This paper explores a variety of different versions of the thesis that natural language is involved in human thinking. It distinguishes amongst strong and weak forms of this thesis, dismissing some as implausibly strong and others as uninterestingly weak. Strong forms dismissed include the view that language is conceptually necessary for thought (endorsed by many philosophers) and the view that language is de facto the medium of all human conceptual thinking (endorsed by many philosophers and social scientists). Weak forms include the view that language is necessary for the acquisition of many human concepts and the view that language can serve to scaffold human thought processes. The paper also discusses the thesis that language may be the medium of conscious propositional thinking, but argues that this cannot be its most fundamental cognitive role. The idea is then proposed that natural language is the medium for non-domain-specific thinking, serving to integrate the outputs of a variety of domain-specific conceptual faculties (or central-cognitive “quasi-modules”). Recent experimental evidence in support of this idea is reviewed and the implications of the idea are discussed, especially for our conception of the architecture of human cognition. Finally, some further kinds of evidence which might serve to corroborate or refute the hypothesis are mentioned. The overall goal of the paper is to review a wide variety of accounts of the cognitive function of natural language, integrating a number of different kinds of evidence and theoretical consideration in order to propose and elaborate the most plausible candidate.

Differential diagnosis of motor symptoms, for example, akinesia, may be difficult in clinical neuropsychiatry. Symptoms may be either of neurologic origin, for example, Parkinson's disease, or of psychiatric origin, for example, catatonia, leading to a so-called “conflict of paradigms.” Despite their different origins, symptoms may appear more or less clinically similar. Possibility of dissociation between origin and clinical appearance may reflect functional brain organisation in general, and cortical-cortical/subcortical relations in particular. It is therefore hypothesized that similarities and differences between Parkinson's disease and catatonia may be accounted for by distinct kinds of modulation between cortico-cortical and cortico-subcortical relations. Catatonia can be characterized by concurrent motor, emotional, and behavioural symptoms. The different symptoms may be accounted for by dysfunction in orbitofrontal-prefrontal/parietal cortical connectivity reflecting “horizontal modulation” of cortico-cortical relation. Furthermore, alteration in “top-down modulation” reflecting “vertical modulation” of caudate and other basal ganglia by GABA-ergic mediated orbitofrontal cortical deficits may account for motor symptoms in catatonia. Parkinson's disease, in contrast, can be characterized by predominant motor symptoms. Motor symptoms may be accounted for by altered “bottom-up modulation” between dopaminergic mediated deficits in striatum and premotor/motor cortex. Clinical similarities between Parkinson's disease and catatonia with respect to akinesia may be related with involvement of the basal ganglia in both disorders. Clinical differences with respect to emotional and behavioural symptoms may be related with involvement of different cortical areas, that is, orbitofrontal/parietal and premotor/motor cortex implying distinct kinds of modulation – “vertical” and “horizontal” modulation, respectively.

It is generally accepted that there is something special about reasoning by using mental images. The question of how it is special, however, has never been satisfactorily spelled out, despite more than thirty years of research in the post-behaviorist tradition. This article considers some of the general motivation for the assumption that entertaining mental images involves inspecting a picture-like object. It sets out a distinction between phenomena attributable to the nature of mind to what is called the cognitive architecture, and ones that are attributable to tacit knowledge used to simulate what would happen in a visual situation. With this distinction in mind, the paper then considers in detail the widely held assumption that in some important sense images are spatially displayed or are depictive, and that examining images uses the same mechanisms that are deployed in visual perception. I argue that the assumption of the spatial or depictive nature of images is only explanatory if taken literally, as a claim about how images are physically instantiated in the brain, and that the literal view fails for a number of empirical reasons – for example, because of the cognitive penetrability of the phenomena cited in its favor. Similarly, while it is arguably the case that imagery and vision involve some of the same mechanisms, this tells us very little about the nature of mental imagery and does not support claims about the pictorial nature of mental images. Finally, I consider whether recent neuroscience evidence clarifies the debate over the nature of mental images. I claim that when such questions as whether images are depictive or spatial are formulated more clearly, the evidence does not provide support for the picture-theory over a symbol-structure theory of mental imagery. Even if all the empirical claims were true, they do not warrant the conclusion that many people have drawn from them: that mental images are depictive or are displayed in some (possibly cortical) space. Such a conclusion is incompatible with what is known about how images function in thought. We are then left with the provisional counterintuitive conclusion that the available evidence does not support rejection of what I call the “null hypothesis”; namely, that reasoning with mental images involves the same form of representation and the same processes as that of reasoning in general, except that the content or subject matter of thoughts experienced as images includes information about how things would look.

