LENA is Listening – with informed consent, of course!
Updated: Feb 25
#Freshfromthelab: Dr Maria Crespo-Llado, who recently completed her PhD at Lancaster University, has been working at the CBCD for a little over a year. Dr Crespo-Llado works on the BRainImaging and Global Health (BRIGHT) project, which looks at the brain and behavioural development of 0 – to 24-month-old babies from the Gambia. (See past blog posts to learn more about the BRIGHT project!)
Dr Crespo-Llado presented data collected from a device called LENA, which stands for Language ENvironment Analysis. The LENA device looks a bit like a walkman, and it sits comfortably inside the pocket of a special LENA vest. Collecting data is remarkably simple —so simple, in fact, that a lot of the parents set it up without any help! They get a “LENA box” in the post with the device and the vest, they put it on their child, and hit “record.” LENA then records the auditory environment around the child for about 7 hours. Whatever the child hears, LENA also hears! Now for the magical part: LENA sorts sounds according to who produces them! It knows whether a sound is produced by the child wearing LENA, a nearby adult (e.g., mom or dad), a nearby child (e.g., brother or sister), or an artificial source (e.g., TV, radio). Dr Crespo-Llado can then upload the data from LENA to her computer and investigate what she wants to know.
Dr Crespo-Llado presented two studies to the CBCD audience. First, she wanted to know how well LENA actually works. I know I felt a bit sceptical when I heard about it’s supposed technological magic. In order to examine whether or not LENA actually does what it says it does, Dr Crespo-Llado and other researchers spent many, many hours hand-coding recordings from LENA. Basically, she took the automated categorisation described above, and checked it by hand. Using this method, she compared how well LENA categorised the speech compared to real people’s categorisations. So, how well does LENA actually do? Remarkably, it does really well! Dr Crespo-Llado found that the categorisation of sounds by LENA versus real-life researchers were incredibly similar. So, it seems that going forward we can trust that LENA will do its job well!
The second LENA investigated how differences in the child’s early language environment related to the child’s later development. Past research shows that babies who hear more language from adults are likely to develop more language skills when they are older (compared to babies who hear less language from adults). In order to investigate this, Dr Crespo-Llado compared LENA data from babies living in the Gambia versus those living in Cambridge. The attitude towards language exposure is very different between these two regions: in the Gambia, people tend to talk to their babies far less than in England. So, Dr Crespo-Llado predicted two things: 1) that the Gambian babies would receive less language input from adults than British babies, and 2) that babies who were spoken to less by adults would have poorer language skills when they got older.
Her findings revealed that, contrary to what she expected, the number of words that adults used with the babies was similar in the Gambia and Cambridge! However, there were some differences between the groups. An interesting analysis revealed that ‘turn-taking’ patterns differed between the Gambian and British infants. Turn-taking can be understood as instances when a child speaks and, within 5 seconds, is answered by an adult. In the older babies (24 months), the British babies experienced a lot more turn-taking than the Gambian infants did. Another analysis revealed that among the younger babies (18 months), both groups produced a similar number of vocalisations. However, at 24 months, the same babies suddenly differed dramatically by country. Specifically, the British infants suddenly produced far more words at 24 months than they did at 18 months (579 more words, to be exact). The Gambian infants showed a far subtler increase (326 more words at 24 months than 18 months).
Finally, it seems that the link between early language experience and later language achievement is more complicated than just “speaking to baby more is better than speaking to baby less.” Dr Crespo-Llado’s results showed that turn-taking might actually be more predictive of good language development than the number of words that adults use around baby. However, she’s still analysing this data! We’ll keep you posted about what she finds