Dickins, T. E. (2003). General Symbol Machines: The First Stage in the Evolution of Symbolic Communication. Evolutionary Psychology, 1(1), 192-209. doi:10.1177/147470490300100116
[Abstract]Humans uniquely form stimulus equivalence (SE) classes of abstract and unrelated stimuli, i.e. if taught to match A with B and B with C, they will spontaneously match B with A, and C with B, (the relation of symmetry), and A with C (transitivity). Other species do not do this. The SE ability is possibly the consequence of a specific selection event in the Homo lineage. SE is of interest because it appears to demonstrate a facility that is core to symbolic behavior. Linguistic symbols, for example, are arbitrarily and symmetrically related to their referent such that the term banana has no resemblance to bananas but when processed can be used to discriminate bananas. Equally when bananas are perceived the term banana is readily produced. This relation is arguably the defining mark of symbolic representation. In this paper I shall detail the SE phenomenon and argue that it is evidence for a cognitive device that I term a General Symbol Machine (GSM). The GSM not only sets the background condition for subsequent linguistic evolution but also for other symbolic behaviors such as mathematical reasoning. In so doing the GSM is not particularly domain-specific. The apparent domain-specificity of, for example, natural language is a consequence of other computational developments. This introduces complexity to evolutionary arguments about cognitive architecture.
[Citing Place (1995/6)]  
Citing Place (1995/6) in context (citations start with an asterisk *):
Section Inferential Effort
* If symbols are part of a stimulus equivalence class what is the exact nature of the relation? Infants learn a sound-to-object relation, and not an object-to-sound relation. The ability to use this symmetrically is a part of the full equivalence relation. It is also likely that infants already have a notion of the indices of the named object. These indices will also be treated symmetrically (although they may be grouped under a concept [...]). Place (1995) has argued that an equivalence class consisting of a name, an object and at least one index of that object is the core of a conceptual representation of that object. Deacon would add that once the name in a particular equivalence class is associated with the names for others then a set of higher-order classes could be formed.
Section Evolved mechanisms and a General Symbol Machine
* Within the stimulus equivalence literature there is debate about whether language is an ontogenetic precursor to the ability to form such classes (Horne and Lowe, 1996) or vice versa (Dickins and Dickins, 2001). The language-first hypothesis rests on a Skinnerian view of language acquisition that fails to account for rapid acquisition. However, Place (1995) refined this and suggested that language indeed leads to the stimulus equivalence ability in infants, but that once that ability is in place it speeds up later word acquisition. Despite this innovation Place’s hypothesis fails to account for the establishment of symmetry in the first instance, arguing instead that all of the equivalence relations are somehow transferred from a Skinnerian training of initial words. There is no evidence whatsoever to support Skinnerian learning of words in infants.