There is disagreement in the literature about the exact nature of the phenomenon of empathy. There are emotional, cognitive, and conditioning views, applying in varying degrees across species. An adequate description of the ultimate and proximate mechanism can integrate these views. Proximately, the perception of an object's state activates the subject's corresponding representations, which in turn activate somatic and autonomic responses. This mechanism supports basic behaviors (e.g., alarm, social facilitation, vicariousness of emotions, mother-infant responsiveness, and the modeling of competitors and predators) that are crucial for the reproductive success of animals living in groups. The Perception-Action Model (PAM), together with an understanding of how representations change with experience, can explain the major empirical effects in the literature (similarity, familiarity, past experience, explicit teaching, and salience). It can also predict a variety of empathy disorders. The interaction between the PAM and prefrontal functioning can also explain different levels of empathy across species and age groups. This view can advance our evolutionary understanding of empathy beyond inclusive fitness and reciprocal altruism and can explain different levels of empathy across individuals, species, stages of development, and situations.

This paper proposes that human expression of pain in the presence or absence of caregivers, and the detection of pain by observers, arises from evolved propensities. The function of pain is to demand attention and prioritise escape, recovery, and healing; where others can help achieve these goals, effective communication of pain is required. Evidence is reviewed of a distinct and specific facial expression of pain from infancy to old age, consistent across stimuli, and recognizable as pain by observers. Voluntary control over amplitude is incomplete, and observers can better detect pain that the individual attempts to suppress rather than amplify or simulate. In many clinical and experimental settings, the facial expression of pain is incorporated with verbal and nonverbal vocal activity, posture, and movement in an overall category of pain behaviour. This is assumed by clinicians to be under operant control of social contingencies such as sympathy, caregiving, and practical help; thus, strong facial expression is presumed to constitute an attempt to manipulate these contingencies by amplification of the normal expression. Operant formulations support skepticism about the presence or extent of pain, judgments of malingering, and sometimes the withholding of caregiving and help. To the extent that pain expression is influenced by environmental contingencies, however, “amplification” could equally plausibly constitute the release of suppression according to evolved contingent propensities that guide behaviour. Pain has been largely neglected in the evolutionary literature and the literature on expression of emotion, but an evolutionary account can generate improved assessment of pain and reactions to it.

We propose that the isomorphism generally observed between the representations composing our momentary phenomenal experience and the structure of the world is the end-product of a progressive organization that emerges thanks to elementary associative processes that take our conscious representations themselves as the stuff on which they operate, a thesis that we summarize in the concept of Self-Organizing Consciousness (SOC).

The Perception-Action Model (PAM) is a cogent theory of how organisms get information about others' experiences. However, such a stimulus-driven mechanism does not handle well the complex choices that humans face about how to respond to this information. Hyperbolic reward discounting permits a reward-driven mechanism for both how aversive empathic experiences can compete for attention and how pleasurable empathic experiences are constrained.

As stressed by Perruchet & Vinter, the SOC model echoes Johnson-Laird's mental model theory. Indeed, the latter rejects rule-based processing and assumes that reasoning is achieved through the manipulation of conscious representations. However, the mental model theory as well as its modified versions resorts to the abstraction of complex schemas and some form of implicit logic that seems incompatible with the SOC approach.

