Introduction

Nineteenth-century psychology began the experimental study of consciousness (Boring, 1950). Two competing early-20th-century North American schools of psychology, structuralism and functionalism, continued this tradition. A new school, behaviorism, attacked psychology’s mentalism, reacting against both structuralism and functionalism (Watson, 1913). “The time seems to have come when psychology must discard all reference to consciousness; when it need no longer delude itself into thinking that it is making mental states the object of observation” (Watson, 1913, p. 163).

Behaviorism soon dominated 20th-century psychology, changing the field’s topics and inspiring new methodologies. Behaviorism aimed to “remove the barrier from psychology which exists between it and the other sciences. The findings of psychology become the functional correlates of structure and lend themselves to explanation in physico-chemical terms” (Watson, 1913, p. 177). For behaviorists, behavioral theories explained, but mentalistic theories did not (Skinner, 1950, 1977, 1990).

Cognitive psychology began to replace behaviorism in the 1950s, bringing mentalism back to psychology (Glenberg et al., 2013; Leahey, 1992; Miller, 2003; Sperry, 1993). Discoveries in cybernetics and computer science inspired the cognitive revolution (Miller et al., 1960; Newell & Simon, 1956, 1961). Cognitivists argued that behaviorism could not explain phenomena such as language (Chomsky, 1959). Cognitivists claimed that behaviorists viewed humans as passive responders. Cognitivists instead viewed humans as active information processors.

Cognitivism dominates modern psychology. For example, my department lists 73 courses in its 2020–21 undergraduate calendar; nearly half (33) explore cognition, with titles such as “Cognitive Psychology,” “Spatial Cognition,” “Introduction to Cognitive Neuroscience,” “Social Cognition,” and “Theory and Learning in Comparative Cognition.”

The cognitive revolution ended decades ago. As the debate between cognitivism and behaviorism faded into history, cognitive psychology’s theoretical foundations also seemed to become forgotten. What is cognitive psychology?

I often ask students to define cognitive psychology to begin my third-year “Foundations of Cognitive Science” course. My students understand cognitive psychology’s core topics (e.g., attention, memory, and thinking), and they know typical methods for studying these topics. However, my students do not know cognitive psychology’s basic assumptions. They do not understand why we can use computers to model cognitive processing. They cannot describe differences between behaviorist and cognitivist explanations.

Why might my students understand cognitive psychology as a practice, as studying core topics via particular methods, but not understand cognitive psychology’s theoretical foundations? Modern textbooks present cognitive psychology in exactly this way.

Modern texts first describe cognitive psychology’s history and then provide several “topics” chapters. Topics move from sensation and perception (cognitive neuroscience, perception, attention) through middle-level topics (different kinds of memory) and end with central processing (language, thinking, problem solving). Modern texts depict cognitive psychology as experimental results about core topics.

Modern texts also define cognitive psychology as using four “approaches”: experimental psychology, cognitive neuroscience (studying normal brains via brain imaging), cognitive neuropsychology (studying psychological deficits arising from brain injury), and simulated cognition using computers. Unfortunately, using such approaches to define cognitive psychology plays fast and loose with theoretical foundations.

For example, cognitive psychology’s theories are functionalist, appealing to what processes do, not to their physical causes. Functionalism makes computer simulations of cognition plausible, even though computers and brains are physically different. However, problems emerge when one endorses functionalism while promoting cognitive neuroscience. Which theoretical foundations permit the physical brain not to matter, but also to matter, at the same time?

The philosophy of science uses functional analysis to answer this question (Cummins, 1983). Functional analysis explains agents as organized systems of functions. Each function is broken down into sub-functions. A functional analysis becomes explanatory by describing physical causes of its simplest functions.

Functional analysis proposes an approach to scientific explanation different from the one used by behaviorism and permits cognitive psychology’s four different approaches to be related. However, cognitive psychology textbooks rarely mention the philosophy of science. In short, students do not understand cognitive psychology’s theoretical foundations because the foundations are not presented in the discipline’s texts.

Why has cognitive psychology reached this state? When cognitive psychology arose, it constantly defended attacks against its core assumptions. Cognitive psychologists were forced to justify their approach. However, after vanquishing behaviorism, cognitive psychology has not faced serious challenges from competing schools of thought. Thus, it is complacent about its theoretical foundations.

In this book, I explore those foundations to address cognitive psychology’s complacency. The book takes a historical perspective but is not a history. It examines classic studies in cognitive psychology because the assumptions underlying classic studies arose while cognitive psychology actively defended its foundations against behaviorism.

As a result, this book offers a different treatment of cognitive psychology. If you want to survey cognitive psychology’s topics, then read a different book, such as a modern survey text. However, my hope is that, if you read this book first, you will better understand traditional topics presented in survey texts.

An older anti-survey text, Richard Mayer’s Thinking and Problem Solving: An Introduction to Human Cognition and Learning (1977), inspired my work in this book. Each chapter in Mayer’s wonderfully short book explores a different assumption about cognition (e.g., thinking as hypothesis testing, or as restructuring problems, or as searching semantic memory, or as information processing). Each chapter then shows how core assumptions are revealed in experimental studies.

Inspired by Mayer, I answer in this book the question “What is cognitive psychology?” by examining the theoretical foundations of cognitive psychology as follows.

Cognitive psychology assumes that cognition is information processing. Chapter 1 uses formal games to introduce information processing and describes similar processing in computers. Thus, Chapter 1 relates computer science to cognitive psychology.

Cognitive psychologists explain cognition in the same manner that computer scientists explain programs. However, cognitive psychologists cannot directly observe cognitive processes. Chapter 2 therefore describes methods for inferring unobservable processes and relates general experimental psychology to cognitive psychology.

Behaviorists criticized cognitive psychology’s mentalistic theories as providing descriptions, not explanations. Chapter 3 describes a different approach, functional analysis, to show how mentalistic theories can explain. The chapter discusses how such analysis affects cognitive psychology’s methods. Thus, Chapter 3 relates the philosophy of science to cognitive psychology.

The first three chapters introduce cognitive psychology’s theoretical foundations by relating cognitive psychology to computer science, to experimental psychology, and to the philosophy of science. These foundations do not restrict cognitive psychology’s variety. Chapter 4 describes a diversity of cognitive theories and relates them to the primary goal of functional analysis: identifying primitive functions, called the cognitive architecture. Thus, Chapter 4 illustrates how the ideas detailed in earlier chapters lead to competing theories, all of which seek the cognitive architecture.

Cognitive psychology not only permits competing architectural ideas but also allows many debates about its theoretical foundations. Chapter 5 introduces those debates. Each section explores a foundational question. Thus, Chapter 5 uses debates about core assumptions to reflect on cognitive psychology’s current state.

These five chapters introduce cognitive psychology by examining its theoretical foundations. The book introduces cognitive psychology to undergraduates but should also interest graduate students and established cognitive psychologists.

What is cognitive psychology? The book offers a definition that recognizes that theoretical foundations affect methodology: cognitive psychology is the branch of general psychology that explains psychological phenomena by using functional analysis to describe information processing.

To understand this definition, we must first understand cognitive psychology’s theoretical foundations. To begin, let us consider what “cognition is information processing” means.