Discrimination of linguistic stress in early infancy.

The high-amplitude sucking (HAS) paradigm was used to evaluate the ability of one- to four-month-old infants to discriminate two artificially synthesized disyllables (/ba bá and bá ba/) which differed solely in the location of perceived stress. One hundred and twenty infants were tested in two experiments. A modification of the HAS paradigm was developed, in which both stimuli are alternated postshift. The results of the first experiment demonstrate that young infants are able to discriminate the acoustic correlates of stress location (fundamental frequency, intensity, and duration) and that the modified HAS paradigm produces significantly stronger evidence for this discrimination than does the standard paradigm. The second experiment determined that infants can discriminate durational differences alone, without concomitant variations in the naturally correlated parameters of fundamental frequency and intensity.