Proceedings of the Annual Meeting of the Cognitive Science Society

Approximate number perception is noisy, but it is unclear what kind of underlying process the noise reflects. Here we provide evidence that approximate number estimation should be thought of as a sampling procedure. We show that the the average of two approximate number estimates of the same stimulus tends to outperform either estimate alone; additionally, the average difference between the two estimates of a given number linearly increases as a function of number, consistent with Weber’s law. Finally, we provide evidence that people report confidence ranges consistent with Weber’s law. This suggests that they represent a distribution of possible responses even on a single trial.