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3 motivation and emotion
JERRY A. HOGAN
INTRODUCTION
The word motivate means “to cause to move,” and I will use the concept of motivation to refer to the study of the immediate causes of behavior: those factors responsible for the initiation, maintenance, and termination of behavior. Thus, motivation is another word for aspects of Tinbergen’s causal question (see Chapter 1). Causal factors for behavior include stimuli, hormones, and the intrinsic activity of the nervous system. How do these factors cause a female rat to behave maternally to her pups? Or a chicken to bathe in dust in the middle of the day? Or a male stickleback fish to stop responding sexually to receptive females? These are the types of questions asked in the first part of this chapter.
Motivated behavior often produces emotion, but the concept of emotion is problematic because there is no consensus about its definition. In the second part of this chapter I will analyze the concept of emotion as applied primarily to humans and conclude with a section on nonhuman emotion and its relation to animal welfare.
Behavior Systems
A major problem in the study of both motivation and emotion is that different authors use these concepts in different ways. The concept of a behavior system is useful in understanding many of these differences. I have proposed perceptual, central, and motor mechanisms as the basic structural units of behavior. These entities are viewed as corresponding to structures within the central nervous system. They consist of an arrangement of neurons (not necessarily localized) that acts independently of other such mechanisms. Perceptual mechanisms analyze incoming sensory information and solve the problem of stimulus recognition. An example is the releasing mechanism discussed in Chapter 2. The motor mechanisms are responsible for coordinating the neural output to the muscles, which results in recognizable patterns of movement. The central mechanisms coordinate the perceptual and motor mechanisms and also provide the basis for an animal’s mood or internal state. These units are called behavior mechanisms because their activation results in an event of behavioral interest: a particular perception, a specific motor pattern, or an identifiable internal state.
Behavior mechanisms can be connected with one another to form larger units called behavior systems, which correspond to the level of complexity indicated by feeding, sexual, and aggressive behavior (Baerends 1976; Hogan 2001). The organization of the connections among behavior mechanisms determines the nature of the behavior system. Thus, a behavior system can be considered a description of the structure of behavior. A pictorial representation of this concept is shown in Figure 3.1.
Figure 3.1 Conception of behavior systems. Stimuli from the external world are analyzed by perceptual mechanisms. Output from the perceptual mechanisms can be integrated by central mechanisms and/or channeled directly to motor mechanisms. The output of the motor mechanisms results in behavior. In this diagram, central mechanism I, perceptual mechanisms 1, 2, and 3, and motor mechanisms A, B, and C form one behavior system; central mechanism II, perceptual mechanisms 3, 4, and 5, and motor mechanisms C, D,and E form a second behavior system; 1-A, 2-B, and so on can also be considered less complex behavior systems. (From Hogan 1988).
Causal factors not only motivate behavior, they can also change the structure of behavior; that is, they have developmental effects. The formation of associations and the effects of reinforcement are developmental processes, and developmental processes have played an important role in many theories of motivation, especially in experimental psychology (see Hogan 1998). In this chapter, I will restrict the term motivation to the modulating effects causal factors have on the activation of behavior mechanisms. Development refers to the permanent effects causal factors have on the structure of the behavior mechanisms and on the connections among the behavior mechanisms and is discussed in Chapters 7 and 8. Emotion is considered to be one of the consequences of activating behavior mechanisms and will be discussed later.
Some Motivational Issues
In addition to problems concerning the definition of the concept of motivation, there have been four issues that have dominated discussions of motivation. 1. What role should a concept of energy play in motivational theories? 2. What is the relative role of internal versus external causal factors? 3. Do causal factors have specific or general effects? 4. Is the locus of action of causal factors peripheral or central? I will briefly discuss each of these issues in this section.
The concept of motivational energy
One attribute of living matter is its activity, the continuous transformation of energy from one form to another. It was natural, therefore, when people began to seek explanations of their own activity, to invoke some concept of energy. And indeed, the earliest scientific theories of motivation invoked concepts such as instinctual impulses (James 1890), libido (Freud 1905, 1915), and psycho-physical energy (McDougall 1923). Within American psychology these concepts became replaced by the concept of drive, but as Lashley (1938) pointed out, drives continued to have all the dynamic properties of the old instinctual urges. A particularly influential theory of motivation was proposed by Lorenz (1937). The core of his theory was an energy variable, action-specific energy, discussed below. For a variety of reasons all these theories were strongly criticized (Hinde 1960), and energy concepts quickly disappeared from most accounts of behavior. However, some authors have pointed out that many of the phenomena that used to be explained using energy concepts are still not accounted for by other concepts: they have suggested that an energy concept may still play a useful theoretical role (e.g., Toates & Jensen 1991; Hogan 1997). We will see some examples later in the chapter.
External versus internal causal factors
In popular usage, the word motivation often refers only to internal causes of behavior. We speak of an animal’s search for food as motivated by hunger, but of chewing and swallowing as reflex actions to stimuli in the mouth. On close inspection, however, it turns out that a thoroughly sated animal will often spit out the
