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Sleep and Memory: The importance of peripheral details

Sleep has been to known to be a critical element for the functioning of humans. Today, in fact, I awoke early to go to the gym after getting a less than satisfying night’s sleep when I was met with the classic dilemma: get out of bed and be a productive person or let the comforts of my bed envelop me and fall back asleep? I chose the former, reluctantly. On days following a poor night of sleep I will pass by nearly everyone (friends, strangers, familiar faces) without really noticing their presence––the only thoughts to which my mind attaches are the idea of taking a nap or waiting for nightfall to come. Generally speaking, sleep patterns can have a profound effect on our physical, emotional, and cognitive capacities. But can sleep actually affect performance when we truly need to focus, such as at a crime scene? The authors of the following study sought to investigate how sleep can affect memory recall. But before I delve into the study, it is important to mention past research on the glaring imperfections of memory recall, as well as the relationship between sleep and memory.

 


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Neisser (1981) studied the testimony of a prominent figure in the Watergate scandal, John Dean. He was asked to recall certain conversations he had with President Nixon, but he was unaware of the fact that such conversations had been recorded. When comparing his sworn testimony with the recordings, there were many inaccuracies, despite the great level of detail that Dean provided. This is an example of someone reconstructing an event and recalling what they think happened. To further illustrate the malleability of memory, Loftus & Palmer (1974) introduced a concept called the misinformation effect. They showed all participants a video of a two-car crash, and thereafter added a manipulation by asking “how fast were the cars going when they (contacted, hit, bumped, collided, smashed) each other?” Those who received the question with the word “collided” or “smashed” reported higher speeds than those in the “contacted” or “hit” condition. In general terms, these studies clearly show how memory recall is certainly not infallible, much to my chagrin (I still think my memory recall is flawless). Lastly, prior studies have looked at the role that sleep can play in memory consolidation, or the way information is encoded and transferred from short-term to long-term memory stores (Diekelmann & Born, 2010). Encoding refers to way we perceive new information, and how we assign meaning to it so it can be stored and retrieved at a later time. These studies show that sleep helps with memory consolidation, which is not a surprise. However, there has been little research on the effect of sleep prior to encountering and encoding new stimuli.

In the current study, researchers had 75 participants watch a two-minute video clip of a bank robbery. They were interested in three sleep-related variables as it pertained to memory recall. First, before watching the video, participants were asked to assess their current level of sleepiness. After the video, they then completed measures pertaining to their previous night’s sleep, both its duration and quality. Thereafter, they answered questions regarding both the central and peripheral details of the crime (central details are those in the foreground of the scene whereas peripheral details are spatially in the background). The only possible responses were “yes,” “no,” or “don’t know.” The principal finding was that as sleep quality decreased and sleepiness increased, participants’ recall for peripheral details was significantly diminished. Clearly, these details were not adequately attended to and thus were not properly encoded. When a stimulus is not encoded, it cannot be available for recall. Although participants responded “don’t know” for roughly a third of the questions, these responses were not included when considering response accuracy––it was only when a “yes” or “no” response was recorded that accuracy was taken into consideration. Although recall for peripheral details worsened as a function of sleepiness, participants were able to accurately recall central details regardless of their prior night of sleep or their sleepiness at the time. So, what’s the big deal? If people can still remember the most important details of a situation without a good night of sleep, how important can sleep really be for memory?

crime

Honestly, I do not know. However, I do think the findings from this study could be generalized in some way. Think of it in terms of studying for a test. If I do not get adequate sleep the night prior, I will likely still remember the key concepts if I’ve done the proper amount of studying. But what if I forget the smaller details, and what if those details are the difference between an A or B in the class? On a different note, I could be driving after staying up too late the previous night. Once again, I will probably be able to notice the cars passing to my left, but what if I don’t see the deer in my periphery that is about to dart across the road in front of my car? Sometimes in life it’s the little things that make all the difference. So rest up, get some sleep, and you’ll be more equipped to remember the seemingly insignificant details of life that could end up being oh so important.

To read the original article, click here

References

Diekelmann, S., & Born, J. (2010). The memory function of sleep. Nature Reviews   Neuroscience, 11(2), 114-126.

Loftus, E. F., & Palmer, J. C. (1974). Reconstruction of automobile destruction: An example of the interaction between       language and memory. Readings in social psychology: The art and science of research, 13(5), 585-589.

