| There has recently been much interest in how limitations in spatial frequency range affect face and object perception. This work has mainly focussed on determining which bands of frequencies are most useful for visual recognition. However, a fundamental question not yet addressed is how spatial frequency overlap (i.e., the range of spatial frequencies shared by two images) affects complex image recognition. Aside from the basic theoretical interest this question holds, it also bears on research about effects of display format (e.g., line-drawings, Mooney faces, etc.) and studies examining the nature of mnemonic representations of faces and objects. Examining the effects of spatial frequency overlap on face and object recognition is the main goal of this thesis.; A second question that is examined concerns the effect of calibration of stimuli on recognition of spatially filtered images. Past studies using non-calibrated presentation methods have inadvertently introduced aberrant frequency content to their stimuli. The effect this has on recognition performance has not been examined, leading to doubts about the comparability of older and newer studies. Examining the impact of calibration on recognition is an ancillary goal of this dissertation.; Seven experiments examining the above questions are reported here. Results suggest that spatial frequency overlap had a strong effect on face recognition and a lesser effect on object recognition. Indeed, contrary to much previous research it was found that the band of frequencies occupied by a face image had little effect on recognition, but that small variations in overlap had significant effects. This suggests that the overlap factor is important in understanding various phenomena in visual recognition. Overlap effects likely contribute to the apparent superiority of certain spatial bands for different recognition tasks, and to the inferiority of line drawings in face recognition. Results concerning the mnemonic representation of faces and objects suggest that these are both encoded in a format that retains spatial frequency information, and do not support certain proposed fundamental differences in how these two stimulus classes are stored. Data on calibration generally shows non-calibration having little impact on visual recognition, suggesting moderate confidence in results of older studies. |
