Students of personality have been primarily interested in motivational dispositions in the individual. They have asked, What motives are there? How many are there? What are the most important motives? How do we know what motives a person has? This chapter's goal is to provide an overview of the answers to such questions that motivational theorists have given and, in particular, to consider how motives might be measured in people. Let us begin with the phenomena that have led theorists to assign motive dispositions to people.

• MOTIVES AS REASONS FOR WHAT PEOPLE SPEND THEIR TIME DOING

To a considerable extent there is a theory of motivation to go with every field of human endeavor. We observe that people do various things frequently and infer that therefore they must want to do them. People eat; therefore, they must want to eat. Some people do well in school, so we infer they have a need for academic success. Children play; therefore, they must have a need to play. Some people save; therefore, there must be a saving drive. People in business often work hard, and since business is organized around making a profit, economic theorists from the time of Karl Marx to the present have assumed they work because of the profit motive. In fact, a modern theorist like John Kenneth Galbraith (1967) has not hesitated to write a chapter in a book on economics entitled “The General Theory of Motivation” based on his observations of the various goals of economic enterprise.

• EARLY ATTEMPTS TO FIND A BIOLOGICAL BASIS FOR MOTIVES

Motives as we experience them are bewilderingly complex. We want to graduate from College. We would like to be respected by others. We want to be loved. We would like to get married. We would like some excitement in our lives. Or perhaps we would just like to be able to study harder. Where do these motives come from? Are they instinctive, as McDougall, Freud, and Maslow argued (see Chapter 2)? Are they simply the product of our learning to satisfy certain biological needs like hunger, as the behaviorist model argued (see Chapter 3)? Do we learn to want these things because our society teaches us that we should want them? Or are there some deeper drives guiding human action that shape society?

Initially many theorists like McDougall had found it easy simply to reason that certain fundamental urges were biologically built in, or instinctive. The behaviorists, however, were skeptical. They felt such a hypothesis was vague and impossible to test empirically. How could one prove that a drive for power, for example, was instinctive rather than built on social learning? Since the behaviorists were oriented entirely toward overt behavior (rather than inner “urges”), they not unreasonably asked what were the fixed action patterns, shown by all human infants (prior to learning), that would signal the presence of an innate power need.

• APPLYING EXPECTANCY-VALUE THEORY TO IMPROVING ACADEMIC PERFORMANCE

As it became evident in the 1960s that human motives were related to important human endeavors like entrepreneurship and management, investigators turned their attention to methods of changing motives to improve Performance. Since the emphasis was on Performance Output rather than on motive change in itself, these efforts to produce change can best be understood in terms of the formula for predicting response Output presented in previous chapters. According to that formula, response Output, given environmental opportunity, is a function of motive strength (M) times probability of success (Ps) times incentive value (V). Technically, response probability can be increased by changing environmental opportunity or any one of the three person variables in the equation. Early efforts to introduce change focused on affecting the probability of success variable. School learning or skill acquisition affects this variable. If people learn how to do something better, it by definition increases the probability of their succeeding at that activity and makes it more likely that they will carry out the activity if they are also motivated to do it and they value it. But motive development courses approached probability of success in a different way. They manipulated the perceived probability of success without teaching skills directly.

In Chapter 6 we examined in detail how individual differences in motive strength can best be measured, because in science, measurement is of central importance. Without it we would still be in the position of McDougall, speculating about what motives there are and how they affect behavior. This chapter and the next chapters in Part 3 attempt to summarize what has been found out about several social motives that have been measured by the method recommended in Chapter 6—by coding fantasy or spontaneous thought patterns. For each motive we will Start by explaining how the method of measuring it in fantasy was developed, then turn to the evidence indicating it really is a measure of a motive using the validity criteria established in Chapter 6, and finally summarize what is known about how people behave who score high in the motive measured in this way. Naturally, there has been curiosity about how people develop a strong motive of one type or another, so at the end of each chapter is a section summarizing what is known about how people acquire such a motive.

The emphasis on measurement may seem boring or unnecessary, but the fact is that progress has been made in the field of motivation only as some standardization in measurement occurred.

