Sorting out sound

Speech analysis is a prototypical categorical mechanism that has been examined behaviorally in work going back to Haskins Laboratory studies in the 1950s: such work examined the perception of continua between phonemes and demonstrated sharp discontinuities consistent with categorical perception. In this issue of Neuron, Raizada and Poldrack examine analysis mechanisms for such processing by measurement of the fMRI BOLD response in the boundary region between different phonemes and argue for a specific amplification mechanism for this type of categorical perception.