Our colleagues have studied the underlying brain activity involved in chunking. As mentioned above, one of the best studied methods for improving verbal memory is through the use of 'chunking' strategies, in which items are recoded into meaningful units or 'chunks.' In one study, by training a volunteer to use complex chunking strategies over the course of 20 months, scientists were able to increase digit span from 7 to a massive 79 items (Ericcson et al, 1980)! On this basis, we concluded that frontal-lobe activity in this task relates to the type of memory process being performed (i.e., storage, reordering) and is not specific to the type of information that is being remembered (i.e., verbal memory).Īn average adult is thought to have a digit span of 7 items (plus or minus 2 Miller, 1956). Both of these tasks required verbal working memory, yet different activation patterns were observed in the brain. We found that both tasks engaged the mid-ventrolateral frontal cortex, but only when participants were recalling in reverse order did the mid-dorsalateral frontal cortex become activated. In one study (Owen et al, 2000), participants either had to recall digits in the order presented (forward recall), or in reverse order (backward recall), with backward being a much more demanding task. Our research has revealed that, while you are performing the digit span task, areas of your frontal cortex become activated. We have been studying how the brain remembers verbal information for nearly ten years. It allows the visual inputs to be recoded so that they can enter your short term verbal store, and it also refreshes decaying representations-without refreshing digits verbally, they would soon be forgotten. As you do this test, you may find yourself mentally rehearsing the string of digits as they appeared on screen this is the rehearsal system in action. The phonological loop comprises a verbal storage system and a rehearsal system. According to one influential cognitive theory, this system has specialised components, one of which, the 'phonological loop,' underlies verbal working memory abilities (Baddeley & Hitch, 1974). Scientists refer to short-term memory, or working memory, as the cognitive system that allows the temporary storage and manipulation of information. The science behind digit span reveals why it's associated more with verbal ability than short-term memory alone. The exact contribution of each test to each performance category may change as more data is collected. The results were published in Neuron in 2012 (Hampshire, Highfield, Parkin, & Owen, 2012). The contribution of each test to each performance category is based on a 'factor analysis' that looked at how tests tend to clump together when measuring a massive set of data. That's right, perhaps surprisingly, it's more closely related to verbal ability than to memory. It's not easy, and requires a lot of practice to master. Experiment with your mental approach to the test to find strategies that work for you.įor most people, 'chunking' is an effective strategy-instead of thinking about each digit separately, think of groups of digits that form a smaller number of meaningful units (chunks).įor example, instead of thinking about 1 4 2 8 5 7 as six digits, thinking of it as three numbers-14, 28, and 57-could make it easier to recall. Your digit span can be increased with the right strategies.

Psyscope digit span