Exposure Duration and Line Length: An Analogy to the Broca-Sulzer Effect in Perception of Extent?

1980 ◽  
Vol 51 (3) ◽  
pp. 945-946 ◽  
Author(s):  
Ted Jaeger ◽  
Charles Kraemer

For 30 undergraduates, brief exposures were shown to increase the apparent length of a line. This enhancement of length diminished as duration of exposure increased, creating an illusion of line length that resembles the Broca-Sulzer brightness anomaly.

Perception ◽  
1995 ◽  
Vol 24 (5) ◽  
pp. 513-524 ◽  
Author(s):  
Michael J Morgan ◽  
Andrew Medford ◽  
Philip Newsome

A line abutting two tilted flanks is apparently shifted towards the orientation orthogonal to the flanks and at the same time is reduced in its apparent length. It has been suggested that both effects are caused by band-pass spatial filtering, followed by location of the end points of the line at the peaks in the filtered image. Here implications of the filtering explanation of these effects are explored further. In the first experiment, it was predicted that orientation thresholds (as opposed to biases) would be increased for short line lengths, and would be further increased by abutting bars. The predictions were confirmed. It was shown in experiment 2 that the orientation shift was reduced by a small (4 min arc) gap between target lines and orthogonal flanks. In experiment 3 the threshold elevations and the orientation shift produced by orthogonal and tilted flanks were compared. Last, in experiment 4, the threshold elevations and orientation shift produced by orthogonal and tilted flanks, at different retinal eccentricities varying from 0 to 3.2 deg were compared, and the prediction that the magnitude of the orientation shift would decrease with line length and increase with eccentricity was confirmed. The connection is explored between the orientation shift and the Zöllner illusion, and demonstrations are presented of the Zöllner effect in which target and inducing lines are of opposite contrast on a gray background. It is concluded that the Judd and Zöllner illusions do not depend upon a single mechanism.


2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.


2008 ◽  
Author(s):  
Clare K. Porac ◽  
Alan Searleman ◽  
Alicia Dunbar
Keyword(s):  

2011 ◽  
Author(s):  
Marc Pratarelli ◽  
Brita Radzymski ◽  
Eric Ayers ◽  
Erica Tryon ◽  
Aaron Randall
Keyword(s):  

2020 ◽  
Vol 2020 ◽  
pp. 1498-1502
Author(s):  
Yongwoog Andy Jeon ◽  
◽  
Yuhosua Ryoo ◽  
Kacy Kim ◽  
Sukki Yoon ◽  
...  

2020 ◽  
Author(s):  
Randolph C Grace ◽  
Nicola J. Morton ◽  
Matt Grice ◽  
Kate Stuart ◽  
Simon Kemp

Grace et al. (2018) developed an ‘artificial algebra’ task in which participants learn to make an analogue response based on a combination of non-symbolic magnitudes by feedback and without explicit instruction. Here we tested if participants could learn to add stimulus magnitudes in this task in accord with the properties of an algebraic group. Three pairs of experiments tested the group properties of commutativity (Experiments 1a-b), identity and inverse existence (Experiments 2a-b) and associativity (Experiments 3a-b), with both line length and brightness modalities. Transfer designs were used in which participants responded on trials with feedback based on sums of magnitudes and later were tested with novel stimulus configurations. In all experiments, correlations of average responses with magnitude sums were high on trials with feedback, r = .97 and .96 for Experiments 1a-b, r = .97 and .96 for Experiments 2a-b, and ranged between r = .97 and .99 for Experiment 3a and between r = .82 and .95 for Experiment 3b. Responding on transfer trials was accurate and provided strong support for commutativity, identity and inverse existence, and associativity with line length, and for commutativity and identity and inverse existence with brightness. Deviations from associativity in Experiment 3b suggested that participants were averaging rather than adding brightness magnitudes. Our results confirm that the artificial algebra task can be used to study implicit computation and suggest that representations of magnitudes may have a structure similar to an algebraic group.


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