Categorical perception for voicing contrasts in normal and lead-treated rhesus monkeys: Electrophysiological indices

Philip A. Morse, Dennis Molfese, Nellie K. Laughlin, Steven Linnville, Frederick Wetzel

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Categorical perception of voicing contrasts was evaluated in rhesus monkeys. The monkeys had been chronically exposed to subclinical levels of lead either from conception to birth, or for approximately 6 months postnatally beginning at birth, or were never exposed to lead. Auditory evoked responses were recorded at 1 year of age from scalp electrodes placed over the left and right hemispheres during stimulus presentation. A late component of the brain responses recorded from the right temporal region of all monkeys discriminated between stimuli in a categorical manner. This pattern of responses was noted to be similar to that previously reported for humans. Categorical discriminations were also noted earlier in the waveforms for control monkeys and for monkeys exposed to lead prenatally, although this discrimination pattern shifted to the left hemisphere of the latter group. No such effects were noted for monkeys exposed to lead postnatally. These results suggest that the neurocortical mechanisms associated with categorical perception for voicing information may be similar across human and nonhuman primates. However, early exposure to lead appears to alter these processes.

Original languageEnglish (US)
Pages (from-to)63-80
Number of pages18
JournalBrain and Language
Issue number1
StatePublished - Jan 1987
Externally publishedYes

ASJC Scopus subject areas

  • Language and Linguistics
  • Experimental and Cognitive Psychology
  • Linguistics and Language
  • Cognitive Neuroscience
  • Speech and Hearing


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