A new theory is taking hold in neuroscience. It is the theory that the brain is essentially a hypothesis-testing mechanism, one that attempts to minimise the error of its predictions about the sensory input it receives from the world. It is an attractive theory because powerful theoretical arguments support it, and yet it is at heart stunningly simple. Jakob Hohwy explains and explores this theory from the perspective of cognitive science and philosophy. The key argument throughout The Predictive Mind is (...) that the mechanism explains the rich, deep, and multifaceted character of our conscious perception. It also gives a unified account of how perception is sculpted by attention, and how it depends on action. The mind is revealed as having a fragile and indirect relation to the world. Though we are deeply in tune with the world we are also strangely distanced from it. (shrink)

Brains, it has recently been argued, are essentially prediction machines. They are bundles of cells that support perception and action by constantly attempting to match incoming sensory inputs with top-down expectations or predictions. This is achieved using a hierarchical generative model that aims to minimize prediction error within a bidirectional cascade of cortical processing. Such accounts offer a unifying model of perception and action, illuminate the functional role of attention, and may neatly capture the special contribution of cortical processing to (...) adaptive success. This target article critically examines this approach, concluding that it offers the best clue yet to the shape of a unified science of mind and action. Sections 1 and 2 lay out the key elements and implications of the approach. Section 3 explores a variety of pitfalls and challenges, spanning the evidential, the methodological, and the more properly conceptual. The paper ends (sections 4 and 5) by asking how such approaches might impact our more general vision of mind, experience, and agency. (shrink)

Recent work on the mechanisms underlying auditory verbal hallucination (AVH) has been heavily informed by self-monitoring accounts that postulate defects in an internal monitoring mechanism as the basis of AVH. A more neglected alternative is an account focusing on defects in auditory processing, namely a spontaneous activation account of auditory activity underlying AVH. Science is often aided by putting theories in competition. Accordingly, a discussion that systematically contrasts the two models of AVH can generate sharper questions that will lead to (...) new avenues of investigation. In this paper, we provide such a theoretical discussion of the two models, drawing strong contrasts between them. We identify a set of challenges for the self-monitoring account and argue that the spontaneous activation account has much in favor of it and should be the default account. Our theoretical overview leads to new questions and issues regarding the explanation of AVH as a subjective phenomenon and its neural basis. Accordingly, we suggest a set of experimental strategies to dissect the underlying mechanisms of AVH in light of the two competing models. (shrink)

A resurgence of interest in inner speech as a core feature of human experience has not yet coincided with methodological progress in the empirical study of the phenomenon. The present article reports the development and psychometric validation of a novel instrument, the Varieties of Inner Speech Questionnaire , designed to assess the phenomenological properties of inner speech along dimensions of dialogicality, condensed/expanded quality, evaluative/motivational nature, and the extent to which inner speech incorporates other people’s voices. In response to findings that (...) some forms of psychopathology may relate to inner speech, anxiety, depression, and proneness to auditory and visual hallucinations were also assessed. Anxiety, but not depression, was found to be uniquely positively related to both evaluative/motivational inner speech and the presence of other voices in inner speech. Only dialogic inner speech predicted auditory hallucination-proneness, with no inner speech variables predicting levels of visual hallucinations/disturbances. Directions for future research are discussed. (shrink)

In the past dozen years a number of theoretical models of schizophrenic symptoms have been proposed, often inspired by advances in the cognitive sciences, and especially cognitive neuroscience. Perhaps the most widely cited and influential of these is the neurocognitive model proposed by Christopher Frith (1992). Frith's influence reaches into psychiatry, neuroscience, and even philosophy. The philosopher John Campbell (1999a), for example, has called Frith's model the most parsimonious explanation of how self-ascriptions of thoughts are subject to errors of identification. (...) "On reflection, it also seems that this is not just one possible theory; it is the simplest theory which has any prospect of explaining the sense of agency, and we ought to work from it, introducing complications only as necessary" (1999a, p. 612). Not everyone agrees. In their recent analysis of alien voices and inserted thoughts in schizophrenia, Stephens and Graham (2000) offer a critique of Frith. Their criticism, however, although serious, is neither deep nor extensive. They outline three points. First, Frith fails to provide an adequate account of why a subject who experiences thought insertion would misattribute that thought to some other agent. Second, Frith does not clarify the distinction between thought insertion and thought influence. And third, Frith fails to explain how a subject can claim both that he is thinking the thought and that the thought is someone else's thought (Stephens and Graham.. (shrink)

Do self‐monitoring accounts, a dominant account of the positive symptoms of schizophrenia, explain auditory verbal hallucination? In this essay, I argue that the account fails to answer crucial questions any explanation of auditory verbal hallucination must address. Where the account provides a plausible answer, I make the case for an alternative explanation: auditory verbal hallucination is not the result of a failed control mechanism, namely failed self‐monitoring, but, rather, of the persistent automaticity of auditory experience of a voice. My argument (...) emphasizes the importance of careful examination of phenomenology as providing substantive constraints on causal models of the positive symptoms in schizophrenia. (shrink)

We welcome Cho and Wu’s suggestion that the study of auditory verbal hallucinations could be improved by contrasting and testing more explanatory models. However, we have some worries both about their criticisms of inner speech-based self-monitoring models and whether their proposed spontaneous activation model is explanatory.

Passivity experiences in schizophrenia are thought to be due to a failure in a neurocognitive action self-monitoring system . Drawing on the assumption that inner speech is a form of action, a recent model of auditory verbal hallucinations has proposed that AVHs can be explained by a failure in the NASS. In this article, we offer an alternative application of the NASS to AVHs, with separate mechanisms creating the emotion of self-as-agent and other-as-agent. We defend the assumption that inner speech (...) can be considered as a form of action, and show how a number of previous criticisms of applying the NASS to AVHs can be refuted. This is achieved in part through taking a Vygotskian developmental perspective on inner speech. It is suggested that more research into the nature and development of inner speech is needed to further our understanding of AVHs. (shrink)