Processes underlying formal thought disorder in psychiatric inpatients

Area of Science:

• Cognitive psychology
• Psychiatry
• Clinical psychology

Background:

• Formal thought disorder (FTD) is a core symptom in various psychiatric conditions.
• Cognitive theories attempt to explain the underlying mechanisms of FTD.
• Existing theories include "excessive yielding to normal bias" and response competition.

Purpose of the Study:

• To empirically test competing cognitive theories of FTD.
• To investigate the role of distractibility in formal thought disorder.
• To differentiate between bias and response competition models in FTD.

Main Methods:

• Two ambiguity tasks were used to test bias and response competition theories.
• A Stroop-type task assessed distractibility in psychiatric inpatients.
• Findings were replicated in a second independent inpatient sample.

Main Results:

• No significant differences were found between thought-disordered and non-thought-disordered patients on ambiguity tasks.
• Thought-disordered patients exhibited an increased effect in the Stroop-type distractibility task.
• This distractibility effect was consistently replicated across samples.

Conclusions:

• Results support a distractibility theory of formal thought disorder.
• Findings suggest a reformulation of bias theory, emphasizing set-based biases over response-specific biases.
• Cognitive deficits, particularly distractibility, are implicated in the manifestation of FTD.