In this paper we propose a novel formulation for the distinguishability of conductivity targets in electrical impedance tomography (EIT). It is formulated in terms of a classic hypothesis test to make it directly applicable to experimental configurations. We test to distinguish conductivity distributions σ₂ from σ₁, from which EIT measurements are obtained with added white Gaussian noise with covariance Σ_n. In order to distinguish the distributions, we must reject the null hypothesis , which has a probability based on the z-score: . This result shows that distinguishability is a product of the impedance change amplitude, the measurement strategy and the inverse of the noise amplitude. This approach is used to explore different current stimulation strategies.