These findings in conjunction with the results of other researchers suggest that context and task both may influence the features used in discriminating symbols. However in the visual search task, participants appeared to use other dimensions such as vertical height and symmetry in discriminating the symbols. The results of the multidimensional scaling analysis suggested that, in the similarity rating task, participants differentiated the symbols primarily on their overall geometric shape. However in some cases, symbols rated as similar proved highly discriminable. Based on the correlation analysis, subjective assessment can predict when two symbols will be highly discriminable. The results were submitted to correlation analysis and multidimensional scaling (MDS) analysis to examine the relationship between the similarity ratings and the visual search task. The discriminability of these shapes was then examined in a visual search task where participants enumerated the number of occurrences of a particular target shape found in a display of distractors. Suggestions are made for additional research that would evaluate the relevance of these two factors more thoroughly.ДЈ ABSTRACT Participants rated the similarity of 90 pairs of symbols based upon ten geometric shapes. The results of the MDS analysis suggested that, in the similarity rating task, participants differentiated the symbols primarily on their overall geometric shape. However in some cases, symbols rated as similar proved highly discriminable in the search task. The results were submitted to correlation and multidimensional scaling (MDS) analysis to examine the relationship between the similarity ratings and the visual search task. Discriminability of these shapes was then examined using a visual search task where participants enumerated the number of occurrences of a particular target shape found in a display of distractors. Participants rated the similarity of ten geometric shapes using a pairedcomparison task. The former task is similar to the process used by a designer in selecting symbols while the latter is an important component of the actual tasks that an user carries out in locating information on a display. It compared the characteristics used in assessing the similarities of a set of symbols in a rating task with those used in picking out symbols in a visual search task. The study reported in this paper addressed this problem. If this is the case, it is important to understand how different conditions and tasks influence the perceptibility and discriminability of symbols. Some of this variability could be due to the wide range of conditions and methodologies used across studies. However, the critical dimensions often vary from study to study. Studies on symbol discrimination usually find that discrimination is a function of the number and kinds of dimensions along which the symbols vary.

To ensure that decisions are made with speed and accuracy, it is important for the symbols in such systems to be discriminated consistently and reliably.

Box Sheppard Avenue West North York, Ontario M3M 3B9 HER MAJESTY THE QUEEN IN RIGHT OF CANADA (1997) as represented by the Minister of National Defence SA MAJESTE LA REINE EN DROIT DU CANADA (1997)- Defense Nationale Canada DEPARTMENT OF NATIONAL DEFENCE - CANADA [DTK QUALITY INSPECTED S'Дў EXECUTIVE SUMMARY The increase in the complexity of computer-based graphical information systems has resulted in a requirement for large symbol sets. 1 December 1997 DCIEM No.97-R-61 MEASURES OF THE DISCRIMINABILITY OF SYMBOL SHAPES Sharon McFadden Ben Bauer Kelly McManus AfipioTsd tax gubiic isiaaml Dtobuaoo ГјnГјastsd Defence and Civil Institute of Environmental Medicine P.O.

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