We very often discover ourselves engaged in inner speech. It seems that this kind of silent, private, speech fulfils some role in our cognition, most probably related to conscious thinking. Yet, the study of inner speech has been neglected by philosophy and psychology alike for many years. However, things seem to have changed in the last two decades. Here we review some of the most influential accounts about the phenomenology and the functions of inner speech, as well as the methodological (...) problems that affect its study. (shrink)

Our target article proposed that language production and comprehension are interwoven, with speakers making predictions of their own utterances and comprehenders making predictions of other people's utterances at different linguistic levels. Here, we respond to comments about such issues as cognitive architecture and its neural basis, learning and development, monitoring, the nature of forward models, communicative intentions, and dialogue.

Currently, production and comprehension are regarded as quite distinct in accounts of language processing. In rejecting this dichotomy, we instead assert that producing and understanding are interwoven, and that this interweaving is what enables people to predict themselves and each other. We start by noting that production and comprehension are forms of action and action perception. We then consider the evidence for interweaving in action, action perception, and joint action, and explain such evidence in terms of prediction. Specifically, we assume (...) that actors construct forward models of their actions before they execute those actions, and that perceivers of others' actions covertly imitate those actions, then construct forward models of those actions. We use these accounts of action, action perception, and joint action to develop accounts of production, comprehension, and interactive language. Importantly, they incorporate well-defined levels of linguistic representation. We show how speakers and comprehenders use covert imitation and forward modeling to make predictions at these levels of representation, how they interweave production and comprehension processes, and how they use these predictions to monitor the upcoming utterances. We show how these accounts explain a range of behavioral and neuroscientific data on language processing and discuss some of the implications of our proposal. (shrink)

Pickering & Garrod (P&G) consider the possibility that inner speech might be a product of forward production models. Here I consider the idea of inner speech as a forward model in light of empirical work from the past few decades, concluding that, while forward models could contribute to it, inner speech nonetheless requires activity from the implementers.

People frequently report that, at times, their thought has a vocal character. Thinking commonly appears to be accompanied or constituted by silently ‘talking’ to oneself in inner speech. In this paper, we explore the specifically epistemic role of inner speech in conscious reasoning. A plausible position—but one I argue is ultimately wrong—is that inner speech plays asolelyfacilitative role that is exhausted by (i) serving as the vehicle of representation for conscious reasoning, and/or (ii) allowing one to focus on certain types (...) of objects or relations, e.g., causal relations, abstracta, counterfactuals, etc., or to consciously entertain structured propositional contents that it would be hard (or impossible) to focus on or entertain with representations in other (e.g., imagistic) formats. According to this position, inner speech doesn't figure as a justificatory element in our reasoning or as the partial epistemic basis of our conclusions—it merely facilitates reasoning through (i) and/or (ii). In contrast to the view that inner speech is amerefacilitator, I establish that (outside of potentially playing roles (i) and/or (ii)) the language we use itself serves as a crucial source of information in reasoning. In other words, we reason from propositions about the language we use in inner speech as opposed to exclusively reasoning from the semantic contents of the speech. My conclusion follows from how we use language as a cognitive tool to keep track of information, e.g., the contents of premises, lemmas, previous reasoning results, etc., in reasoning. (shrink)

People frequently report that their thought has, at times, a vocal character. Thinking commonly appears to be accompanied or constituted by silently ‘talking’ to oneself in inner speech. In this paper, I argue that inner speech ‘utterances’ can constitute occurrent propositional attitudes, e.g., occurrent judgments, suppositions, etc., and, thereby, we can consciously reason through tokening a series of inner speech utterances in working memory. As I demonstrate, the functional role a mental state plays in working memory is determined in a (...) flexible and context sensitive manner by metacognitive monitoring and control procedures. An inner speech utterance functions as an occurrent judgment (and, thus, as a premise, lemma, or conclusion in a line of conscious reasoning) when it is experienced with a level of certainty that exceeds one’s threshold of confidence for acceptance. In virtue of an agent experiencing an inner speech utterance with a sufficient level of certainty, the utterance plays the functional role of an occurrent judgment through, e.g., terminating inquiry and causing overt actions (like overtly asserting the words rehearsed in inner speech). (shrink)

