The Influence of Sleep On Memory. Jaraad Mootee. Huron College

Transcription

1 Sleep and Memory Vs Abstract/Concrete 93 The Influence of Sleep On Memory Jaraad Mootee Huron College The current study aims to examine the influence of sleep on general memory recall and its relationship to different strengths of encoding using abstract and concrete words. The study aims to recreate the procedure in the study by Soave (2010) and uses materials from Paivio (1968). Participants are randomly set into one of four, awake or asleep functions, and abstract or concrete words. Participants memorized a list of word pairs, and then entered an intermission periodfilledwith either wakefulness or sleep. Following the 12 period intermission, participants were given half the word pairs and asked to complete the pairs. The results of the study didn't show a significant relationship between the constructs due to methodological issues. The study of sleep and its influence on memory recall has had extensive cover but varying results. Gais, MoUe, Helms and Bom (2002) examined changes in EEG activity during nocturnal sleep after the effect of different learning tasks. The study was specifically looking at sleep spindle activity during sleep, and its relationship to the tasks. Participants learned a set of word lists, and afterwards were tested on their memory for consistency. The participants then slept and were tested after 30 minutes during the next morning (Gais et al, 2002). The participants slept in a sleep lab for the three nights for control purposes and EEG monitoring. Participants were also asked to take part in a non-learning task to compare results. The study found that sleep spindle activity was significantly higher after the learning task as opposed to the

2 Sleep and Memory Vs Abstract/Concrete 94 non-learning task (Gais et al, 2002). Sleep spindle activity was found highest during thefirst90 minutes of sleep. The study also found there was a positive correlation with successful recall ability and sleep spindle activity. The results found that the higher brain activity after teaming tasks could allude to memory consolidation, but further testing was required since the correlation study could have had hidden confounds. The study provides a biological relation between sleep's influences on memory recall. There have been particular studies done to enhance activity by using differing periods of sleep. Philal and Bom (1997) looked at the difference between short wave sleep and rapid eye movement and its relationship to memory. There were four groups of participants during the study. The early sleep group (which tested SWS), the early awake group, the late awake group, and the late sleep group (which tested REM). The participants were involved in two tasks, a paired associate task, and a mirror tracing task. The results showed that participants in the increased SWS group outperformed in the paired associate task while the increased REM group performed better in the mirror tracing group. Both groups performed better than the awake groups. Wagner, Gais and Bom (2001) did a similar study involving SWS and REM. Participants had to memorize a portion of text. The text was either neutral or emotional. In both cases the REM group outperformed, while the SWS still performed over the awake group.

3 Sleep and Memory Vs Abstract/Concrete 95 Many studies agree that the influence of sleep on memory provides positive recall, however to what amoimt of sleep provided positive memory recall. In a study done by Lahl, Wispen, Williegens, and Pietrowsky (2008) they found the mere onset of sleep promotes memory consolidation. They had participants memorize a set of 30 words followed by a retention period. Lahl et al (2008) used four different groups, the short sleep group, the long sleep, the short awake and the long awake. The short groups had a 6 minute retention period, whereas the long had a 60 minute retention period. The results of the study foimd that the mere onset of sleep helped start the consolidation process even after the sleep was interrupted. Stickgold, Whidbee, Schermer, Patel, and Hobson (2000) compared memory recall between sleep and awake groups on a visual recognition task. Their results found that participants that had received more than 6 hours of sleep outperformed the awake group significantly, however participants under 6 hours of sleep did not see significant improvement in visual recognition. Stickgold et al (2000) found that increased amounts of sleep correlated with increased visual recognition performance. Jenkins and Dallenbach (1924) performed a study in which they compared recall between participants put into 8 groups. Participants who slept for 1, 2,4 or 8 hoursfilledthis time with either sleep or wakefiilness. Participants had to memorize nonsense syllables and then were

