Fig. 1. Concepts underlying a neurosemiotic simulation. (a) Minimum brain architecture chosen for our simulations, containing two domains for primary sensory representation (RD1S), one domain for secondary sensory association (RD2) and one domain for primary motor representation (RD1M). (b) Simplified representation of the minimum brain architecture, in which circles stand for domains of representation in the monkey brain (RDs). (c) Control architecture of the apprentice creature used in our simulations. Each contains multiple relays in RD1S and RD1M. (d) Each apprentice contains also some relays dedicated to the association between images and sounds, i.e. RD2. (e) Picture of the simulation console showing preys, predators, bushes and trees.

Fig. 2. Storyboard of sign process of alarm call communication employing vervet monkeys’ minimum brain architecture. Each frame is constituted of letters, arrows and circles. T1, T2, T3, etc., represent instants in time. External objects presented to a monkey brain comprise predator images (a–c), corresponding alarm-calls vocalized by other monkeys (A–C), and reactive behaviors from neighboring monkeys that may be visible to other brains (F refers to “flee”; S refers to “stay”). Circles stand for domains of representation in the minimum brain (RDs). Circle colors indicate different types of neural representations according to their semiotic relationships—red for object and blue for interpretant. The white color designates a de-activated RD (circle) or the absence of an external object. Arrows represent signs, i.e. patterns of connectivity between brain areas, or between a brain area and the external world. Green arrows indicate instantiation of a connectivity pattern, i.e. the action of a sign translating from an object to an interpretant. Black arrows in T1 indicate latent (inactive) signs. Memory for a representation is indicated as letters outside the boundaries of circles in T1. Information about the particular identity of an external object is represented by outside letters in T1, T9 and T13 (arbitrary moments of occurrence); this information is preserved within the brain as indicated by letter inside circles thereafter. At T3, interpretants within RD1S become internal (neural) objects to be represented downstream, determining the repetition of T3 in the next frame, and so on. Every instantiation of a representation in RD2 causes a slight increase in memory of that representation. Every instantiation of a representation must be interpreted as either an Icon, or an Index, or a Symbol; memory of a representation (A) of the object (a) is defined as the probability of observing (A) given a certain context of object presentation that might or not include (a). In addition, external objects may also carry the capacity to signify reward or punishment. This capacity (object value) is defined as positive and negative variables that can increase or decrease the memory of associated representations. −S refers to negative value imposed on brain representations associated with “stay”; +F refers to positive value imposed on brain representations associated with “flee”. (a) Infant simultaneously presented with predator image and alarm call. (b) Adult simultaneously presented with predator image and alarm call. Once again an escape response is generated earlier (T9) than in infants (T17). This crucial symbolic step occurs in T5, when RD2 interprets the ascending iconic representation “A” as “AaF”). (c) Adult presented with an alarm-call only.

Fig. 3. Naïve preys develop vocal symbol learning spontaneously after a few thousand iterations. The number of iterations required for learning has an inverse relationship with the tutor–apprentice ratio.

Fig. 4. Vocal symbol learning is highly resistant to apprentice-generated auditory noise (a), but is strongly impaired by apprentice-generated visual mis-identification of predators (b) and by tutor unreliability (c).