Our conscious thought, at least at times, seems suffused with language. We may experience thinking as if we were “talking in our head”, thus using inner speech to verbalize, e.g., our premises, lemmas, and conclusions. I take inner speech to be part of a larger phenomenon I call inner semiotics, where inner semiotics involves the subjective experience of expressions in a semiotic (or symbol) system absent the overt articulation of the expressions. In this paper, I argue that inner semiotics allows (...) us to bootstrap our way into entertaining thoughts about exact numbers and quantities that we couldn't prior to our competence with a numeric code. I establish that our arithmetic thoughts literally occur as (internal ‘articulations’ of) expressions in a numeric code. However, a problem arises for my view: just as we can slip in overt speech, producing an utterance that deviates from what we mean to say, there is very good evidence that we can slip in inner speech as well. If our arithmetic thought occurs in a numeric code, it's far from clear how we determine when a covert utterance constitutes a slip. In closing, I provide an account of what makes an inner speech utterance a slip. (shrink)

Many theorists claim that inner speech is importantly linked to human metacognition (thinking about one's own thinking). However, their proposals all rely upon unworkable conceptions of the content and structure of inner speech episodes. The core problem is that they require inner speech episodes to have both auditory-phonological contents and propositional/semantic content. Difficulties for the views emerge when we look closely at how such contents might be integrated into one or more states or processes. The result is that, if inner (...) speech is especially valuable to metacognition, we do not currently understand why it is. The article concludes with two positive proposals for understanding the content and structure of inner speech episodes, which should serve as constraints on future accounts of the metacognitive value of inner speech. (shrink)

Despite the ubiquity of inner speech in our mental lives, methods for objectively assessing inner speech capacities remain underdeveloped. The most common means of assessing inner speech is to present participants with tasks requiring them to silently judge whether two words rhyme. We developed a version of this task to assess the inner speech of a population of patients with aphasia and corresponding language production deficits. As expected, patients’ performance on the silent rhyming task was severely impaired relative to controls. (...) More surprisingly, however, patients’ performance on this task did not correlate with their performance on a variety of other standard tests of overt language abilities. In particular, patients who were generally unimpaired in their abilities to overtly name objects during confrontation naming tasks, and who could reliably judge when two words spoken to them rhymed, were still severely impaired (relative to controls) at completing the silent rhyme task. This seems to suggest that inner speech was more severely impaired in these patients than outer speech. However, these results should also cause us to critically reflect on the relation between inner speech and silent rhyme judgments more generally. (shrink)

On a widely held view, episodes of inner speech provide at least one way in which we become conscious of our thoughts. However, it can be argued, on the one hand, that consciousness of thoughts in virtue of inner speech presupposes interpretation of the simulated speech. On the other hand, the need for such self-interpretation seems to clash with distinctive first-personal characteristics that we would normally ascribe to consciousness of one’s own thoughts: a special reliability; a lack of conscious ambiguity (...) and incomprehensibility; and a sense of causal agency. I try to resolve this puzzle by proposing an account for the requisite self-interpretation of inner speech in terms of Bayesian probabilistic inference. Drawing on “perceptual loop” accounts of speech control, I argue that such interpretive probabilistic inferences are used for the control of inner speech, and that as a consequence of this function, they are biased toward the correct interpretations. I conclude by showing how this model can explain the first-personal characteristics of consciousness of one’s own thoughts. In the case of the sense of causal agency, the resulting explanation yields novel accounts for “audible thoughts” and thought insertion. (shrink)

On a widely held view, episodes of inner speech provide at least one way in which we become conscious of our thoughts. However, it can be argued, on the one hand, that consciousness of thoughts in virtue of inner speech presupposes interpretation of the simulated speech. On the other hand, the need for such self-interpretation seems to clash with distinctive first-personal characteristics that we would normally ascribe to consciousness of one’s own thoughts: a special reliability; a lack of conscious ambiguity (...) and incomprehensibility; and a sense of causal agency. I try to resolve this puzzle by proposing an account for the requisite self-interpretation of inner speech in terms of Bayesian probabilistic inference. Drawing on “perceptual loop” accounts of speech control, I argue that such interpretive probabilistic inferences are used for the control of inner speech, and that as a consequence of this function, they are biased toward the correct interpretations. I conclude by showing how this model can explain the first-personal characteristics of consciousness of one’s own thoughts. In the case of the sense of causal agency, the resulting explanation yields novel accounts for “audible thoughts” and thought insertion. (shrink)

