This section discusses a second type of verb frame alternation that involves the external argument of verbs, and which is normally referred to as middle formation. The middle is one of the three voices that are typically found in the Indo-European language family: active, middle and passive. Whereas passivization involves the demotion of the external argument to adjunct status, middle formation involves the complete removal of the external argument from the verb frame, as is clear from the impossibility of adding an agentive door-phrase to the middle construction in (145).

Middles are further characterized by a lack of specific time reference, in the sense that the constructions refer to an individual-level property of their subject, and by the fact that they contain some evaluative modifier like gemakkelijk'easily'. Middle formation can be divided into four main types: regular, adjunct, impersonal and complex reflexive middles; cf. Ackema & Schoorlemmer (2006). Section 3.2.2.1 will begin by briefly characterizing these four subtypes and specify a number of properties they all share. Sections 3.2.2.2 to 3.2.2.5 will discuss the four main types in more detail.