Long-term memory for a spatial task in young chicks

Two-day-old chicks, Gallus gallus domesticus, were faced with a spatial task requiring them to make a detour around a U-shaped barrier in order to join a group of conspecifics placed beyond it. Chicks made one detour trial, and were then retested after delays of 30 min, 3 h and 24 h. When retested, the chicks took significantly less time to make the detour, even at 24 h. Chicks that failed to solve the task on the first trial within the time limit (600 s) took as long as naive chicks, when tested again 24 h later, suggesting that long-term memory for the task requires a form of one-trial learning. Since many chicks chose the same direction of detour on both the first trial and the retest, they may have simply shown a stereotyped preferential response. In a further experiment to test this possibility, we used a more complex version of the apparatus: the direction of detour first chosen by the chick was always blocked, and a subsequent detour in the opposite direction was required to complete the task. This time, chicks did not choose the same direction on the first test and when tested 24 h later. However, they proved able to remember the correct direction for at least 24 h if they were allowed to learn the correct path in a series of five trials. Copyright 1999 The Association for the Study of Animal Behaviour.