Introduction

In addition to being comprehensible, a graphical symbol should have sufficient perceptual quality to enable the eventual user population in a practical situation to identify its elements correctly. If the symbol's ultimate meaning is to be understood, it is essential that its elements be identifiable. As an example to clarify this concept of identifiability, consider Figure 1. A person who sees this “lost and found” symbol should be able to report that the symbol consists of a question mark, a glove and an umbrella. If, for example, the glove is seen as a hand, the symbol's identifiability is insufficient. On the other hand, the umbrella would be correctly identified by the description “triangle apex down with a curved line at the top”. Stated more generally, an element is considered to be identified correctly, if either an accurate, shape-wise description is given, or the object intended to be depicted is named.

Figure 1 — Graphical symbol for the referent “lost and found” or “lost property”

For designers of graphical symbols, ISO provides guidelines and requirements to support the realization of optimal perceptual quality, such as ISO 22727 and ISO 3864‑3.

However, applying requirements and criteria can never guarantee an optimal design outcome. There may be times when there is a need to examine empirically key aspects of proposed graphical symbols. Such a need may arise, for example, during initial design in order to determine how elements within a symbol are identified when the symbol subtends a small visual angle (due to small symbol size and/or large viewing distance), or after comprehension testing has shown there to be difficulties in interpreting a symbol and it is desired to scrutinize the elements making up the symbol as an aid in generating improvements. This part of ISO 9186 describes a test method for assessing the identifiability of symbol elements. The core of this test method is to show a symbol to appropriately representative respondents and have them describe what they see. The respondents' task is to name the elements of the symbol's image content. This procedure will assist in locating those elements within a symbol that may be the source of difficulty.

BS ISO 9186-2:2008

Graphical symbols. Test methods - Method for testing perceptual quality

Current

Published:

31 Jul 2009