A General Correspondence Approach to Apparent Motion

Perception ◽  
1993 ◽  
Vol 22 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Terry Caelli ◽  
Mark Manning ◽  
David Finlay
Keyword(s):  
Apparent Motion ◽  
Constraint Satisfaction ◽  
General Framework ◽  
Feature Weights ◽  
General Correspondence ◽  
Perceived Motion

A general framework is considered for how different features of image parts determine the perceived direction of apparent motion between these parts as a function of their internalized feature weights. It is shown how the compatibility and constraints between pairwise part correspondences also play important roles in the types of perceived motion between parts; this process is modelled via a multivariate constraint-satisfaction procedure.

Effect of Element Size on Stereoscopic Apparent Motion

2003 ◽  
Vol 96 (3_suppl) ◽  
pp. 1187-1193 ◽  
Author(s):  
Hiroyuki Ito
Keyword(s):  
Motion Perception ◽  
Apparent Motion ◽  
Forced Choice ◽  
Spatial Displacement ◽  
Motion Direction ◽  
Element Size ◽  
Random Dot Stereograms ◽  
Perceived Motion

Spatial displacement limits in stereoscopic (cyclopean) apparent motion were measured from sequentially presented two-frame random-depth configurations. Each depth configuration was defined by stereoscopically near or far elements of various sizes. The limits were compared with those in luminance-defined apparent motion. The subject's task was 2-alternative forced-choice of the perceived motion direction of the sequentially presented two-frame random-dot stereograms. The spatial displacement limit below which correct motion perception arose with stereoscopic configurations was larger in proportion to increases in size of elements. The values were almost consistent with those measured by luminance-defined configurations with the same element sizes. This result suggests that the strategy for discrimination of motion direction of random configurations is similar in both stereoscopic and luminance-defined apparent motion.

scholarly journals Optimal Implementation of Watched Literals and More General Techniques

2013 ◽  
Vol 48 ◽  
pp. 231-252 ◽  
Author(s):  
I. P. Gent
Keyword(s):  
Constraint Satisfaction ◽  
General Framework ◽  
Search Tree ◽  
Constant Factor ◽  
Worst Case ◽  
Backtracking Search ◽  
Run Time ◽  
Unit Propagation ◽  
Implementation Technique ◽  
Optimal Implementation

I prove that an implementation technique for scanning lists in backtracking search algorithms is optimal. The result applies to a simple general framework, which I present: applications include watched literal unit propagation in SAT and a number of examples in constraint satisfaction. Techniques like watched literals are known to be highly space efficient and effective in practice. When implemented in the `circular' approach described here, these techniques also have optimal run time per branch in big-O terms when amortized across a search tree. This also applies when multiple list elements must be found. The constant factor overhead of the worst case is only 2. Replacing the existing non-optimal implementation of unit propagation in MiniSat speeds up propagation by 29%, though this is not enough to improve overall run time significantly.

scholarly journals Scrambling the skin: A psychophysical study of adaptation to scrambled tactile apparent motion

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0227462
Author(s):  
Tatjana Seizova-Cajic ◽  
Sandra Ludvigsson ◽  
Birger Sourander ◽  
Melinda Popov ◽  
Janet L. Taylor
Keyword(s):  
Apparent Motion ◽  
Constant Velocity ◽  
Stimulus Onset ◽  
Object Motion ◽  
Local Motion ◽  
Motion Direction ◽  
Good Test ◽  
Motion Sequence ◽  
Velocity Motion ◽  
Perceived Motion

An age-old hypothesis proposes that object motion across the receptor surface organizes sensory maps (Lotze, 19th century). Skin patches learn their relative positions from the order in which they are stimulated during motion events. We propose that reversing the local motion within a global motion sequence (‘motion scrambling’) provides a good test for this idea, and present results of the first experiment implementing the paradigm. We used 6-point apparent motion along the forearm. In the Scrambled sequence, two middle locations were touched in reversed order (1-2-4-3-5-6, followed by 6-5-3-4-2-1, in a continuous loop). This created a double U-turn within an otherwise constant-velocity motion, as if skin patches 3 and 4 physically swapped locations. The control condition, Orderly, proceeded at constant velocity at inter-stimulus onset interval of 120 ms. The 26.4-minute conditioning (delivered in twenty-four 66-s bouts) was interspersed with testing of perceived motion direction between the two middle tactors presented on their own (sequence 3–4 or 4–3). Our twenty participants reported motion direction. Direction discrimination was degraded following exposure to Scrambled pattern and was 0.31 d’ weaker than following Orderly conditioning (p = .007). Consistent with the proposed role of motion, this could be the beginning of re-learning of relative positions. An alternative explanation is that greater speed adaptation occurred in the Scrambled pattern, raising direction threshold. In future studies, longer conditioning should tease apart the two explanations: our re-mapping hypothesis predicts an overall reversal in perceived motion direction between critical locations (for either motion direction), whereas the speed adaptation alternative predicts chance-level performance at worst, without reversing.

Psychophysical Method and Phoria as Variables Determining Apparent Motion Perception

1966 ◽  
Vol 22 (1) ◽  
pp. 147-152 ◽  
Author(s):  
Alan W. Rusnak
Keyword(s):  
Motion Perception ◽  
Apparent Motion ◽  
Horizontal Plane ◽  
Psychophysical Method ◽  
Perceived Motion ◽  
Method Of Constant Stimuli

Psychophysical method, degree of heterophoria, and type of heterophoria (esophoria and hyperphoria) were studied as variables affecting the perception of beta motion in 25 male Ss and 25 female Ss. Esophoria was more disruptive of motion perception than hyperphoria, for all Ss, with the stimuli presented in a horizontal plane. The method of constant stimuli produced greater mean durations of perceived motion in the male Ss than the method of serial exploration but was non-significant for females. Degree of heterophoria did not significantly affect mean durations of perceived motion for either group, leading to the conclusion that beta motion is a highly stable phenomenon

Structural Constraints: Further Evidence from Apparent Motion in Depth

Perception ◽  
1993 ◽  
Vol 22 (3) ◽  
pp. 323-334 ◽  
Author(s):  
Maurice Hershenson
Keyword(s):  
Apparent Motion ◽  
Three Dimensional ◽  
Structural Constraints ◽  
Motion Patterns ◽  
Motion In Depth ◽  
Point Patterns ◽  
Light Point ◽  
Rigidity Constraint ◽  
Second Category ◽  
Perceived Motion

The three-dimensional (3-D) apparent motion of lines, outline triangles, and light points was studied in four experiments. The stimulus sequences were beginning and end patterns of 3-D motions of a line and a triangle. Light-point patterns corresponded to the ends of the lines and the vertices of the triangles. Perceived motion of lines and light-point pairs resembled the distal motions that were used to construct the proximal patterns. The correspondence was striking for configurations that appeared to move in depth. Outline triangles and light-point triplets produced a strong correspondence between distal and perceived motions when the three sides appeared to be translating in depth. The correspondence was reasonably good for the other motion patterns when scoring included an appropriate second category. The results support the conception of structural or internalized constraints: light points were processed as if they were connected (unity constraint) and proximal change in linear size (or distance between light points) was perceived as rigid 3-D motion (rigidity constraint).

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