• THE MOTIVATIONAL SEQUENCE

What is needed now is a general model of motivated behavior. Experimentalists deal with motivation—with short-term situational influences like food, variety, requests for obedience, or electric shock that arouse approach or avoidance behavior immediately. Personality theorists or clinicians typically think in terms of motives, that is, stable dispositions that organize or explain much of what a person says and does. How do these two approaches fit together? What exactly is a motive disposition, and how should individual differences in its strength be measured? According to clinicians, some people, like Freud, have a strong need for fame, recognition, or power. How do we determine how weak or how strong the power motive is in different individuals? How is a disposition like the power motive aroused by a Situation, and when aroused, how does it influence what the person does? These are the questions to which this chapter is addressed.

Motives are based on emotionally arousing incentives, which were discussed in the previous chapters. The incentives Start out by being natural in the sense that they innately give rise to different types of positive or negative emotions. As we have seen, however, their nature changes rapidly with learning.

• COGNITIVE INFLUENCES ON MOTIVE AROUSAL

Several theorists, notably Weiner (1980a) and Heckhausen (1980), have stressed the great importance of cognitive factors in the motivation-action sequence. As Weiner (1979) puts it, “Comprehension Stands with hedonism as among the primary sources of motivation.” He feels that in motivation theory too much emphasis has been placed on affective arousal and not enough on the understanding the person has of what is happening during a motivation-action sequence, which determines whether affective arousal occurs or not.

A great many empirical studies have been carried out to clarify the relationship between cognition and motivation, but before reviewing them it is worth reexamining Figure 6.1, which identifies the key factors in a motivation-action sequence. Arousal demands (cues) typically contact an incentive, which, if it relates to an existing motive disposition, leads to an aroused motive or motivation to act. When, how, and whether this motivation gets converted into action is influenced by skills, cognitions (values), and opportunities, which determine whether a particular kind of behavior occurs or not.

As noted previously, Weiner, Atkinson, and others use the term motivation to describe the final excitatory potential for an act (the impulse to a given act) after it has been influenced by expectations and values, whereas we use the term motivation in the more restricted sense to refer to an aroused motive before it is influenced by expectations and values that shape preferences for particular acts.

Motivation has always fascinated people and will continue to fascinate them so long as there are people around to wonder why human beings and animals behave as they do. Nearly everyone develops an explicit or implicit theory of motivation. We think we know why our parents are sometimes disagreeable and try to continue to control what we do: they want the pleasure of continuing to dominate us. Or we think we know why our girlfriend or boyfriend has abandoned us: he or she prefers to be with someone with greater prestige or more possessions than we have. Or we think we know why we cannot seem to study very hard: we have a low need to achieve. Authors, philosophers, economists, politicians, and the people next door have all operated in terms of theories of motivation. Shakespeare vividly portrayed the lust for power in MacBeth and the longings of love in his Sonnets. Plato explored the nature of love in the Symposium. Economists think in terms of the desire to acquire possessions, and they write of the importance of the profit motive. Political observers from Machiavelli to the present have stressed the importance of the desire for power in human affairs.

• THE MEANING OF LOVE

People appear to have a basic need or desire to be with other people, just as most animals prefer to be with other members of their species. Part of the need is sexual in origin and biologically adaptive, because the two sexes must get together in order to reproduce the species. The need to affiliate with others includes sexual contacts, but it is much broader, including various types of emotional interpersonal attachments that may grow out of natural contact incentives as outlined in Chapter 4. What has always Struck observers about this need is how important it is to life and health, how pervasive it is, and how it appears in many different forms. The word love is commonly used to describe various types of affiliative ties, and everyone agrees that it is important to satisfy the love need, yet no one is quite sure, in the words of a popular song, “What is this thing called love?” Before we review modern psychology's attempt to answer this question, it will be helpful to turn first to an ancient treatment of the topic in Plato's Symposium. The Speakers at this banquet, as reported by Plato, managed to mention most of the important themes that have characterized discussions of the psychology of love ever since.

This book is not a textbook of biophysics, cell biology or the electrophysiology of excitable cells, as there are already a number of excellent books available which deal with these subjects. The book instead is an attempt to describe the origins and derivations of the principles upon which these other books are based.