4 Sleep and Memory Vs Abstract/Concrete 9^ tested on their ability to recall as many of the syllables as possible. Results of this study showed sleep conditions performed better than the awake conditions, and as the hours increased in amount of time slept, so did the significant performance difference between conditions (Jenkins and Dallenbach, 1924). Studies also have shown the types of words memorized have different strength in recall. In a study done by Paivio (1965), he measured the difference between two kinds of words that participants can remember, concrete and abstract. The results of the study concluded concrete word recall performed significantly better over abstract words. Paivio concluded it was due to the imagery associated with recall that helped with memory encoding. Paivio, Yuile, and Madigan (1968) furthered his hypothesis by using a panel of participants to measure approximately 900 words on scales of concreteness, imagery, and meaningfiilness. Paivio et al. (1968) observed that concrete words had a strong relationship with imagery and meaningfiilness. In a previous study, The Influence of Sleep on Memory by Soave (2010), attempted to find the effect of sleep pertaining to memory recall. Influenced by past studies in sleepinfluenced memory recall, Soave used a design construct similar to the study by Jenkins and Dallenbach (1924). Instead of using non-sense syllables to test participants, he substituted word

5 Sleep and Memory Vs Abstract/Concrete 9-7 pairsfromthe study done by Paivio (1968). Soave tested recall differences of 8 pairs of abstract words on half of participants and concrete words on the other half of participants. The study did not prove his hypothesis that memory recall on both sets of words, should be superior in the sleep group as opposed to the awake group. The results of Soave's study (2010) were limited by a ceihng effect in thefinaldata. Thefinalresult was potentially skewed by several methodological factors. Soave collected datafrom24 participants, which might not have been sufficient enough a sample size to reflect the main population. He also experienced a large amount of female psychology university students as participants, where the concentration of study might potentially affect the data on memorization. Due to the nature of the study, Soave explained about a lack of control. Some participants might have cheated, and some did not fulfill time constraints during the study. Since the data collection was done independently there were a lot of mitigating factors for the results of the study. This study aims to replicate The Influence of Sleep on Memory by Soave (2010). Soave's study (2010) featured issues with limiting factors, which will be changed in this present study. Instead of 8 pairs, this study will be using 16 pairs to avoid any potential ceiling effect. Soave also discussed the improved methodology of the experiment if there was an increase in the range and number of participants. This study aims to include 40 participants as opposed to 24,froma

6 Sleep and Memory Vs Abstract/Concrete 98 wider range of studies and ages, and will attempt to include an even distribution of sex. The study will compare the difference between concrete words against abstract words, and their different level of memory encoding strength, against the influence of sleep on memory. This study aims to prove the general hypothesis that sleep influences memory recall positively (Soave, Jenkins & Dallenbach, Lahl et al., Stickgold et al., Gais et al., 2002) Method Participants Participants used in this study were primarily from the University of Western Ontario. The participants were aged from 18 to 22, and of the 21 participants, there were 12 male, and 9 female. Participants werefromdifferent faculties and academic backgrounds. Participants were from the middle to upper levels of economic wealth, and comefroma variety of ethnic backgroimds. Materials The study used a differing selection of 16 concrete word pairs and 16 abstract word pairs than the study done by Soave (2010). The word pairs were takenfrompaivio's word lists (Paivio et al. 1968). The concrete words were chosen with respect to high imagery and concreteness

7 Sleep and Memory Vs Abstract/Concrete 99 rating. The abstract words were chosen conversely with a lower imagery and concreteness rating. The full 16 word pairs were shown on one page given to the participant for retention, the 8 pairs with 8 missing words on another for recall measurement. The word lists for the two sets are located in appendix B. Procedure After being randomly assigned into one of the four groups, awake-abstract, sleepabstract, awake-concrete, sleep-concrete, the participants were handed a consent form explaining the nature of the study. Participants were not made aware of what group they were in. The awake group was given a set of word pairs to memorize in the morning, and then 12 hours later asked to complete the word pairs. The sleep groups were asked to memorize the word pairs at night, and then 12 hours later, asked to complete the word pairs in the morning. During the memorization phrase, participants are given an unlimited amount of time to memorize the words, however will be asked to repeat the word list twice to ensure proper recall. They were given the abstract word Ust or the concrete word list depending on their group. The tests were done between social networking, instant messaging, or written. Those who participated online were ed the text file and asked to it back when finished. Results

8 Sleep and Memory Vs Abstract/Concrete ^s:: Sleep AwaKe Awake - Asleep 4 2 Concrete Abstract Figure 1. Shows the mean performance of recall between the concrete and abstract constructs against the awake and asleep group.

