Accession Number : ADA138761

Title :   The Detection of Nonplanar Surfaces in Visual Space.

Descriptive Note : Technical rept.,


Personal Author(s) : Uttal,W R ; Brogan,J ; McCreight,K ; Robertson,S ; White,P

PDF Url : ADA138761

Report Date : 01 Mar 1984

Pagination or Media Count : 268

Abstract : This monograph presents the results of a series of 17 experiments designed to provide a partial answer to two questions concerning the detection of dotted forms in dotted visual masks: (1) What is the effect of the spatial geometry of three-dimensional, nonplanar forms on their detectability? (2) What is the effect on the signal-to-noise ratio on their detectability? The results of the study indicate that the spatial geometry exerts virtually no effect until a threshold level of geometrical complexity is exceeded by the stimulus forms. Beyond that threshold, the effects of form are significant but modest in absolute amplitude. The results further indicate that a putative large effect of form obtained with sinusoidal stimuli actually results form a violation of the Shannon-Weaver sampling theorem from information theory and is thus due to inadequate definition of the form rather than to the nature of the form. On the other hand, the signal-to-noise ration strongly influences detectability, regardless of whether it is manipulated by varying the number of dots in the stimulus-form or by varying the number of masking dots. This study failed to extend a highly successful autocorrelation-type theory from twp-dimensions to three-dimensions. The implications and background of this study are discussed in detail.

Descriptors :   *Visual perception, Detection, Surfaces, Masking, Geometric forms, Spatial distribution, Three dimensional, Signal to noise ratio, Threshold effects, Stimuli, Amplitude, Experimental data

Subject Categories : Psychology
      Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE