Possessive nouns

The apostrophe

We use an apostrophe to show possession, but the position of the apostrophe depends on whether the noun that possesses something is singular or plural:

singular = noun + apostrophe ‘s’ = ’s:

• a driver’s behaviour

plural = noun + plural ‘s’ + apostrophe = s’:

• drivers’ behaviour

Note that irregular plurals have an apostrophe ‘s’ after the plural ending:

• a child’s development
• children’s development

Possessive nouns vs. modifying nouns

One of the most common errors we find in writing happens when a noun should be used as a modifier rather than a possessive. When using a noun to modify another noun, there is no plural or possessive marker, as the noun is behaving like an adjective (i.e. we could replace 'driver' and 'child', respectively, with words like 'disruptive' and 'early': 'disruptive behaviour', 'early development'):

• driver behaviour
• child development

Incorrect

(1a) In this study, we examine typical driver’s behaviour.

(1b) In this study, we examine typical drivers behaviour.

Correct

(1c) In this study, we examine typical driver behaviour.

Incorrect

(2a) Child’s development involves the biological, psychological and emotional changes that occur in human beings between birth and the end of adolescence.

(2b) Children development involves the biological, psychological and emotional changes that occur in human beings between birth and the end of adolescence.

Correct

(2c) Child development involves the biological, psychological and emotional changes that occur in human beings between birth and the end of adolescence. 

Possessive 's' or 'of' structure

Possession in English can be indicated using either the possessive ‘s’ or an 'of' structure:

• the driver’s behaviour
• the behaviour of the driver

Often, there is a free choice between these forms, with no significant difference in meaning or focus. However, the concept of end-focus often comes into play. This relates to the principle in English that important information often comes later in a phrase, clause or sentence, where it has more focus.

• the driver’s behaviour (focus on 'behaviour')
• the behaviour of the driver (focus on 'the driver')

There is also the principle of end-weight in English, which relates to the positioning of longer phrases last in a sequence. In fact, it can sound awkward if a long possessive comes before a noun, as illustrated in the examples (3a) and (3b) (the noun phrase is in bold):

Problematic

(3a) the driver who was being observed’s behaviour

Better

(3b) the behaviour of the driver who was being observed