Six monkeys (Macaca mulatta) learned to discriminate visually between pictures of objects. Each pair of pictures was presented only once per day (24-h intervals between successive trials with the same pair). Choice of the correct picture of a pair produced immediate food reward. One set of 20 pairs was learned before operation and a second set of 20 different pairs was learned after the amygdala had been removed bilaterally in three of the monkeys. The amygdalectomized animals were severely r...