Applying the Law of Comparative Judement to Target Signature Evaluation

The Law of Comparative Judgement LCJ is a psychophysical tool that can be used to scale complex phenomena that lack easily identified physical parameters. Target signatures represent such phenomena. In a demonstration exercise, a search difficulty value was found using the LCJ. These LCJ scale values were compared to search times and probabilities of detection from a search experiment run in the Netherlands. The scale values were not linearly related to search time and probability of detection, but correlated very well with the logarithm of mean search time r 0.936 and the cube of the number of correct responses r 0.954. A chi-squared goodness-of-fit test gave 94.6 confidence in the fit of the LCJ scale to the experimental data. While the LCJ results in a scale with no natural zero point and arbitrary units, this tool can be used to construct a standard scale This paper illustrates how a standard clutter scale might be constructed using the LCJ. The LCJ could be a valuable tool in target signature evaluation either when used in conjunction with scaling equations that permit conversion to familiar quantities such as mean search time and probability of detection, by providing relative search difficulty values, or by making possible a psychophysically meaningful clutter scale.