By Matthew Warren

For decades, linguists have debated the extent to which language influences the way we think. While the more extreme theories that language determines what we can and can’t think about have fallen out of favour, there is still considerable evidence that the languages we speak shape the way we see the world in more subtle ways.

For instance, people are better at perceiving the difference between light and dark blue if they have dedicated words for those colours (like in Russian) than if they don’t (like in English). But it turns out it’s not just the words that we use: the way in which a language is structured – its syntax – is also important. In a recent study in Scientific Reports, Federica Amici and colleagues show that the word order of a language predicts how good its speakers are at remembering the first or last parts of a list.

The team conducted memory tasks with speakers of eight different languages around the world. Four of the languages were what’s known as right-branching – Ndonga, Khmer, Thai and Italian – and four were left-branching – Japanese, Korean, Khoekhoe and Sidaama. They included 24-30 speakers of each language, and tested them in their local area, with the help of a translator where necessary.

In a right-branching language, the most important part of a phrase, known as the “head”, comes first, followed by words that give more information about that word. So in the phrase “The tiger who came to tea”, the head ‘tiger’ is at the beginning of the sentence, followed by words that reveal more about him (i.e. that he came to tea).

A left-branching language is the opposite: the extra information comes first, and the head is at the end of the sentence. The same phrase in a left-branching language would be something like “who came to tea, the tiger”. (English is mainly right-branching, but has some left-branching tendencies: we put adjectives before the noun that they modify, as in “the hungry tiger”, rather than “the tiger hungry”).

In right-branching languages, the meaning of a sentence is clear from the start because the head is encountered immediately. But in left-branching languages, speakers need to keep a lot of information in mind before they get to the important part of the sentence that clarifies what it’s all about. So the researchers wondered whether speakers of left-branching languages would be generally better at remembering the early parts of lists of stimuli.

The participants completed three tests designed to tap into working memory, which involves holding information in mind while also processing other information – a key skill in language. For each test, they viewed a sequence of pictures (or some other visual sequence) while simultaneously completing a second distracting task like performing mental arithmetic or judging whether an image was symmetrical. At the end of each series they had to recall the sequence they’d seen in the correct order. These sequences varied across tests and included pictures of animals and objects, different numbers of blue circles, and red squares in a series of grids.

The team then compared how well the speakers of the two kinds of language remembered stimuli from the first and second halves of the sequences. As they predicted, left-branching speakers were better at recalling the first half of lists than right-branching speakers, and worse at recalling the second half.

The results show how the languages we speak can have fairly broad influences on cognition, say the authors. “Specific characteristics of a language appear to predict not only the way we perceive and conceptualize the world,” they write, “but also the way we process, store and retrieve information.”

The research also demonstrates how differences in culture and language can bias findings in psychology. For example, based almost entirely on Western participants, memory researchers have found that people tend to recall the first and last parts of lists better than the middle parts – phenomena referred to as the “primacy” and “recency” effects – which have long been considered a fundamental aspect of how memory works. It is clear from this new study that the language participants speak could have a significant impact on these kinds of results, potentially challenging whether human memory always works that way.

But for now, the study remains preliminary. The overall differences in memory between left- and right-branching languages appear fairly small, and the eight languages the authors studied are just a tiny fraction of the more than 7,000 spoken around the world. Whether the results will be replicated in a larger sample remains to be seen.

—The word order of languages predicts native speakers’ working memory

Matthew Warren (@MattbWarren) is Staff Writer at BPS Research Digest