9 Sleep and Memory Vs Abstract/Concrete After analyzing the data with a 2 X 2 ANOVA, focusing on the concrete and abstract conditions and the variable recall scores, recall of concrete word pairs after sleep was more effect than the other constructs. Participants who recalled concrete words after sleep (M = 11.75) performed slightly better over the awake group (M = 11). The concrete word pair conditions exhibited better recall compared to abstract conditions, in both the awake and sleep intermission cases, as observed infigure1. Discussion The results of this study did not replicate the suppiort of sleep promoting superior recall and memory encoding. The study didn'tfinda significant relationship between sleep and wakefulness and concrete and abstract words, contrary to otherfindings.this was due mostly to methodological issues in the nature of the study. Thefindingswere supposed to represent a significant difference between the sleep and awake groups, with the sleep outperforming the awake condition. The g^ in performance was supposed to increase when the superior sleep group was paired with stronger-encoded concrete word pairs. A large issue in this study was the nature of control. Participants were given a lot of fi"eedom during some testing and retention periods, allowing participants to potentially skew validity. Testing done impersonally had the potential for the participant to simply look up the

10 Sleep and Memory Vs Abstract/Concrete 2 Q2 original word pair list online. Another issue is the problem with the large amount of potential confounding factors. Different variables in participant exposure or setting during the intermission period could have had an effect on the data. For control purposes it would be ideal for future studies to keep the participants during sleep in a similar or identical environment. By far the largest mitigating factor in this study was the data collection. The study's sample size was too small to reflect the general population. The nature of this study requires participants to memorize the word pairs. Due to limiting environmental factors and choice of participants in the study, participants who were all university students, were less likely to participate since they had other obligations to memorize material, which would interfere with the study and conversely. Futiue studies should seek to extend a longer period of time to collect college student participants in order to obtain a more general sample.

11 Sleep and Memory Vs Abstract/Concrete 103 References Paivio A., Yuille J. C, Madigan, S. A., Concreteness Imagery and Meaningfulness: Values for 925 Nouns, Journal of Experimental Psychology Monograph Supplement. Jan Vol 76 nol part 2 Soave, A. (2010). The Influence of Sleep on Memory. The Huron University College Journal of Cognitive Psychology. Jenkins, J. G., & Dallenbach, K. M. (1924). Obliviscence during Sleeping and Waking. American Journal of Psychology, 35, Paivio, A (1965), Abstractness, Imagery, and Meaningfulness in Paired-Associate Learning. Journal of Verbal Learning and Behaviour, 4, Stickgold, R., Whidbee, D., Schirmer, B., Patel, V., & Hobson, J.A. (2000). Visual Discrimination Task Improvement: A Multi-Step Process Occurring During Sleep. Journal of Cognitive Neuroscience, 12, Wagner, U., Gais, S., & Bom. (2001). Emotional Memory Formation is Enhanced Across Sleep Intervals with High Amoimts of Rapid Eye Movement Sleep. Learning and Memory, Olaf, L., Wispel C, Willigens, B., Pietrowsky, R. (2008) an Ultra Short Episode Of Sleep Is Sufficient to Promote Declarative Memory Performance. Journal of Sleep Research. Vol 17(1), Plihal, W., & Bom, J. (1997). Effects of Early and Late Noctumal Sleep on Declarative and Procedural Memory. Journal of Cognitive Neuroscience, 9, Gais, S., Molle, M., Helms, K., Bom, J. (2002). Learning-dependent Increases in Sleep Spindle Density. The Journal ofneuroscience. Vol 22 (15),

12 Sleep and Memory Vs Abstract/Concrete 104 Appendix A SS Df MS F Awake Asleep Interaction Error Total X2 ANOVA Summary Table for Awake/Asleep interaction with Concrete/Abstract

13 Appendix B Word List (Concrete) Cheese Bird Queen Tank Child Corn Day Baby Sheep Fox Girl Egg Horse House Moon Fish Ant Fire Tree Stone Dirt Water Elbow Box Book Wheat Train Hen Plane Photo Duck Boy

14 Word List (Abstract) Fate Hint Idea Simple Courage Length Memory Mind Free Moment Reliable Theory Truth Liberty Lie Fate Original Justice Opinion Health Duty Sick Fact History Happiness Life Sincere Honesty Cost Empathy Effort Bravery

15 Word List [Concrete) Cheese Bird Queen Tank Child Corn Day Baby Sheep Fox Girl Egg Horse House Moon Fish

16 Word List [Abstract) Fate Hint Idea Simple Courage Length Memory Mind Free Moment Reliable Theory Truth Liberty Lie Fate