In our lab, we use a number of experimental techniques that are able to capture the processing of written text as it unfolds. We have done extensive work using eye-tracking methodology, monitoring the eye movements of readers as they engage in normal silent reading. We also use other measures such as lexical decision tasks, naming tasks, semantic categorization tasks, masked priming tasks, and self-paced reading tasks. Each of these measures gives us a fascinating picture of the mental processes involved during reading. For example, the amount of time that people spend fixating on a word provides us with an index of the degree of processing difficulty on that word.
Now, consider the differences in the eye-movement record following brain damage. The example below is from a patient with Pure Alexia who suffered from a stroke which caused damage to Visual Word Form Area (VWFA), an area located in the left occipitotemporal region of his brain. Our research suggests that damage to this area causes difficulty in processing multiple letters in parallel, resulting in a letter-by-letter reading strategy.