Table 1.

Overview of the stages of word meaning structure (WMS) and the development in executive functioning (EF) and theory of mind (ToM) that they allow for.

WMS stages					WMS in EF	WMS in ToM
	Age	Referent	What can be described	Example: “whale”
Syncretic concepts	From 1 year old	Relation to referent is not fixed in any way, the referent can change depending on the context.	Aspects of the world can be labeled.	“Whale” may refer to a whale, one of its properties (e.g., a whale cry) or its context (the sea).	Labeling stimuli and representing them in working memory in the absence of their referent.	Verbally labeling emotions in the body, and facial expressions in others.
Object concepts	From 1.5 years old	Objects and object-specific properties. Objects are usually defined by their shape.	Properties can be verbally attributed to objects.	“Whale” refers to the shape of a whale.	Specific labeling and representation of (absent) objects and their properties.	Attributing emotions to specific agents.
Everyday concepts	From 3 years old	Objects, object-specific properties, and relations between objects (i.e., situations).	All aspects of the sensory world, as well as non-sensory aspects and fantasy worlds (understood in concrete, everyday terms).	“Whales are big and they swim in the sea.”	Representing verbal plans consisting of several consecutive steps that span into the far future.	Perspective taking; passing false belief tasks; attributing cognitive states, understood in a concrete, everyday manner.
Logical concepts	From 7 years old	Sharp linguistically defined categories based on necessary and sufficient attributes, or other (subordinate) words.	Coherent and logical understanding of the sensory and non-sensory world.	“A ‘whale’ is a mammal, because female whales have mammary glands.”	Creating precise and coherent verbal plans based on an accurate understanding of the non-sensory world	Coherent and potentially accurate understanding of mental states and underlying processes.
Systemic concepts	From 12 years old (if ever)	Sharp linguistically defined categories that are defined explicitly in relation to each other, but one object may belong to multiple categories depending on the context.	Valid understanding of sensory and non-sensory world whereby premises of conclusions are consciously selected and justified.	It is understood that a whale can be categorized as either a mammal or a fish, depending on the definition.	Greater ability to contextualize plans to specific circumstances in the context of larger goals	Understanding mental states in the context of the mind as a whole system.

Word meaning development lays the basis for the corresponding EF and ToM development, but the latter may need more time to develop. The mammal example is based on Toomela (2003).