Neisser, U. (1981). John Dean’s Memory: A case study. Cognition, 9(1), 1-22. Doi:10.1016/0020-277(81)90011-1

Thorley, C. (2013). The effects of recent sleep duration, sleep quality, and current sleepiness on eyewitness memory. Applied Cognitive Psychology, 27(5), 690-695.

 

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  1. emlandry
    October 22nd, 2015 at 01:12 | #1

    As someone who rarely gets the recommended 8 hours, studies examining the effects of sleep deprivation always make me stop and think. More often than not, they make me seriously regret staying up so late, as the evidence is usually pretty overwhelming that sleep deprivation has palpable effects on cognitive functioning.

    The fact that the “sleepy” participants in this study failed to encode peripheral stimuli reminded me of our discussion of the use of eye-movement tracking during dual-task experiments. The particular study I’m reminded of looked at the effects of the use of hands-free devices while driving. Participants using a hands-free device while driving were found to perform a decreased visual scan, effectively reducing their field of vision. This diminished scanning pattern had significant effects on their ability to recall stimuli that had been presented in the environment, effectively decreasing their awareness of their surroundings. So, not only were they not encoding these objects, but they actually weren’t seeing them due to decreased eye movement.

    This article made me wonder if sleep deprivation has the same effect on eye movement patterns. A quick online search produced several studies that note impaired visuomotor performance with sleep deprivation (Alhola & Polo-Kantola, 2007). Thus, I am left wondering where sleep deprivation rears it’s head in the line of cognitive processing; were the participants in the Thorley (2013) study not even fixating on peripheral stimuli, or were they fixating but unable to recall it later due to a failure to encode?

    Overall, I think your discussion of this study and it’s implications was intriguing, and the topic has certainly left me interested in how my questionable sleeping habits may be having an effect on my cognitive abilities!

    Reference
    Alhola, P., & Polo-Kantola, P. (2007). Sleep deprivation: Impact on cognitive performance. Neuropsychiatric Disease and Treatment, 3(5), 553-567.

  2. October 8th, 2014 at 13:34 | #2

    This is an interesting study, and it definitely relates well to what we have discussed in class about both attention and memory, particularly in their faults.

    I looked at a study about sleep for Health Psych, and it stressed the importance of sleep as a chance for the brain to clear out the “junk” that builds up throughout the day, enabling better performance the next as well as sustained cognitive function in the long-run. It essentially serves as maintenance, and any machine is going to perform less efficiently without regular maintenance.

    So, it makes sense that lack of sleep would contribute to a lower level of alertness, heightening the likelihood that one might miss less critical features in his or her environment. In line with the capacity framework models of attention, if our attentional resources are limited by lack of sleep, it would require fewer attentional resources to attend to the central details of the surrounding environment.

    I think it would have added to the study though if they had looked at participants’ general sleep habits, to see the difference in the impact of one poor night’s sleep and a sustained period of sleep deprivation, and if it was the long term lack of sleep that was the main driver.

  3. May 9th, 2014 at 11:48 | #3

    I think this is a very interesting study. The hook at the beginning is particularly interesting, because it relates to everyone in some way — inevitably, everyone has either been tired and failed to notice a friend after having the classic “wake up dilemma.” The one criticism that I have of your introduction is that, based upon your statement about not acknowledging friend, I expected you to go into a discussion of face recognition rather than how sleep impacts memory.

    Additionally, I would have liked to hear more about the Diekelmann & Born (2010) article and how sleep impacts memory. I understand that as one’s duration of sleep decreases, his memory for smaller, more peripheral details decreased; however, I do not understand the processes by which this occurs. Perhaps you could have gone into more detail on how improper encoding and attention due to this lack of sleep impacts memory. From taking Cognitive Psychology we understand that attention and encoding are key to memory because without it, items will not be retained; however, those who have not taken the class may not have as rich as an understanding as we do. This sort of discussion can be inserted after you mention Diekelmann and Born (2010) or where you mention encoding and attention in your second to last paragraph. Lastly, I might have mentioned that Loftus and Palmer (1974) were interested in the impact that leading questions could have on eyewitness testimony, because, while such a study does investigate the malleability of memory, it does so in a very specific way.

    Overall, this was a very intriguing post because of its ability to connect with the reader. I like how you end it by proposing scenarios in which this information could prove useful.

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