Evidence suggests that human time perception is likely to reflect an ensemble of recent temporal experience. For example, prolonged exposure to consistent temporal patterns can adaptively realign the perception of event order, both within and between sensory modalities (e.g. Fujisaki et al., 2004 Nat. Neurosci., 7, 773-778). In addition, the observation that 'a watched pot never boils' serves to illustrate the fact that dynamic shifts in our attentional state can also produce marked distortions in our temporal estimates. In the current study we provide evidence for a hitherto unknown link between adaptation, temporal perception and our attentional state. We show that our ability to use recent sensory history as a perceptual baseline for ongoing temporal judgments is subject to striking top-down modulation via shifts in the observer's selective attention. Specifically, attending to the temporal structure of asynchronous auditory and visual adapting stimuli generates a substantial increase in the temporal recalibration induced by these stimuli. We propose a conceptual framework accounting for our findings whereby attention modulates the perceived salience of temporal patterns. This heightened salience allows the formation of audiovisual perceptual 'objects', defined solely by their temporal structure. Repeated exposure to these objects induces high-level pattern adaptation effects, akin to those found in visual and auditory domains (e.g. Leopold & Bondar (2005) Fitting the Mind to the World: Adaptation and Aftereffects in High-Level Vision. Oxford University Press, Oxford, 189-211; Schweinberger et al. (2008) Curr. Biol., 18, 684-688). / Wellcome Trust, College of Optometrists

Bibliography: p. 165-184. / xvi, 184 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis explores the issue of copying natural vision processes with regard to providing sensing information in real-time to the lowest control levels of an autonomous vehicle. It is argued that the interpretation of sensory data should result in a level of perception which is tailored to the requirements of the control system. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1996?

Bibliography: leaves 188-203. / xxii, 203 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / In this thesis insect vision principles are applied to the main mechanism for motion detection. Advanced VLSI technologies are employed for designing smart micro-sensors in which the imager and processor are integrated into one monolithic device. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 1996

Visual information about the form of an object and its movement in the world can be processed independently. These processing streams must be combined, since our visual experience is of a unitary stream of information. Studies of interactions between motion and form processing can therefore provide insight into how this combination occurs. The present thesis explored two such interactions between motion and spatial coding in human vision. The title of the thesis, “Pencils and Erasers”, serves as an analogy for the thesis’ principal findings. I investigate one situation in which moving patterns can impair the visibility of stationary forms, and another in which the visibility of form is enhanced by motion. In motion-induced blindness (MIB; Bonneh, Cooperman, & Sagi, 2001), salient stationary objects can seem to disappear intermittently from awareness when surrounded by moving features. Static forms proximate to motion can be “erased” from awareness. The thesis contributes to the answer to a simple question: why does MIB happen? My interpretation of this phenomenon emphasises the possible functional benefit of such an eraser around moving form: to suppress artifacts of visual processing from awareness. Chapter 2 demonstrates that motion per se is not required for MIB (Wallis & Arnold, 2008). MIB depends on the rate of luminance change over time, rather than the velocity (or change in position) of the inducing mask. MIB can therefore be characterised as a temporal inhibition, which does not critically depend on direction selective (motion) mechanisms. A similar mechanism of temporal inhibition that does not depend on motion is that which suppresses motion streaks from awareness. The human visual system integrates information over time. Consequently, moving image features produce smeared signals, or “motion streaks”, much like photographing a moving object using a slow shutter speed. We do not experience motion streaks as much as might be expected as they are suppressed from awareness in most circumstances. Evidence suggests that this suppression is enacted by a process of local temporal inhibition, and does not depend on motion mechanisms – much like MIB. These similarities led us to propose that MIB and motion streak suppression might reflect the same mechanism. In the case of MIB, physically present static targets may not be differentiated from signals arising from within the visual system, such as a motion streak. Chapter 3 of the thesis presents four converging lines of evidence in support of this hypothesis (Wallis & Arnold, 2009). The link between MIB and a mechanism of temporal inhibition that serves to suppress motion streaks is further strengthened by a recent report from our laboratory of a new visual illusion, Spatio-Temporal Rivalry (STR; Arnold, Erskine, Roseboom, & Wallis, in press), that is included in the present thesis as an appendix. Why does MIB occur? I suggest that at its base level, MIB reflects the activity of this simple visual mechanism of temporal inhibition (see Gorea & Caetta, 2009). This mechanism might usually serve a functional role in everyday vision: for example, by suppressing the perception of motion streaks. The second motion and form interaction investigated in the thesis represents a situation in which motion can improve form sensitivity. In some situations, observing a moving pattern can objectively improve sensitivity to that pattern after the offset of motion. The visual system can “pencil in”, or improve the visibility of, subsequent visual input. When a form defined by its motion relative to the background ceases to move, it does not seem to instantly disappear. Instead, the form is perceived to remain segregated from the background for a short period, before slowly fading. It is possible that this percept represents a consequence of bias or expectation, not a modulation of static form visibility by motion. Contrary to this possibility, Wallis, Williams and Arnold (2009) demonstrate that alignment sensitivity to spatial forms is improved by pre-exposure to moving forms (Chapter 4). I suggest that the subjective persistence of forms after motion offset and this spatial facilitation may represent two consequences of the same signal. The experiments herein address one situation in which moving patterns can impair the visibility of stationary forms and one in which moving patterns enhance the visibility of stationary forms. Therefore, the present thesis characterises two interactions between form and motion processing in human vision. These mechanisms of “pencil” and “eraser” facilitate the clear perception of objects in our visual world.

Thesis (Ph.D.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (p. 133-137).

Thesis (M.S.)--Indiana University, 2003. / Includes bibliographical references (leaves 56-64). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (Ed. D.)--Illinois State University, 1972. / Title from title page screen, viewed Sept. 27, 2004. Dissertation Committee: Max R. Rennels (chair), Richard A. Salome, Ronald Halinski, Macon L. Williams, Fred V. Mills. Includes bibliographical references (leaves 75-79). Also available in print.

Thesis (Ph. D.)--Washington State University, May 2009. / Title from PDF title page (viewed on Apr. 21, 2010). "Department of Psychology." Includes bibliographical references (p. 39-43).

Thesis (Ph.D.)--University of Alberta, 2009. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Centre for Neuroscience. Title from pdf file main screen (viewed on August 25, 2009). Includes bibliographical references.

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 100-110).