Cost and conflict in animal signals and human language

Abstract

The ''costly signaling'' hypothesis proposes that animal signals are kept honest by appropriate signal costs. We show that to the contrary, signal cost is unnecessary for honest signaling even when interests conflict. We illustrate this principle by constructing examples of cost-free signaling equilibria for the two paradigmatic signaling games of Grafen (1990) and Godfray (1991). Our findings may explain why some animal signals use cost to ensure honesty whereas others do not and suggest that empirical tests of the signaling hypothesis should focus not on equilibrium cost but, rather, on the cost of deviation from equilibrium. We use these results to apply costly signaling theory to the low-cost signals that make up human language. Recent game theoretic models have shown that several key features of language could plausibly arise and be maintained by natural selection when individuals have coincident interests. In real societies, however, individuals do not have fully coincident interests. We show that coincident interests are not a prerequisite for linguistic communication, and find that many of the results derived previously can be expected also under more realistic models of society.

Psychological adaptations for assessing gossip veracity

“…Although for language to evolve, most speech must have been honest in the EEA (Lachmann et al 2001;Silk et al 2000), this does not imply that deception and error were absent. If error and deception were frequent enough, there would have been a selection pressure for adaptations to assess the believability of language signals.…”

“…Language is a "cheap" signaling system that could only have evolved if commu-nication were mostly honest in ancestral environments, implying that language evolved in a social context involving cooperation, shared interests, coordination, and/or repeated interactions with opportunities to punish deception (Lachmann, Szamado, and Bergstrom 2001;Silk, Kaldor, and Boyd 2000). Speech should be honest when "on average, the incentive to the signaler to misrepresent the state of the world [is] outweighed by the incentive not to do so" (Lachmann et al 2001:13189).…”

Predictable and Predictive Emotions: Explaining Cheap Signals and Trust Re-Extension

“…Interested readers are encouraged to further examine the message content in Supplementary Material. form of spoken or written words to negotiate trust between individuals with conflicting interests (Lachmann et al, 2001). Our study suggests that cheap-to-produce messages are reliable because they are influence by predictable emotions in reliable ways.…”

“…Where demonstrated behavior has informed investors of a trustee's untrustworthiness, messages may be sent with the intention of persuading investors that the trustee is more trustworthy than inferred from cues alone. Many find it quite puzzling that so-called "cheap signals" can effectively be used to negotiate trust between individuals with conflicting interests (Lachmann et al, 2001) and that it is even possible for promisebreakers to rebuild damaged trust by issuing apologies . Below we review why trust can be built with the help of cheap-to-produce messages and why those who re-extend trust to previously untrustworthy individuals (e.g., to promise breakers) may take their messages into consideration.…”

Strategic Choice of Preferences: The Persona Model

“…It underlies the common observations that people cannot "change their mood on arbitrarily short timescales," and therefore their actions often "betray the way they feel," that is, signal their persona. (See the discussion in Frank (1987);Frith (2008), and of costly signaling in general in Spence (1973Spence ( , 1977; Lachmann et al (2001).) In short, it would appear that humans have some ability, at least at a subconscious level, to adopt a persona / emotion that is binding on them and that they are forced to semi-honestly signal.…”