Neurocognitive Development: Normative Development

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• Publisher: Elsevier
• Year: 2019
• ISBN:
  9780444641519
• Topic: Medicine
• Subtopic: Neurology

This is one of a two-volume work on neurocognitive development, focusing separately on normative and non-normative development. The normative volume focuses on neurology, biology, genetics, and psychology of normative cognitive development. It covers the development of intellectual abilities, visual perception, motor function, language, memory, attention, executive function, social cognition, learning abilities, and affect and behavior. The book identifies when and how these functions develop, the genetics and neurophysiology of their operation, and their evaluation and assessment in clinical practice.

This book will serve as a comprehensive reference to researchers in cognitive development in neuroscience, psychology, and medicine, as well as to clinicians and allied health professionals focused on developmental disabilities (child neurologists, pediatric neuropsychologists, child psychiatrists, speech and language therapists, and occupational therapists.)

• Summarizes research on normative neurocognitive development
• Includes intellectual abilities, language, memory, attention, motor function, and more
• Discusses genetics and environmental influences on development
• Provides interdisciplinary information of use to both researchers and clinicians

Section IV

Neuroscientific basis of typical functional neurodevelopment

Chapter 11: Intellectual abilities

Roberto Colom* Department of Biological and Health Psychology, Universidad Autónoma de Madrid, Madrid, Spain
^* Correspondence to: Roberto Colom, Ph.D., Biological and Health Psychology, Universidad Autonoma de Madrid, Facultad de Psicologia, Madrid 28049, Spain. Tel: + 34-914-974-114, Fax: [phone]. email address: [email protected]

Abstract

Intelligence is a crucial psychologic construct for understanding human behavioral differences. This construct is based on one of the most replicated findings in psychology (the positive manifold): individuals can be reliably ordered according to their cognitive performance. Those showing high levels in ability X are more likely to show high levels in the remaining abilities, while those showing low levels in ability X are more likely to show low levels in the remaining abilities. Intelligence is characterized as a general cognitive ability integrating more than 80 distinguishable but related abilities. The mainstream definition states that intelligence is a general mental ability for reasoning, planning, solving problems, think abstractly, comprehending complex ideas, and learning. Intellectual abilities are measured by standardized tests showing highly reliable and valid indices. Intelligence is a highly stable psychologic trait, but different abilities change following disparate trends across the life span. These average trends, however, (a) hide the wide range of individual differences in the rates of change and (b) are consistent with the fact that abilities show orchestrated changes, which is consistent with the positive manifold. This chapter presents examples of the conventional testing paradigm along with recent developments based on cognitive psychology and cognitive neuroscience.

Keywords

Intelligence; Intellectual abilities; Standardized tests; Psychometric models; Cognitive psychology; Cognitive neuroscience

Definition of Intelligence

Humans perceive, attend, memorize, speak, reason, and do things that other humans can see. Furthermore, there are substantial individual differences in what humans do inside their brains with the information out there. All humans speak, but there are huge variations in the way they use language. All humans can memorize information in the long term, but its organization and how it is managed may change dramatically from person to person. All humans can reason, but reasoning problems with low, medium, and high levels of complexity cannot be completed by them all with the same efficiency.

We can focus on each of these cognitive and intellectual abilities (perception, attention, memory, language comprehension, language production, visuospatial processing, reasoning, etc.) and there might be sound motives for doing that. However, it is a fact of nature that humans must combine online all these factors for showing behaviors that may or may not be appropriate for the situation at hand. “Appropriate” means adaptive, but the term also involves (a) active selection of the right context considering its varied features, and, especially, (b) modifying the situations when required to achieve the desired outcome. The noted combination of cognitive factors fits the psychologic concept of intelligence. Indeed, this concept can be characterized as an integrative general cognitive ability (usually denoted by the letter g) (Colom and Martínez, 2019).

In this regard, the scientific community defines intelligence as “a very general mental capability that involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly, and learn from experience” (Gottfredson et al., 1997; Warne et al., 2018). From the framework that this definition provides, several standardized measures (tests) have been developed in the last century. We show in the following text a case example of these measures, but for now it is enough to say that the scores obtained after the administration of well validated standardized tests do show excellent reliability and valid psychometric properties (Sackett et al., 2017).

Strenze (2015) summarized several meta-analyses regarding the predictive validity of intelligence scores obtained after the administration of standardized tests. Table 11.1 shows a subset of the results reported by this author.

Table 11.1

Predictive validity of intelligence scores obtained from standardized tests (Strenze, 2015)

Criterion measure	Predictive validity
Educational attainment	0.56
Job performance	0.53
Skill acquisition in work training	0.38
Becoming a leader of a group	0.25
Income	0.20
Having anorexia nervosa	0.20
Participation in group activities	0.18
Creativity	0.17
Traffic accident involvement	− 0.12
Having schizophrenia	− 0.26

Research has identified more than 60 socially relevant correlates of intelligence scores (Jensen, 1998; Hunt, 2011a,b), and perhaps the most striking relationship has been identified by cognitive epidemiology (Deary et al., 2010). Here is an example.

Studying 75,252 individuals, Calvin et al. (2017) reported associations between premorbid intelligence assessed at 11 years of age and several causes of death (coronary heart disease, stroke, smoking related cancers, respiratory disease, digestive related disease, external causes, and dementia) analyzed 68 years later: higher scores on a standardized intelligence test, administered in childhood, were associated with lower risk of mortality 7 decades later (Fig. 11.1).

Fig. 11.1 Association between intelligence (Moray House test) assessed at age 11 and 3 causes of death (age and sex adjusted hazard ratios and 95% confidence intervals) at age 79. Data from the Scottish Mental Survey 1947 (Calvin, C., Batty, G.D., Der, G., et al., 2017. Childhood intelligence in relation to major causes of death in 68 year follow-up: prospective population study. BMJ 357, j2708).

These are examples of the observed effect sizes (Cohen's d): (1) respiratory disease (d = 0.44), (2) coronary heart disease (d = 0.46), and (3) stroke (d = 0.46). The remaining outcomes fell in the range d = 0.48–0.53, except for cancers that were not related to smoking.

Why do scientists find these intelligence–health associations interesting? At least two hypotheses have been proposed.

First, the system integrity hypothesis suggests that individual differences in the integrity of the organism may account for the relationship between premorbid intelligence and health outcomes. Performance on intelligence tests captures brain efficiency and also a high-performance body in general: “low cognitive ability is a marker of neuroanatomical deficits that increase vulnerability to multiple different common psychiatric disorders” (Caspi and Moffitt, 2018).

Second, people make decisions that promote healthy brains in healthy bodies. Life can be conceived as a very long intelligence test and, therefore, people showing higher in...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Handbook of Clinical Neurology 3rd Series
• Foreword
• Preface
• Contributors
• Section I: Introduction to neurodevelopmental disabilities
• Section II: Biological basis of typical neurodevelopment
• Section III: Plasticity, vulnerability and evolutionary constraints of the developing brain
• Section IV: Neuroscientific basis of typical functional neurodevelopment
• Section V: Etiologies of neurodevelopmental disorders
• Index