Editing Animal cognition (section)

=====Delayed response=====
Delayed response tasks are often used to study short-term memory in animals.  Introduced by Hunter (1913), a typical delayed response task presents an animal with a stimulus such as colored light, and after a short time interval the animal chooses among alternatives that match the stimulus, or are related to the stimulus in some other way. In Hunter's studies, for example, a light appeared briefly in one of three goal boxes and then later the animal chose among the boxes, finding food behind the one that had been lighted.<ref>{{cite book | vauthors = Hunter WS | date = 1913 | title = The delayed reaction in animals and children | series = Behavior Monographs | volume = 2}}</ref> Most research has been done with some variation of the "delayed matching-to-sample" task. For example, in the initial study with this task, a pigeon was presented with a flickering or steady light. Then, a few seconds later, two pecking keys were illuminated, one with a steady light and one with a flickering light. The bird got food if it pecked the key that matched the original stimulus.<ref>{{cite journal | vauthors = Blough DS | title = Delayed matching in the pigeon | journal = Journal of the Experimental Analysis of Behavior | volume = 2 | issue = 2 | pages = 151–60 | date = April 1959 | pmid = 13801643 | pmc = 1403892 | doi = 10.1901/jeab.1959.2-151}}</ref>

A commonly-used variation of the matching-to-sample task requires the animal to use the initial stimulus to control a later choice between different stimuli. For example, if the initial stimulus is a black circle, the animal learns to choose "red" after the delay; if it is a black square, the correct choice is "green".  Ingenious variations of this method have been used to explore many aspects of memory, including forgetting due to interference and memory for multiple items.<ref name="Shettleworth" />