Achievement

How abstract are the units of cognition? To recognize "cat", do we identify abstract speech segments /k/ /æ/ /t/ to match against such sequences stored in our mental dictionary? Or do we compare the speech stream to memorized speech streams stored in memory, finding the greatest similarity to past exemplars of "cat"? Trainee Michael Wolmetz's experiments showed that, after hearing words in which speech segments had been altered systematically, listeners generalized what they unconsciously learned about these altered segments---suggesting they had learned to recognize abstract /k/ even in altered words not previously experienced. However he also showed that it is possible to simulate such generalization in a computational model containing no abstract segments, using only memorized exemplars including the altered speech. Finally, he obtained neuroimaging evidence that, rather than abstract segment sequences, the brain stores the particular, speaker-dependent details of experienced words.