940 resultados para Motion perception (Vision)


Relevância:

90.00% 90.00%

Publicador:

Resumo:

Fruiting bodies represents human engagement with and consciousness of a corresponding presence in our landscape. ʻFruiting Bodiesʼ is an instance of the application of this practice employed to ask the viewer to consider how strange is the phenomenon of the fruiting tree. Is it promiscuous to offer your seed openly to the elements, to any who will take it. Is this forbidden? Is it profligate to hide your progeny inside gifts so tempting in their appeal to that most primitive desire, hunger? Is this wholly mere biological expedience evolved to ensure the widest migration of your offspring? Or does it derive from some boundless cosmic generosity? These images invite you to come close to the tree, where within its arms you will find shelter from the sun at its zenith and from the autumnal rains. Fruit is the focus of Jamesʼs lens as it circles deep into the embrace of limbs and leaves.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Fruiting bodies represents human engagement with and consciousness of a corresponding presence in our landscape. ʻFruiting Bodiesʼ is an instance of the application of this practice employed to ask the viewer to consider how strange is the phenomenon of the fruiting tree. Is it promiscuous to offer your seed openly to the elements, to any who will take it. Is this forbidden? Is it profligate to hide your progeny inside gifts so tempting in their appeal to that most primitive desire, hunger? Is this wholly mere biological expedience evolved to ensure the widest migration of your offspring? Or does it derive from some boundless cosmic generosity? These images invite you to come close to the tree, where within its arms you will find shelter from the sun at its zenith and from the autumnal rains. Fruit is the focus of Jamesʼs lens as it circles deep into the embrace of limbs and leaves.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Fruiting bodies represents human engagement with and consciousness of a corresponding presence in our landscape. ʻFruiting Bodiesʼ is an instance of the application of this practice employed to ask the viewer to consider how strange is the phenomenon of the fruiting tree. Is it promiscuous to offer your seed openly to the elements, to any who will take it. Is this forbidden? Is it profligate to hide your progeny inside gifts so tempting in their appeal to that most primitive desire, hunger? Is this wholly mere biological expedience evolved to ensure the widest migration of your offspring? Or does it derive from some boundless cosmic generosity? These images invite you to come close to the tree, where within its arms you will find shelter from the sun at its zenith and from the autumnal rains. Fruit is the focus of Jamesʼs lens as it circles deep into the embrace of limbs and leaves.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Fruiting bodies represents human engagement with and consciousness of a corresponding presence in our landscape. ʻFruiting Bodiesʼ is an instance of the application of this practice employed to ask the viewer to consider how strange is the phenomenon of the fruiting tree. Is it promiscuous to offer your seed openly to the elements, to any who will take it. Is this forbidden? Is it profligate to hide your progeny inside gifts so tempting in their appeal to that most primitive desire, hunger? Is this wholly mere biological expedience evolved to ensure the widest migration of your offspring? Or does it derive from some boundless cosmic generosity? These images invite you to come close to the tree, where within its arms you will find shelter from the sun at its zenith and from the autumnal rains. Fruit is the focus of Jamesʼs lens as it circles deep into the embrace of limbs and leaves.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

European Renaissance and Romantic landscape appeared in vistas. The conditions of the industrial revolution and, according to Patrick Maynard and Jonathon Crary, the film camera especially, led to a Modernist re-vision vividly recorded in Xavier Herbert’s contrary Modernist vision, prompted by seeing the Australian bush, its ‘... stunted trees, the mulga and the wilga and the gimlet gum, doing a kind of dance, spinning past, seeming to swing away from the train to the horizon and race ahead, to come back...the same set of trees in endless gyration’.

