Signal Theory: Is Deception Useful?

A field of biology that studies the possible evolutionary utility of deception.

Signal theory

The theory of signals, or signaling theory, brings 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 patterns evolutionary, and likewise it can help us to differentiate when the signals emitted are honest or dishonest.

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

Sign theory: is deception evolutionary?

Studied in the context of biological and evolutionary theory, deception or lying can take on an adaptive sense. Transferred from there to the study of animal communication, deception is understood as strongly linked to persuasive activity, since it consists mainly of providing false information for the benefit of the issuer, even if it means detriment to the issuer (Redondo, 1994).

This has been studied by biology in different species of animals, including humans, through the signals that some individuals send to others and the effects they 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 traversed by the constant exchange of different signals. Especially when it comes to an interaction that involves a certain conflict of interest, the signals exchanged may seem honest, even if they are not.

In this 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 way, so that this allows it 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 emitting a certain signal, the behavior of the receiver is modified, for the benefit of the person emitting it.

These are honest signals when the behavior corresponds to the intended intention. On the other hand, these are dishonest signals when the behavior appears to have one intention, but in reality it has another, which is also potentially harmful to the recipient, and surely beneficial to the person who emits it.

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

1. The dishonest signal is extinguished

According to signal theory, deception 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 spread rapidly.

But what happens when the receiver has already developed the ability to detect rogue 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 reduces the benefit of the sender of the deception, and finally causes its extinction.

From the above it can also happen that dishonest signals are eventually replaced by honest signals. At least temporarily, while increasing the likelihood that they will be used with dishonest intentions. An example of this is the threat displays made by seagulls. Although there is a wide variety of such displays, they all appear to serve the same function, meaning that a potentially rogue set of signs has been set as honest signs.

2. The dishonest signal is fixed

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

An example of the latter is the following: a flock shares an alarm signal that warns of the presence of a predator. It is a sincere sign, which serves for the protection of the species.

However, if any of the members emit the same signal, not when a predator approaches, but when they experience a failure in the competition for food with other members of the same species, this will give them an advantage over their flock and would that the signal (now misleading) is transformed and maintained. In fact, several species of birds perform false alarm signals to distract others and thus obtain food.

The handicap principle

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

In this sense, the existence of some honest signals would be guaranteed by their cost, and the existence of dishonest signals as well. This ultimately represents 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 “handicap”).

Application in the study of human behavior

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

For example, an attempt has been made to understand, evaluate and even predict the authenticity of different intentions, objectives and values ​​generated in the 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 on the fringes 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 communication process.

Bibliographic references:

  • Handicap principle (2018). Wikipedia The Free Encyclopedia. Retrieved September 4, 2018.Available at
  • 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.). Ethology: Introduction to the Science of Behavior. Publications of the University of Extremadura, Cáceres, pp. 255-297.
  • Grafen, A. and Johnstone, R. (1993). Why we need ESS signaling theory. Philosophical Transactions Of the Royal Society B, 340 (1292).

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