The Introduction summarises the core themes of the book and outlines how the argument will proceed over the course of its chapters. It explains why the issue it centres around – namely, how the law grapples with the impact of mental disorder on decision-making – is so important, and why successfully navigating the tension between respect for (and deference to) idiosyncratic values, and protection from disorder or impairment, must be a precondition of England and Wales adopting ‘fused’ mental capacity and health legislation, or a more CRPD-compliant statutory framework. It also explains how the book relates to the existing literature in this area, which has focused in recent years on concerns about the binary nature of the capacity framework, and on the individualistic and rational ‘liberal subject’ on which this framework rests. Finally, it elaborates briefly on some of the concepts which the book will draw upon, in particular what is meant by ‘values’ and ‘beliefs’.

Processing speed and cognitive control show a negative correlation. The more automatic a behavior the less cognitive control is needed and the information is processed faster. Faster processing allows the system to integrate more content efficiently. The chapter uncovers how this interaction between processing speed and cognitive control is influenced by age; task type and complexity; targeted cognitive functions; and children’s language skills. Although the analysis of the relationship between processing speed and cognitive control reveals notable individual differences, monolingual children with developmental language disorder (DLD) generally perform slower than their typically developing peers, whereas bilingual children often outperform their monolingual peers in processing speed. Bilingual children with DLD provide an unparalleled opportunity to study the joint effects of bilingualism and DLD on processing speed. The preliminary findings suggest that bilingualism does attenuate the negative effects of DLD but only in simple task conditions.

The foregoing discussion has highlighted the fundamental fragility of assessments of capacity, which hinge on a series of complex yet unavoidable clinical judgements about the person’s cognitive capacities and the origins of the beliefs or values that motivate their decision. This chapter will explore the implications of this for best interests assessments and, in particular, the extent to which due weight is currently being given to the person’s authentically held values and beliefs in the assessment of their best interests. Drawing on case law, interviews, and post-legislative scrutiny of the Mental Capacity Act, it will conclude that despite a number of empowering court decisions, the lack of direction contained in the Act on how to apply the MCA has still resulted in different weight being attributed to the agent’s wishes. Moreover, the trend towards greater empowerment has not yet trickled down to decisions being taken on the ground by doctors and care workers, which still remain characterised largely by paternalism and risk aversion. Those undertaking best interests assessments could therefore benefit from a more unified starting point and greater clarity on the factors which ought to influence the degree of weight accorded to the individual’s wishes.

The focus in this chapter is on methodological problems in cognitive-linguistic research, with particular attention to the bilingualism and the childhood language impairment literatures. The discussion is centered around the importance of having solid conceptual frameworks, appropriate participant selection criteria, sensitive and reliable tasks, and corresponding data analysis. Efficient and dynamic research designs are needed if we want to respond to the challenges created by today’s diverse language practices and life experiences of children. Although it is impossible to offer wide-ranging solutions to all of these questions in one chapter, the goal is to demonstrate the complexity of the problems and illustrate how the use of an individual-differences approach and the collaboration among researchers, educators, and clinicians may bridge the gap between scientific research and clinical and educational practice to improve research, assessment, and intervention of cognitive control in speakers from diverse cultural and linguistic backgrounds.

The complex interactions between cognitive control and language ability and those between cognitive control and language proficiency are reviewed first separately and then in relationship to each other, and in association with the development of academic skills and social interactions. Both behavioral and neurophysiological studies suggest that language ability and proficiency modulate the engagement of cognitive control processes, particularly working memory, attention, and interference control. Thus, better language abilities and higher bilingual language proficiencies are associated with superior cognitive control performance, whereas language disorder and low bilingual language proficiency are linked to weaker cognitive control performance. Response inhibition, however, does not show a close link with language skills; children with different language abilities and proficiencies may perform similarly on tasks of response inhibition. Age, prior experience, and variation in task types may all influence these relationships.

