Not Everybody Has an Inner Voice: Behavioral Consequences of Anendophasia.

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.

Are you thinking what I'm thinking? Perspective-taking in a language game.

Many theories of communication claim that perspective-taking is a fundamental component of the successful design of utterances for a specific audience. In three experiments, we investigated perspective-taking in a constrained communication situation: Participants played a word guessing game where each trial required them to select a clue word to communicate a single target word to their partner. In many cases, the task requires participants to take the perspective of their partner when generating, evaluating, and selecting potential clue words. For example, if the target word was 'heart', the first word that came to mind might be 'love', but this would not in fact be a very useful clue word. Instead, a word like 'cardiovascular' is much more likely than 'love' to make the partner guess 'heart'. Pairs of participants took turns giving and receiving clues to guess target words, receiving feedback after each trial. In Experiment 1, participants appeared unable to improve their perspective-taking over repeated interactions, despite a baseline performance that suggested strong perspective-taking abilities. In Experiment 2, which included extensive feedback after each trial and only target words for which good clues existed and which required perspective-taking, some measures of perspective-taking showed modest improvements. In Experiment 3, which was conducted online, we used Experiment 2 feedback with Experiment 1 target words. As in Experiment 1, participants did not improve over the course of the game in Experiment 3. The results of these three experiments show quite strong limits on people's ability to adapt and improve perspective-taking without the context provided by interaction history and growing common ground.

Mind over body: Interfering with the inner voice is detrimental to endurance performance.

In two preregistered experiments, we investigated whether covert language is involved in sustained physical efforts, specifically if people are less able to push themselves physically when distracted from using inner speech. In both experiments, participants performed 12 cycling trials (Experiment 1: N = 49; Experiment 2: N = 50), each lasting 1 min where participants were required to cycle as fast as possible while simultaneously engaging in either a visuospatial task, a verbal task or no interference. Experiment 1: Participants performed worse in the verbal interference condition compared with the control condition (d = 0.29) and verbal interference performance was numerically but not significantly worse than visuospatial interference (d = 0.22). Experiment 2: A more demanding interference task yielded significant slower cycling with verbal interference compared to both control (d = 1) and visuospatial interference (d = 0.43). These results indicate that inner speech plays a causal role in control of sustained physical efforts.

"Stay focused!": The role of inner speech in maintaining attention during a boring task.

Is inner speech involved in sustaining attention, and is this reflected in response times for stimulus detection? In Experiment 1, we measured response times to an infrequently occurring stimulus (a black dot appearing at 1-3 min intervals) and subsequently asked participants to report on the character of their inner experience at the time the stimulus appeared. Our main preregistered hypothesis was that there would be an interaction between inner speech and task relevance of thought with reaction times being the fastest on prompts preceded by task-relevant inner speech. This would indicate that participants could use their inner voice to maintain performance on the task. With generalized linear mixed-effects models fitted to a gamma distribution, we found significant effects of task relevance but no interaction with inner speech. However, using a hierarchical Bayesian analysis method, we found that trials preceded by task-relevant inner speech additionally displayed lower standard deviation and lower mode (independently of the main effect of task relevance), suggestive of increased processing efficiency. Due to deviations from the preregistered sampling and analysis procedures, we replicated our findings in Experiment 2. Our results add support to the hypothesis that inner speech serves a functional role in top-down attentional control. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Verbal interference paradigms: A systematic review investigating the role of language in cognition.

This paper presents a systematic review of the empirical literature that uses dual-task interference methods for investigating the on-line involvement of language in various cognitive tasks. In these studies, participants perform some primary task X putatively recruiting linguistic resources while also engaging in a secondary, concurrent task. If performance on the primary task decreases under interference, there is evidence for language involvement in the primary task. We assessed studies (N = 101) reporting at least one experiment with verbal interference and at least one control task (either primary or secondary). We excluded papers with an explicitly clinical, neurological, or developmental focus. The primary tasks identified include categorization, memory, mental arithmetic, motor control, reasoning (verbal and visuospatial), task switching, theory of mind, visual change, and visuospatial integration and wayfinding. Overall, the present review found that covert language is likely to play a facilitative role in memory and categorization when items to be remembered or categorized have readily available labels, when inner speech can act as a form of behavioral self-cuing (inhibitory control, task set reminders, verbal strategy), and when inner speech is plausibly useful as "workspace," for example, for mental arithmetic. There is less evidence for the role of covert language in cross-modal integration, reasoning relying on a high degree of visual detail or items low on nameability, and theory of mind. We discuss potential pitfalls and suggestions for streamlining and improving the methodology.

Valence, form, and content of self-talk predict sport type and level of performance.

In this paper, we aimed to test whether we could predict sport type (badminton or running) and marathon proficiency from the valence, form, and content of the athletes' self-reported inner speech. Additionally, we wanted to assess the difference between self-talk during high intensity and low intensity exercise. The present study corroborated existing research - we were able to predict both sport type in Study 1 and intensity level as well as marathon proficiency in Study 2 from questionnaire data using machine learning models. In Study 1, we found that badminton players engage more in worry and anxiety-control while runners are more prone to task disengagement. Interestingly, it seemed in Study 2 that the more participants engaged in condensed, positive, and repetitive self-talk when not pushing themselves, the slower their fastest marathons and half marathons were. We discuss potential explanations for these findings and make suggestions for future research.