Those who assume domain specificity or conceptual modularity face Fodor’ Paradox (the problem of “combinatorial explosion”). One strategy involves postulating a metamodule that evolved to take as input the output of all other specialized conceptual modules, then integrates these outputs into cross-domain thoughts. It’ difficult to see whether this proposed metamodular capacity stems from language or theory of mind.

We argue that the pivotal role assigned by Northoff to the principle of top-down modulation in catatonia might successfully be applied to other symptoms of schizophrenia, for example, hallucinations. Second, we propose that Northoff's account would benefit from a more comprehensive analysis of the cognitive level of explanation. Finally, contrary to Northoff, we hypothesize that “top-down modulation” might play as important a role as “horizontal modulation” in affective-behavioral alterations.

According to Pylyshyn, depictive representations can be explanatory only if a certain kind of first-order isomorphism exists between the mental representations and real-world displays. What about a system with second-order isomorphism (similarities between different mental representations corresponding with similarities between different real-world displays)? Such a system may help to address whether “depictive” representations contribute to the visual nature of imagery.

The facial expression of pain is the end product of a complex process that is, in part, emotional. The evolutionary study of facial expression must account for the social nature of human consciousness and should address the questions of why empathy exists, the adaptive importance of empathy, and whether facial expression is a mechanism of empathy and second-person consciousness.

Thought uses meaning but not necessarily language. Meaning, in the form of a set of possible concepts and ideas, is a nonphysical reality that lay waiting for brains to become smart enough to represent these ideas. Thus, the brain evolved, whereas meaning was discovered, and language was invented – collectively – as a tool to help the brain use meaning.

Human pain experience and expression evolved to serve a range of social functions, including warning others, eliciting care, and influencing interpersonal relationships, as well as to protect from physical danger. Study of the relatively specific, involuntary, and salient facial display of pain permits examination of these roles, extending our appreciation of pain beyond the prevalent narrow focus on somatosensory mechanisms.

In agreement with some of the ideas expressed by Perruchet & Vinter (P&V), we believe that some phenomena hitherto attributed to “unconscious” processing may in fact reflect a fundamental distinction between direct and reflexive forms of consciousness. This dichotomy, developed by the phenomenological tradition, is substantiated by examples coming from experimental psychology and lesion neuropsychology.

A composite cognitive model of a neuropsychiatric condition should integrate clinical symptoms with the impairments of cognitive information processing. A model of catatonia, for example, should emphasize deficits of nonconscious information processing that impair a patient's ability to use implicit motor feedback for execution and termination of a voluntary motor activity.

The “Perky effect” is the interference of visual imagery with vision. Studies of this effect show that visual imagery has more than symbolic properties, but these properties differ both spatially (including “pictorially”) and temporally from those of vision. We therefore reject both the literal picture-in-the-head view and the entirely symbolic view.

A primary function of empathy is to help individuals form and maintain social bonds. Empathy should thus occur only when individuals seek to solidify social bonds, and not in response to any opportunity to process others' emotions. Empathy should also involve only certain types of emotion – specifically, emotions that facilitate social bonds – and not any and all types of emotion.

Right brain-damaged patients with unilateral neglect, who ignore left-sided visual events, may also omit left-sided details when describing known places from memory. Modulating the orienting of visual attention may ameliorate imaginal neglect. A first step toward explaining these phenomena might be to postulate that space-related imagery is a cognitive activity involving attentional and intentional aspects.

The hypothesis in the target paper is that the cognitive function of language lies in making possible the integration of different types of domain-specific information. The case for this hypothesis must consist, at least in part, of a constructive proposal as to what feature or features of natural language allows this integration to take place. This commentary suggests that the vital linguistic element is the relative pronoun and the possibility it affords of forming relative clauses.