The Introduction provides a brief review of the overall aims and conceptual and methodological approaches of the book, with a focus on the dynamic interactions between cognitive control and language. It highlights the interdisciplinary nature of the discussions and the integration of behavioral and neurophysiological outcomes throughout the chapters. A further goal is to point to the need for a connection between theoretical models and educational/clinical practices and to facilitate a discussion between researchers and educators/clinicians. The Introduction also includes a short summary of each chapter by presenting the main ideas and critical issues about the development of cognitive control in children with various language skills (e.g., children with language talent, children with bilingualism as their first language, children with developmental language disorder, emerging bilingual speakers).

Where the real basis for finding someone to lack capacity is that you consider the beliefs or values that motivate their decision to be distorted by a mental illness, such that the decision is not authentically desired and so is unworthy of respect, this entails a number of empirical and normative claims. This chapter will interrogate these claims by reference to the wide-ranging literature on the nature of mental disorder, and on differing conceptions of autonomy and authenticity (as a component of autonomous decision-making). It will be concluded that while an agent acting on the basis of disordered beliefs or values will often be acting inauthentically (and thus non-autonomously), this will not always be the case, and situations could arise in which there is reason to believe that the agent would endorse or sanction their belief, even knowing it is derived from illness. Moreover, once the shaky conceptual ground on which such judgements must be made is acknowledged, it becomes essential that these judgements are brought out into the open, where they can be subject to appropriate scrutiny.

This chapter provides an overview of the interactions among language, cognition, and social context by examining how individuals with different language abilities and varying language proficiencies respond to assorted social-communicative demands. The analysis of the social context reveals how local (e.g., language register use) and global (e.g., culture, socioeconomic status) changes affect children’s cognitive control and language performance, as indicated by neural and behavioral findings. Social context at the local level is more dynamically changing than the context at the global level, which is more predictable. Children rely on different cognitive control functions in neutral, cooperative, and competitive social contexts. They adapt their cognitive system more efficiently in cooperative and competitive contexts, compared to a neutral one. Children’s behavior across these social situations is most strongly influenced by their age, cultural background, socioeconomic status, language skills, and emotion regulation.

The law adopts a cliff-edge approach to capacity, drawing a bright line between those who are deemed to have the capacity to make a decision and those who are not. This reflects Enlightenment ideas about the limits of legitimate state authority, according to which substantial justification is required before the state can interfere with the autonomous choices of its citizens. Given its role in distinguishing those who are capable of making autonomous choices (to whom the state defers) from those who are not, it is generally assumed that the test for capacity must be neutral as to the substance of the values, beliefs, or reasons underpinning any given decision, so as to leave proper space for individual autonomy. As a result, the Mental Capacity Act 2005 adopts a process-orientated account of capacity, which focuses on whether certain of the person’s cognitive capacities are intact, and not on the outcome of the decision, or on the substance or origins of values or beliefs which underpin it.

This chapter considers how the law might be reformed so as to better capture circumstances in which an agent’s capacity for autonomous decision-making is being undermined by a disorder or impairment which affects the values or beliefs that the agent applies to the information. It will begin by exploring the merits of including an ‘appreciation’ criterion in the test for capacity, before going on to consider whether more other, more explicit, criteria would be preferable. It will conclude that the challenges inherent in devising a workable legal test lean in favour of the law adopting a more blunt approach which focuses on the origins of the values or beliefs that the agent applies to the information in their decision-making. A new limb of the MCA is therefore proposed, which asks whether the person is unable to make a decision because the values or beliefs by which they evaluate the relevant information have been caused by or altered as a consequence of the person suffering from a disorder, illness, or impairment. Various potential challenges to such a provision will be explored and responded too.

This chapter introduces the key concepts and major theoretical accounts of cognitive control (e.g., conflict monitoring, the expected value of control) that seek to answer fundamental questions about the control mechanisms, the recruitment of control resources, the selection of task-relevant processes, and the prevention of interference. Although some of the theories focus more on the regulatory processes, while others on the evaluative mechanisms, most of them complement each other. Essential questions, such as the sources of capacity limitations, the continuum between control and automaticity, cognitive flexibility as a marker, the effects of contextual changes, and individual differences in both behavioral performance and neural activity are critically discussed throughout the chapter. The most widely used behavioral paradigms and their outcome measures (e.g., congruency effects, intrusion cost, switching cost, practice effects, post-error slowing and post-error reduction of interference) are presented and linked to different conceptual constructs.