Thwart Stress Effects on Memory

It is well known that stress can impair memory. Everyone has had some experience of this kind. As a student suffering test anxiety, grades are likely to suffer. In high-stakes social or business interactions, the stress may well cause memory to fail us, as when Presidential candidate Rick Perry forgot the name of the agency he wanted to abolish if elected, or when we forget a friend’s name in the process of making a social introduction. How does stress do this? Is there anything we can do about it?

First, we need to know what stressful events do to the body and brain. Brain freezes, like Rick Perry's, probably occur because thinking can get so preoccupied with the stress-inducing stimuli that other thoughts cannot emerge. But other kinds of stress-induced memory impaired come from the well-known “fight or flight” response in which stress activates the release of adrenalin into the blood stream. Adrenalin has many bodily effects that support fight or flight, such as raising heart rate and blood pressure, and increasing arousal perhaps to the point of anxiety and fear. The increased attentiveness may have a fleeting beneficial effect on memory, as has been demonstrated in laboratory experiments. But the other effects of adrenalin on anxiety and distress are likely to impair memory.

The other thing that happens during stress is the activation of the anterior pituitary gland’s release of ACTH, which in turn activates another part of the adrenal gland to dump cortisol into the blood stream. In the short term, cortisol can have many beneficial effects for combatting stress, such as mobilizing white blood cells and enhancing the immune system. But cortisol binds to cells in the brain’s hippocampus, the area that converts new experiences into memory. This binding actually disrupts the memory-forming process. Ultimately, if stress continues, the synaptic regions deteriorate, making the impairment permanent.

The effects of both adrenalin and cortisol were revealed in an interesting study of mild social stress. Here, the focus was on a theory of how stress effects on memory might be thwarted by a learning technique called forced retrieval. Prior research with students, had shown, that the usual study technique of re-reading notes or text is not nearly as effective as requiring the learner to actively retrieve the information, as one might do, with flash cards, for example. Just a few months ago, I posted a blog on this forced retrieval phenomenon as a key element in “strategic studying.”

This new research was aimed at testing the possibility that forced retrieval might protect learners from the memory deficits caused by stress. In the study on the first day, 120 subjects studied a list of 30 nouns or images of nouns one at a time. Then, one half of the group restudied the items while the other half practiced retrieval by recalling as many items as they could (but without feedback telling them if they got it right). One the next day, half of each group were stressed by being required to solve hard math problems and by giving speeches in front of two judges and three peers. Then they were tested. Twenty minutes later they took a second test on items that had not been tested on the first test. The results revealed that retrieval practice yielded better results.

  

On the first test, we see that the stressed learners who just studied the items the day before had fewer of the items remembered on the first test given immediately after the stress. But there was no such effect on the stressed leaners who used retrieval practice during the initial learning. This protective effect of retrieval practice was evident on the second test 25 minutes later. In fact, the retrieval practice effect was better than on the first test, even though different items were tested. You may have noticed that the stressed study group on the second test did worse than they did on the first test. This is attributed to a mild effect of adrenalin, which as mentioned above can have some benefit on memory. Adrenalin’s action is immediate and is apparently swamped on the second test by the delayed release of cortisol, which shows up by the second test. Students might note that the magnitude of difference may appear small, but in percentage terms could equal to more than two letter grades (compare the two stressed groups on the delayed test).

To explain why forced retrieval works, the authors speculate that it provides better initial encoding. That is, the new information is registered more strongly if you make yourself try to retrieve it. This is consistent with the everyday experience that most of us have had wherein information that strongly grabs our attention is more likely to be remembered. Forced retrieval is a way to make ourselves pay better attention to what we are trying to lean.

Readers wanting to learn more about improving memory are urged to check “Memory Medic’s” books, Memory Power 101 and Better Grades, Less Effort.

               

Sources:

Klemm, W. R. (2016). Strategic studying. October 9, http://thankyoubrain.blogspot.com/2016/10/strategic-studying.html

Smith, Amy M. et al. (2016). Retrieval practice protects memory against acute stress. Science. 354 (6315), 1046-1047.

What Is the Optimal Spacing for Study?

We have all been told by teachers that learning occurs best when we spread it out over time, rather than trying to cram everything into our memory banks at one time. But what is the optimal spacing? There is no general consensus.

