Timberlake, Gawley, and Lucas (1986) found that rats were unable to anticipate future resources (food) that were delayed by 16 minutes or more. The 15 minute period during which the rats were able to anticipate food which would be available in the future IS called the time horizon. The present experiment sought an explanation of the fact that the animals in the Timberlake et al (1986) study could not anticipate free food beyond 15 minutes and to also examine whether the time horizon of rats can be lengthened. In most sessions, a single response bar (left or right) was presented at the start of the session. One bar was associated with 30 minutes of a progressive ratio schedule. The other bar was associated with the same progressive ratio schedule, followed by 5 minutes of free food. The bar presented alternated randomly from day to day. Once every 5 sessions, both bars were presented at the start of the session, and the animals chose between them. None of the animals consistently chose the PR and FF schedule suggesting that in this contingency, rats cannot "anticipate" over a 30 minute gap.
Lyn '92, Sandra, "Choice, Commitment and Time Horizon" (1992). Honors Projects. 72.