From Context to Code: Information Transfer Constrains the Emergence of Graphic Codes

Humans commit information to graphic symbols for three basic reasons: as a memory aid, as a tool for thinking, and as a means of communication. Yet, despite the benefits of transmitting information graphically, we still know very little about the biases and constraints acting on the emergence of stable, powerful, and accurate graphic codes (such as writing). Using a reference game, where participants play as Messengers and Recipients, we experimentally manipulate the function of the task (communicative or non-communicative) and investigate whether this shapes the emergence of stable, powerful, and accurate codes for both synchronous and asynchronous modes of information transfer. Only in the Dialogue condition, where Messenger and Recipient are two different persons communicating within the same time frame (i.e., synchronously), do we consistently observe the emergence of stable, powerful, and accurate graphic codes. Such codes are unnecessary for participants in Recall, where Messenger and Recipient are the same person transferring information within the same time frame, and they fail to emerge in Correspondence, where Messenger and Recipient are two different persons communicating across time frames (i.e., asynchronously). Lastly, in the Mnemonic condition, where Messenger and Recipient are the same person at different points in time, participants achieve high accuracy but with codes that are suboptimal in terms of power and stability. Our results suggest that the rarity and late arrival of stable, powerful, and accurate graphic codes in human history largely stems from strong constraints on information transfer. In particular, we suggest that these constraints limit a code's ability to reach an adequate tradeoff between information that needs to be explicitly encoded and information that needs to be inferred from context.