interpreted to mean that individuals who speak multiple languages have a broader, more diverse view of the world, even when speaking only one language at a time. Some bilinguals feel that their personality changes depending on which language they are speaking; thus multilingualism is said to create multiple personalities. Xiao-lei Wang states in her book Growing up with Three Languages: Birth to Eleven: "Languages used by speakers with one or more than one language are used not just to represent a unitary self, but to enact different kinds of selves, and different linguistic contexts create different kinds of self-expression and experiences for the same person." However, there has been little rigorous research done on this topic and it is difficult to define "personality" in this context. François Grosjean wrote: "What is seen as a change in personality is most probably simply a shift in attitudes and behaviors that correspond to a shift in situation or context, independent of language." However, the Sapir-Whorf hypothesis, which states that a language shapes our vision of the world, may suggest that a language learned by a grown-up may have much fewer emotional connotations and therefore allow a more serene discussion than a language learned by a child and to that respect more or less bound to a child's perception of the world. A 2013 study found that rather than an emotion-based explanation, switching into the second language seems to exempt bilinguals from the social norms and constraints such as political correctness. Hyperpolyglots While many polyglots know up to six languages, the number drops off sharply past this point. People who speak many more than this—Michael Erard suggests eleven or more—are sometimes classed as hyperpolyglots. Giuseppe Caspar Mezzofanti, for example, was an Italian priest reputed to have spoken anywhere from 30 to 72 languages. The causes of advanced language aptitude are still under research; one theory suggests that a spike in a baby's testosterone levels while in the uterus can increase brain asymmetry, which may relate to music and language ability, among other effects. While the term savant generally refers to an individual with a natural or innate talent for a particular field, people diagnosed with savant syndrome are typically individuals with significant mental disabilities who demonstrate profound and prodigious capacities or abilities far in excess of what would be considered normal, occasionally including the capacity for languages. The condition is associated with an increased