No / Natural visual scenes are a rich source of information. Objects often carry luminance, colour, motion, depth and textural cues, each of which can serve to aid detection and localization of the object within a scene. Contemporary neuroscience presumes a modular approach to visual analysis in which each of these attributes are processed within ostensibly independent visual streams and are transmitted to geographically distinct and functionally dedicated centres in visual cortex (van Essen & Maunsell, 1983; Zihl, von Cramon & Mai, 1983; Maunsell & Newsome, 1987; Tootell, Hadjikhani, Mendola, Marrett & Dale, 1998). In the present study we ask how the visual system localizes objects within this framework. Specifically, we investigate how the visual system assigns a unitary location to objects defined by multiple stimulus attributes, where such attributes provide conflicting positional cues. The results show that conflicting sources of visual information can be effortlessly combined to form a global estimate of spatial position, yet, this conflation of visual attributes is achieved at a cost to localization accuracy. Furthermore, our results suggest that the visual system assigns more perceptual weight (Landy, 1993; Landy & Kojima, 2001) to visual attributes which are reliably related to object contours.

Automated positioning systems designed to measure three-dimensional locations of objects are of paramount importance to flexible manufacturing applications. These systems should perform in an industrial environment, withstanding obstacles of solid objects and must be immune from external influences including changes in atmospheric conditions and surrounding noise. Automated positioning systems should also be free of mechanical contact and able to perform without having to establish a line-of-sight with the measured object. In this thesis, a novel design is proposed for the spatial measurement of the six degrees of freedom industrial robots and autonomous vehicles. Not only does the proposed system comply with the above characteristics, but it is also capable of achieving better resolutions than CCD cameras, easier to implement, safer than laser devices and more accurate than ultrasound systems.[...] / Doctor of Philosophy in Engineering

No / Precortical color vision is mediated by three independent opponent or cardinal mechanisms that linearly combine receptoral outputs to form L/M, S/(L+M), and L+M channels. However, data from a variety of psychophysical and physiological experiments indicate that chromatic processing undergoes a reorganization away from the basic opponent model. Frequently, this post-opponent reorganization is viewed in terms of the generation of multiple ¿higher order¿ chromatic mechanisms, tuned to a wide variety of axes in color space. Moreover, adaptation experiments have revealed that the synthesis of these mechanisms occurs at a level in the cortex following the binocular integration of the inputs from each eye. Here we report results from an experiment in which the influence of chromatic adaptation on the perceived visual location of a test stimulus was explored using a Vernier alignment task. The results indicate that not only is positional information processed independently within the L/M, S/(L+M), and L+M channels, but that when adapting and test stimuli are extended to non-cardinal axes, the existence of multiple chromatically tuned mechanisms is revealed. Most importantly, the effects of chromatic adaptation on this task exhibit little interocular transfer and have rapid decay rates, consistent with chromatic as opposed to contrast adaptation. These findings suggest that the reorganization of chromatic processing may take place earlier in the visual pathway than previously thought.