Summary: Napping influences memory in the right hemisphere of the brain, inducing false memories in a word recall test, researchers report.
Source: Lancaster University.
A study by John Shaw and Professor Padraic Monaghan of Lancaster University found that sleep influenced false memories in a memory recognition test taken after a nap.
They tested two groups of people, with one having slept for up to 1 hour 45 minutes while the other group stayed awake.
Both groups were asked to focus on a central fixation point on a computer screen while 48 test words appeared on the left or right of the dot. The participants were then instructed to press a yes or no key according to whether they had previously seen the word or not.
The test words contained lists of related words such as “bed, rest, awake, tired, dream, snooze, nap, snore.”
The tests asked the participants to recall or recognise words which were part of the original list (seen-old), not related to the list (unseen-new) or not previously seen but related to the theme of the list (unseen-lure words eg “sleep”).
The group which had had a nap was “significantly more likely” to identify unseen-lure words as old, thinking they had seen them before when they had not.
Curiously, sleep was revealed to influence memory in just one half of the brain. Sleep affected the right hemisphere of the brain by encouraging it to accept more of the unseen-lure words than the left hemisphere. This effect was not found for the group that stayed awake.
“We found that whereas sleep increased overall false memory recognition, this varies according to the hemisphere that was being accessed during retrieval, with the right half of the brain being more susceptible to false memories and the left half was found to be more resilient against accepting unseen words as previously seen.”
Source: Lancaster University
Publisher: Organized by NeuroscienceNews.com.
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Original Research: Abstract for “Lateralised sleep spindles relate to false memory generation” by John J. Shaw and Padraic Monaghan in Neuropsychologia. Published May 2018.
Lateralised sleep spindles relate to false memory generation
Sleep is known to enhance false memories: After presenting participants with lists of semantically related words, sleeping before recalling these words results in a greater acceptance of unseen “lure” words related in theme to previously seen words. Furthermore, the right hemisphere (RH) seems to be more prone to false memories than the left hemisphere (LH). In the current study, we investigated the sleep architecture associated with these false memory and lateralisation effects in a nap study. Participants viewed lists of related words, then stayed awake or slept for approximately 90 min, and were then tested for recognition of previously seen-old, unseen-new, or unseen-lure words presented either to the LH or RH. Sleep increased acceptance of unseen-lure words as previously seen compared to the wake group, particularly for RH presentations of word lists. RH lateralised stage 2 sleep spindle density relative to the LH correlated with this increase in false memories, suggesting that RH sleep spindles enhanced false memories in the RH.