Commutation test  In semiotics, the commutation test is used to analyze a signifying system. The test identifies signifiers as well as their signifieds, value and significance. This test is a metalingual subjective system for analysing textual or other material. It has evolved from a limited method for investigating the structure of individual signs (per Roman Jakobson). Its primary uses are to:  The initial assumption is that the communication to be analysed represents both a cognitive use of the sign system and a statement that refers to the values of the addresser. The purpose of the test is therefore to illuminate the addresser's intention in using the code in this particular way. It works through a process of substitution, assessing the extent to which a change in the signifier leads to a change in the signified. The first step, therefore, is to exclude one signifier from the material to be analysed. This is a test of redundancy: to identify what meaning is lost (if any) by omitting that sign. It will be relatively unusual to find that one sign is completely superfluous, but more common to find that the contribution of the one sign to the whole meaning is relatively weak. The weakness or strength of its contribution can be calibrated more exactly by placing alternate (synonymous and antonymous) signs in the context. This will enable the analyst to make a judgment on the distinctiveness of the particular signifier chosen by the author/artist and of its value to the meaning, i.e. as more or less necessary for maintaining the meaning and/or rule structure in different occurrences. By changing the collocation between two of the existing signifiers, and so changing their original relationship, the relative significance of each signifier can be considered. Further, by also placing the original sign into different contexts, it can be seen whether the sign becomes more or less distinctive. The nature of the process will be determined by the form of the media to be analysed. In textual or pictorial media where individuals are the theme of the content, this might involve a substitution of words that are synonymous, or of imagery parallel in classes representing age, gender, ethnicity, religion, ability, etc. to assess the extent to which overall meaning is affected. In visual media generally, substituting different mise en scènes or backgrounds may change the significance of objects or people in the foreground. Colour selections may affect the perceived attractiveness of the scene or of individuals whose clothing is changed. The presence or absence of branded or generic goods, of stylish or outmoded clothing, etc. may help to suggest the contribution of the original signifier.