Learning and Brain Plasticity
There is ongoing controversy regarding whether to emphasize instruction of the alphabetic principle (e.g. phonics) or instruction of whole words in the teaching of reading. We have addressed these issues by examining behavioral changes in adults when learning to read a novel orthography with teaching of the alphabetic principle (i.e. letter instruction) or teaching of whole words. We have shown that letter instruction results in greater between session gains, suggesting that this form of instruction engages procedural learning mechanisms. We have also shown that letter instruction results in greater alphabetic knowledge, but that whole word instruction results in greater sensitivity to larger orthographic units such as the rime. Indeed, whole word instruction may foster the acquisition of word specific representations but allow for less generalization. At least for alphabetic systems, it appears that a multi-method instructional approach is beneficial. Our studies have also revealed that learning depends on reading skill and phonological ability, highlighting the importance of considering pre-existing individual differences.
Our long-term goal is to use neuroimaging to predict which individuals will be most responsive to specific kinds of instruction, and determine whether learning can be enhanced through non-invasive brain stimulation. Our interest in the effect of method of instruction on reading acquisition has led us to series of studies examining neural changes when adult English speakers are learning Chinese characters. We have shown that learning related changes in occipito-parietal cortex are correlated with long-term retention of characters. In terms of enhancing learning, we have shown that stimulation to the left temporo-parietal cortex can increase reading fluency, particularly in low skill readers. Moreover, stimulation of the left temporo-parietal cortex can accelerate learning of a novel orthography. Our current studies examine whether the similarity of the first to second language influences the transition from hippocampal to cortical dependency.