Although throughout history many cultures have spread the myth that bilingualism has negative effects at the psychological level , scientific research in recent decades clearly indicates that in reality the mastery of more than one language has positive consequences.

In this article we will describe the relationship of multilingualism with intelligence, personality and creativity . As we shall see, speaking more than one language produces changes at a mental level mainly through the improvement of cognitive flexibility and abstract reasoning.

Defining Bilingualism and Multilingualism

A person is said to be multilingual when he or she can communicate naturally in more than one language, especially if he or she has acquired the skills at an early age. When someone masters two languages we talk about bilingualism , those who know three languages are trilingual, and so on.

There is debate about the degree of proficiency required to be considered multilingual. Many experts narrow the definition to the ability to be reasonably fluent in a second language, while others consider that a strong knowledge of at least two languages is required.

For a long time there have existed prejudices regarding the psychological effects of bilingualism in traditionally monolingual cultures; bilingual people were attributed with lower intelligence, less mastery of languages and moral and characteristic alterations.

The first research on multilingualism confirmed this kind of perspective, although it had serious methodological problems that invalidated its results. Stricter studies carried out later not only refuted these hypotheses but also showed that bilingualism can have beneficial effects on cognition .

However, it should be borne in mind that many of these benefits are rather the consequence of multiculturalism, a natural outcome of learning several languages. Knowing more than one language facilitates familiarity with different perspectives and improves abstract thinking, since multilingualism requires complex conceptual reasoning .

Types of bilingualism

Cummins made a proposal that is known as the “threshold hypothesis”. According to this author, bilingualism can have positive or negative effects depending on the degree of competence in the languages and different psychosocial variables, such as the prestige of both languages.

Thus, Cummins stated that bilingual people who do not reach a minimum threshold in both languages may suffer negative effects; in these cases we would speak of subtractive bilingualism. Subsequent research has suggested that bilingual persons with low language proficiency may be slightly disadvantaged in arithmetic.

On the other hand, when the upper threshold of linguistic competence is exceeded, additive bilingualism is produced , which has a positive influence on cognition , as we will see below. These effects are more intense the greater the mastery of the languages.

Multilingualism, Cognition and Intelligence

The research reveals that the cognitive structure of bilingual people is different from that of monolingual people. Specifically, IQ is explained by a greater number of factors; this means that cognitive skills are more diversified in those who learn more than one language during their development.

In addition, multilingualism has been associated with greater cognitive flexibility. This means that bilingual people tend to have more ability to find alternative solutions to problems and to choose the best option from those available.

On the other hand, as we have already mentioned, multilingualism favours the development of abstract reasoning and the handling of concepts. This has been attributed to a greater awareness of the fact that words do not designate absolute realities but have an important arbitrary component.

Consequently, multilinguals would have a greater capacity to focus on structures rather than on the elements that make them up, as well as to reorganize them. This includes a verbal dimension but also involves perception.

Influence on personality

Many multilingual people report that their personality changes depending on the language they use; these changes have been confirmed by some studies. However, they are generally attributed to the adoption of a different contextual framework depending on the culture to which each language is associated, which would be independent of the language used.

However the hypotheses of linguistic relativity state that language influences the way we think and feel. Thus, the learning of more than one language could facilitate the development of different facets of the personality. Furthermore, it is believed that speaking in the second language makes many bilinguals leave aside social conventions.

On the other hand, the social context can influence personality and psychological well-being through the attitude towards bilingualism. For example, Latin American children may be looked down upon in the United States because they speak a different language; such situations also interfere with normal language learning.

Relationship with creativity

The beneficial effects of bilingualism on creativity are associated with cognitive flexibility . The ability to adopt different perspectives and reorganise mental content produces clear improvements in creativity, especially in people who have a high command of more than one language

J. P. Guilford described two types of reasoning: convergent and divergent. While convergent thinking is sequential (moves “in a straight line”), divergent reasoning explores multiple alternatives more spontaneously and is based on the relationships between the whole and its component elements.

The concept of divergent reasoning is very close to that of creativity . The measures of cognitive fluency, flexibility and originality, which Guilford defined as the central skills of divergent reasoning and the creative process, have been shown to be consistently higher on average in multilingual than in monolingual people.