies, there were more rod-setting errors in the direction of the tilt of the inducing figure with a small gap than with a large one. These findings are consistent with the idea that in the case of small gap size local interactions contribute to determining the RF illusion. The actual length of the rod was varied in order to keep the gap constant across different frame tilts; therefore these findings cannot be due to the co-variation between gap size and frame tilt which is typical of standard apparatuses. The effect of frame amputations was compared to the full-square condition. According to Wenderoth and Beh, amputations that maintain the two orthogonal contours of the square produce the typical angular function of the RF illusion. This prediction was confirmed in both studies. However, results indicate that the full square has a stronger illusory effect in the case of a small degree of tilt of the inducing stimulus, irrespective of gap size. It is suggested that this ‘square superiority’ effect is related to global, not local, mechanisms. To pursue Wenderoth and Beh's observations, amputations close to the vertical meridian were used in one experiment and those close to the horizontal meridian in the second experiment. Contrary to predictions, these conditions produced overlapping results.

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

The Indices of Creative Cities: the Global and Local Aspects

2015 ◽  
Vol 4 (1) ◽  
pp. 95 ◽  
Author(s):  
Tomas Kačerauskas
Keyword(s):  
High Tech ◽  
Melting Pot ◽  
Creative Cities ◽  
Global And Local

The paper deals with the indices of creative cities. Author analyses the different creativity indices suggested by both the followers and the critics of R. Florida. The author criticizes the Florida’s indices such as Bohemian, Melting pot, Gay, High tech, Innovation, Talent indices, as well as Minor integrative (diversity) and Major integrative indices. The indices of other authors presuppose the questions about the role of the region in defining certain creativity indices. The author makes conclusion that the uniform formula of creativity indices is impossible for two reasons. First, the creativity indices depend on the region of a city. Second, the very strategy to have the uniform creativity indices makes the cities similar to each other and no more unique, consequently, no more creative; as result, this strategy is anti-creative.

Leading Professionals

2017 ◽  
Author(s):  
Laura Empson
Keyword(s):  
Mergers And Acquisitions ◽  
Distributed Leadership ◽  
Investment Banks ◽  
Professional Organizations ◽  
Power Dynamics ◽  
Consulting Firms ◽  
Complex Power ◽  
Plural Leadership ◽  
External Stimuli

This book analyses the complex power dynamics and interpersonal politics that lie at the heart of leadership in professional organizations, such as accounting, law, and consulting firms, investment banks, hospitals, and universities. It is based on scholarly research into many of the world’s leading professional organizations across a range of sectors, including interviews with over 500 senior professionals in sixteen countries. Drawing on the latest academic theory to analyse exactly how professionals in organizations come together to create ‘leadership’, it provides new insights into how leaders lead when there is no traditional hierarchy to support them, their own authority is contingent, and they must constantly renegotiate relationships with relatively autonomous professional peers. It explores how leaders persuade highly intelligent, educated, and opinionated professionals to work together; how change happens within professional organizations; and why leaders so often fail. Part I introduces the concept of plural leadership, analysing how leaders establish and maintain their positions within leadership constellations, and the implications for governance in the context of collective or distributed leadership. Part II examines the complex, challenging relationships between professionals as they seek to influence their organizations, including the phenomena of leadership dyads, insecure overachievers, social control, and the rise of the management professional. Part III examines the shifts in the locus of power as professional organizations grow, adapt, and react to external stimuli such as mergers and acquisitions and economic crises. The conclusion identifies the paradoxes inherent in professional organizations and examines the role of leaders in attempting to reconcile them.

scholarly journals T cell–specific STAT3 deficiency abrogates lupus nephritis

Lupus ◽  
2019 ◽  
Vol 28 (12) ◽  
pp. 1468-1472 ◽  
Author(s):  
N Yoshida ◽  
F He ◽  
V C Kyttaris
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lupus Nephritis ◽  
Lupus Erythematosus ◽  
Cell Responses ◽  
Cytokines And Chemokines ◽  
Novel Approach ◽  
Cell Tissue ◽  
External Stimuli

Signal transducer and activator of transcription (STAT) 3 is a regulator of T-cell responses to external stimuli, such as pro-inflammatory cytokines and chemokines. We have previously shown that STAT3 is activated (phosphorylated) at high levels in systemic lupus erythematosus (SLE) T cells and mediates chemokine-induced migration and T:B cell interactions. Stattic, a small molecular STAT3 inhibitor, can partially ameliorate lupus nephritis in mice. To understand the role of STAT3 better in T-cell pathophysiology in lupus nephritis and its potential as a treatment target, we silenced its expression in T cells using a cd4-driven CRE-Flox model. We found that lupus-prone mice that do not express STAT3 in T cells did not develop lymphadenopathy, splenomegaly, or glomerulonephritis. Moreover, the production of anti-dsDNA antibodies was decreased in these mice compared to controls. To dissect the mechanism, we also used a nephrotoxic serum model of nephritis. In this model, T cell–specific silencing of STAT3 resulted in amelioration of nephrotoxic serum-induced kidney damage. Taken together, our results suggest that in mouse models of autoimmune nephritis, T cell–specific silencing of STAT3 can hamper their ability to help B cells to produce autoantibodies and induce cell tissue infiltration. We propose that STAT3 inhibition in T cells represents a novel approach in the treatment of SLE and lupus nephritis in particular.

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