Aug 26, 2009 Comments Off
Working memory (WM) is the cognitive system responsible for the temporary storage and manipulation of information and plays an important role in both learning and focusing attention. Considerable research has documented that many children and adults with ADHD have WM deficits and that this contributes to difficulties associated with the disorder. For an excellent introduction to the role of WM deficits in ADHD, click here.
A simple example illustrates the importance of WM for particular academic tasks. Try adding 3 and 9 in your head. That was probably easy for you. Now trying adding 33 and 99. That was probably more difficult. Finally, try adding 333 and 999. This is quite challenging for most adults even though each calculation required is trivially easy. The challenge occurred because you need to store information — the sum of 3+9 in the one’s column and then ten’s column — as you process the remaining part of the problem, i.e., 3+9 in the hundred’s column, and this taxed your WM. If your WM capacity was exceeded, you could not complete the problem successfully.
This simple problem also illustrates the difference between short-term memory (STM) and WM. Short-term memory simply involves retaining information in mind for short periods of time, e.g., remembering that the problem you need to solve is 333+999. Working memory, in contrast, involves mentally manipulating — or ‘working’ with — retained information and comes into play in a wide range of learning activities. For example, to answer questions about a science chapter, a child not only has to correctly retain factual information but must mentally work with that information to answer questions about it. Thus, when a child’s WM capacity is low relative to peers, academic performance is likely to be compromised in multiple areas.
Because WM deficits play an important role in the struggles experienced by many individuals with ADHD, it is important to consider how different interventions address this aspect of the disorder. In this study, the authors were interested in comparing the impact of Working Memory Training and stimulant medication treatment on the WM performance of children diagnosed with ADHD.
Participants were 25 8–11 year-old children with ADHD (21 boy and 4 girls) who were being treated with stimulant medication. Children’s memory performance was assessed on 4 occasions using the Automated Working Memory Assessment (AWMA), a computerized test that measures verbal short-term memory, verbal working memory, visuo-spatial short-term memory, and visuo-spatial working memory.
At time 1, the assessment was conducted when children had been off medication for at least 24 hours. The second assessment occurred an average of 5 months later and when children were on medication. The third assessment occurred after children had completed 5 weeks of Cogmed Working Memory Training using the standard training protocol (see below). The final assessment occurred approximately 6 months after training had ended. This design enabled the researchers to make the following comparisons:
- WM performance on medication vs. off medication (T1 vs T2)
– WM performance on medication vs. after training (T2 vs. T3)
– WM performance immediately after training ended vs. 6 months following training (T3 vs. T4)
This final comparison provided information on whether any benefits provided by the training had endured.
In addition to measuring STM and WM at each time point, measures of IQ were collected at times 1, 2, and 3.
- Working Memory Training -
WM training was conducted using the standard Cogmed training protocol with each child completing 20–25 training sessions within a 25 day period. The training requires the storage and manipulation of sequences of verbal, e.g., repeating back a sequence of digits in reverse order, and/or visuo-spatial information, e.g., recalling the location of objects on different portions of the computer screen.
Difficulty level is calibrated on a trial by trial basis so the child is always working at a level that closely matches their performance. For example, if a child successfully recalled three digits in reverse order, on the next trial he had to recall four. When a trial was failed, the next trial was made easier by reducing the number of items to be recalled. This method of ‘adaptive training’ is thought to be a key element because it requires the child to ‘stretch’ their WM capacity to move through the program.
- Results -
- Impact of Short-Term Memory and Working Memory -
Medication vs. no medication — When tested on medication, Read the rest of this entry »