Trace deletion, theta-roles, and cognitive strategies

Area of Science:

• Psycholinguistics
• Neurolinguistics
• Cognitive Science

Background:

• Agrammatic aphasia is characterized by deficits in language production and comprehension.
• Previous research suggests agrammatic comprehension is selective, but the precise nature of this selectivity is debated.
• The Trace-Deletion Hypothesis (TDH) proposes that agrammatic patients delete empty pronouns (traces) and use a default strategy.

Purpose of the Study:

• To investigate the selectivity of comprehension deficits in agrammatic patients.
• To examine how thematic verb structure influences comprehension of active and passive sentences.
• To test the predictions of the Trace-Deletion Hypothesis (TDH) with varying verb argument types.

Main Methods:

• An anagram task was employed to assess agrammatic patients' comprehension.
• Active and passive sentences featuring verbs with Agent, Instrument, or Experiencer external arguments were used.
• Performance was analyzed based on sentence type and verb's thematic role.

Main Results:

• Patients performed above chance on all active sentences.
• Comprehension of passive sentences with Agent or Instrument verbs was at chance.
• Comprehension of passive sentences with Experiencer verbs was below chance.

Conclusions:

• The findings demonstrate a highly selective grammatical deficit in agrammatic patients.
• Results support a linguistic theory incorporating a lexicon with thematic labels and a thematic hierarchy.
• Data provide strong evidence for the TDH, requiring both trace deletion and a default Agent-first strategy for agrammatic comprehension.