monkey". A more time consuming way to evaluate REG algorithms is by letting humans judge the Adequacy (How clear is the description?) and Fluency (Is the description given in good and clear English?) of the generated expression. Also Belz and Gatt evaluated referring expressions using an experimental setup. The participants get a generated description and then have to click on the target. Here the extrinsic metrics reading time, identification time and error rate could be evaluated. Notes References Computational linguistics Natural language processing