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Mandler, J.M. & McDonough, L. (1995). Long-term recall of event sequences in infancy. Journal of Experimental Child Psychology, 59, 457-474.
I. Do young infants have the ability to conceptually represent the correct temporal order of events? Is the deferred imitation measure a valid measure of recall abilities? These questions are pertinent to those who study early memory in infants.
II. Piaget used deferred imitation as an indication of recall abilities in his 16-month-old daughter. Other researchers have used the same measure to test recall abilities in younger infants. Objections to the use of this measure are based on: 1) sensorimotor processes may underlie observational learning and 2) repetition priming experiments with amnesic adults suggest that the presence of the object may prime the action performed on it. In both cases, the validity of the measure is questioned. However, research using deferred imitation with amnesic adults (adults who have no ability to recall past events; McDonough et al., in press) show that they cannot recall action sequences after a 24 hour delay. Along with other considerations, it seems reasonable to conclude that deferred imitation is a valid measure of recall. More recent research by Bauer & Mandler (1992) showed that 11-month-olds represent the order in which causal events and familiar events occur and they can reproduce such for immediate imitation. The goal of the present experiments is to see if infants can recall the temporal organization of novel events with causal (enabling) or arbitrary orders after 20 second, 24 hour and 3 month delays.
III. In Experiment 1, 18 infants at 11-months of age were tested. In Experiment 2, the same infants were tested again 3 months later when they were 14-months of age. A control group of 18 naïve 14-month-olds were also tested. The following events were tested: Causal events were 1) make a rattle and 2) make a rocking horse; Arbitrary events were 1) put a ring on the bear’s arm and brush its head and 2) place a hat on the bunny and feed it a carrot. Four assessments were taken: 1) A baseline measure to evaluate what infants would do with the objects spontaneously; 2) Imitation after a 20 sec. delay; 3) Imitation after a 24 hour delay; and 4) Imitation after a 3 month delay. Infants’ interactions with the objects were videotaped and scored by two raters naïve to the hypotheses of the experiment.
IV. The results were evaluated in terms of the number of actions performed, the number of sequences performed, and the number of sequences performed in the correct order in each assessment period. The results showed:
1. Imitation of the actions in the causal events was significantly greater at the 20 sec and 24 hour delay than at baseline. However, imitation of the actions in the arbitrary events was greater at the 20 sec delay than at baseline but no evidence for recall was found after the 24 hour delay.
2. Recall was found for the temporal order of the causal events but not the arbitrary ones. (Not enough arbitrary actions were recalled to show memory for temporal order.)
3. Recall for the actions and sequences of the causal events was found after the 3 month delay. No recall was found for the arbitrary events.
4. Time analyses showed that time allotted for imitation of the arbitrary events was longer than for causal events; therefore, poor performance on the arbitrary events was not due to any experimenter bias. Infants actually had more time to perform the arbitrary events.
V. 11-month olds can encode two action novel causal events and recall them after a delay of 3 months. Infants begin to forget arbitrary events after 24 hours and after 3 months forgetting is nearly complete. This difference is consistent throughout development as shown in data based on early verbal comprehension. Recall in young children as well adults using both verbal report and deferred imitation measures shows the same pattern. Causal connections both chunk material into organized units and provide a retrieval plan that orders the output of recall whether the material is events or stories. The findings of the present research are also consistent with the idea that infants are sensitive to causal relations in terms of physical causality, understanding objects as causal agents and hands as object-moving or supporting agents.