Comparisons Of Source Memory And Target Memory: Event-related Potentials During Retrieval And Task Difficulty

The memory for the origin of an item that comes into the cognitive system is called source memory, while the memory for where an item has gone is called target memory. Both source memory and target memory are related with recollection in the episodic memory. Two experiments were conducted to compare source memory with target memory. Both experiments used the paradigm which simulates item transferring in daily life. Twenty one participants completed simple old/new items recognition tasks first. Then participants were arranged by computer program to receive items from one of the two virtual persons in source tasks, and to give away items to one of two other virtual persons in target tasks. In test phase participants were asked to recognize the source and target of each item presented. Their EEGs were recorded at retrieving. It turned out that there was no significant difference between the accuracies of source memory and target memory; ERPs of correct item memory showed significant old/new difference at N300 (300-400ms):old items< new items; and they showed significant old/new difference at LPC (400-600ms):old items> new items. ERPs of correct retrieval of source memory and that of target memory showed no difference at N300, but a margin significant difference at LPC-which is related with recollection:target memory> source memory. In experiment 2,24 participants were asked to receive items and then immediately give away the item by the computer programs. Each participant should learn the same material repeatedly, till his/her source memory and target memory accuracy reach 90%. Source memory needed less times to reach the aim than target memory. It is implied that quantitive differences may exist between target memory and source memory.