Interfering with Inner Speech Selectively Disrupts Problem-Solving and is Linked with Real-World Executive Functioning

Purpose: According to Vygotskian theory, verbal thinking serves to guide our behavior and underpins critical self-regulatory functions. Indeed, numerous studies now link inner speech usage with performance on tests of executive function. However, the selectivity of inner speech contributions to multi-factorial executive planning performance and links with real-world functioning are limited. Therefore, the present study seeks to fill this gap in our knowledge. Method: Fifty-one adults completed the Tower of London under two conditions: (1) articulatory suppression and (2) foot tapping as well as self-ratings of real-world executive functioning (utilizing the Behavior Rating Inventory of Executive Function-Adult version). Results: Interfering with inner speech selectively disrupted Tower of London performance over and above a simultaneous motor task (i.e., foot tapping). Furthermore, this selectivity in performance was linked with real-world self-monitoring. Conclusion: These results provide further evidence for specific links between verbal thinking and executive function (particularly using multifactorial tasks of planning) and suggest that inner speech might serve as a key intervention target in clinical disorders where executive function deficits are prominent.