Space at the coincidence of ‘landscape’ and ‘human’ is being radically refigured in contemporary photomedia to deal with being; noun and verb. Practice by Australians Daniel Crooks, David Stephenson, Kristian Haggblom and Marian Drew, and my own, positions a third figure, the self, in our confounding landscape.
Drawing on the theories of phenomenology, 'ecological psychology' and psychogeography, we explore by analogy the way our articulated body, mobile head, and socketed eyes concert to search our space. Condensing space with time creates a visceral awareness of the environment; the scratching thorns as much as the soaring treetops. From a revealed connection between body and environment come signs of mind and attention.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Ziel der vorliegenden Arbeit war es, mithilfe von Dressurexperimenten in Kombination mit dem Einsatz von Neuropharmaka die Bedeutung des retinalen ON-Kanals für zwei visuelle Leistungen des Goldfisches – das kontrastabhängige zeitliche Auflösungsvermögen sowie die Wellenlängenunterscheidungsfähigkeit - zu untersuchen. Da die Tiere nach der pharmakologischen Blockade keinerlei verändertes Verhalten zeigten, kann davon ausgegangen werden, dass der retinale ON-Kanal weder für die Prozessierung des kontrastabhängigen zeitlichen Auflösungsvermögens noch für die Wellenlängenunterscheidungsfähigkeit eine maßgebliche Rolle spielt. Aus den Versuchen zur Wellenlängenunterscheidungsfähigkeit kann des Weiteren abgeleitet werden, dass der ON-Kanal auch für die spektrale Empfindlichkeit der Tiere bei der gegebenen Beleuchtungs- und Dressurbedingungen (L+-Dressur) keine Bedeutung zu haben scheint. Nach den Versuchen zum kontrastabhängigen zeitlichen Auflösungsvermögen kann festgehalten werden, dass das zeitliche Auflösungsvermögen des Goldfisches sich mit abnehmendem Stimuluskontrast verändert: Der für die Tiere wahrnehmbare Flickerfrequenzbereich wird mit abnehmendem Kontrast geringer. Die Flimmerfusionsfrequenz wird im oberen Frequenzbereich früher erreicht; im unteren Flickerfrequenzbereich tritt mit abnehmendem Kontrast auch eine untere Grenze des zeitlichen Auflösungsvermögens auf. Des Weiteren zeigen die Ergebnisse aus den Verhaltensversuchen zu den kontrastabhängigen zeitlichen Übertragungseigenschaften eine gute Vergleichbarkeit zu elektrophysiologisch gewonnenen Antworten von ON bzw. OFF-Bipolarzellen. Ebenso ähneln sich die Kurvenverläufe zum kontrastabhängigen zeitlichen Auflösungsvermögen und die aus den Versuchen zur kontrastabhängigen Ganzfeldbewegungswahrnehmung – einer visuellen Leistung, deren Prozessierung eines ON-Kanal-Beitrages bedarf. Diese Ergebnisse deuten darauf hin, dass das zeitliche Auflösungsvermögen wie auch die Ganzfeldbewegungswahrnehmung hauptsächlich von retinalen Verarbeitungsprozessen abhängen.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Active head turns to the left and right have recently been shown to influence numerical cognition by shifting attention along the mental number line. In the present study, we found that passive whole-body motion influences numerical cognition. In a random-number generation task (Experiment 1), leftward and downward displacement of participants facilitated small number generation, whereas rightward and upward displacement facilitated the generation of large numbers. Influences of leftward and rightward motion were also found for the processing of auditorily presented numbers in a magnitude-judgment task (Experiment 2). Additionally, we investigated the reverse effect of the number-space association (Experiment 3). Participants were displaced leftward or rightward and asked to detect motion direction as fast as possible while small or large numbers were auditorily presented. When motion detection was difficult, leftward motion was detected faster when hearing small number and rightward motion when hearing large number. We provide new evidence that bottom-up vestibular activation is sufficient to interact with the higher-order spatial representation underlying numerical cognition. The results show that action planning or motor activity is not necessary to influence spatial attention. Moreover, our results suggest that self-motion perception and numerical cognition can mutually influence each other.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

The aim of this functional magnetic resonance imaging (fMRI) study was to identify human brain areas that are sensitive to the direction of auditory motion. Such directional sensitivity was assessed in a hypothesis-free manner by analyzing fMRI response patterns across the entire brain volume using a spherical-searchlight approach. In addition, we assessed directional sensitivity in three predefined brain areas that have been associated with auditory motion perception in previous neuroimaging studies. These were the primary auditory cortex, the planum temporale and the visual motion complex (hMT/V5+). Our whole-brain analysis revealed that the direction of sound-source movement could be decoded from fMRI response patterns in the right auditory cortex and in a high-level visual area located in the right lateral occipital cortex. Our region-of-interest-based analysis showed that the decoding of the direction of auditory motion was most reliable with activation patterns of the left and right planum temporale. Auditory motion direction could not be decoded from activation patterns in hMT/V5+. These findings provide further evidence for the planum temporale playing a central role in supporting auditory motion perception. In addition, our findings suggest a cross-modal transfer of directional information to high-level visual cortex in healthy humans.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Previous studies on motion perception revealed motion-processing brain areas sensitive to changes in luminance and texture (low-level) and changes in salience (high-level). The present functional magnetic resonance imaging (fMRI) study focused on motion standstill. This phenomenon, occurring at fast presentation frequencies of visual moving objects that are perceived as static, has not been previously explored by neuroimaging techniques. Thirteen subjects were investigated while perceiving apparent motion at 4 Hz, at 30 Hz (motion standstill), isoluminant static and flickering stimuli, fixation cross, and blank screen, presented randomly and balanced for rapid event-related fMRI design. Blood oxygenation level-dependent (BOLD) signal in the occipito-temporal brain region MT/V5 increased during apparent motion perception. Here we could demonstrate that brain areas like the posterior part of the right inferior parietal lobule (IPL) demonstrated higher BOLD-signal during motion standstill. These findings suggest that the activation of higher-order motion areas is elicited by apparent motion at high presentation rates (motion standstill). We interpret this observation as a manifestation of an orienting reaction in IPL towards stimulus motion that might be detected but not resolved by other motion-processing areas (i.e., MT/V5).