To understand and apply the principles of excitability requires a knowledge of subjects as diverse as physiology, physics, mathematics, statistics, signal and system analysis. It is a difficult task to obtain this knowledge because the jargon in other fields is often obscure, mathematical proofs are frequently abstruse and generally many original manuscripts have to be consulted. We can both testify to the frustrations that accompany such efforts and this has therefore been written in an attempt to enable the reader to acquire more easily this knowledge. Half of the book is appendices which deal with many of the key concepts from a fairly basic level.

We have assumed that the reader has only a modest mathematical background (about G.C.E. ‘O’ level) and most formulae are derived from first principles. For people with mathematical ability this approach may be somewhat tedious but we make no apologies for this. We consider it necessary that most of the steps in the derivation of an important equation are left in. Far too often have we struggled to follow mathematical proofs that are presented by an author in two lines which in reality take pages to derive.

Introduction

In the previous chapter we showed that acetylcholine (Ach) is released in discrete packets (quanta) in an all-or-none way from the presynaptic nerve terminal. In this chapter we derive a statistical model of quantal release that occurs in synaptic transmission. Since the release of transmitter is probabilistic, the postsynaptic membrane potential randomly fluctuates around a mean value. These fluctuations, or membrane noise, will be analysed in some detail in the latter part of the chapter and used as an example of the way in which membrane noise can be studied more generally.

A probabilistic model of quantal release

It was seen in the last chapter that the actual number of quanta released is not an exact constant and, in fact, the number changes in a random way with every action potential that invades the nerve terminal. (The average number of released quanta per action potential depends on factors such as the calcium or the magnesium concentrations in the bathing fluid. Under normal conditions the average number of quanta released is around 1000. If the calcium is replaced by magnesium the average number of quanta released per action potential may be quite small. It is this situation that we shall be analysing.) Since the exact number of quanta released is not constant, this means that it is possible (although unlikely) that some action potentials may not release any quanta, while others will release one, or two, or more, quanta.

Diffusion of non-electrolytes in solution

In Chapter 2 we discussed the movement of ions in solution under the influence of an electric field. In this chapter we will first consider the movement of non-electrolytes down concentration gradients and then the movements of electrolytes subject to the joint effect of an electric field and a concentration gradient.

Figure 3.1a shows a slab of a solid non-electrolyte, interfaced to a cuboid of solvent of length l and of unit cross-sectional area (1 cm2).

The solid non-electrolyte might, for example, be sugar and sugar molecules can be imagined to be dissolving from the face of the sugar slab into the solvent. The solvent is unstirred and assumed not to react with the non-electrolyte. At time t, after the sugar slab has come into contact with the solvent, we obtain a concentration profile of the type shown in Figure 3.1b (t). This profile is due to solute molecules which move from a high concentration (the face of the sugar slab) to the lower concentration in the solvent. At different times (t1, t2, …, t) different concentration profiles will be obtained.

Fick's First Law

A quantitative treatment of these concentration profiles was first carried out by Fick (who adapted the problem previously solved by Fourier for the conduction of heat through a slab) and assumed that the rate at which a solute flows through a plane of area A at right angles to the flow, is proportional to this area A.

APPENDIX 1. Units and numbers

When electrophysiologists measure currents, voltages cr concentrations they measure physical quantities that are the same physical quantities that a physicist or chemist might deal with. In order to characterize precisely these entities it is necessary to specify two things:

1. (1) The quality of the units, and

2. (2) The numerical size of the units used.

Dimensions

We shall deal first with the quality of physical units and this quality is called the dimension. Natural scientists have agreed on a number of different systems of units. The two most widely used systems are the c.g.s. system in which the fundamental units are:

1. (L) length – centimetre

2. (M) mass – gram

3. (T) time – second

and then there is the MKS system with the fundamental units of:

1. (L) length – metre

2. (M) mass – kilogram

3. (T) time – second

The latter is the so-called rationalized MKS system, more closely related to the International System of Units (SI), which is coming steadily into universal use.

In Table 1 we give some physical units that are used in the two systems. More detailed information is available in Quantities, Units, and Symbols, a report by the Symbols Committee of the Royal Society, 2nd edn, 1975, and in Units of Measurement, Preprint from the Geigy Scientific Tables, 7th edn, 1968 (Basle, Switzerland: Geigy).