Vection in depth during treadmill walking

Vection has typically been induced in stationary observers (ie conditions providing visual-only information about self-motion). Two recent studies have examined vection during active treadmill walking--one reported that treadmill walking in the same direction as the visually simulated self-motion impaired vection (Onimaru et al, 2010 Journal of Vision 10(7):860), the other reported that it enhanced vection (Seno et al, 2011 Perception 40 747-750; Seno et al, 2011 Attention, Perception, & Psychophysics 73 1467-1476). Our study expands on these earlier investigations of vection during observer active movement. In experiment 1 we presented radially expanding optic flow and compared the vection produced in stationary observers with that produced during walking forward on a treadmill at a 'matched' speed. Experiment 2 compared the vection induced by forward treadmill walking while viewing expanding or contracting optic flow with that induced by viewing playbacks of these same displays while stationary. In both experiments subjects' tracked head movements were either incorporated into the self-motion displays (as simulated viewpoint jitter) or simply ignored. We found that treadmill walking always reduced vection (compared with stationary viewing conditions) and that simulated viewpoint jitter always increased vection (compared with constant velocity displays). These findings suggest that while consistent visual-vestibular information about self-acceleration increases vection, biomechanical self-motion information reduces this experience (irrespective of whether it is consistent or not with the visual input)

Evidence for parallel consolidation of motion direction and orientation into visual short-term memory

Recent findings have indicated the capacity to consolidate multiple items into visual short-term memory in parallel varies as a function of the type of information. That is, while color can be consolidated in parallel, evidence suggests that orientation cannot. Here we investigated the capacity to consolidate multiple motion directions in parallel and reexamined this capacity using orientation. This was achieved by determining the shortest exposure duration necessary to consolidate a single item, then examining whether two items, presented simultaneously, could be consolidated in that time. The results show that parallel consolidation of direction and orientation information is possible, and that parallel consolidation of direction appears to be limited to two. Additionally, we demonstrate the importance of adequate separation between feature intervals used to define items when attempting to consolidate in parallel, suggesting that when multiple items are consolidated in parallel, as opposed to serially, the resolution of representations suffer. Finally, we used facilitation of spatial attention to show that the deterioration of item resolution occurs during parallel consolidation, as opposed to storage.This work was supported by an Australian Postgraduate Award to R. R., an NHMRC Early Career Fellowship (1054726) to D. A., and an Australian research Council Grant (DP110104553) to M. E

Direct evidence for encoding of motion streaks in human visual cortex

Temporal integration in the visual system causes fast-moving objects to generate static, oriented traces ('motion streaks'), which could be used to help judge direction of motion. While human psychophysics and single-unit studies in non-human primates are consistent with this hypothesis, direct neural evidence from the human cortex is still lacking. First, we provide psychophysical evidence that faster and slower motions are processed by distinct neural mechanisms: faster motion raised human perceptual thresholds for static orientations parallel to the direction of motion, whereas slower motion raised thresholds for orthogonal orientations. We then used functional magnetic resonance imaging to measure brain activity while human observers viewed either fast ('streaky') or slow random dot stimuli moving in different directions, or corresponding static-oriented stimuli. We found that local spatial patterns of brain activity in early retinotopic visual cortex reliably distinguished between static orientations. Critically, a multivariate pattern classifier trained on brain activity evoked by these static stimuli could then successfully distinguish the direction of fast ('streaky') but not slow motion. Thus, signals encoding static-oriented streak information are present in human early visual cortex when viewing fast motion. These experiments show that motion streaks are present in the human visual system for faster motion.This work was supported by the Wellcome Trust (G.R., D.S.S.), the European Union ‘Mindbridge’ project (B.B.), the Australian Federation of Graduate Women Tempe Mann Scholarship (D.A.), the University of Sydney Campbell Perry Travel Fellowship (D.A.) and the Brain Research Trust (C.K.)

AS GOOD AS AN ARMY: Mapping Smallpox during the Seven Years’ War in North America

There is substantial evidence that smallpox was widespread in North American during the Seven Years’ War. However, there have been no attempts to determine the extent to which it occurred. This thesis will map outbreaks of smallpox from the beginning stages of the conflict in 1752 through to the close of the Anglo-Indian War in 1765. It aims to demonstrate the far-reaching nature of a smallpox epidemic that lasted the duration of the war, and during other periods of intense conflict. After a preliminary consideration of effects the epidemic had on the war, it is clear that future studies are required to determine its full impact

AS GOOD AS AN ARMY: Mapping Smallpox during the Seven Years’ War in North America

There is substantial evidence that smallpox was widespread in North American during the Seven Years’ War. However, there have been no attempts to determine the extent to which it occurred. This thesis will map outbreaks of smallpox from the beginning stages of the conflict in 1752 through to the close of the Anglo-Indian War in 1765. It aims to demonstrate the far-reaching nature of a smallpox epidemic that lasted the duration of the war, and during other periods of intense conflict. After a preliminary consideration of effects the epidemic had on the war, it is clear that future studies are required to determine its full impact

Tilt aftereffects and tilt illusions induced by fast translational motion: evidence for motion streaks

Fast-moving visual features are thought to leave neural \u27streaks\u27 that can be detected by orientation-selective cells. Here, we tested whether \u27motion streaks\u27 can induce classic tilt aftereffects (TAEs) and tilt illusions (TIs). For TAEs, participants adapted to random arrays of small Gaussian blobs drifting at 9.5 deg/s. Following adaptation to directions of 15, 30, 45, 60, 75, and 90 degrees (clockwise from vertical) subjective vertical was measured for a briefly presented test grating. For TIs, the same motions were presented in an annular surround and subjective vertical was measured for a simultaneously presented central grating. All motions were 50% coherent, with half the blobs following random-walk paths and half following a fixed direction. Strong and weak streaks were compared by varying streak length (the number of fixed-walk frames), rather than by manipulating speed, so that speed and coherence were matched in all conditions. Strong motion streaks produced robust TAEs and TIs, similar in magnitude and orientation tuning to those induced by tilted lines. These effects were weak or absent in weak streak conditions, and when motion was too slow to form streaks. Together, these results indicate that motion streaks produced by temporal integration of fast translating features do effectively adapt orientation-selective cells and may therefore be exploited to improve perception of motion direction as described in the \u27motion streaks\u27 model

A Manual of Gothic Mouldings

Manual de molduras góticas.Copia digital. España : Ministerio de Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 2021Posiblemente impreso en los primeros 30 años del siglo X