Inner speech has been shown to vary in form along several dimensions. Along condensation, condensed inner speech forms have been described, that are supposed to be deprived of acoustic, phonological and even syntactic qualities. Expanded forms, on the other extreme, display articulatory and auditory properties. Along dialogality, inner speech can be monologal, when we engage in internal soliloquy, or dialogal, when we recall past conversations or imagine future dialogues involving our own voice as well as that of others addressing us. (...) Along intentionality, it can be intentional (when we deliberately rehearse material in short-term memory) or it can arise unintentionally (during mind wandering). We introduce the ConDialInt model, a neurocognitive predictive control model of inner speech that accounts for its varieties along these three dimensions. ConDialInt spells out the condensation dimension by including inhibitory control at the conceptualization, formulation or articulatory planning stage. It accounts for dialogality, by assuming internal model adaptations and by speculating on neural processes underlying perspective switching. It explains the differences between intentional and spontaneous varieties in terms of monitoring. We present an fMRI study in which we probed varieties of inner speech along dialogality and intentionality, to examine the validity of the neuroanatomical correlates posited in ConDialInt. Condensation was also informally tackled. Our data support the hypothesis that expanded inner speech recruits speech production processes down to articulatory planning, resulting in a predicted signal, the inner voice, with auditory qualities. Along dialogality, covertly using an avatar’s voice resulted in the activation of right hemisphere homologues of the regions involved in internal own-voice soliloquy and in cerebellar deactivation, consistent with internal model adaptation. Switching from first-person to third-person perspective resulted in activations in precuneus and parietal lobules. Along intentionality, compared with intentional inner speech, mind wandering with inner speech episodes was associated with greater bilateral inferior frontal activation and decreased activation in left temporal regions. This is consistent with the reported subjective evanescence and presumably reflects condensation processes. Our results provide neuroanatomical evidence compatible with predictive control and in favor of the assumptions made in the ConDialInt model. (shrink)

Inner speech emerges in early childhood, in parallel with the maturation of the dorsal language stream. To date, the developmental relations between these two processes have not been examined. We review evidence that the dorsal language stream has a role in supporting the psychological phenomenon of inner speech, before considering paediatric studies of the dorsal stream’s anatomical development and evidence for its emerging functional roles. We examine possible causal accounts of the relations between these two developmental processes, and consider their (...) implications for phylogenetic theories about the evolution of inner speech and the accounts of the ontogenetic relations between language and cognition. (shrink)

Background: Many people with aphasia and people without brain injury talk to themselves in their heads, i.e., have “inner speech.” Inner speech may be more preserved compared with spoken speech for some people with aphasia and may serve a variety of functions (e.g., emotion regulation), which motivates us to provide a high-fidelity characterization of it. Researchers have used multiple methods to measure this internal phenomenon in the past, which we combine here for the first time in a single study. -/- (...) Aims: We compare performance between individuals with and without aphasia on inner speech tasks that assess inner speech “inthe- moment” to general subjective impressions of inner speech to tease apart the relationship of aphasia severity to inner speech. Methods and Procedures: Twenty people with mild-moderate aphasia and twenty neurotypical controls completed several inner speech tasks, including objective silent rhyme judgements (picture, written, and auditory), subjective reports of inner speech during naming, and subjective rating scales about inner speech experience more generally. -/- Outcomes and Results: In-the-moment inner speech during silent rhyming tasks was associated with aphasia severity only for picture and written rhyming but not auditory rhyming. In-the-moment inner speech reports during silent naming were not associated with aphasia severity, nor were the subjective ratings about general inner speech experience. Individuals with and without aphasia demonstrated a variety of subjective general inner speech experiences, demonstrating heterogeneity of this phenomenon more broadly. -/- Conclusions: Methods of measuring inner speech complement each other and speak to different facets of the inner speech phenomenon, and clinicians and researchers must carefully choose the method(s) that will provide the information about inner speech that they desire. (shrink)

Inner speech travels under many aliases: the inner voice, verbal thought, thinking in words, internal verbalization, “talking in your head,” the “little voice in the head,” and so on. It is both a familiar element of first-person experience and a psychological phenomenon whose complex cognitive components and distributed neural bases are increasingly well understood. There is evidence that inner speech plays a variety of cognitive roles, from enabling abstract thought, to supporting metacognition, memory, and executive function. One active area of (...) controversy concerns the relation of inner speech to auditory verbal hallucinations in schizophrenia, with a common proposal being that sufferers of AVH misidentify their own inner speech as being generated by someone else. Recently, researchers have used artificial intelligence to translate the neural and neuromuscular signatures of inner speech into corresponding outer speech signals, laying the groundwork for a variety of new applications and interventions. (shrink)