What do we mean by bilingualism?

Bilingualism is the ability to understand and/or use two or more languages.
The term therefore also includes multilingualism, referring to the knowledge and/or use of several different languages.

A bilingual individual does not necessarily have equal fluency in both languages.

Moreover, bilingual people are able to use one language over another depending on the context and purpose—for example, in family settings or at school. Therefore, a bilingual person may not have the same communication skills in both languages.

Bilingualism is not a disorder, and there is no scientific evidence that it causes or contributes to any language or communication difficulties.

Language is fundamental to a person’s identity, reflecting the culture connected to it. It is therefore essential to respect and value the multilingual identity of individuals.

L1 and L2

When we talk about bilingualism or multilingualism, we refer to L1 and L2.

  • L1: the primary language to which a person is exposed—often called the “mother tongue.”
  • L2: a second language, typically acquired later, most commonly through school or structured environments.

Some bilingual individuals learn two languages simultaneously from birth. Even in these cases, a perfect balance between the two languages is rare.

Types of Bilingualism and the “Silent Phase”

There are two main types of bilingualism:

  • Simultaneous bilingualism: when an individual is exposed to two or more languages from birth. This does not mean the exposure is equal across languages.
  • Sequential bilingualism: when the second language (L2) is acquired after initial exposure to the first language (L1). This typically happens in school settings when children begin to hear and use a different language than the one spoken at home.

The “silent phase” can occur when a child enters a school environment where the language spoken is different from their mother tongue.
During this phase, the child realizes their first language cannot be used to communicate and begins acquiring L2. This is a natural stage in second-language acquisition.

Scientific literature suggests that if this phase lasts more than one month after L2 exposure, a consultation with a specialist may be advisable.
However, other studies indicate that the silent phase can last up to six months or even a year. It’s important to follow professional guidance to best support communication development during this time.

The Effects of Bilingualism on the Brain

Being exposed to more than one language is a tremendous asset. Many studies have investigated how bilingualism affects cognitive and neural systems—with impressive results.

Research has found a strong correlation between bilingualism and effective cognitive control.
In bilingual individuals, both languages are activated at once (language co-activation). The constant need to manage attention between two languages and to select the correct one for the context and interlocutor (code-switching) strengthens executive control mechanisms.

Bilingual speakers tend to show:

  • Better ability to ignore irrelevant information
  • Enhanced concentration
  • Greater resistance to distraction

Neuroimaging techniques have also shown that learning and using more than one language throughout life stimulates areas of the brain involved in language processing and executive functions—resulting in increased volume and thickness in those regions.

Protection Against Cognitive Decline

When a second language is learned in adulthood, the brain’s ability to change (neuroplasticity) is more limited, meaning that learning may take more time and effort.

However, the benefits of bilingualism extend beyond childhood. A study by the University of York found that bilingualism enhances cognitive reserve, potentially delaying the onset of early Alzheimer’s symptoms.

These findings suggest that bilingualism may have a protective role against cognitive decline.

By Cecilia Brogi and Nicole Luciana Zocchi