Retention of Ordinal Position Information with Limited and Extended Serial Training

Abstract

To examine the possibility that position cues are temporal and therefore ineffective early in serial runway training, rats were runway trained on a three-trial series of different rewards. The series was SNP', where Sand P' refer to series trials that concluded with four sucrose or eight plain Noyes pellets, respectively. The middle trial was never rewarded (N) . Early in training, a significant pattern of running slowly on the middle trial and rapidly on the initial and terminal trials had emerged. Transfer tests to series of trials (NNN) never rewarded after this limited training (on Day 19) and later after extended training (Day 39) , each gave evidence that the rats relied upon position cues in the tests. The three-trial patterns established before the tests were retained on the three trials of the NNN series. The results suggest the prevalence of position learning, but they work against the idea that position cues are temporal and effective only with extended training.Just as in the development of theoretical models for human serial learning, realization of the importance for animals of information about the ordinal position of items in a list followed an initial theoretical emphasis on the role of the memories of list items. Though position learning is now emphasized (e.g., Henson, 1998) in human cognition, it began receiving attention (e.g., Bower, 1971 ;Ebenholtz, 1972) long after memoryassociation theories (e. g., Ebbinghaus, 1913) had developed rich traditions. The study of memories, usually of differing reward events, in animal serial learning also has a long history that has produced clear evidence for animals employing reward memories in serial problems; and the understanding of the nature of those memories is now fairly sophisticated (reviewed by Capaldi, 1994). Evidence that animals use information about the position of items in a list is recent, but also clear

An Attempt at Blocking of Position Learning by Training with Reward-Memory Associations

“…One possibility entertained by Capaldi et al (1997) was that position learning requires extensive training, but reward-memory learning occurs rapidly. However, Burns and Criddle (2001) found that slower running on the middle trial of an SNP series appeared also on the middle trial of an NNN transfer series after both limited and extensive training.…”

“…New experiments examining the duration of training in Phase 2 using this procedure would be informative, but the data from Burns and Criddle (2001) suggest that the overshadowing of memory cues occurs quite early.…”

“…The apparatus used in the experiment reported here was the runway used by Burns and Criddle (2001). It was L-shaped and painted flat black, 233.7 cm long and 10.0 cm wide , covered with vented clear plastic.…”

“…Usually, the series employed confound position and memory cues, and it is from experiments with this confounding that much of the evidence for position learning comes. An example of such evidence was reported by Burns and Criddle (2001) who trained rats on an SNP series. Here, S may be associated with N, but N also appears exclusively in the second series position.…”

“…In an overshadowing procedure cues are presented in compound and later tests of the associative strength of the individual cues may indicate that the learning of one element of the compound was moderated (overshadowed) by the other element of the compound. The Burns and Criddle (2001) procedure, for instance, can be thought of as involving a compound (position and memory) cue. The NNN transfer test changed the memory component of the compound while holding the position component constant.…”