Sanjeev R. Bhatia, B.P.T.

Human memory and the ability to recall vast amounts of trivia and unrelated information have intrigued scientists and researchers for quite some time. However, sometimes memory is inconsistent in its retrievability. Research on memory often focuses on “consolidation,” used here to refer to the organization of memory in the brain over time to make recollection more permanent and easily accessible. One technique is called chunking. Chunking is used in daily life without even thinking. For example, it is much easier to remember a phone number if it is split into parts as compared to remembering it as a continuous 10 digit number, and musicians use chunking to remember the notes of lengthy songs. Why does breaking a long sequence into shorter parts make it easier to remember? What happens to these chunks of information once we memorize them?

Recent research looked at effects of consolidation on chunks of information in a procedural learning task. Researchers made participants learn a 12 key sequence by repetitively performing the sequence. Once the participants had adequately learned and improved in their performance, they were invited for a second session 24 hours later, in which each participant recited the sequence solely from recall. This time delay allowed for consolidation (organization) of the learned sequence in the brain. The aim was to decipher the patterning of the chunks that the participants made of the 12 key sequence. This was done by comparing the speed and accuracy of all the elements across trials by each participant and comparing results between participants. The expected results were to find a great improvement in performance of certain elements in the sequence across different chunks and less improvement in the remaining elements.

All participants had different patterns and numbers of chunks. Despite the different patterning, they found, as expected, a great improvement in speed as well as accuracy in performance of the task over the 24 hr. delay period. This was due to memory consolidation during the delay. There was also more improvement in the first element of each chunk compared to the rest of the elements in that chunk. This showed how consolidation affects different elements in a sequence differently and helps recall and performance of procedural memory.

  Further Readings:

• Walker, M.P., et al. (2003). Dissociable stages of human memory consolidation and reconsolidation. Nature, 425, 616-620.
• Wright, D.L., et al. (2010). Daytime sleep condenses the time course of motor memory consolidation. Nature Neuroscience, 10: 1206-1213.
• Bo, J., & Seidler, R.D. (2009). Visuospatial working memory capacity predicts the organization of acquired explicit motor sequences. Journal of Neurophysiology, 101: 3116-3125.