Volunteers from the UCL Communication Clinic have been helping to tackle this question by taking part in Dr Vitor Zimmerer’s research.

One answer is that sentences with more complicated ‘grammar’ are more difficult. Another answer is that how often you hear or say a sentence is important. For example, the sentences “I don’t know” and “You don’t know” are equally complicated, but people use “I don’t know” much more often. Words in commonly used sentences are stored together as a ‘formula’ in the brain, and are less affected by brain injury such as a stroke.  Formulas are easier to say for many people with aphasia.

We all use formulas; they are a natural part of communication. But if you are limited to formulas, you will find it harder to talk about new situations that need less common or entirely new sentences.

Vitor’s research uses a computer program to calculate how much a person uses formulas. The future aim is to develop therapy that starts with these easier kinds of sentences, and then builds more and more flexibility in communicating.

If you are interested in taking part in research projects, please contact the clinic.