scholarly journals Motion Extrapolation Into the Blind Spot

2008 ◽  
Vol 19 (11) ◽  
pp. 1087-1091 ◽  
Author(s):  
Gerrit W. Maus ◽  
Romi Nijhawan
Keyword(s):  
Blind Spot ◽  
Moving Object ◽  
Final Position ◽  
Transient Signals ◽  
Motion Extrapolation ◽  
Lag Effect ◽  
History Of

The flash-lag effect, in which a moving object is perceived ahead of a colocalized flash, has led to keen empirical and theoretical debates. To test the proposal that a predictive mechanism overcomes neural delays in vision by shifting objects spatially, we asked observers to judge the final position of a bar moving into the retinal blind spot. The bar was perceived to disappear in positions well inside the unstimulated area. Given that photoreceptors are absent in the blind spot, the perceived shift must be based on the history of the moving object. Such predictive overshoots are suppressed when a moving object disappears abruptly from the retina, triggering retinal transient signals. No such transient-driven suppression occurs when the object disappears by virtue of moving into the blind spot. The extrapolated position of the moving bar revealed in this manner provides converging support for visual prediction.

scholarly journals Perceptual compression of space through position integration

2006 ◽  
Vol 273 (1600) ◽  
pp. 2507-2512 ◽  
Author(s):  
Barrie W Roulston ◽  
Matt W Self ◽  
Semir Zeki
Keyword(s):  
Visual Space ◽  
Moving Object ◽  
Final Position ◽  
Short Time Period ◽  
Stationary Stimulus ◽  
Time Period ◽  
Lag Effect ◽  
Moving Stimulus ◽  
Short Time ◽  
Direction Opposite

The mechanism of positional localization has recently been debated due to interest in the flash-lag effect, which occurs when a briefly flashed stationary stimulus is perceived to lag behind a spatially aligned moving stimulus. Here we report positional localization observed at motion offsets as well as at onsets. In the ‘flash-lead’ effect, a moving object is perceived to be behind a spatially concurrent stationary flash before the two disappear. With ‘reverse-repmo’, subjects mis-localize the final position of a moving bar in the direction opposite to the trajectory of motion. Finally, we demonstrate that simultaneous onset and offset effects lead to a perceived compression of visual space. By characterizing illusory effects observed at motion offsets as well as at onsets, we provide evidence that the perceived position of a moving object is the result of an averaging process over a short time period, weighted towards the most recent positions. Our account explains a variety of motion illusions, including the compression of moving shapes when viewed through apertures.

Motion extrapolation in the flash-lag effect depends on perceived, rather than physical speed

2021 ◽  
Author(s):  
Jane Yook ◽  
Lysha Lee ◽  
Simone Vossel ◽  
Ralph Weidner ◽  
Hinze Hogendoorn
Keyword(s):  
Luminance Contrast ◽  
Moving Object ◽  
Neural Representation ◽  
High Contrast ◽  
Motion Extrapolation ◽  
Lag Effect ◽  
Temporal Averaging ◽  
Perceived Speed ◽  
Perceived Velocity ◽  
Static Noise

In the flash-lag effect (FLE), a flash in spatiotemporal alignment with a moving object is often misperceived as lagging behind the moving object. One proposed explanation for the illusion is based on predictive motion extrapolation of trajectories. In this interpretation, observers require an estimate of the object′s velocity to anticipate future positions, implying that the FLE is dependent on a neural representation of perceived velocity. By contrast, alternative models of the FLE based on differential latencies or temporal averaging should not rely on such a representation of velocity. Here, we test the extrapolation account by investigating whether the FLE is sensitive to illusory changes in perceived speed when physical speed is actually constant. This was tested using rotational wedge stimuli with variable noise texture (Experiment 1) and luminance contrast (Experiment 2). We show for both manipulations, differences in perceived speed corresponded to differences in the FLE: dynamic versus static noise, and low versus high contrast stimuli led to increases in perceived speed and FLE magnitudes. These effects were consistent across different textures and were not due to low-level factors. Our results support the idea that the FLE depends on a neural representation of velocity, which is consistent with mechanisms of motion extrapolation. Hence, the faster the perceived speed, the larger the extrapolation, the stronger the flash-lag.

