Study Of Effects Of "Digit-image"Mnemonics Training On Children’s Digit Memory

As was proposed in the theoretical frameworks skilled memory theory (SME, Chase&Ericsson,1981,1982) and Long Term Working Memory (LT-WM, Ericssion&Delaney,1998,1999; Ericsson&Kintsch,1995; Ericsson, Patel,&Kintsch,2000) by Ericcson et al., high memory performance was considered been benefited from specific encoding strategies. Novelty information could be processed into meaningful items that had been previous studied in long term memory by using the encoding strategy. Previous behavior studies of Hu et al., acquired several experiments on Chao Lv revealing that chunks and images played an important role in facilitating the superior digit memory (Hu, Ericcson, Yang&Lu,2009; Hu&Ericsson,2012). Jing (2012) drew a similar conclusion that there were strong correlation between mnemonics such as "digit-image" encodings and superior digit memory performance by conducting memory tests on Feng Wang and exploring the mechanism of his claimed200-digit superior digit-memory span. As reported by Feng Wang, he attributed his digit memory expertise to the deliberate training on "digit-image" mnemonics and using it as frequently as possible.To explore the influence of deliberate training on "digit-image" mnemonics on children’s short term digit memory and investigate the possible ERPs and cerebral cortex correlate to the cognitive process using specific mnemonic, we conducted this study.A group of12-year-old children was instructed to learn a series of100unique images, corresponding to2-digit groups of00-99respectively, and was trained to use the association to help memorize series of digits, with the practice time of at least60minutes per day for8days. Three experiments were performed on the subjects twice before and after training. Taskl was the classic digit-memory span task. In task2, participants were acquired to memorize two digit matrices of4*5-digit numbers within one minute and to subsequently recall. In task3, participants memorized2020-digit sequences with the present speed of2s/digit while at the same time ERPs were collected.The average performance of corrected recalled digits on all3tasks was significantly increased after training. ANOVA analysis of recall time on digits located "odd" and "even" showed that "2-digit" grouping law was acquired by participants while memorizing sequentially presented digits. Such behavioral performance support that deliberate training on digit-image mnemonics improved the2-digit grouping process and memory performance.ERPs data showed a N700component with its peak latency at around700ms increased after stimuli onset during post-training tasks, and usually observed higher peak distributed at middle part of cerebral cortex than left and right cortex. This result was consistent with the previous speculation that N700may reflect the access of specific characteristics of the imaged item or activation in a working memory system specific to mental imagery. Similar result was found on FN400, a component which was considering relevant to the increased familiarity of items which should be benefit by activation of informative mental images.The present study demonstrated that digit-image mnemonic training facilitated the children’s digit memory performance and the possible ERPs data support the hypothesis. We propose that the middle cortex distinct ERP component (N700, FN400) is sensitive to the use of mental imagery. However, further studies and reliable data still need to detailed explore the neural mechanism underlying the usage of digit-image mnemonics.