Science for Non-scientists

When we speak, we sometimes make errors. These mistakes can be embarrassing and haunt us for years. Where do speech errors really come from? Do they express our hidden desires and repressed wishes as Freud claimed? Do they tell us something about how our brains work?

It turns out that speech errors can tell us more about how people’s brains work than about what they secretly wish for. But don’t be disappointed. What they tell us about our brains is even more fascinating! In fact, some of the most comprehensive models of language production are based on data from speech errors.

When we type quickly, we also make errors. Often, we can correct these errors quickly, sometimes without even looking at our hands. We are also aware that we made an error. So which come comes first? Do we first become aware that we made an error and then correct it? Or do we correct an error and then become aware of it? The first possibility sounds more likely, but in fact, our studies show that people sometimes correct their errors without being aware of them. So, counterintuitively, your brain/body may correct a typing error before you even know it’s there.

When a child speaks, is he or she using the same or different mechanisms as adults? Children are not as proficient as adults in speaking. They make many more mistakes than adults. This may mean that their brains process language completely differently than adults. Or it may mean that they are simply using a less developed version of the adult language production system. Our lab creates fun games for children which elicit accidental slips of the tongue. By comparing these slips to those made by adult speakers, we can learn how similar or different the child and adult language production systems are.

When someone has a stroke, they sometimes have trouble speaking for years afterwards. What exactly is wrong? More importantly, how can it be fixed? Over the years, we and our colleagues have studied language production in stroke survivors extensively. Although each stroke survivor is unique, there are similarities among certain individuals which helps identify different kinds of problems. Some researchers and clinicians prefer clinical categories, such as Broca’s and Wernicke’s aphasia. We prefer to define the problem by investigating its origin.

• Some individuals have problems finding the right word.
• Some have the word, but have trouble finding the right sounds to produce the word.
• Some have the word and the sounds, but have too many other words in their head at the same time interfering with their ability to choose the right word.
• Some can get the right words, but can’t put them into sentences.

There are also individuals who have preserved communication ability in one modality but not another. For example, they can still speak, but can no longer write.

Each kind of problem stems from a specific deficit in a specific part of the language production system in the brain. So it’s important to understand the problem at the level of each individual. Our lab is committed to this approach, and always welcomes stroke survivors to join. Please see Information About Aphasia for more details.