Lexical-semantic and executive deficits revealed by computational modelling: A drift diffusion model perspective

Area of Science:

• Cognitive Neuroscience
• Psycholinguistics
• Neurobiology

Background:

• Flexible language use depends on integrating conceptual knowledge with executive control.
• Word-picture matching (WPM) tasks reveal interference effects, but the underlying neural mechanisms remain unclear.
• The drift diffusion model (DDM) provides a framework for analyzing decision-making processes.

Purpose of the Study:

• To investigate the cognitive mechanisms underlying word-picture matching interference using the drift diffusion model (DDM).
• To examine the impact of left-frontal and left-temporal lesions on WPM performance and its underlying computational parameters.
• To differentiate between semantic and executive control contributions to WPM interference.

Main Methods:

• Analysis of word-picture matching (WPM) performance in patients with left-temporal (N=5) or left-frontal (N=5) lesions and matched controls (N=12).
• Application of the drift diffusion model (DDM) to estimate decision threshold, drift rate, starting point, and non-decision time.
• Comparison of DDM parameters between control participants and patient groups for related and unrelated word-picture pairs.

Main Results:

• In controls, WPM interference was characterized by a higher decision threshold for related word-picture pairs, suggesting an executive control mechanism.
• No significant differences in drift rate were observed in controls, indicating that the quality of evidence accumulation was not affected.
• Patients with both temporal and frontal lesions showed increased drift rate and decision threshold for unrelated pairs, suggesting broader impacts on cognitive computations.

Conclusions:

• Word-picture matching interference primarily involves executive control mechanisms rather than solely semantic processing.
• Damage to both left-frontal and left-temporal cortices similarly affects cognitive computations in WPM.
• Lexical-semantic memory and semantic control mechanisms play interactive and diverse roles in flexible language processing.