Acknowledging how farmers learn is a forced passage to the impact of knowledge generation and the way to link extension to research. This Janvry et al. (2016) paper presents an interesting perspective. It presents a few concepts such as “private learning” (learning-by-doing) by Bayesian updating. This consists of direct learning from own individual actions over time. There is also “social learning” (learning from others) with Bayesian updating and aggregation of observations collected from others according to a chosen pattern of weights.