Chapter 6 Introduction

Young man: Photodisc/Getty Images; landscape: peter zelei/Vetta/Getty Images
Licensed Material is being used for illustrative purposes only; person depicted in the licensed Material is a model

The kaleidoscope that makes a day or a year of mental life has both fast-moving and slow-moving components. Sensations, perceptions, thoughts, and muscle movements flit through our consciousness and behavior at speeds measured in milliseconds. But slower changes, measurable in minutes or hours, modulate and help direct these rapid changes. These slower-changing components of the mind are referred to as behavioral states; they include variations in motivation, emotion, and level of arousal.

Are you hungry right now, or angry, or sleepy? Even as you attempt to study this chapter, your mental state affects your capacity to pay attention, and it may direct your attention to some things over others. If you are hungry, your thoughts of food may capture most of your attention. If you are sleepy, your reaction even to the most interesting ideas in the chapter might be “oh hmmmm…zzzzzz.” Clearly, your mental state affects your momentary thoughts and actions. But what affects your mental state? What exactly makes you hungry, angry, or sleepy? This question links psychology tightly to the study of the brain and its interactions with the body’s internal environment as well as the external environment.

This chapter is about the physiological underpinnings of motivation and emotion. You will read first about the general concept of motivation from a physiological perspective, then about reward mechanisms in the brain, and then about hunger, the sexual drive, sleep, dreams, and emotionality—in that order. Social and cultural influences on motivation and emotion, which are only touched on here, are discussed more fully in later chapters.