flow over to a behavior system that was not blocked (e.g., nest building) and a displacement activity would be seen. The appropriate behavior might be prevented from occurring because of interference from an antagonistic behavior system (e.g., fear or escape) or the absence of a suitable object or thwarting of any sort.
This theory was formulated in the framework of Lorenz’s model of motivation, which accounts for the graphic metaphor of energy sparking over or overflowing. In more prosaic terms, this is actually a theory in which causal factors have general as well as specific effects. Many examples of displacement activities are described as being incomplete or hurried—the stickleback does not calmly proceed to build a nest during a boundary conflict—and such observations give support to a theory that posits general effects of causal factors. It can be noted that Freud’s (1940/1949) theory of displacement and sublimation of sexual energy (libido) is basically the same as the overflow theory: sexual energy is expressed in nonsexual activities such as creating works of art.
The alternative theory is called the disinhibition theory. In essence, it states that a strongly activated behavior system normally inhibits weakly activated systems. If, however, two behavior systems are strongly activated (e.g., sex and aggression), the inhibition they exert on each other will result in a release of inhibition on other behavior systems (e.g., parental) and a displacement activity will occur. The general idea was proposed by several scientists, but the most detailed exploration of the theory was made by Sevenster (1961). He studied displacement fanning in the male stickleback, which often occurs during courtship before there are any eggs in the nest. The sex and aggression behavior systems are known to be strongly activated during courtship. By careful measurements, it was possible to show that fanning occurred at a particular level of sex and aggression when their mutual inhibition was the strongest. Of special importance for the disinhibition theory, the amount of displacement fanning that occurred depended on the strength of causal factors for the parental behavior system. When extra CO2 was introduced into the water, there was an increase in fanning.
The primary difference between the two theories is that according to the disinhibition theory the displacement activity is motivated by it own normal causal factors and the conflict between systems merely serves a permissive role; whereas according to the overflow theory the displacement activity is motivated by causal factors for one or both of the conflicting systems. In the disinhibition theory, causal factors always have specific effects; in the overflow theory, they have general effects. Which theory is correct? As is so often the case, neither theory, by itself, is able to account for all the phenomena associated with displacement activities. The disinhibition theory is in many ways more satisfying because it only requires that causal factors have their normal and expected effects on behavior. Nonetheless, more general effects of causal factors must be invoked to account for the frantic or excited aspects of displacement activities seen in many situations.
It is frequently true that the causation of a behavior pattern is even more complicated. For example, ground pecking occurs as a displacement activity during aggressive encounters between two male junglefowl. Arguments for considering this activity as a displaced feeding movement include the fact that it is often directed to food pieces on the ground and the fact that it occurs more frequently when the animals are hungry. This same activity can also be considered redirected aggression, and experimental evidence also supports this interpretation. Thus, one behavior pattern can be both a displacement activity and a redirected activity at the same time (Feekes 1972). Each contribution to the causation of a behavior pattern can be analyzed separately, but the list of causal factors affecting the behavior pattern can be very long. Indeed, multiple causation of behavior is the rule rather than the exception. The causation of behavior is a very complex question, and it is unreasonable to expect a simple answer.
Mechanisms of Behavioral Change
What determines when a particular behavior will occur, how long it will continue, and what behavior will follow it? One can imagine that all an animal’s behavior systems are competing with each other for expression, perhaps in a kind of free-for-all. For example, if the level of causal factors for eating is very high, the hunger system will inhibit other systems and the animal will eat. As it eats, the causal factors for eating will decline while the causal factors for other behaviors, say drinking, will become higher than those for eating and the animal will change its behavior. If a predator approaches, the escape system will be strongly activated, which will inhibit eating and drinking, and the animal will run away. And so on.
Unfortunately, as attractive as this account appears, it is clearly an oversimplification of reality. Perhaps its most serious shortcoming is that if there were a real free-for-all and only the most dominant behavior system could be expressed, many essential but generally low-priority activities might never occur. If a hungry animal never stopped to look around for danger before the predator was upon it, it would not long survive. Since most animals do survive, this must imply that the rules for behavioral change are more complex than the “winner take all” model. Lorenz (1966) has compared the interactions among behavior systems to the working of a parliament that, though generally democratic, has evolved special rules and procedures to produce at least tolerable and practicable compromises between different interests. The special rules that apply to interactions among behavior systems have only begun to be studied, but a few principles are beginning to emerge.
One important mechanism for behavioral change arises from the fact that most behavior systems are organized in such a way that “pauses” occur after the animal has engaged in a particular activity for a certain time. The level of causal factors for the activity may remain very high, but during the pause other activities can occur. For example, in many species, feeding occurs in discrete bouts; between bouts there is an opportunity for the animal to groom, look around, drink, and so on. It appears that the dominant behavior system (in this case, the hunger system) releases its inhibition on other systems for a certain length of time. During the period of disinhibition, other behavior systems may compete for dominance according to their level of causal factors or each system may, so to speak, be given a turn to express itself. McFarland (1974) has compared these kinds of interactions among behavior systems with the “time-sharing” that occurs when multiple users share the same computer system.
A striking example of this sort of behavioral organization is the incubation system of certain species of birds. Broody hens sit on their eggs for about 3 weeks. Once or twice a day, the hen gets off the eggs for about 10 minutes. During this interval she eats, drinks, grooms, and defecates. The proportion of the 10 minutes spent eating will vary depending on the state of her hunger system, but even 24 hours of food deprivation does not change the pattern of leaving the eggs (Sherry et al. 1980).
Another type of mechanism for behavior change depends upon the reaction of an animal to discrepant feedback. A male Siamese fighting fish, for example, will not display as long to its mirror image as to another displaying male. This is because the behavior of the mirror image is always identical to the behavior of the subject, but identical responses are not part of the “species expectation” of responses to aggressive display (Bols 1977). These mechanisms, and undoubtedly many others, all interact to produce the infinite variety of sequences of behavior characteristic of the animal in its natural environment.
Human Emotion
Emotion is one of the consequences of activating various behavior mechanisms. But specifying the concept in more detail is problematic because there is no consensus about its definition. Books have been written on the subject (e.g., Ekman & Davidson 1994; Barrett & Russell 2015), and two major journals, Emotion and Emotion Review, publish studies on emotion. The term usually refers to certain subjective experiences called feelings, but observable features often accompany them. I have defined a feeling as the activation of a specific central behavior mechanism (Hogan 2015), but characterizing those behavior mechanisms that subserve emotion is as intractable as the concept of emotion itself. I think some insight into the problem can be gained by considering some of the views of