However we do know that immediately after a learning experience the memory of the event is extremely volatile and easily lost. It's like looking up a number in the phone book: if you think about something else at the same time you may have to look the number up again before you can dial it. School settings commonly create this problem. One learning object may be immediately followed by another, and the succession of such new information tends to erase the memory of the preceding ones.

Memory researchers have known for a long time that repeated retrieval enhances long-term retention. This happens because each time we retrieve a memory, it has to be reconsolidated and each such reconsolidation strengthens the memory. Though optimal spacing intervals have not been identified, research confirms the importance of spaced retrieval. No doubt, the nature of the information, the effectiveness of initial encoding, competing experiences, and individual variability affect the optimal interval for spaced learning.

One study revealed that repeated retrieval of learned information (100 Swahili–English word pairs) with long intervals produced a 200% improvement in long-term retention relative to repeated retrieval with no spacing between tests. Investigators compared different-length intervals of 15, 30, or 90 minute spacing that expanded (for example, 15-30-45 min), stayed the same (30-30-30 min) or contracted (45-30-15 min) revealed that no one relative spacing interval pattern was superior to any other.[1]

Another study[2] has revealed that the optimally efficient gap between study sessions depends on when the information will be tested in the future. A very comprehensive study of this matter in 1,350 individuals involved teaching them a set of facts and then testing them for long-term retention after 3.5 months. A final test was given at a further delay of up to one year. At any test delay, increasing the inter-study gap between the first learning and a study of that material at first increased and then gradually reduced final test performance. Expressed as a ratio, the optimal gap equaled 10-20% of the test delay. That is, for example, a one-day gap was best for a test to be given seven days later, while a 21-day gap was best for a test 70 days later. Few of any teachers or students know this, and their study times are rarely scheduled in any systematic way, typically being driven by test schedules for other subjects, convenience, or even the teacher's whim.

The bottom line: the optimal time to review a newly learned experience is just before you are about to forget it. Obviously, we usually don't know when this occurs, but in general the vast bulk of forgetting occurs within the first day after learning. As a rule of thumb, you can suspect that a few repetitions early on should be helpful in fully encoding the information and initiating a robust consolidation process. So, for example, after each class a student should quickly remind herself what was just learned—then that evening do another quick review. Before the next class on that subject, the student should review again. Teachers help this process by linking the next lesson to the preceding one.

Certain practices will reduce the amount of time needed for study and the degree of long-term memory formation. These include:

• Don't procrastinate. Do it now!

• Organize the information in ways that make sense (outlines, concept maps)

• Identify what needs to be memorized and what does not.

• Focus. Do not multi-task. No music, cell phones, TV or radio, or distractions of any kind.

• Association the new with things you already know.

• Associate words with mental images and link images to locations, or in story chains

• Think hard about the information, in different contexts

• Study small chunks of material, in short intervals. Then take a mental break.

• Say out loud what you are trying to remember.

• Practice soon after learning and frequently thereafter at spaced intervals.

• Explain what you are learning to somebody else. Work with study groups later.

• Self-test. Don't just "look over" the material. Truly engage with it.

• Never, never, ever CRAM!

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[1] Karpicke, J. d., and Bauernschmidt, a. 2011. Spaced retrieval: absolute spacing enhances learning regardless of relative spacing. J. Exp. Psychol. 37 (5) 1250-1257.

[2] Cepeda, N. J. et al. 2008. Spacing effects in learning. A temporal ridgeline of optimal retention. 19  (11): 1095-1102

Judging Learning Effectiveness During Learning

When students study, they may monitor their progress during a study session by periodically forming judgments on how well they are remembering the material. Such judgments guide how much further study is deemed necessary. Researchers have studied this matter in the case of paired associate learning (where you learn lists of word pairs like dogs-cats, newspaper-book, etc.).  In particular, researchers looked for correlations between later memory recall either immediately after learning or after a short delay in which judgments about learning are based on a covert attempt to recall. Results indicate that making judgments about how well something will be remembered can be just as efficient as taking an actual test.

In delayed judgments, the student typically makes an initial covert recall effort and then, based on that, judges how well the material was learned. Future recall tends to correlate with predictions on recall on a future test. That is not so surprising, other than the fact that other studies have shown students over-estimate what they have learned and under-estimate how much additional student would be beneficial.

