Editing Animal cognition (section)

==== Interval timing ====
Survival often depends on an animal's ability to time intervals. For example, rufous hummingbirds feed on the nectar of flowers, and they often return to the same flower, but only after the flower has had enough time to replenish its supply of nectar. In one experiment hummingbirds fed on artificial flowers that quickly emptied of nectar but were refilled at some fixed time (e.g. twenty minutes) later. The birds learned to come back to the flowers at about the right time, learning the refill rates of up to eight separate flowers and remembering how long ago they had visited each one.<ref>{{cite journal | vauthors = Henderson J, Hurly TA, Bateson M, Healy SD | title = Timing in free-living rufous hummingbirds, Selasphorus rufus | journal = Current Biology | volume = 16 | issue = 5 | pages = 512–5 | date = March 2006 | pmid = 16527747 | doi = 10.1016/j.cub.2006.01.054 | doi-access = free | bibcode = 2006CBio...16..512H}}</ref>

The details of interval timing have been studied in a number of species.  One of the most common methods is the "peak procedure". In a typical experiment, a rat in an [[operant chamber]] presses a lever for food.  A light comes on, a lever-press brings a food pellet at a fixed later time, say 10 seconds, and then the light goes off. Timing is measured during occasional test trials on which no food is presented and the light stays on.  On these test trials, the rat presses the lever more and more until about 10 sec and then, when no food comes, gradually stops pressing.  The time at which the rat presses most on these test trials is taken to be its estimate of the payoff time.

Experiments using the peak procedure and other methods have shown that animals can time short intervals quite exactly, can time more than one event at once, and can integrate time with spatial and other cues. Such tests have also been used for quantitative tests of theories of animal timing, such as Gibbon's [[Scalar expectancy|Scalar Expectancy Theory]] ("SET"),<ref>{{cite journal | vauthors = Gibbon J | year = 1977 | title = Scalar expectancy theory and Weber's law in animal timing | journal = Psychological Review | volume = 84 | issue = 3| pages = 279–325 | doi=10.1037/0033-295x.84.3.279}}</ref> Killeen's Behavioral Theory of Timing,<ref>{{cite book | vauthors = Killeen PR | date = 1991 | chapter = Behavior’s time. | veditors = Bower G | title = The psychology of learning and motivation | volume = 27 | pages = 294–334 | location = New York | publisher = Academic Press}}</ref> and Machado's Learning to Time model.<ref>{{cite journal | vauthors = Machado A, Pata P | date = 2005 | title = Testing the Scalar Expectancy Theory (SET) and the Learning to Time model (LeT) in a double bisection task. | journal = Animal Learning & Behavior | volume = 33 | issue = 1 | pages = 111–122 | doi = 10.3758/BF03196055 | pmid = 15971498 | s2cid = 16623835 | doi-access = free}}</ref> No one theory has yet gained unanimous agreement.<ref name="Shettleworth" />