Principle of duality: expression of new meanings by rearranging linguistic units such as sounds or words. us at the sound level of language ; there are about 38 different sounds or signals in English. The word “not” consists of three individual sounds which, if placed in a different order, permit us to form the word “ton”. The same principle is involved in the production of sentences, as we can use the same words but produce different meanings by rearranging the words: “The dog chased the cat” vs. “The cat chased the dog”. The principle of duality as illustrated here is not inherent in animal languages.

Reference to abstract concepts: the ability to refer to abstract concepts, future and past situations, persons/objects not present

Nature of acquisition Intensionality: the purposes and intentions to which language can be used (Metalinguistic communication)