Inside SFU's Phonological Processing Lab

by Jonathan Waldie - Cognitive Science Major

Doctor Ashley Farris-Trimble’s Phonological Processing lab at SFU is focused on experimental phonology, and is doing important exploratory research on the connection between phonological theories and human cognition. According to Professor Farris-Trimble, phonological analysis is analogous to looking at language data and thinking of it like a puzzle. This approach helps researchers to understand the underlying phonological forms of a language, and how these forms relate to the phonetic variations that come out in speech. “We’ve made a lot of progress in this theoretical idea of the abstract becoming concrete,” Dr. Farris-Trimble explained.

Dr. Farris-Trimble began researching and teaching linguistics at SFU in May of 2013, after completing her Post Doctorate at the University of Iowa, where she worked in a psychology lab. Her work there involved looking at language processing by working with people with cochlear implants—this experience kindled her interest in connecting phonology with cognition, and helped inspire the projects that are on-going in her present-day lab at SFU.

One of the major on-going projects in the Phonological Processing lab concerns the linguistic phenomenon of Canadian Raising, which is a process where a low vowel is raised to a mid vowel in a particular context. The height of a vowel (low, mid or high) represents where the tongue is in the mouth when that vowel is produced. Phonological theory suggests that all Canadians share the same underlying representation of the vowel—this is the low vowel sound. However, some Canadians have a phonological rule that instructs them to raise this vowel resulting in a different sound actually being produced for speech—the mid vowel. This is the process responsible for the infamous way some Canadians and northern Americans pronounce the word “about”.

Using data gathered from this project, Dr. Farris-Trimble is exploring the nature of phonological theories in relation to real-life language use. Artificial models and even computer simulations that only mimic the behaviour we see in humans may not be conducive to building relevant theoretical models of cognition. “When we have phonological processes, does the listener know that those things are happening and use them to figure out what words they are hearing? Or do we only use what’s on the surface, and this idea of having something more abstract is not happens in real life?” she asks.

Professor Farris-Trimble is using eye tracking techniques to put these phonological theories to the test. She uses a particular implementation of eye tracking known as Eye Tracking in a Visual World Paradigm. “The Visual World Paradigm is the specific idea of giving people a variety of things to look at that all have some relationship to one another and measuring the timing of when they look at things relative to the timing of what they are hearing," she explains.

In lexical activation there is the theory that as people process incoming words they begin activating all the words that match with the signal as processed so far until the end of the word is reached and you have ruled out all the lexical items in your cognitive inventory that do not match. Generally, this leaves the listener with the one lexical item that most closely resembles the word as processed in its entirety. Before coming to SFU, Dr. Farris-Trimble published an article with her colleague Bob McMurray at the University of Iowa on the reliability of Eye Tracking in the Visual World Paradigm. You can see the full article here if you have SFU library access, or a summary here if you do not.

During the testing process, participants sit in front of a computer outfitted with eye tracking technology, and observe four images on the screen. Each image has an associated word, and these words are related to each other phonologically. The researchers play an audio clip corresponding to one of the pictures and the participants click on the matching picture. As an example: on the screen there might be pictures portraying bible, biking, and biting, along with an unrelated filler word like hammer. For speakers who use Canadian Raising, biking and biting are similar in pronunciation in that they have raised vowels (unlike bible). This is notable in comparison to phonological theory predicting that all three words have the same vowel underlyingly. The goal of the eye-tracking task, then, is to determine which words a listener activates upon hearing different types of vowels. For example, the researchers might play an audio clip of the word "bible" for the participant and track whether the participant looks at "biking", which is an underlying match but not a surface match.

This helps Dr. Farris-Trimble and her research assistants determine whether listeners are making decisions based on surface representations, or if they are working backwards to the underlying vowel which is the same for all the words. "It turns out the second prediction is a little bit more true, or at least that is what our preliminary results seem to suggest," Dr. Farris-Trimble noted, although she stressed that these results are preliminary and are still in the process of being tested and analyzed. Should her final results confirm this, phonological theory will have experimental data backing it up.

Dr. Farris-Trimble offered additional data that suggests these processes are actually taking place: “we hypothesize that a word that undergoes the application of multiple phonological rules will be processed more slowly than a word that undergoes fewer or no rules”. This is similar to the work done on mental rotation tasks by Shepard & Metzler (1971), who found that the time required for mental processing of an object was positively correlated with the degree of rotation.  For phonology, the variable length of processing words suggest that we are working backwards towards an underlying representation.

This is just some of the work being done by Dr. Farris-Trimble and her team and it will assuredly have interesting ramifications for linguistics and the cognitive sciences as they try to determine what is actually going in our minds when we use language. It is of great benefit to SFU to have Dr. Ashley Farris-Trimble conducting her research here. If you are interested in assisting in this foundational research, Dr. Farris-Trimble told us you can approach her at the end of the semester as other students are moving on, and inquire about becoming a research assistant. Learn more about the Phonological Processing Lab here.

More information on Canadian Raising can be found here.

Shepard, R., & Metzler, J. (1971). Mental Rotation Of Three-Dimensional Objects. Science, 701-703.