As mentioned in the first point made by Sinnemäki, it is vital to treat complexity and difficulty as two separate concepts. There are a few reasons as to why one should separate complexity and difficulty, as explained below:

• Description and operation are two separate tasks;

These two tasks can be done independently of one another. Native speakers are naturally able to talk fluently. They often do this without thinking about language description. To some degree however, description is possible without fluency. For example, it is possible for a new learner of a language to be able speak the language and yet make minimal mistakes, even without being fluent in the language.

• The problem of finding a user-type neutral definition for complexity (Miestamo, 2008:24-29);

Different user-types (eg. speakers, hearers, 1st language acquirer, 2nd language learner) may have experienced different linguistic patterns, hence varying degrees of difficulty of using and processing a particular language. This in turn, can cause conflicting results in measuring complexity. A more objective and theory-based perspective should therefore be adopted in approaching complexity to avoid conflicting results in the measurement of complexity.

• To avoid the problems in the evaluation measure of early generative grammar (Chomsky, 1965; Chomsky & Halle, 1968);

Researchers have long struggled with the evaluation measure of early generative grammar. This evaluation measure was used in child language acquisition as it was assumed that the framework that had a more brief description of the system would therefore allow a more accurate link to language acquisition. What researchers failed to realise was that “the shortest description was not necessarily the most plausible one psychologically” (Kiparsky 1968). It is thus important to separate complexity and difficulty in order to avoid the problems that were faced by researchers in the past.

• Possible to determine independently the processing responses of the different types of complexity (Hawkins, 2004 & 2009).

Separating complexity and difficulty could show the varying degrees of processing responses of the different types of complexities.