Flanked objects are difficult to identify using peripheral vision. This is visual crowding. Crowding is the perceptual bottleneck for reading (Pelli et al., 2007) and object recognition (Pelli & Tillman, 2008). Theories for crowding had been suggested, but the underlying neural mechanism remained unclear. Some perceptual manipulations had been shown to break crowding, hinting the cortical locus of crowding. In the first part of the current study, we ask whether illusory contour formation survives crowding of illusion inducers. We measured the contrast thresholds for discriminating the rotation angle of a target Kanizsa inducer with and without flankers. When the other three Kanizsa inducers were rotated to misalign with the target, we observed strong crowding indicated through contrast threshold elevation. Interestingly, however, subjects were able to judge the shape (thin vs. fat) of the illusory Kanizsa square even when the individual inducers were flanked. Internal representation of the percept in the inducer-aligned condition was further studied through the classification image technique. Classification images indicated that illusory contours were formed and used in the perceptual decision task in both the non-flanked and flanked conditions. These findings suggest that crowding happens after illusory contour formation. In the second part, we ask if Chinese character orientation affects crowding. Fifty commonly used traditional Chinese characters were selected as stimuli. We measured the contrast threshold for identifying upright and inverted target surrounded by either upright or inverted flankers. At 5? eccentricity, we observed an interaction effect between target and flanker orientation on crowding: upright flankers produced a stronger crowding effect than inverted flankers for inverted but not upright target. Follow-up experiments showed that the observation was not due to a rise of detection sensitivity for upright flankers or a change of spatial extent between upright and inverted target. Yet, adding an enclosure to flankers eliminated the flanker orientation effect, suggesting that the flanker orientation effect may be attributed to the facilitation of texture perception in the periphery. At 10? eccentricity, upright target was generally more immune from crowding, further supporting that crowding takes place after Chinese character orientation has been coded. From previous fMRI studies, we know that lateral occipital complex (LOC) is the cortical site that first responds to Kanizsa?s illusory contours (Murray et al., 2002) and the fusiform gyrus is sensitive to the inversion of Chinese character (Kao, Chen, & Chen, 2009). Taken together with our findings, we infer that crowding happens at or after the two cortical locations. / published_or_final_version / Psychology / Master / Master of Philosophy

OBJECTIVES: Investigate changes in mandibular incisor position resulting from Invisalign correction of the crowded dentition. MATERIALS AND METHODS: A retrospective chart review was undertaken on 61 adult Caucasian patients. Subjects were categorized into 3 groups based on the value of pre-treatment crowding of the lower dentition; 20 mild (2.0-3.9mm), 22 moderate (4.0-5.9mm) and 19 severe (>6.0mm). Cephalometric radiographs were measured to determine lower incisor changes. Interproximal reduction (IPR) and changes in arch width were also measured. Statistical evaluation of T0 and T1 values using paired t-tests and ANCOVA were applied to evaluate mean value changes. RESULTS: Lower incisor position and angulation changes were statistically significant in the severe crowding group. There were no statistically significant differences in lower incisor position between the mild and moderate crowding groups. There was a statistically significant increase in buccal expansion in each of the 3 groups. CONCLUSIONS: Invisalign® treatment can successfully resolve mandibular arch crowding using a combination of buccal arch expansion, interproximal reduction and lower incisor proclination. When there is <6mm of crowding, lower incisor position remained relatively stable. In more severely crowded dentitions (>6mm), the lower incisors proclined and protruded to allow for arch alignment.

Thesis (B.A.(Hons.)) -- University of Adelaide, Dept. of Psychology, 1978.

Thesis (Ph. D.)--Ohio State University, 1977. / Includes bibliographical references (leaves 103-108). Available online via OhioLINK's ETD Center.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 1990. / Vita. Includes bibliographical references (leaves 336-350).

No description available.

No / Identifying a target is more difficult when distracters are present within a zone of interaction around the target. We investigated whether the spatial extent of the zone of interaction scales with the size of the target. Our target was a letter T in one-of-four orientations. Our distracters were four squared-thetas in one-of-two orientations, presented one in each of the four cardinal directions, equidistant from the target. Target-distracter separation was varied and the proportion of correct responses at each separation was determined. From these the extent of interaction was estimated. This procedure was repeated for different target sizes spread over a 5-fold range. In each case, the contrast of the target was adjusted so that its visibility was constant across target sizes. The experiment was performed in the luminance domain (grey targets on grey background) and in the chromatic domain (green target on equiluminant grey background). In the luminance domain, target size had only a small effect on the extent of interaction; these interactions did not scale with target size. The extents of interaction for chromatic stimuli were similar to those for luminance stimuli. For a fixed target visibility, decreasing the duration of the stimulus resulted in an increase in the extent of interaction. The relevance of our findings is discussed with regard to a variety of proposed explanations for crowding. Our results are consistent with an attention-based explanation for crowding.

Store image research has attempted to identify factors contributing to formation of positive or negative perceptions of stores by consumers. These factors include tangible and intangible elements. Of the tangible factors, store atmosphere (including store layout and congestion level) is often identified as contributing to store image. Intangible factors influencing store image include emotional or psychological reactions that consumers have in response to various tangible store factors. One of these emotional responses is retail crowding. Retail crowding is a state of psychological stress occurring in consumers in response to perceived high density levels in stores. Crowding literature suggests that environmental cues, including layout and density level, contribute to this stress level. The overall purpose of this study was to expand on current research by incorporating the concept of retail crowding with store image research.

NIMBY is widely used acronym for people's unwilingness to house noxious facilities in their immediate neighborhood. People feel that they are somewhat and they expect to be compensated for this. Goal of this thesis is to evaluate influence of monetary compensations on people's willingness to accept these facilities. Evaluates effects of Crowding Theory, extristic and intristic motivations on willingness to accept these facilities. Used method was qualitative analysis in form of controlled interviews with key stakeholders (mayor and town citizens). Author tries to evaluate if the NIMBY effect is the main reason for generally bad acceptance of this facilities. This thesis explores the NIMBY effect on construction of one of these facilities in town Chotíkov with a view on the gradual development of view throughout the population of this town.

No description available.