Before revision:  The main result is that decisive Poisson signal creates the most dispersed decision time distribution (in mean-preserving spread order ), and the pure accumulation of information creates the least dispersed. This implies that for a decision maker with convex discount function, decisive Poisson signal is the optimal learning strategy .
After revision:  The main result is that decisive Poisson signal creates the most dispersed decision time distribution (in mean-preserving spread order are deterministic distribution and exponential distribution. The result implies that when time preference is risk loving (e.g. standard or hyperbolic discounting), Poisson signal is the optimal learning strategy .