Information about ongoing research at the lab.

The Alberta Language Function Assessment Battery
Research by Chris Westbury & Signy Sheldon

     Aphasia is the name given to language deficits following brain damage, most commonly strokes. According to the Heart & Stroke Foundation of Alberta, approximately 1,100 Albertans become aphasic each year. These patients often face a frustrating existence with a reduced quality of life. One difficulty in helping them is that the symptoms of aphasia can vary widely because language comprehension and production are complex processes that rely on many different regions of the brain. Understanding the symptoms of aphasia has proven to be a difficult task, because of the complex relation between this multitude of identified language functions and the brain tissue underlying those functions. The relation between brain tissue and function is variable between individuals. This makes it problematic to study aphasia using a lesion-based approach, which first identifies the site of brain damage, and then infers what the problem is from that information. Most modern aphasia research instead focuses on a function-based approach to aphasia, which attempts to map the functional deficit directly by a careful assessment of the language system’s function.

Click the play button to view this animation which comes from the ALFAB. What is being tested here is the ability to produce a sentence using the verb "put" in combination with the objects in the movie in a particular order (the green element must come first in the sentence, the yellow second, and the red last).

     The Alberta Language Function Assessment Battery (ALFAB) is a computerized battery of tests relating to many different aspects of language function. It is computerized in order to enable us to test many different aspects of language at the same time. The results are scored by a computer program that can look for patterns of performance within tests and between tests. There are so many patterns that need to be considered that it would be very difficult for a human being to score the tests by hand.
      Most of the tests in the ALFAB look at single word access, which is surprisingly complex. Words can be produced and understood in different ways, through writing or speech. Since some aphasic patients have troubles with one form but not the other, we need to test both written and spoken words. Different kinds of words are stored in the brain in different places. We need to consider the difference between abstract nouns like ‘peace’ and concrete words like ‘dog’, as well as the difference between verbs like ‘eat’ and nouns like ‘cat’. Sometimes aphasic patients can read written words or repeat spoken words, but not understand what those words mean, so we need to test access to word meaning independently of access to word form (how the word looks or sounds). Words that are similar to many other words- as ‘cat’ is similar to ‘hat’, ‘bat’, ‘kit’, and ‘can’- are sometimes easier and sometimes more difficult to access than unusual words like ‘aphasia’. For this reason we need to carefully control for how similar words are to other words, and test different kinds of similarity. Some words are made up of smaller word-like pieces (called ‘morphemes’), as ‘running’ is formed from the words ‘run’ and the ending ‘ing’. Some aphasics have particular trouble with understanding or producing complex words that have more than one morpheme in them, so we have tests designed to examine this aspect of language.
      Of course words are also used together, in compound words such as ‘blackboard’ as well as in much more complex ways in sentences. Some of the tests in the ALFAB are designed to assess ability to create and understand written or spoken compound words and sentences.
       There are many other complexities in studying language. Because we are trying to test as many aspects of language as we can, we need to have many tests and occasionally many items in each test. Some of the tests ask you to look at or listen to words and make various kinds of decisions about them. Others ask to you to say or write the name of a pictured item or repeat a spoken word or read a written word. Still other ask you to speak or write sentences to describe short cartoons.
      The ultimate goal of this research is to build a large database of scores on all of the language tests. By analyzing this database, we hope to make discoveries about how language is organized in the brain, and how it can break down following brain damage.

To download the ALFAB (Mac and Windows versions available) please click here.

©2005  WestburyLab   chrisw at ualberta dot ca