An NSF-funded project led by Adrian Staub (PI) and Lisa Sanders (Co-PI) is investigating the question of exactly how a word's predictability in a sentence (e.g. It had started to rain, so the man opened his _______) influences how the word is processed.
“Developing effective methods for teaching reading, and effective interventions for reading difficulties and disabilities, requires an understanding of the cognitive processes involved in fluent reading. Recent research has suggested that skilled reading may be aided by our ability to predict upcoming words. Readers use their knowledge of their language and the world to anticipate or predict the words that they are likely to encounter; words that are correctly predicted are more easily recognized,” Staub and Sanders explain.
The researchers are using both eyetracking (tracking eye movement) and EEG (recording electrical activity of the brain) simultaneously to monitor human subjects as they read specially designed sentences onscreen. A word's predictability influences both how long the eyes spend on the word in normal reading, and an EEG response known as the N400. The N400 is a negative electrical potential, broadly distributed across the scalp, that peaks about 400 milliseconds after a word is encountered. Because this response is time-locked to the onset of a specific stimulus or event, it is known as an event-related potential (ERP).
ERPs such as the N400 are difficult to detect in raw EEG data because there are so many different forms of brain activity happening all at once. To detect the N400, the EEG on many trials must be added together; the background ‘noise’ is canceled out, leaving only the ‘signal’ of interest.
“A paradox that motivates the present research is that eye movements reflect a word's predictability only when the word can be pre-processed in peripheral vision, before it is directly inspected. In contrast, ERPs reflect a word's predictability even without such pre-processing. By achieving a better understanding of what these two methods are telling us, and the source of the differential effects, we hope to further our knowledge of the ways in which making unconscious predictions about upcoming words can benefit readers,” Staub and Sanders say.