Key notions in the study of communication

I am enthusiastic about Thom Scott-Phillips’ book. It integrates cutting-edge research in several fields, from biology to pragmatics, relevant to the study of the evolution of human communication and it redirects the whole enterprise in a new, much more promising direction. This, however, is not the place to wax lyrical about the book; so, let me focus on a single conceptual question of broad relevance where Thom makes a very valuable contribution, but one that, I believe, still needs more work on the part of all of us.

In chapter 2, table 2-1, Thom proposes a set of “definitions of key terms in communication” developing the idea that “if an action [of one organism] causes a reaction [of another organism], and both are designed for the purposes of playing that role in the interaction [between the two organisms], then we can term the action a signal and the reaction a response, and the overall interaction communicative. If however, one half or the other was not designed for these purposes, then the action is either a cue or a coercitive behaviour.”

The idea of defining key notions in the study of communication and related phenomena in term of the presence or absence of interfacing designs or functions is a brilliant one (suggested by John Maynard Smith and David Harper and developed in an original way by Thom), but one that raises a number of difficult issues. I’ll focus on just one such issue.

The issue comes, in good part, from the fact that this approach is rooted in ethological approaches to communication. There, what matters is the behaviour of the interacting organisms. Their internal cognitive states and processes, if considered at all, are just a part of the mechanism causing the expected behaviour. What matters is the behaviour.

The ethological approach, whatever its great merits, isn’t such a good source of insight when you study forms of communication the success of which cannot be identified in terms of any behavioural reaction, as in much of human communication. The basic reaction to communication is, in all cases, cognitive; it may, as generally in animal communication, be a trigger to a specific behavioural response. Even in the human case, the cognitive reaction may be aimed at causing a specific behavioural reaction, as when what is communicated is a request (“pass the sugar, please!”). Much of human communication, however, isn’t aimed at causing some specific behavioural response. The production of this post, for example, is an instance of communicative action designed to elicit in you, readers, just a cognitive reaction. This post might also elicit a behavioural reaction is some of you (yawning or buying Thom’s book, for example), but this is not what it is designed to do.

Thom’s definitions are more appropriate for communication aimed at a behavioural response. Even there, the cognitive component makes communication special, in a way that is not reflected in his definitions. Thom definitions, actually, would be appropriate to talk not just of communicaction but of all forms of interaction where there is a difference between action and reaction. Communication, however, is about providing a cognitive input and causing a cognitive reaction (which may but need not be a way of in turn causing a behavioural reaction). I would suggest that this should be reflected in the way it gets defined. Otherwise, we extend our notion in a way that I find unhelpful.

With Thom’s definitions, somewhat pardoxically,

1) Mating would provide in itself the perfect example of communication since the action of one organism and the reaction of the other are each designed for this interaction. This is true not only of mating in animals that commonly do communicate in, around, and through mating, but also of mating between, say, two haploid yeasts of opposite mating types the behaviour of which can be parsimoniously described without invoking at all the notion of communication.

2) The relationship between beetles feeding on elephant dung and elephants would count as one of ‘cue’: the dung being the cue that the elephants produce and from which beetles benefit, the production of the benefit being an undesigned action and the feeding being a designed reaction.

3) Any designed type of action of one organism on another with no designed reaction (for example the action of a parasite plant feeding on its host) should count as "coercion"—which it is, of course, in this example but in the ordinary sense of ‘coercion’ rather than the one intended by Thom. (Actually, Thom’s example in his book of a women being pushed from her chair is a case of coercion in the ordinary sense, so, I may be misunderstanding him.)

The word "coercion", by the way, works much better for non-cognitive interactions than for cognitive ones. For the cognitive case, I much prefer "manipulation" for what Thom has (or should have) in mind. "Coercion" may be a well-established term in one strain of biological writing on the issue, but "manipulation" has a good pedigree too, including in biology, and well beyond.

Why, you might well ask, not use for communication a classification that works for all kind of interactions? Because communication has some quite specific features that would not be properly identified under such a general definition.