Relevância:

90.00% 90.00%

Publicador:

Resumo:

In this study, we compared direction detection thresholds of passive self-motion in the dark between artistic gymnasts and controls. Twenty-four professional female artistic gymnasts (ranging from 7 to 20 years) and age-matched controls were seated on a motion platform and asked to discriminate the direction of angular (yaw, pitch, roll) and linear (leftward–rightward) motion. Gymnasts showed lower thresholds for the linear leftward–rightward motion. Interestingly, there was no difference for the angular motions. These results show that the outstanding self-motion abilities in artistic gymnasts are not related to an overall higher sensitivity in self-motion perception. With respect to vestibular processing, our results suggest that gymnastic expertise is exclusively linked to superior interpretation of otolith signals when no change in canal signals is present. In addition, thresholds were overall lower for the older (14–20 years) than for the younger (7–13 years) participants, indicating the maturation of vestibular sensitivity from childhood to adolescence.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

OBJECTIVE Visuoperceptual deficits are common in dementia with Lewy bodies (DLB) and Alzheimer disease (AD). Testing visuoperception in dementia is complicated by decline in other cognitive domains and extrapyramidal features. To overcome these issues, we developed a computerized test, the Newcastle visuoperception battery (NEVIP), which is independent of motor function and has minimal cognitive load.We aimed to test its utility to identify visuoperceptual deficits in people with dementia. PARTICIPANTS AND MEASUREMENTS We recruited 28 AD and 26 DLB participants with 35 comparison participants of similar age and education. The NEVIP was used to test angle, color, and form discrimination along with motion perception to obtain a composite visuoperception score. RESULTS Those with DLB performed significantly worse than AD participants on the composite visuoperception score (Mann-Whitney U = 142, p = 0.01). Visuoperceptual deficits (defined as 2 SD below the performance of comparisons) were present in 71% of the DLB group and 40% of the AD group. Performance was not significantly correlated with motor impairment, but was significantly related to global cognitive impairment in DLB (rs = -0.689, p <0.001), but not in AD. CONCLUSION Visuoperceptual deficits can be detected in both DLB and AD participants using the NEVIP, with the DLB group performing significantly worse than AD. Visuoperception scores obtained by the NEVIP are independent of participant motor deficits and participants are able to comprehend and perform the tasks.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

We seek to determine the relationship between threshold and suprathreshold perception for position offset and stereoscopic depth perception under conditions that elevate their respective thresholds. Two threshold-elevating conditions were used: (1) increasing the interline gap and (2) dioptric blur. Although increasing the interline gap increases position (Vernier) offset and stereoscopic disparity thresholds substantially, the perception of suprathreshold position offset and stereoscopic depth remains unchanged. Perception of suprathreshold position offset also remains unchanged when the Vernier threshold is elevated by dioptric blur. We show that such normalization of suprathreshold position offset can be attributed to the topographical-map-based encoding of position. On the other hand, dioptric blur increases the stereoscopic disparity thresholds and reduces the perceived suprathreshold stereoscopic depth, which can be accounted for by a disparity-computation model in which the activities of absolute disparity encoders are multiplied by a Gaussian weighting function that is centered on the horopter. Overall, the statement "equal suprathreshold perception occurs in threshold-elevated and unelevated conditions when the stimuli are equally above their corresponding thresholds" describes the results better than the statement "suprathreshold stimuli are perceived as equal when they are equal multiples of their respective threshold values."

Relevância:

90.00% 90.00%

Publicador:

Resumo:

National Highway Safety Bureau, Washington, D.C.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Mode of access: Internet.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

PURPOSE. To investigate the effect of age on optokinetic nystagmus (OKN) in response to stimuli designed to preferentially stimulate the M-pathway. METHOD. OKN was recorded in 10 younger (32.3 +/- 5.98 years) and 10 older (65.6 +/- 6.53) subjects with normal vision. Vertical gratings of 0.43 or 1.08 cpd drifting at 5 degrees/s or 20 degrees/s and presented at either 8% or 80% contrast were displayed on a large screen as full-field stimulation, central stimulation within a central Gaussian-blurred window of 15 diameter, or peripheral stimulation outside this window. All conditions apart from the high-contrast condition were presented in a random order at two light levels, mesopic (1.8 cdm(-2)) and photopic (71.5 cdm(-2)). RESULTS. Partial-field data indicated that central stimulation, mesopic light levels, and lower temporal frequency each significantly increased slow-phase velocity (SPV). Although there was no overall difference between groups for partial-field stimulation, full-field stimulation, or low-contrast stimulation, a change in illumination revealed a significant interaction with age: there was a larger decrease in SPV going from photopic to mesopic conditions for the older group than the younger group, especially for higher temporal frequency stimulation. CONCLUSIONS. OKN becomes reflexive in conditions conducive to M-pathway stimulation, and this rOKN response is significantly diminished in older healthy adults than in younger healthy adults, indicative of decreased M-pathway sensitivity.