Does the Church-Turing thesis describes the workings of the human brain?

 Modern computers are based on the Von Neuman architecture, which consists in a central processor that executes sequentially one operation at a time over a given data according to some predefined instructions stored in a memory. Such machines can be reduced to a universal Turing machine, furthermore, the Church-Turing thesis postulates that any computation can be described as a program of the so called universal Turing machine. The thesis can be equivalently formulated as: any computation is a sequence, and such sequence can be composed further into more complex sequences by a concatenation rule common to the smaller sequences. Does human computation follow the Church-Turing thesis? The parallel wiring of human brain seems to deny it,  in fact, the computer metaphor for the brain is inaccurate and crude, as many authors (Edelman) have carefully discussed.

Sackur and Dehaene’s interpretation of the experimental data from some basic arithmetic computation suggests that the old cognitive dispute between sequential and parallel brain processing is better understood in terms of conscious and unconscious computation, understanding such concepts in terms of Neural Darwinism (or equivalently, Workspace Theory). Conscious processing according to this thesis would consist in multiple serial stages of stochastically accumulated evidence, i.e., the operation of the human brain is approximately serial, a Von Neuman-like machine. [Sackur and Dehaene. 2009, 209], or we should better say: although the architecture of our computers and the human brain are not commensurable, the linking of two conscious processes of the brain have an almost-sequential character, that can be accurately described by the model of a Von-Neuman like machine.

References

Sackur, Jérôme and Dehaene, Stanislas. The cognitive architecture for chaining of two mental operations. Cognition 111 (2009) 187–211.