scholarly journals Saccades reveal that allocentric coding of the moving object causes mislocalization in the flash-lag effect

2009 ◽  
Vol 71 (6) ◽  
pp. 1313-1324 ◽  
Author(s):  
Stefanie I. Becker ◽  
Ulrich Ansorge ◽  
Massimo Turatto
Keyword(s):  
Moving Object ◽  
Lag Effect

scholarly journals The Ottoman origins of capitalism: uneven and combined development and Eurocentrism

2013 ◽  
Vol 40 (2) ◽  
pp. 325-347 ◽  
Author(s):  
KEREM NISANCIOGLU
Keyword(s):  
International Relations ◽  
Ottoman Empire ◽  
Early Modern Period ◽  
Blind Spot ◽  
Historical Processes ◽  
Uneven And Combined Development ◽  
History Of ◽  
Transition To Capitalism ◽  
The One ◽  
Do So

AbstractThe history of capitalism's origins is unmistakably Eurocentric, placing sixteenth-century developments in politics, economy, culture, and ideology squarely within the unique context of Europe. And while the disciplinary remit of International Relations (IR) should offer a way out of such European provincialism, it too has been built on largely Eurocentric assumptions. In Eurocentric approaches, the Ottoman Empire has been absent, passive, or merely a comparative foil against which the specificity and superiority of Europe has been defined. And yet, the Ottoman Empire was arguably the most powerful actor in the Early Modern period. In this article, I argue that any history of capitalism's origins must therefore account for the historical importance of the Ottomans. In doing so, this article seeks to address the non-European blind-spot, both in theorisations of capitalism's origins and in IR theory, by reincorporating the material significance of the Ottoman Empire in historical processes, which led to the transition to capitalism. I do so by utilising the theory of Uneven and Combined Development, and in the process seek to defend its credentials as a non-Eurocentric social theory on the one hand and as a sociologically and historically sensitive theory of international relations on the other.

scholarly journals Optimal Smoothing in Visual Motion Perception

2001 ◽  
Vol 13 (6) ◽  
pp. 1243-1253 ◽  
Author(s):  
Rajesh P. N. Rao ◽  
David M. Eagleman ◽  
Terrence J. Sejnowski
Keyword(s):  
Visual System ◽  
Moving Objects ◽  
Visual Motion ◽  
Moving Object ◽  
Motion Direction ◽  
Visual Motion Perception ◽  
Statistical Framework ◽  
Lag Effect ◽  
Propagation Delays ◽  
Optimal Smoothing

When a flash is aligned with a moving object, subjects perceive the flash to lag behind the moving object. Two different models have been proposed to explain this “flash-lag” effect. In the motion extrapolation model, the visual system extrapolates the location of the moving object to counteract neural propagation delays, whereas in the latency difference model, it is hypothesized that moving objects are processed and perceived more quickly than flashed objects. However, recent psychophysical experiments suggest that neither of these interpretations is feasible (Eagleman & Sejnowski, 2000a, 2000b, 2000c), hypothesizing instead that the visual system uses data from the future of an event before committing to an interpretation. We formalize this idea in terms of the statistical framework of optimal smoothing and show that a model based on smoothing accounts for the shape of psychometric curves from a flash-lag experiment involving random reversals of motion direction. The smoothing model demonstrates how the visual system may enhance perceptual accuracy by relying not only on data from the past but also on data collected from the immediate future of an event.

