Quarterly Journal of Experimental Psychology
ISSN: 0033-555X (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/pqje19
Visual comparison of random-dot patterns: Evidence concerning a fixed visual association between features and feature-relations David H. Foster To cite this article: David H. Foster (1978) Visual comparison of random-dot patterns: Evidence concerning a fixed visual association between features and feature-relations, Quarterly Journal of Experimental Psychology, 30:4, 637-654, DOI: 10.1080/14640747808400690 To link to this article: http://dx.doi.org/10.1080/14640747808400690
Published online: 29 May 2007.
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Date: 06 November 2015, At: 04:03
Quarterly Journal of Experimental Psycliology (1978) 30, 637-654
Downloaded by [Chinese University of Hong Kong] at 04:03 06 November 2015
VISUAL COMPARISON OF RANDOM-DOT PATTERNS : EVIDENCE CONCERNING A FIXED VISUAL ASSOCIATION BETWEEN FEATURES AND FEATURE-RELATIONS* DAVID H. FOSTER Department of Communication and Neuroscience, University of Keele, Staflordshire, ST5 5BG, U.K. Subjects made Same-Different judgements on pairs of briefly presented randomdot patterns: they had to judge in separate experiments either whether the members of each pair were identical in shape or whether the number of dots in each pattern was the same. When one pattern was the rotated version of the other, the proportion of Same responses varied with the angle of rotation in the same way for the two types of judgement. From these and other data obtained with pattern pairs in which members differed in shape and in dot-number, the following inferences are made. First, in making both kinds of Same judgements, a fixed visual association is established between local features (dot-clusters within the pattern) and certain spatial relations between these local features. Thus when spatial-relation information is in principle irrelevant to the pattern-comparison task, as in judgements of dot-number, this information is not separated from the relevant local-feature information in the pattern representation. Second, in bcth tasks, a common description of the patterns in terms of local features and feature-relations is used in making a Same judgement. Third, some shape discrimination independent of orientation and some dot-number discrimination independent of shape are each the result of the process mediating Different decisions.
Introduction Sutherland (1968, 1973) has put forward a theory of visual pattern recognition based on structural descriptions, that is, representations which specify local pattern features and spatial relations between local pattern features. Typical local features might be edges, bars, and curves; typical feature-relations might be “left of”, “above”, and “joined to”. Such a scheme may be contrasted with a simple classificatory approach, where local or global features are specified but not interrelated, or with a template matching procedure in which the whole pattern is subjected to certain normalizing transformations before a match is made (see Neisser, 1967, and Sutherland, 1973).
* The experiments described here were carried out while the author was in the Department of Physics, Imperial College of Science and Technology, London. The results of a preliminary analysis of part of the experimental data were reported in a previous paper (Foster, 1977). 003 3-55 5x/78/040637
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$02 .oo/o
@ I978 The Experimental Psychology Society
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Downloaded by [Chinese University of Hong Kong] at 04:03 06 November 2015
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D. H. FOSTER
Although there exists a body of data concerning the probable form of local features selected by the visual system, little appears to be known about the encoding of feature-relations (Barlow, Narasimhan and Rosenfeld, 1972; Sutherland, I 973), and, in particular, about the nature of the association of relations with local features and the extent to which relations may be suppressed or "switched-off" within the internal representation. It is certainly possible to discriminate patterns on the basis of local features alone (Neisser, 1964), but some authors (Bamber, 1969; Nickerson, 1972) have suggested that Same-Different judgements are determined by two distinct processes, a Different decision being the result of a comparison of individual features, and a Same decision being the result of a comparison of the patterns as wholes. In the present study, we analyse the association between relations and local features by examining how Same responses are affected by changes in the relational structure of stimulus patterns. Before the principle of the experiment is explained, the description of the internal representation and comparison operation is made more precise. Consider two patterns A and B which are to be visually compared. Suppose that they have respective internal representations R and S of the following form:
The elements fiand gi are the local features and the sequences (Y:, Y,: . . ,, Y?) and ( s f , s;, . . . , sy) are the relations which connect the f, and g , to other local features f, and g,, j # i, in A and B respectively. These representations are not necessarily unique (Sutherland, 1973), nor complete in the sense that all the information in the patterns A and B is contained in R and S. The scheme is adequate, however, for the present purposes. For the patterns A and B to be judged as being the same, it might be supposed that their representations R and S should coincide exactly, that is, after a possible re-ordering, f
ISSN: 0033-555X (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/pqje19
Visual comparison of random-dot patterns: Evidence concerning a fixed visual association between features and feature-relations David H. Foster To cite this article: David H. Foster (1978) Visual comparison of random-dot patterns: Evidence concerning a fixed visual association between features and feature-relations, Quarterly Journal of Experimental Psychology, 30:4, 637-654, DOI: 10.1080/14640747808400690 To link to this article: http://dx.doi.org/10.1080/14640747808400690
Published online: 29 May 2007.
