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Not Everybody Has an Inner Voice: Behavioral Consequences of Anendophasia

DOI: 10.1177/09567976241243004
Nedergaard, J. S. K., & Lupyan, G. (2024). Not everybody has an inner voice: behavioral consequences of anendophasia. Psychological Science, 35(7), 780–797. doi:10.1177/09567976241243004

Abstract

It is commonly assumed that inner speech—the experience of thought as occurring in a natural language—is a human universal. Recent evidence, however, suggests that the experience of inner speech in adults varies from near constant to nonexistent. We propose a name for a lack of the experience of inner speech—anendophasia—and report four studies examining some of its behavioral consequences. We found that adults who reported low levels of inner speech ( N = 46) had lower performance on a verbal working memory task and more difficulty performing rhyme judgments compared with adults who reported high levels of inner speech ( N = 47). Task-switching performance—previously linked to endogenous verbal cueing—and categorical effects on perceptual judgments were unrelated to differences in inner speech.

Authors

  • Johanne S. K. Nedergaard1
  • Gary Lupyan2

Understanding Inner Speech: Exploring Anendophasia

Overview/Introduction

Inner speech, or the experience of thinking in words, is often assumed to be a universal human trait. However, recent research suggests that this experience varies greatly among individuals, with some people experiencing little to no inner speech. This paper introduces the term anendophasia to describe the absence of inner speech and explores its behavioral consequences through a series of studies.

Methodology

The researchers conducted four studies involving 93 adult participants divided into two groups: those with high levels of inner speech and those with low levels. Participants were assessed on various tasks, including:
  • Verbal Working Memory Task: Participants recalled lists of words with different phonological and orthographic similarities.
  • Rhyme Judgment Task: Participants judged whether the names of images rhymed.
  • Task Switching Task: Participants alternated between addition and subtraction tasks, with varying cues.
  • Categorical Effects on Visual Discrimination Task: Participants made judgments about visual similarities between images.

Key Findings

  • Verbal Working Memory: Participants with less inner speech performed worse in recalling words, especially those with phonological similarities.
  • Rhyme Judgments: Those with less inner speech had more difficulty making rhyme judgments, indicating a reliance on phonological memory.
  • Task Switching: Inner speech did not affect performance, suggesting that task-switching abilities are not dependent on inner speech.
  • Compensatory Strategies: Participants with less inner speech often used external verbalization (talking out loud) to improve performance, effectively compensating for their lack of inner speech.

Implications

The findings suggest that inner speech plays a significant role in certain cognitive tasks, particularly those involving verbal memory and phonological processing. However, individuals with anendophasia can employ alternative strategies to achieve similar performance levels. This research highlights the diversity in human cognitive experiences and suggests that educational and cognitive strategies could be tailored to accommodate these differences.

Limitations

The study's limitations include a relatively small sample size and the reliance on self-reported measures of inner speech, which may introduce bias. Additionally, the tasks used may not fully capture the complexity of inner speech experiences.
In conclusion, while not everyone experiences inner speech, those who do not can still perform effectively on cognitive tasks by using alternative strategies. This research opens the door to further exploration of individual differences in cognitive processing and their implications for learning and memory.