A retrieval attempt directly reveals evidence of how well memory has formed. The act of retrieval itself may enhance learning. Successful retrieval could constitute an additional reinforcing learning opportunity. Indeed, other studies have shown that testing may lead to better final recall than a comparable amount of study. When an item is retrieved in covert recall and leads to a high judgment of learning, the item gets a long-term memory boost.

In the present study, the researchers directly compared final recall and delayed judgments of learning of paired association of lists of 40 words in Swedish (the native language of the subjects) and Swahili under differing testing conditions. One hundred twenty-one Swedish college students were divided into experimental groups: 1) repeated study and testing (study-test, “ST group”), 2) repeated study and termination of testing after the first successful recall test (study-test, dropout,“STd” group), and 3) repeated study and judgments of learning (study-judgment of learning “STjol” group).

Testing involved presenting the first word of a pair to serve as a cue to probe for recall of the associated word. All groups received four initial learning episodes with 5 seconds per item, after which they had 8 seconds to respond to test on the item (ST, STd) or render a judgment on their prediction of cued recall for that item a week later (STjol). All groups were compared for their performance on the same test a week later.

The ST group went through four successive study-test sessions, in each of which they studied all 40 word pairs on a computer screen. Immediately at the end of the list, the students took a 30-second distractor test (math quizzes). Then their recall was explicitly tested by presenting each Swahili word, whereupon they had 8 seconds to provide the Swedish equivalent. Students experienced four such study and test sessions. A similar procedure was used for the STd group, except that on any given test, each correctly recalled item was dropped from subsequent tests; thus the number of word pairs dropped from 40 on the first test to the number of pairs missed on the previous test.

The STjol group experienced a similar process including the 30 second distractor task, except that the test trials were replaced by jol trials. That is, instead of being required to provide the Swedish word that matched the Swahili probe word, the subjects were given 8 second to render a judgment for each word pair by answering this question: “How certain are you that you will recall the Swedish word in a week when we test you again? “ Students used a rating scale of 20% sure, 40%, 60%, 80%, 100%.

During the learning phase, the two ST groups increased their scores at about the same rate from the first session to the fourth. Thus, dropping a pair from testing once it was recalled correctly did not seem a disadvantage to learning. Authors assume the jol groups would have increased scores similarly, but of course they were not explicitly tested during the learning phase. Their prediction scores did, however, increase over the four sessions at a similar rate as recall did in the ST groups.

The key issue was elucidated on the memory test a week later. The ST group had better recall than the STd group, thus revealing that dropping items during study had long-term consequences. This is reminiscent of studies by others on flash cards that showed that best long-term recall was produced by re-testing with all cards in the deck, including those that were

answered correctly in a previous self-test.

The jol group performed better on the final test than the STd group but results were about the same as those for the ST group. Thus, making a delayed judgment during the learning phase about how well one has learned was just as effective for recall a week later as actually being tested during the learning phase.

What do we make of that? It seems that to make a prediction for ability to recall word pairs, a person has to first make a covert recall effort. If you covertly recall a word readily, you would like give a judgment rate of 100%, whereas if you struggled with covert recall, you might judge future recall at only 40%, for example. To make such judgments, the learner has to monitor the learning in real time. Such monitoring in order to render a judgment entails covert self-testing, which these results suggest is just as effective long term as explicit testing.

Such results confirm what we know about memory being promoted by self-testing, whether explicit or covert. As a practical matter for study strategies where it is inconvenient to take actual tests during study sessions, it prudent to conduct covert self-testing wherein a student asks questions like “how well have I remembered this item?” If the answer is “not well,” more study is called for.  Confident judgments will tend to be confirmed when taking a real test later. In other words, making judgments about learning effectiveness during a learning phase helps a student to monitor progress and know how much time to devote to study. In addition, making such estimates seems, in itself, to promote learning because covert self-testing is required.

Sources:

Jönsson, F. U., Hedner, M., and Olsson, M. J. (2012). The testing effect as a function of explicit testing of instructions and judgments of learning. Experimental Psychology. 59 (5): 251-257.

Roediger, H. L., and Karpicke, J. D. 2006. Test enhanced learning. Taking memory tests improves long-term retentio