Arbitrary Imitation, Pattern Completion and the Origin and Evolution of Human Communication

Arbitrary imitation, Pattern Completion and the Origin and Evolution of Human Communication Monica Tamariz (monica@ling.ed.ac.uk) Language Evolution and Computation, PPLS The University of Edinburgh 3 Charles Street, Edinburgh EH8 9AD, UK Abstract he did not even attempt to. Mindlessly imitated behavior, especially if it is not costly, may entrench the use of non-functional patterns in a community; this increases the degree of structure (reduces randomness) in the cultural environment, which therefore becomes easier to process and learn. This paper explores the role of arbitrary imitation in the origin of communication in our species. Recent approaches to the evolution of human communication propose that humans evolved a unique biological adaptation, the socio-cognitive capacity for theory of mind (Tomasello, 1999) or symbolic reference (Deacon, 1997). This adaptation presupposes and relies on non-communicative behavior being already in place (Tomasello et al. 1997), for instance the behavior sequences observed in chimpanzees resulting from ontogenetic ritualisation (Tomasello & Call, 1997). During the transition to communication, non-communicative behavior would come to be understood as a reflection of others’ meanings or intentions. In this study I explore an alternative kind of pre-communication behavior system caused by the evolution of the general cognitive capacity to decouple means from ends, instantiated as the abstraction of form from function and the abstraction of behavior from the producer of behavior. Existing accounts of the origin of human communication assume a pre-existing behavioral system shared among members of a social group. This paper is concerned with the origin of that system; specifically, it explores its characteristics and functionality as well as the circumstances under which it could have appeared. A number of agent-based computer simulations test whether the capacities for arbitrary imitation and pattern completion can lead to a behavioral system that could be co-opted for communication. The results show that arbitrary imitation and pattern completion may indeed generate a population-wide shared behavioral system whose structure reflects the structure of the environment, and therefore could easily have been co-opted for communication. This system may have paved the way for other biological capacities widely believed to be necessary for communication, such as shared intentionality and symbolicity, to co-evolve. Introduction Much human socially transmitted culture arguably depends on arbitrarily copying learnt patterns whose function or origin is often unknown to the learner. This is illustrated by Gergely and Csibra’s (2006) Sylvia’s ham recipe story: Sylvia always cut the end of the ham when she cooked it because that is the way her mother did it; when the mother saw her do that, and asked why, Sylvia told her: “Because that is the way you always did it”. The mother explained that her pan was too small to hold a whole ham, and that was why she had to cut off the end. Children engage in mindless imitation of elaborate actions even when these are irrelevant for the desired goal (Horner & Whiten, 2005; Lyons, Young & Keil, 2007; Whiten et al., 1996), or even for no apparent goal, as illustrated by the personal observation (which partly inspired this research) of a 24-month-old who, after seeing his mother clap her hands to try and catch moths on multiple occasions, interrupted his playing to clap when he saw a moth in the room, even if the moth was so far he could not possibly catch it – and Arbitrary imitation for pattern completion Imitation has been proposed as one capacity that preceded and may have afforded the evolution of communicative behavior (Donald, 1991; Zlatev, 2007). Tomasello (1999) claimed that only human cultural behavior involves true imitation, or replication of the means that another individual employed to obtain an end or function, as opposed to emulation, or achieving the same function as the other individual, regardless of the means employed. I focus on arbitrary imitation, or replication of behavior irrespective of whether it can be identifiable as a means to an end or not. Possible motivations for arbitrary imitation include a conformity bias (Asch 1955) and a pattern completion (hereafter, PC) bias. I focus on the latter. PC is the activation of a complete representation upon exposure