Learning and Memory Experiment

Learning and Memory Experiment

By:
Debra Titone (dtitone@mclean.harvard.edu)
Psychology Research Laboratory
McLean Hospital & Harvard Medical School

Introduction
Method
Data Output and Predictions
References

The Learning and Memory experiment is a study of transverse patterning, which is a learning paradigm that requires learning a series of arbitrary discriminations. Namely, 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 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.

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Method

In this experiment, there are two sequences of discrimination learning trials. The first presents discrimination learning trials that involve non-transverse learning. The second presents trials involving transverse learning. Each sequence has three phases.

In Phase I 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 II, 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 II, the program seamlessly moves into Phase III 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.

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Data Output and Predictions

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 trials to criterion is computed for each phase of each sequence (i.e., the Phase I AB discrimination for each sequence, the phase II BC discrimination for each sequence, and the AC phase III discrimination for each sequence), there are six measures total. The critical prediction is that it will take subjects significantly more trials to reach criterion in Phase III 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 from data collected in Spring 2001 (N=110) are consistent with this prediction.

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Data Format for Downloadable csv file

The data obtained via the Download data link on the PsychExperiments homepage are comma delimited. The first entry (up to the first comma) is the affiliation of the research participant. Typically this is the class to which the participant belongs. Non-affiliated participants use the default entry of Interested Person. Next is the randomly assigned ID code for the research participant. The third and fourth entries are the data and time (24-hour format) on the server when the data were received. Because no data is collected on subject variables in this experiment, raw data come next. The data consist of 6 "trials." The first data entry for each trial is a trial number (1-6). This is followed by a text entry for for trial type which is either NTP (Non-transverse patterning) or TP (Transverse patterning). Next is a numeric entry for Phase with the values being 1, 2, and 3. Last is the trials to criterion measure. The minimum value is 14, which reflects error-free performance.l

The table below gives the data format (excluding user information) The text line below that shows a complete data set for one research participant.

Trial Number	Trial Type	Phase	Trials to Criterion	Trial Number	Trial Type	Phase	Trials to Criterion	etc.
1,	NTP,	1,	24	2,	NTP,	2,	29,	etc.

U. of Malaga--RuzSoler and Torres Metodologia experimental,MBS589,12/1/2002,06:41,1,Day1,11/30/2002,1/1/1900 1:33:00 PM,1,FalseMemory,10,0,0,10,1,2,Day2,12/1/2002,1/1/1900 1:44:00 PM,1,FalseMemory,10,0,0,10,1,

References:

Dusek JA, Eichenbaum H. The hippocampus and transverse patterning guided by olfactory cues. Behav Neurosci. 1998 Aug;112(4):762-71.

Reed JM, Squire LR. (1999). Impaired transverse patterning in human amnesia is a special case of impaired memory for two-choice discrimination tasks. Behav Neurosci, 113(1):3-9.

Spence, K.W. (1952). The nature of the response in discrimination learning. Psychological Review, 59, 89-93.

Wu X, Tyrcha J, Levy WB. A neural network solution to the transverse patterning problem depends on repetition of the input code. Biol Cybern. 1998 Sep;79(3):203-13.