Evaluating the relationship between sublexical and lexical processing in speech perception: Evidence from aphasia

Area of Science:

• Neuroscience
• Psycholinguistics
• Speech Perception

Background:

• Previous studies suggested aphasic patients outperform on lexical compared to sublexical perception tasks.
• This challenged speech perception models assuming obligatory sublexical processing.
• Prior research lacked matched phonological similarity and task demands between lexical and sublexical tasks.

Purpose of the Study:

• To investigate aphasic patients' performance on matched lexical and sublexical speech perception tasks.
• To re-evaluate speech perception models in light of controlled experimental conditions.

Main Methods:

• Tested 13 aphasic patients on auditory-written syllable matching (AWSM), syllable discrimination, word discrimination, lexical decision, and picture-word matching (PWM).
• Controlled for phonological similarity of stimuli and task demands across lexical and sublexical tasks.
• Compared patient performance against control groups.

Main Results:

• When tasks were not matched, some patients showed intact lexical perception despite impaired sublexical perception.
• When tasks were matched, most patients were impaired on both lexical and sublexical tasks.
• Lexical task performance was not significantly better than sublexical task performance in matched conditions.

Conclusions:

• Findings support speech perception models that include obligatory sublexical processing.
• Results challenge models that do not require sublexical processing for lexical access.
• Careful matching of task demands and stimulus properties is crucial in speech perception research.