Submit your article to this journal
Article views: 17
View related articles
Citing articles: 7 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=pqje19 Download by: [Chinese University of Hong Kong]
Date: 06 November 2015, At: 04:03
Quarterly Journal of Experimental Psycliology (1978) 30, 637-654
Downloaded by [Chinese University of Hong Kong] at 04:03 06 November 2015
VISUAL COMPARISON OF RANDOM-DOT PATTERNS : EVIDENCE CONCERNING A FIXED VISUAL ASSOCIATION BETWEEN FEATURES AND FEATURE-RELATIONS* DAVID H. FOSTER Department of Communication and Neuroscience, University of Keele, Staflordshire, ST5 5BG, U.K. Subjects made Same-Different judgements on pairs of briefly presented randomdot patterns: they had to judge in separate experiments either whether the members of each pair were identical in shape or whether the number of dots in each pattern was the same. When one pattern was the rotated version of the other, the proportion of Same responses varied with the angle of rotation in the same way for the two types of judgement. From these and other data obtained with pattern pairs in which members differed in shape and in dot-number, the following inferences are made. First, in making both kinds of Same judgements, a fixed visual association is established between local features (dot-clusters within the pattern) and certain spatial relations between these local features. Thus when spatial-relation information is in principle irrelevant to the pattern-comparison task, as in judgements of dot-number, this information is not separated from the relevant local-feature information in the pattern representation. Second, in bcth tasks, a common description of the patterns in terms of local features and feature-relations is used in making a Same judgement. Third, some shape discrimination independent of orientation and some dot-number discrimination independent of shape are each the result of the process mediating Different decisions.
Introduction Sutherland (1968, 1973) has put forward a theory of visual pattern recognition based on structural descriptions, that is, representations which specify local pattern features and spatial relations between local pattern features. Typical local features might be edges, bars, and curves; typical feature-relations might be “left of”, “above”, and “joined to”. Such a scheme may be contrasted with a simple classificatory approach, where local or global features are specified but not interrelated, or with a template matching procedure in which the whole pattern is subjected to certain normalizing transformations before a match is made (see Neisser, 1967, and Sutherland, 1973).
* The experiments described here were carried out while the author was in the Department of Physics, Imperial College of Science and Technology, London. The results of a preliminary analysis of part of the experimental data were reported in a previous paper (Foster, 1977). 003 3-55 5x/78/040637
+ I8
$02 .oo/o
@ I978 The Experimental Psychology Society
637
Downloaded by [Chinese University of Hong Kong] at 04:03 06 November 2015
638
D. H. FOSTER
Although there exists a body of data concerning the probable form of local features selected by the visual system, little appears to be known about the encoding of feature-relations (Barlow, Narasimhan and Rosenfeld, 1972; Sutherland, I 973), and, in particular, about the nature of the association of relations with local features and the extent to which relations may be suppressed or "switched-off" within the internal representation. It is certainly possible to discriminate patterns on the basis of local features alone (Neisser, 1964), but some authors (Bamber, 1969; Nickerson, 1972) have suggested that Same-Different judgements are determined by two distinct processes, a Different decision being the result of a comparison of individual features, and a Same decision being the result of a comparison of the patterns as wholes. In the present study, we analyse the association between relations and local features by examining how Same responses are affected by changes in the relational structure of stimulus patterns. Before the principle of the experiment is explained, the description of the internal representation and comparison operation is made more precise. Consider two patterns A and B which are to be visually compared. Suppose that they have respective internal representations R and S of the following form:
The elements fiand gi are the local features and the sequences (Y:, Y,: . . ,, Y?) and ( s f , s;, . . . , sy) are the relations which connect the f, and g , to other local features f, and g,, j # i, in A and B respectively. These representations are not necessarily unique (Sutherland, 1973), nor complete in the sense that all the information in the patterns A and B is contained in R and S. The scheme is adequate, however, for the present purposes. For the patterns A and B to be judged as being the same, it might be supposed that their representations R and S should coincide exactly, that is, after a possible re-ordering, f
