A reader found an error in our manuscript, kindly notified us, and we then submitted the following correction letter to IEEE Potentials in January 2009.

Dear IEEE Potentials,

One of your readers, Hailiang Tao of Duke University, recently contacted us and pointed out an error in an equation contained in our article:

How Many Neurons Must One Man Have, Before You Call Him a Man?

published in the November/December 2008 issue of IEEE Potentials (27:6, 26-33).

In Figure 4, there is an equation:

T=P^S – 1

Where T=total number of states in the population, S=number of states per neuron, and P=total number of neurons in the population.

The equation contains an error. The equation should be:

T=S^P – 1

For S = 32 and P = 2, the value for T in Case 1 in figure 4 is therefore not 4.2 x 10^9 but 1023. For S = 13 and P = 2 in Case 2, T is therefore not 8191 but 168.

This minor error does not affect the conclusions of the manuscript; we are pleased the readers are vigilant!

Sincerely,

Timothy Marzullo and Hirak Parikh

University of Michigan, Ann Arbor