Complexity drives speech sound development: Evidence from artificial language training

Traditionally, learning is assumed to take place with exposure to simpler elements first followed by exposure to elements with increasing levels of difficulty. Recent reports suggest that exposure to complex elements leads to more widespread changes. However, whether learning via exposure to complex or to simple elements is more beneficial is a matter of ongoing debate. In the current study, using behavioral and electrophysiological measures, we aimed at understanding this by comparing subjects trained with complex speech sounds with those trained with simple speech sounds in a 5-day pseudoword-picture training paradigm. We found that though the subjects learned both complex and simple speech sounds to similar degrees, subjects who were trained with complex stimuli demonstrated more generalizations to novel complex and simple stimuli, whereas those trained with simple stimuli exhibited generalization only to simple but not to complex stimuli (Experiment 1). Along with behavioral measures, using mismatch negativity, we found that training with complex stimuli can lead to more extensive neural changes for both complex and simple stimuli as compared with training with simple stimuli (Experiment 2). In artificial language learning, learning with complex stimuli appears to be more effective than training with simple stimuli as far as generalization is concerned.