Why does for some words the context of usage change? Often we can identify phases of intensive context changes in which clues to possible causes can be found. Examples of such phases are:
- controversial discussions in which the proponents or opponents of a position use central words in completely different contexts;
- punctual events such as natural disasters, historical events or technological changes, in which not only new words are introduced but at the same time old words are used in new contexts;
- cyclical events such as „Olympia“, in which the location of the event and the names of the actors acting or affected change in a time cycle determined by the event.
For the recognition of context changes, the lecture introduces the measure of context volatility. This makes it possible to quantify the rates of context change of words in a diachronic corpus over a given period of time and to identify exploratively those words whose context of use has changed conspicuously over this period. Normalising the rate of change, words of different frequency classes can also be compared with each other. Compared to the pure frequency analysis, low-frequency words can thus also be included in the analysis, for example, for the detection of weak signals, which are often indicated by early changes in the context of usage of low-frequency words. In addition to the highly volatile words, words whose contexts of usage change little over a longer period of time can also be identified, for example, because they are part of a formulaic language in a technical or legal context, or because they represent a political or social consensus in the period under consideration.