There is, in particular, a basic asymmetry, of major evolutionary significance between the "reaction", which is primary, can stand on its own, and doesn’t need any manipulative or signalling "action" to be adaptive, and the "action" side, which is adaptive only if there are receiver with a cognitive capacity to react.

Take the "cue" situation. It is just the ordinary situation of any organism involved in any perception-based cognitive activity. Such an organism has mechanisms designed to take advantage of some specific features in its environment, features that indicate something of relevance to it and that are, therefore cues (in the ordinary sense at least). Cues in this sense may be provided not only by other organisms but by anything that can affect sensory receptors. Organisms pick cues of impeding changes of weather, cues of the presence in useful quantity of various important substances, water, minerals, and so on. Cues of biological origin are, of course, centrally important: much of cognition is in the business of recognising and processing cues of the presence of mates, or of prey, or of predators, i.e. other organisms (which also have an interest in being or not being recognized).

Insect-eating birds are equipped to detect insects, and more specifically, to discriminate types of insects according to the benefits and costs there may be in eating them. The distinctive features of various species of insects provide cues for this discrimination. It may be in the interest of some species of insects to evolve (1) features that make them bad prey, and (2) features that advertise the fact that they are bad preys, as is famously the case with Monarch butterflies, which are poisonous and highly recognizable. The distinctive pattern of their wings is a classic example of interspecies "signalling", in Thom’s exact sense: it is designed to cause a reaction in birds and this reaction is itself designed. My point here being that you need cognition at the reaction end of the interaction, but not necessarily at the action end: the Monarch butterflies’ pattern is not an output of their cognitive processes. More generally, signalling, even in its broad biological sense, is an exploitation of cognitive capacities in the recipients. This signalling can be "designed" by natural selection. It needn't be intended or even cognized in any way by the signaller. Signalling needn’t involve any cognitive capacity.

Describing "coercion" or, as I prefer to call it, manipulation, as involving a designed action but no designed reaction is not strictly incorrect, but it may be quite misleading when one sticks to cases of cognitive reaction. Manipulation works by exploiting a cognitive mechanism, and it does so by providing an input with features that the mechanism is designed to react to but that, in this case,—and this is what makes it manipulation rather than signalling—provide the wrong input for further inference. So there is a designed reaction that is being exploited, but its function isn't to be so exploited, making the case different from that of signalling.

The Viceroy butterfly, whose wing pattern mimics that of the Monarch, is picked up by a cognitive mechanism in birds that evolved to pick such patterns—the mechanism isn't precise enough however to distinguish the Viceroy from the Monarch exact pattern (see figure); you may have trouble doing so yourself—, but it leads in this case to the mistaken inference that the butterfly is poisonous and shouldn’t be eaten (actually, as Olivier Morin warns me, whether the Viceroy is genuinely palatable and hence whether this whole classical example of "Batesian mimicry" is genuine has become controversial, but even so, it serves my illustrative purpose). Unlike coercion as defined by Thom, manipulation in this sense is restricted to actions that take advantage of the limits of the receiver’s cognitive mechanism by producing, in the case of mimicry, false positive, and, in the case of camouflage, false negatives (I would describe all this in terms of the proper and actual domains of the cognitive mechanisms involved). In other terms, the possibility of coercion/manipulation is dependent on the existence of cue-picking mechanisms whereas the possibility of cue-picking (i.e. of cognition) isn’t symmetrically dependent on the existence of coercion/manipulation.

One of the effect of this dependence of manipulation on genuine cues and, often, on actual honest signals, is that there is a continuum of cases between manipulation and signalling. Think of the expression of genuine emotions that can also involve a good dose of manipulation.

Thom’s “definitions of key terms in communication” raise several other important issues having to do, for instance, with the relationship between biological and cultural functions (both well-exemplified in human language) and with the graded vs. categorical character of these or any such definition (as suggested by the signalling manipulation continuum I have just alluded to). So I tend to see these definitions as a good provisional tool for the use Thom makes of them, but also as a way to frame some very basic and not yet resolved conceptual issues in the study of communication.