The theory of signals, or signalling theory , groups together a set of studies from the field of evolutionary biology, and suggests that the study of the signals exchanged in the communication process between individuals of any species can account for their evolutionary patterns, and can also help us to differentiate when the signals emitted are honest or dishonest.

We will see in this article what signal theory is, what honest and dishonest signals are in the context of evolutionary biology, as well as some of their consequences in studies of human behavior.

Signal theory: is deception evolutionary?

Studied in the context of biological and evolutionary theory, deception or lying can acquire an adaptive meaning . Transferred to the study of animal communication, deception is understood as being strongly linked to persuasive activity, since it consists mainly of providing false information for the benefit of the sender, even if it means harming the sender (Redondo, 1994).

The above has been studied by biology in different species of animals, including human beings , through the signals that individuals send to each other and the effects that these produce.

In this sense, evolutionary theory tells us that the interaction between individuals of the same species (as well as between individuals of different species), is crossed by the constant exchange of different signals. Especially when it is an interaction that involves some conflict of interest, the signals exchanged may seem honest, even if they are not.

In this same sense, the theory of signals has proposed that the evolution of an individual of any species is marked in an important way by the need to emit and receive signals in an increasingly perfected manner, so that this allows him to resist the manipulation of other individuals .

Honest Signs and Dishonest Signs: Differences and Effects

For this theory, the exchange of signals, both honest and dishonest, has an evolutionary character, since when a certain signal is emitted, the receiver’s behavior is modified, to the benefit of the one who emits it.

These are honest signs when the behavior corresponds to the apparent intent. On the other hand, they are dishonest signals when the behaviour appears to have an intention, but in reality has another one which is also potentially harmful for the receiver , and certainly beneficial for the sender.

The development, evolution and destiny of the latter, the dishonest signals, can have two possible consequences for the dynamics of some species, according to Redondo (1994). Let us see them below.

1. The dishonest signal is extinguished

According to signal theory, deceptive signals are especially emitted by those individuals who have an advantage over others. In fact, it suggests that in an animal population where there are predominantly honest signals, and one of the most biologically effective individuals initiates an honest signal, the latter will expand with speed .

But what happens when the receiver has already developed the ability to detect the dishonest signals? In evolutionary terms, the individuals who receive the dishonest signals generated increasingly complex evaluation techniques, in order to detect which signal is honest and which is not, which gradually diminishes the benefit of the transmitter of the deception , and finally causes its extinction.

From the above it can also happen that dishonest signals are eventually replaced by honest ones. At least temporarily, while increasing the probability that they will be used with dishonest intentions. An example of this is the threatening displays made by seagulls . Although there is a great variety of such displays, they all seem to have the same function, which means that a set of potentially dishonest signals have been set as honest signals.

2. The dishonest signal is fixed

However, another effect can occur in the presence and increase of dishonest signals. This is that the signal becomes permanently fixed in the population, which happens if all honest signals are extinguished. In this case, the dishonest sign remains no longer a dishonest sign, because in the face of the lack of sincerity the deception loses its meaning. It remains, then, as a convention that loses connection with the initial reaction of the one who receives it .

An example of the latter is as follows: a flock shares an alarm signal that warns of the presence of a predator. This is a sincere signal, which serves to protect the species.

However, if one of the members gives that same signal, but not when a predator approaches, but when it experiences a failure to compete for food with other members of its species, this will give it an advantage over its flock and cause the (now misleading) signal to be transformed and maintained. In fact, several species of birds perform false alarm signals to distract others from getting food.

The handicap principle

In 1975, the Israeli biologist Amotz Zahavi proposed that the emission of some honest signals is so costly that only the most biologically dominant individuals can afford to perform them .

In this sense, the existence of some honest signals would be guaranteed by the cost involved, and the existence of dishonest signals as well. This is finally a disadvantage for less dominant individuals who want to give false signals.

In other words, the benefit acquired by the emission of dishonest signals would be reserved only for the most biologically dominant individuals. This principle is known as the handicap principle (which in English can be translated as “disadvantage”).

Application in the study of human behavior

Among other things, signal theory has been used to explain some patterns of interaction , as well as the attitudes displayed during coexistence between different people.

For example, attempts have been made to understand, evaluate and even predict the authenticity of different intentions, objectives and values generated in interactions between certain groups.

The latter, according to Pentland (2008), occurs from the study of their signaling patterns, which would represent a second communication channel . Although this remains implicit, it allows us to explain why decisions or attitudes are made in the margin of the most basic interactions, such as in a job interview or in a first coexistence between strangers.

In other words, it has served to develop hypotheses about how we can know when someone is genuinely interested or attentive during a communicative process.

Bibliographic references:

  • Handicap principle (2018). Wikipedia The Free Encyclopedia. Retrieved September 4, 2018. Available at https://en.wikipedia.org/wiki/Handicap_principle.
  • Pentland, S. (2008). Honest Signals: How They Shape Our World. The MIT Press: USA.
  • Redondo, T. (1994). Communication: theory and evolution of signals. In: Carranza, J. (ed.). Etología: Introducción a la Ciencia del Comportamiento (Ethology: Introduction to Behavioural Science), Publications of the University of Extremadura, Cáceres, pp. 255-297.
  • Grafen, A. and Johnstone, R. (1993). Why we need ESS signalling theory. Philosophical Transactions Of the Royal Society B, 340(1292).