Animals and human beings communicate in a variety of ways; on an evolutionary level, this has great significance. One theory that talks about it is signal theory.framed within evolutionary biology.

In this article we will learn what this theory consists of, what signals are, what types of signals exist, what types of communication can be produced and how we can apply this theory to the study of human behavior.

Signal Theory: What is it?

Signal theory, also called signalling theoryis a theory that is framed within biology (specifically, evolutionary biology). It tries to explain how individuals or living beings communicate with each other through the emission of signals.

In addition, this theory has mathematical and physical bases in relation to communication systems. In other words, it can measure observed phenomena.

Thus, signal theory encompasses a body of knowledge related to evolutionary biology. It aims to explain and describe how animals deceive each other through signals, and how this becomes an evolutionary pattern, important for the evolution of species.

As we shall now see, signals are emitted to make a profit, to manipulate or to protect against another deception. These can be of different types (sincere or not), as we will also see below.

The signs: what are they?

The fundamental concept of this theory is signals. But what are these? They can be behaviors, features, actions, sounds, structures… specific to each species; in addition, they have the function of benefiting the individual or animal that emits them (as well as their receptors, depending on the type of signal and the context).

The signals have a certain intensity, a certain cost a certain purpose. Sometimes the signals intrinsically carry a risk to the issuer.

Signal theory states that signals are used to communicate, for example, through the signals that females emit to select their pairs. The function of the signals is to benefit the transmitter of the signals, through the receiver modifying its behavior. That is to say, they are signals that are emitted to achieve something.

Signal theory holds that signals evolve, as do species. Thus, with evolution the signals are emitted and received better. Through the study of these communication patterns, signal theory attempts to study the evolutionary patterns of species.

Animals

Signal Types

Broadly speaking, the signs can be of two types: honest or dishonest.. The former improve the aptitude of the receiver, and the latter harm it. Honest signals are usually sincere, while dishonest signals are deception.

A characteristic shared by all signals is that they are intentional, deliberately produced; instead, when they are produced “by mistake”, unintentionally (e.g. an animal creaking leaves in its path and alerting predators), they are considered clues.

1. Honest Signs

Honest Signs are characterized because the behavior or the issued action (signal) corresponds to the intention of the issuerThat is to say, the animal “does not hide anything”, it does not lie, it is a sincere signal.

These signals, like dishonest signals, are broadcast for personal (or shared) benefit.

2. Dishonest signals

The dishonest signals posed by signal theory, on the other hand, are actually tricks emitted by the animalthat is, they appear to have an intention that is not real. In addition, this intention is negative for the receiver, and can harm him; for the sender, on the other hand, it is beneficial. These signals are emitted especially by species that have some kind of evolutionary advantage.

Dishonest signals can produce two types of consequences for species dynamics: extinction and fixation. Let’s see what each of them consists of:

2.1. Extinction

According to signal theory, one consequence of dishonest signals is their extinction. This occurs because species are progressively able to detect when the signal is honest or dishonest, through repeated exposure to them.

At the same time, this causes the benefits initially obtained by the issuer through its signal to be extinguished. It is an evolutionary and somewhat adaptive process.

It can also happen, but with time, that the dishonest signals are replaced by honest signals; this happens temporarily, and happens so that they can be applied again in a dishonest way (it is a kind of “deception” of the animal).

2.2. Fastening

However, another consequence may occur with dishonest signals, according to signal theory. Thus, dishonest signals can end up being fixed on the population (when their presence increases). This causes the honest signals to be extinguished, because the dishonest prevail and dominate the environment.

Let’s set an example to understand it better. Imagine birds that emit honest warning signals when a possible predator appears, in order to warn the other birds, to “protect” them. However, another group of birds ends up emitting the same alarm signals when they are competing for food with members of their own species, in order to “deceive” them into believing that a predator is actually coming.

That is to say, in this case the birds use the signs as a way of keeping the food, scaring away the other birds; it is a dishonest sign, because it is a deception, which ends up transforming from its initial form, staying and fixing itself.

Principle of handicap

An interesting concept of signal theory is the concept of the “handicap” (or principle of the handicap).

Amotz Zahavian Israeli biologist, spoke of this principle in 1975. He argued that sometimes, the emission of signals (both honest and dishonest) could involve a very high cost for the species, which meant that only the most biologically dominant beings could emit any kind of signals.

This implies that the beings with a clear biological disadvantage (less dominant), had disadvantage at the time of emitting both honest and dishonest signals. Thus, only biologically dominant beings could emit signals, especially dishonest (deception). This phenomenon is called the “handicap principle.”.

Types of communication

As we have seen, signals serve to communicate (also to warn, to transmit…). But what is communicated? What types of communication exist?

The communication raised by signal theory can be of different typesIt can be a communication to cooperate (in order to get food, to get sexually matched…), a communication to compete (relations between prey and predators), a communication to get help (for example, offspring claiming food), and so on.

On the other hand, communication between animals can occur between enemies, or between “companions” or collaborators, as well as between members of the same species and between members of different species.

The Theory of Signals in Human Behavior

What’s the point of signal theory if we think about human behavior? Do you have applications? The answer is yes; this theory has been used especially to explain patterns of interaction between people, as well as attitudes manifested in relations of coexistence.

One of its applications in social interactions is the study of the authenticity of different communicative patterns (intentions, objectives, gestures…). This allows us to answer questions such as: When do we know that someone is lying? When is a signal honest? When does someone really have an interest in what we are communicating? etc.

Bibliographic references

  • Barrett L, Dunbar R, Lycett J (2002) Human evolutionary psychology. Princeton, NJ: Princeton University Press.

  • Bradbury, JW; Vehrenkamp, SL (1998). Principles of animal communication. Sunderland, MA: Sinauer.

  • Grafen, A (1990). “Biological signals as handicaps. Journal of Theoretical Biology 144 (4): 517-546.

  • Guzmán, G. (2018). Signal Theory: Is Deception Useful? Psychology and mind.