Inner Speech

Table of Contents
Inner speech represents a fundamental aspect of human cognition and consciousness, manifesting in various forms and serving multiple functions in mental life. At LISN, we investigate this phenomenon through multiple complementary approaches: examining its varieties and manifestations, studying its role in reading comprehension, mapping its neural underpinnings, and exploring its contribution to consciousness and self-awareness. This comprehensive approach allows us to build a deeper understanding of how inner speech shapes human thought and experience.
Varieties of Inner Speech
Inner speech encompasses distinct varieties, each serving unique cognitive functions. Dialogic inner speech enables internal conversations where multiple perspectives are mentally represented, while condensed inner speech operates in abbreviated thought patterns without full syntactic structure. Evaluative inner speech facilitates self-reflection and assessment, and motivational inner speech serves to regulate behavior and emotional states. These varieties differ not only in their form but also in their cognitive and behavioral impacts. Understanding these distinctions is crucial for comprehending how inner speech supports various mental processes, from problem-solving to emotional regulation.
At LISN, we employ multiple complementary methods to investigate these inner speech varieties. Through experience sampling, we capture real-time manifestations of different inner speech types across various cognitive tasks. Our innovative combination of think-aloud protocols with advanced EEG analysis helps identify distinct neural signatures for different inner speech subtypes. By applying machine learning techniques to these neural patterns, we’re developing new frameworks for understanding how different forms of inner speech contribute to cognitive processing. Through these research avenues, LISN aims to establish a comprehensive taxonomy of inner speech varieties and their roles in human cognition.
Hearing Words off the Page
When reading direct speech, many people report experiencing vivid inner voices, complete with distinctive tones, accents, and emotional qualities. This phenomenon represents a specialized manifestation of inner speech that bridges written language and auditory experience. The vividness of these inner voices can vary based on factors such as emotional engagement with the text, reading proficiency, and individual differences in cognitive style. This experience often enhances text comprehension and memory retention, particularly for dialogue-rich narratives.
At LISN, our research has revealed the sophisticated neural and cognitive mechanisms underlying this phenomenon. Our groundbreaking studies have demonstrated increased neural activity in the auditory cortex during silent reading of direct speech (Yao, Belin, & Scheepers, 2011), accompanied by synchronous auditory cortical oscillations (Yao et al., 2021). We’ve also found that eye movements during reading align with the natural rhythm of the imagined inner voice (Yao & Scheepers, 2011). Our current research explores how early experiences of learning to read aloud might establish automatic links between text and auditory experiences, and how inner voice simulation might serve as a prosocial mechanism reinforced by the brain’s reward system (Alderson-Day et al., 2020).
Neural Mechanisms of Inner Speech
The neural architecture supporting inner speech involves a sophisticated network of brain regions working in concert. This network encompasses multiple circuits, including speech production mechanisms (involving motor planning, coordination, and execution areas) and speech perception mechanisms (involving various temporal and parietal regions that support phonological and semantic processing). These core circuits interact dynamically with areas responsible for memory, attention, and emotional processing, creating a complex neural symphony that enables various forms of inner speech.
At LISN, our research focuses on understanding these neural mechanisms and how they support inner speech’s diverse phenomenology. We’ve highlighted the rhythmic nature of inner speech (Yao, 2025) by observing increased neural activity in auditory regions associated with speech prosody (Yao, Belin, & Scheepers, 2011) and more synchronous auditory cortical oscillations (Yao et al., 2021). Our recent meta-analysis (Pratts, Pobric, & Yao, 2023) suggests that inner speech may be supported by both a motor-driven pathway involving speech production circuits and an auditory pathway engaging perceptual mechanisms, potentially underpinning different inner speech subtypes. We are also employing machine learning to identify the neural features that characterise these subtypes, aiming for a more nuanced understanding of inner speech and its role in cognition. Through these research avenues, LISN seeks to deepen our understanding of the neural mechanisms of inner speech and its various subtypes.
Inner Speech in Self-Consciousness
Inner speech plays a fundamental role in human consciousness, serving as a critical bridge between thought and self-awareness. This internal dialogue shapes our sense of self, influences decision-making, and mediates between different levels of consciousness, from focused attention to mind-wandering states. The relationship between inner speech and consciousness has profound implications for understanding both normal cognitive function and various psychological conditions, where alterations in inner speech often correspond to changes in self-awareness and conscious experience.
At LISN, we’re pioneering new approaches to understanding this relationship through innovative research designs. Our studies capitalise on recent discoveries about aphantasia and other individual differences in mental experience to examine how variations in inner speech abilities affect self-awareness and consciousness. Using advanced EEG techniques, we’re developing objective measures of inner speech during self-referential processing, while our machine learning algorithms are creating new frameworks for classifying brain states related to different forms of inner dialogue. This research not only advances our theoretical understanding but also has practical implications for addressing conditions like rumination, depression, and auditory verbal hallucinations, where the relationship between inner speech and consciousness becomes disturbed.