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Schizophr Res. 2019 Jun;208:124-132. doi: 10.1016/j.schres.2019.03.028. Epub 2019 Apr 11.

Normal categorical perception to syllable-like stimuli in long term and in first episode schizophrenia.

Author information

1
Department of Psychiatry, University of Pittsburgh, Suite 420, 3501 Forbes Avenue, Pittsburgh, PA 15213, USA; Department of Psychology and Center for Integrative Neuroscience, University of Nevada, Reno, Mack Social Science, 1664 N Virginia Street, Reno, NA, 89557, USA.
2
Department of Psychiatry, University of Pittsburgh, Suite 420, 3501 Forbes Avenue, Pittsburgh, PA 15213, USA.
3
Department of Psychiatry, University of Pittsburgh, Suite 420, 3501 Forbes Avenue, Pittsburgh, PA 15213, USA; Department of Psychology, Carnegie Mellon University, Baker Hall, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA.
4
Department of Psychology, Carnegie Mellon University, Baker Hall, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA.
5
Department of Psychiatry, University of Pittsburgh, Suite 420, 3501 Forbes Avenue, Pittsburgh, PA 15213, USA. Electronic address: salisburyd@upmc.edu.

Abstract

Schizophrenia is associated with deficits in language processing that are evident even at first-episode. However, there is debate as to how early in the processing stream the linguistic deficits appear. We measured categorical processing of artificial syllables that varied in voice-onset time (VOT), and how sensory biasing impacts categorical perception. VOT varied in 5 ms increments from 0 ms (strong /ba/) to 40 ms (strong /pa/). Participants chose whether a syllable sounded more like /ba/ or /pa/. Twenty-two individuals with long-term schizophrenia (Sz) were compared to 21 controls (HCSz), and 17 individuals at their first-episode of schizophrenia (FE) were compared to 19 controls (HCFE). There were three conditions: equiprobable - each syllable had an equal probability of being presented; /ba/-biased - 0 ms VOT (strong /ba/) presented 70% of the time; /pa/-biased - 40 ms VOT (strong /pa/) presented 70% of the time. All groups showed categorical perception and category shifts during biased conditions. Sz and FE were statistically indistinguishable from controls in the point of categorical shift, slope of their response function, and the VOT needed to reliably perceive /pa/. Together, this suggests intact ability to map acoustic stimuli to phonetic categories when based on timing differences in voiced information, both early and late in the disease.

KEYWORDS:

Categorical perception; First episode; Schizophrenia; Syllable; Voice onset time

PMID:
30982643
PMCID:
PMC6607915
[Available on 2019-12-01]
DOI:
10.1016/j.schres.2019.03.028

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