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Biomedical subjects

B Gillam

Publications and source records attributed to B Gillam.

31 records · Page 2Linked to original sources
PubMed1984

Aggregation and unit formation in the perception of moving collinear lines.

The degree to which collinear lines are treated as a unit in resolving rotary motion in depth was investigated with the use of parallel projection to make direction of motion ambiguous. The proportion of time that the collinear lines appeared to rotate in the same direction was used as an index of their perceptual coherence. When the gap between the lines was small, there was strong grouping of the lines with respect to direction of motion as well as appearance of rigidity for the configuration. For larger gaps the grouping for direction of motion was maintained, but the lines appeared to have different axes of rotation leading to an appearance of nonrigidity. It is concluded that line elements can be aggregated for the resolution of certain properties without constituting a unit in any general sense.

Depth Perception↗
PubMed1981

Separation relative to length determines the organization of two lines into a unit.

The probability that two lines will form a perceptual unit, in the sense of reversing together under conditions of depth ambiguity, decreases as their separation is increased. In these studies, the critical separation for perceptual grouping is shown to be neither the retinal nor distal separation, but the ratio of separation to line length.

Depth Perception↗
PubMed1981

False perspectives.

Textbook accounts of perception frequently contain grossly wrong perspective drawings and/or statements about perspective which misrepresent the available monocular information about distance and size, as well as giving the unfortunate impression that perspective alone elicits only a weak impression of recession. An early example of such a false perspective is the 'Ames window', which is not a correct rendering of a slanted window.

Depth Perception↗
PubMed1976

Grouping of multiple ambiguous contours: towards an understanding of surface perception.

Coplanar lines of different orientations rotating in depth and viewed in parallel projection may appear to rotate in different directions and reverse independently of each other, or they may appear coplanar and all reverse together. The frequency of the latter "grouped" appearance for lines with an orientation range of 30 degrees was a function of the number of lines in a given space. Grouping was greater for lines converging to an implicit vanishing point and for lines with collinear edges regardless of their orientations. Line length, and by inference, interline separation also had effect of the nature of the response.

Analysis of Variance↗