Learning and Memory
Experiment developed by Debra Titone, McGill University
(Editor: Karen Brakke, Spelman University)
The Learning and Memory experiment is a study of transverse patterning, which is a learning paradigm that requires learning a series of arbitrary discriminations (Spence, 1952). For example, when A and B are paired, A is correct; when B and C are paired, B is correct; and when A and C are paired, C is correct. The third of these discriminations is relatively difficult to learn because the AC discrimination goes against a logical inference about what stimulus should be reinforced given that A is reinforced over B, and B is reinforced over C. This paradigm has been studied in many different species, and there is evidence suggesting that an intact hippocampal system is critical to "solving" the transverse patterning problem. Additionally, computer simulations of transverse patterning, as well as behavioral studies with human and non-human animals (Dusek & Eichenbaum, 1998), suggest that the way animals are trained on the initial discriminations affects whether AC can be correctly solved as "C". The training method used here is a staged form of training, which is supposed to reliably elicit correct transverse patterning performance.
In this experiment, there are two sequences of discrimination learning trials. The first presents discrimination learning trials that involve non-transverse learning as in Figure 1. The second presents trials involving transverse learning such as in Figure 2. Each sequence has three phases. In Phase 1 of the non-transverse learning sequence, participants see repetitions of AB pairs and are instructed to figure out which pattern is "hiding the coin." For the AB pair, the "coin" is "hiding" under the "A" stimulus. Once the participant gets 14 correct trials in a row, the program seamlessly moves into Phase 2, in which AB pairs are presented along with BC pairs. Again, the "A" stimulus is correct for the AB pairs, and now, the "B" stimulus is correct for the BC pairs. Once the participant gets 14 correct trials in a row in Phase 2, the program seamlessly moves into Phase 3 in which AB and BC pairs are intermixed with AC pairs. Because this is the "non-transverse patterning" sequence, the "A" stimulus is reinforced for the AC pairs.
In the second set of discrimination learning trials, termed the "Transverse Patterning" sequence, participants are presented with pictures of flowers that are arbitrarily designated as the "A", "B", and "C" stimuli, and are instructed to figure out which "flower" is "hiding" the "bumble-bee." The procedure is formally equivalent to what was just described for the "Non-transverse patterning" sequence, with the one important exception that when participants are presented with AC pairs, C is the reinforced stimulus.
|Figure 1: Non-traverse learning||Figure 2: Traverse learning|
The first column provides the UserID, or the number that each person receives upon completion of the experiment. The second column contains the ClassID. Gender, age, hand preference and date of participation are listed next, and are self-explanatory.
The experimental data consist of six trials. First, you will find the three trials for the tranverse patterning (i.e., TP1, TP2, TP3) conditions. Data reflect the number of trials required to obtain a perfect score. The minimum value is 14, or error free performance. Similarly, data from the non-transverse patterning (i.e., NTP1, NTP2, NTP3) are contained in the next three columns and they contain the number of trials to earn a perfect score.
Performance in this experiment is measured by recording "trials to criterion", which is the number of trials needed in order for learners to be correct on 14 straight trials. Because the trials to criterion value is computed for each phase of each sequence (i.e., transverse and non-transverse) there are six measures total. The critical prediction is that it will take participants significantly more trials to reach criterion in Phase 3 for the "Transverse Patterning" sequence (which is labeled TP in the database) than for the "Non-transverse Patterning" sequence (which is labeled NTP). The data shown below are consistent with this prediction.
|Figure 4 - Learning and Memory Graph Analysis|
Although transverse patterning tasks such as this may be readily mastered by many adults, some people have great difficulty performing correctly on them. For example, people with amnesia often fail to complete such tasks successfully, presumably because of hippocampal impairment (Reed & Squire, 1999; Rickard & Grafman, 1998). This underscores the importance of the hippocampal system in forming memories even of short duration that involve learning new configurations of stimuli. Several years ago, Berch and Israel (1974) found that fourth-graders also had trouble mastering basic transverse patterning tasks unless they were provided extra, nonspatial, cues. What might this say about the development of learning and memory?
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