Review of Empirical Research Article
Dewar, Michaela, Alber, Jessica, Butler, Christopher, Cowan, Nelson, & Della Sala, Sergio. (2012). Brief Wakeful Resting Boosts New Memories Over the Long Term. Psychological Science, 23(9), 955-960. doi: 10.1177/0956797612441220
1. All research must have a justification why it is conducted. What justification do the authors provide for conducting the current study? In your view, is the objective of the experiment important for the field?
This study was performed to investigate how to consolidate the learning of new memories so that they can be recalled at future times. The authors have evidence from previous research studies on both human adults and rats, that individuals are more likely to remember newly learned words or behaviours if a period of ‘wakeful resting’ followed the learning process. Functional MRI studies had also shown evidence of data encoding-related neural activity in the brain during the postlearning wakeful period. However, all of these studies assessed the storing and recall of memory over a short period only, and they did not assess whether the consolidation of new memories persisted for long, such as after a week. Therefore, the true benefit of wakeful resting in maintaining the memory of new learning had not been assessed. Also, the benefit of wakeful resting had not ben assessed for ageing individuals, who have more problems with memory and learning than young adults. Based on this background, the authors designed experiments to investigate whether the memory consolidation effect of wakeful resting would also promote the retention of learning after 1 week, in ageing adults.
In my view, the authors have a valid reason for conducting this study, as their experiment would assess how useful wakeful resting is for maintaining new learning for a long period. This objective is important in the field of psychology because if the experiments were successful, they would lead to new interventions to help elderly individuals learn new memories which is currently a troublesome procedure for them. It would also help improve teaching strategies in various educational settings.
2. Discuss how the independent and dependent variables are operationally defined. How could these constructs be operationally defined in a different way?
The independent variable was the learning intervention after 2 stories had been read to the participants: 10 minutes of wakeful resting for one group, and 10 minutes of playing ‘spot-the difference’ game for the other group.
The dependent variable was the number of story units (out of total 25) correctly recalled by the participants, after 15-30 minutes since hearing the stories, and 1 week afterwards. The dependent variable was also the retention score for each participant, calculated using the number of story units recalled.
The independent variable could have been defined differently by asking the participants to watch a television show instead of play the spot the difference game for 10 minutes. The dependent variable could have been different by using a list of words to recall, instead of the number of story units.
3. What type of design was used here, and why was this type of design appropriate for the goals of the study?
This was an experimental study design, with 2 groups of interventions: wakeful resting versus playing the spot the difference game. This design was appropriate as it allowed the control of various confounding factors, and assessed the sole effect of the difference in intervention on the amount of information that could be recalled.
The design also consisted of 2 experiments. In the first experiment, the participants were allowed to recall the stories immediately after hearing them and before the interventions were given, while no recall opportunity was given in experiment 2. Thus, experiment 2 controlled for the effect of immediate recall, which can possibly affect memory recall at later times.
4. What sample do the authors utilize in this study? Is the sample appropriate for the purposes of the study?
The sample was 14 ageing individuals, of mean age 72 years, who did not have any neuropsychological condition as proven by extensive testing. This sample is appropriate as it allowed the investigation of wakeful resting as a memory booster for elderly individuals who have the most problems with memory. However, the sample size at 14 seems inappropriately small, with the possibility of incorrect conclusions.
5. What inferential statistics do the authors use? In what way were the inferential statistics appropriate for the data or research questions?
Between-subjects one-way analysis of variance was used for statistics testing, with reporting of F statistic, p value and eta square (ηp2) values. This test was appropriate for the data, as means of retention scores and mean number of story units recalled were compared between the groups. Also, this test allowed the comparison of 3 mean values at the same time, which would not be possible with other tests for means such as the student’s t test – the scores and story units immediately after hearing the story, 15-30 minutes after hearing the story, and after 7 days.
6. What conclusions do the authors reach? Do you think the conclusions they reach are justified?
The authors concluded that, in ageing individuals, wakeful resting leads to significant memory enhancement after a 15 to 30 minute period, and this effect persists at 7 days as well. Also, the memory enhancement with wakeful resting occurred in the absence of a recall opportunity given after hearing the story and before the intervention. They also proposed that ‘the long-lived effect of wakeful resting was the result of superior memory consolidation that took place during the 10-minute period’, and that memory consolidation was comparatively difficult if other activities such as a mental game.
These conclusions are justified, however, they do not adequately reflect the fact that the memory enhancement is in comparison to the specific setting of a distracting game being played immediately after the learning period, and that the recall does decline after 7 days with wakeful resting, although the decline is less compared to that with the distracting game. To truly validate these conclusions, the experiment needs to be performed by comparing wakeful resting with a variety of other settings, such as going to sleep or watching television.
7. Are the conclusions in accordance with the previous research the authors discuss?
The conclusions concur with the previous research, as all these studies show that wakeful resting improves the storage and recall of learned information within 30 minutes of the learning process. In the context of previous experiments, these results supported the hypothesis that wakeful resting provided an environment of ‘minimal interference, during which the various elements of an encoded story can be replayed more often than is possible during activity-filled (interference) periods, which are the norm in everyday life’
8. What other limitations (not discussed in the article) might apply?
The study had a very small sample size of 14 participants. Significant differences can be difficult to rely on with such a small number.
The authors used the spot the difference game with pictures, as a substitute for the normal activity-filled periods of daily life. However, this game may have been more distracting than normal daily activities and may have had a negative impact on memory consolidation of the stories, leading to a much greater apparent improvement in recall with wakeful resting. The experiment would need to be conducted in various control settings for true comparisons.