In risk assessment of a neurotoxic chemical, it may be necessary to assess its effect on cognitive function, the information-processing capacity of the animal. Such effects may be inferred from behavioral effects only after other explanations have been ruled out. Learning, memory, attention, and performance are elements of cognitive function that can be assessed in a variety of tests described in this unit: autoshaping the lever-press response, repeated acquisition in the radial maze, delayed matching to position, two-light visual discrimination, visual signal detection, and multiple fixed interval/fixed ratio operant schedule.