Owen Aldis about his book and the methods he used:

The research methods employed in this study are mainly those of zoologists (ethologists) who study animal behavior as distinguished from the methods of American psychologists. Although the two research tradi­tions have tended to converge in recent years, ethologists have generally stressed the study of behavior under natural conditions, field studies, broad surveys of the behavior patterns of a species (ethograms), precise description, and classification, while American psychologists have placed greater emphasis on laboratory studies, more narrowly focused studies of individual behaviors, experimentation, quantification, and statistics. American psychologists have been eager to emulate the most advanced methods of twentieth century natural science, and by the usual standards of twentieth century science, American psychology appears more ad­vanced than ethology. However, as I shall argue in the final chapter, these appearances can be deceptive. Elementary observation, description, and classification must in many cases precede more advanced methods of study. In their haste to embrace the most advanced methods, psy­chologists have often skipped over some of the more primitive stages that most other sciences have had to pass through. Premature quantification, based on classifications that are too broad or too crude, can be misleading or meaningless, and detailed description must often precede classification.

Naturalistic Observation
Although it may not seem very “scientific” by twentieth-century standards, one can sometimes learn a great deal about behavior by simply sitting down and watching it, and the value of simple observations of this kind is often enhanced by making them under natural conditions.

In the literature on animal behavior, there are many examples of be­ haviors studied by psychologists under artificial conditions that, when re-examined by ethologists under more natural conditions, turned out to be distorted (review in Eibl- Eibesfeldt, 1970). These facts are now well known, and today most animal psychologists have learned to rear their animals under more natural conditions. However, the distortions that result from studying human behavior under artificial conditions are less well recognized.

It is extremely simple to observe play behavior under natural con­ ditions so that there is really no excuse for studying it under artificial conditions. Some other forms of human behavior, however, most notably fear and aggression, which may occur only rarely, present more difficult problems. Consequently, they have almost never been studied under natural conditions, and psychologists have resorted to the study of all sorts of substitute situations instead. However, I do not think that at­ tempts to make observations of real human behavior should be aban­doned just because they are difficult-more patience, more ingenuity, and new methods (for example, hidden camera techniques) will be needed. We cannot sidestep these difficulties by studying surrogate situations; we must study the real thing.

In addition to play, fear, and aggression, I suspect that there are a number of other human behaviors that can be studied profitably by ethological methods. The most notable of these is the ontogeny of exploratory and manipulatory behaviors in infants and young children.