When do children start to understand words such as “yesterday” and “tomorrow”?

By Xirui He [Original research by Tillman, Marghetis, Barner, & Srinivasan, 2017]

How much do children (age3 to 8) understand deictic time words in terms of deictic status, sequential order and remoteness?

To learn a language, children get their source of information from the events that the words refer to and the linguistic context in which the words appear. They make hypothesis about word meanings and verify if their hypothesis is correct. Deictic time words are more difficult for children to learn because these words are more abstract, and require more acquaintances to understand them. There are three facets of understanding deictic time words: deictic status, sequential order, and remoteness.

Deictic status is understanding yesterday as the past and tomorrow as the future. Sequential order is for example putting 10 days ago, 3 days ago, yesterday, now, tomorrow in the right order. Remoteness is the relative distance the words are represented, for example 10 days ago is farther than yesterday from now. Children start to produce deictic time words from an early age, although they might not use them correctly like adults. How much do children age 3 to 8 understand deictic time words and their deictic status, sequential order, and remoteness?

How was it addressed?

The researchers study children’s mental study of deictic time words by evaluating how they represent these words (such as yesterday and tomorrow) on a left-to-right timeline. The participants are children from age 3 to 8 with 16 children in each age category. The material that the researchers used were colored pencils and papers with horizontal timelines printed on it. The researchers asked children to indicate where on the timeline an event is associated with a specific time period.

After collecting all the data, the researchers did a four-step analysis. First, they assessed the children’s understanding of deictic status, sequential order, and temporal remoteness. Next, they determined the typical ages of acquisition of facets of meaning. Then, they calculated contingencies between adult-like knowledge of these facets of meaning. Lastly, they studied the connection between the children’s performance on the timeline task and their ability to answer non-spatial, verbal forced choice questions about deictic time words.

What did the researchers find?

The researchers found that the accuracy of the words’ deictic meaning increased by age. 7-year-old performance was very similar to adults. Knowledge of relative sequential order also increased with age. 8-year-old performance was like adults. Knowledge of temporal remoteness (relative distance from “now”) also improved gradually with age, but more slowly than deictic meaning and sequential order. 8-year-olds performed like adults.


By looking at the graphs showing the relationship between ages and accuracy, the researchers found that knowledge of deictic status and sequential order are highly linked, but not remoteness. Children’s performance on verbal questions showed that 7-year-old abilities were indistinguishable from adults. This suggests that the timeline task is a valid measure of semantic knowledge.

What does the finding mean? Why is it important?

The finds help us understand the developmental process in which deictic status, order and remoteness emerge in children, and how they acquire the knowledge. Their results show that temporal remoteness is developed independently and much later. Children understand deictic status and order before remoteness indicates that they initially draw on linguistic context to constrain their early hypothesis about word meanings. This is different from researchers’ hypothesis that children initially start to understand these words by event memories and make inference about meanings of deictic time words associated with those events.

Children start using deictic time words beginning at an early age, they have partial understanding of these words even though they use them in incorrect ways. There is a long delay between when they start using deictic time words and using them correctly.


Children’s understanding of ‘‘implications of ownership’’

By Dan Zhu [original research by Rossano, F., Rakoczy, H., & Tomasello, M., 2011]

If we take a teddy bear from a three-year-old, is she going to cry, screaming or allow me to take it away from her? How about if the teddy bear is not hers? We want to figure it out by conducting a series of research on Children’s understanding of ‘‘implications of ownership’’.

Each child was tested in three conditions, with two trials per condition. In each condition, a puppet performed actions on a target object, with the crucial difference between conditions being who owned the target object. The conditions were:

–Child: object owned by child.
–Third party: object owned by E2.
–Control: object owned by puppet herself.

The research had children directly involved in interactions involving property rights violations and they could respond potentially nonverbally, which opened the possibility that even 2-year-old children might show some understanding.

The children protested reasonably frequently when their own property was either taken from them or thrown away – several times more often than when anyone else’s property was similarly taken or thrown away.

The 2-year-olds appreciated that a third party’s property rights were being violated, but just did not care as much as they did about their own property. Most often when their own item of clothing was taken or thrown away, they still protested more often when a pup- pet took or threw away a third party’s clothing than when the puppet did this (legitimately) Young children’s emerging understanding of the normative dimension of property as it applies to all persons equally in an agent-neutral manner.

Now we see that two- to 3-year-old children were tested, as this is the age at which they show some normative awareness in the domain of game rules.