People may be learning while they're sleeping -- an unconscious form of memory that is still not well understood, according to a study by Michigan State University researchers.
The findings are highlighted in the Journal of Experimental Psychology: General.
"We speculate that we may be investigating a separate form of memory, distinct from traditional memory systems," said Kimberly Fenn, assistant professor of psychology and lead researcher on the project. "There is substantial evidence that during sleep, your brain is processing information without your awareness and this ability may contribute to memory in a waking state."
In the study of more than 250 people, Fenn and Zach Hambrick, associate professor of psychology, suggest people derive vastly different effects from this "sleep memory" ability, with some memories improving dramatically and others not at all. This ability is a new, previously undefined form of memory.
"You and I could go to bed at the same time and get the same amount of sleep," Fenn said, "but while your memory may increase substantially, there may be no change in mine." She added that most people showed improvement.
Fenn said she believes this potential separate memory ability is not being captured by traditional intelligence tests and aptitude tests such as the SAT and ACT.
"This is the first step to investigate whether or not this potential new memory construct is related to outcomes such as classroom learning," she said.
It also reinforces the need for a good night's sleep. According to the National Sleep Foundation, people are sleeping less every year, with 63 percent of Americans saying their sleep needs are not being met during the week.
"Simply improving your sleep could potentially improve your performance in the classroom," Fenn said.
The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Michigan State University.
- Kimberly M. Fenn, David Z. Hambrick. Individual differences in working memory capacity predict sleep-dependent memory consolidation.. Journal of Experimental Psychology: General, 2011; DOI: 10.1037/a0025268
Decades of research have established that “online” cognitive processes, which operate during conscious encoding and retrieval of information, contribute substantially to individual differences in memory. Furthermore, it is widely accepted that “offline” processes during sleep also contribute to memory performance. However, the question of whether individual differences in these two types of processes are related to one another remains unanswered. We investigated whether working memory capacity (WMC), a factor believed to contribute substantially to individual differences in online processing, was related to sleep-dependent declarative memory consolidation. Consistent with previous studies, memory for word pairs reliably improved after a period of sleep, whereas performance did not improve after an equal interval of wakefulness. More important, there was a significant, positive correlation between WMC and increase in memory performance after sleep but not after a period of wakefulness. The correlation between WMC and performance during initial test was not significant, suggesting that the relationship is specific to change in memory due to sleep. This suggests a fundamental underlying ability that may distinguish individuals with high memory capacity. (PsycINFO Database Record (c) 2011 APA, all rights reserved)