Southern Poetry: Antebellum to Contemporary

2019 ◽  
Author(s):  
Claire Raymond
Keyword(s):  
African American ◽  
Jim Crow ◽  
Blind Spot ◽  
The South ◽  
Rural South ◽  
History Of ◽  
American Poets ◽  
Southern Poetry ◽  
History Of The South

Southern poetry embraces dichotomous elements: it contains poems lauding the Confederacy, and also poems deeply critical and mournful of the racist violence, oppression, and racist terrorism that characterize the region’s history. Yet a common thread runs through Southern poetry—attention to the land, the rural South as a character in its own right, and with that attention to the land a quality of haunting and being haunted by the history of the South: the violence of colonization, enslavement, the Civil War, Reconstruction, Jim Crow. Twentieth-century poet Etheridge Knight, born in Mississippi, lyrically describes the earth of Mississippi merging with the graves of his ancestors, calling him home to a place where, as a black man, he is not safe. Nineteenth-century poet Sidney Lanier, born in Georgia and, like Knight, a man who had experienced imprisonment, shapes in his poetry a mythical country where trees and rivers and indigenous crops become forces superseding the human; but Lanier, a soldier for the Confederacy, does not mention enslavement in his poetry. In Southern poetry, this blind spot—the white Southern poet who does not see or reflect upon the racist violence of enslavement, Jim Crow, lynching—is often submerged into a poetry melancholic and obsessed with unnamable violence and loss, even as African American poets of the South often name this loss in terms of personal memory. Myth—of the aristocratic, agrarian South—in white Southern poetry, and memory—of personal risk and suffering—in African American Southern poetry, can be understood together as a common pull to write the land, albeit from different perspectives.

Hyperbaric oxygen therapy awareness within a doctor population

2020 ◽  
pp. 39-50
Author(s):  
Kurt Magri ◽  
◽  
Sarah Bigeni ◽  
Charles Paul Azzopardi ◽  
Liberato Camilleri ◽  
...  
Keyword(s):  
Hyperbaric Oxygen ◽  
Linear Models ◽  
Scoring Systems ◽  
Blind Spot ◽  
Developed Country ◽  
Referral Rates ◽  
Logistic Regression Models ◽  
History Of ◽  
Hyperbaric Medicine ◽  
Willingness To Refer

Hyperbaric medicine is a relatively young specialty that remains in the blind spot of most doctors’ awareness. This study endeavors to identify the level of awareness of the indications for hyperbaric oxygen (HBO2) therapy among a doctor population in a developed country and factors which may improve referral rates. An anonymized questionnaire was distributed to doctors licensed to practice in Malta. Questions included physician specialty, demographics and previous exposure to diving and/or hyperbaric medicine. Moreover, two scoring systems were used to score subjects on HBO2-related topics. Binomial logistic regression models and generalized linear models were used in the statistical analysis. A total of 152 full replies were obtained and analyzed. Respondents who had visited a hyperbaric unit (HBU) (p=0.002) or attended a lecture on HBO2 (p=0.006) scored better than their counterparts, indicating better awareness of HBO2 indications and local chamber location. A previous HBU visit (p=0.001), being a hospital-based doctor (p=0.027) and a history of scuba diving (p=0.03) were associated with willingness to refer patients for HBO2 in the future. Encouraging visits to an HBU has been shown to be associated with multiple factors, which are expected to result in improved referral rates. Targeted educational sessions to doctors and medical students are likely to be beneficial in improving correct referral of patients for HBO2. The findings from this study may prove useful in improving appropriate referral rates of patients who may benefit from this useful treatment modality.

Representations of History: From Acedia to the Dialectical Image in Bourlem Guerdjou's Vivre au paradis

PMLA ◽  
2009 ◽  
Vol 124 (5) ◽  
pp. 1878-1882 ◽  
Author(s):  
Réda Bensmaïa
Keyword(s):  
Historical Memory ◽  
Blind Spot ◽  
Algerian War ◽  
Colonial History ◽  
Dialectical Image ◽  
History Of ◽  
The Veil ◽  
Set Up ◽  
A Site

Can a film based on fiction contribute to the restoration of historical memory? can films help fill in the blanks of history? What exactly is the filmmaker's position? What faculty and what means does he or she require to make such a prodigious feat possible? Are films capable of creating sites of memory, and by what means? What traces will make it possible to set up markers in a site of a scotoma? The questions become increasingly precise: Can cinema lift the veil that colonial history has thrown over the history of the Algerian War? And what can the nature of the blind spot be if every effort has been made to keep it hidden?

Sign in / Sign up

Export Citation Format

Share Document