Elderly Health Journal

The Effect of Working Memory Rehabilitation on Visual Memory and Memory Span

Mansour Mahmoudi Aghdam ¹, Esmaeil Soleimani ^*1, Ali Issa Zadegan ¹
 

1. Department of Psychology, School of Literature and Humanities, Urmia University, Urmia, Iran

Article history
Received 6 May 2020
Accepted 7 Dec 2020 

A B S T R A C T

Keywords: Rehabilitation, Cognition, Memory Span, Visual Memory, Aged

Introduction
 

    Our understanding of aging and its effects on cognition has improved significantly over the past 50 years. In the next decade, for the first time in human history, the number of people over the age of 60 will be more than children (1). The most common cognitive complaint among the elderly is memory problems. It is estimated that 56% of elderly who visit clinical centers, complain of memory problems (2). Memory is divided into sensory, short-term, working, and long-term memory in terms of information retention period and in terms of the type of information that enters and stores in memory, it is divided into spatial, visual, olfactory, auditory, haptic, and taste (food) memory (3). Also, the types of memory differ in terms of information storage capacity and memory span, and the term memory span is more commonly used for short-term memory (4).
    One type of memory that has been studied in the present study is visual memory. Visual memory contains visual representations that store information about the perceptual characteristics of the observed stimuli (5). Active visual memory declines from about age 21 onwards, and its capacity is halved at age 75. Age-related decline in visual memory has been observed in various features (such as color, location, and orientation) and during encryption (6). Numerous different studies, including, Brockmole & Logie (7), Pardhan et al. (8), have shown a decline in visual memory function with age.
    Another dependent variable of the present study was memory span. According to the American Psychological Association, memory span means the number of things that can be remembered immediately after a presentation. Items usually include letters, words, numbers, or syllables that participants must reproduce in order (9). Many studies have been done on the memory capacity in the elderly, including Wiliams & Kemper (10), Gordon-Salant & Cole (11), Keating et al. Affleck-Brodie (12), and the results of all of them have shown that aging affects memory capacity and reduces it.
    So far, many interventions have been made to improve visual memory and memory span in the elderly, including Computer-Based Visual Training (13), Stroboscopic Visual Training (14), and Transcranial direct current stimulation (15). The intervention in the present study is working memory rehabilitation. Baddeley defines working memory as the brain system that provides temporary storage and manipulates information needed to perform complex cognitive tasks such as language, perception, learning, and reasoning (16). Memory rehabilitation is one of the results of cognitive rehabilitation. Memory rehabilitation includes instructions and exercises on memorization, organization, and extensive processing strategies used during encryption. Various studies have shown that memory rehabilitation has positive effects on cognitive functions in old age (17). Memory rehabilitation programs are based on the principle that cognition can be changed in the elderly, and memory rehabilitation interventions facilitate the flexibility of the brain through the teaching of various strategies that help to better encrypt and retrieve information (18). The performance of working memory tasks can be improved through training (19). Working memory training can be a credible way to help the elderly to maintain some of their daily abilities and functions (20). Various studies have shown that working memory rehabilitation improves memory capacity and memory span (21). The results of Russi et al. study (22) showed that the elderly with memory problems benefit from memory rehabilitation, and this rehabilitation enhances their memory span. The results of a study by Kihoon et al. (23) showed that rehabilitation programs are effective on elderly visual memory. Various studies on the effect of memory rehabilitation on visual memory have shown that memory rehabilitation affects the visual memory of the elderly (24).
    Improving the quality of life and health, increasing life expectancy has led to a high prevalence of the elderly population and increasing this class of the population, consequently will increase the physical and cognitive problems caused by increasing age and cause great concern about this group of has created crowds (25). Research shows that memory rehabilitation is an effective way to improve cognitive functions, and given that not much research has been done on the effectiveness of this method on memory functions in the elderly, and due to population growth in recent years, the inevitability of age-related cognitive problems and its high prevalence in old age, research in this field seems necessary and the purpose of this study was to answer the question: Does working memory rehabilitation affect visual memory and memory span in the elderly?
 
Methods
Study design and participants
    This was a quasi-experimental study with pretest-posttest design and a control group. Working memory rehabilitation was considered as an independent variable and visual memory and memory span were considered as dependent variables. The study population included all elderly people who lived in Millad Bukan Nursing Home from April to July 2019 (N = 120). Among these individuals, 30 elderly people were selected by convenience sampling method and then randomly assigned to two experimental and control groups (15 people each) (26).
    The inclusion criteria included: completion of consent form, age range 65 to 85 years, ability to read and write, being male, absence of acute and chronic psychological disorders (such as schizophrenia, depression, bipolar disorder, obsessive-compulsive disorder, Post-traumatic stress disorder, severe anxiety disorder, dementia) based on an interview by a psychologist, absence of significant physical illness based on a physical examination by a physician, and absence of vision and hearing problems based on optometrist and audiometrist examinations. The exclusion criteria were including: incomplete answering to the questions, participating in other psychotherapy sessions at the same time, and refusing to continue participating.
Instrumentation
    Wechsler Memory Span Test: Wechsler developed his Intelligence Scale in 1939, which consisted of two parts: the verbal scale and the functional scale and digit span subtests is a part of the verbal scale of the Wechsler Intelligence Test. This test is used to measure instant parrot-like memory, focus and accuracy, displacement (the ability to move thought patterns from direct to reverse digits), sequencing or listening chains, and parrot-like learning. Digit span is a test for short-term memory and attention. The examiner read a list of three to nine digits calmly and aloud. The examinee should remember and repeat the auditory information in order. High scores on inverted digits indicate a person's ability to be flexible, focused, patient with stress, and to make, maintain, and check visual mental images. Direct digits indicate parrot-like memory (27). The test is performed in such a way that if the examinee is not successful in the first attempt, the second attempt digits are performed. If the examinee fails in both attempts, the test is stopped. The score of the examinee is equal to the successful repetition of the numbers of the last series of the first and second attempts. The maximum score is 7 for direct numbers and 7 for reverse numbers. The reliability of the test with the test-retest method for Iranian women and men was reported to be 0.90 and 0.92, respectively (28). In Iran, Sadeghi et al. reported that the split half reliability coefficient of the test was 0.95 and the reliability coefficient of its subscales was 0.71 (29). Also, in some studies, Cronbach's alpha for the test was 0.96 and for all subscales was higher than 0.87 (30). In the present study, Cronbach's alpha of this questionnaire was 0.65.
    Kim Karad Visual Memory Test: The test was developed in 1945 by Kim Karad. This test is part of the visual memory function measurement test. This test contains of a 16-cell cardboard sheet that has a picture in each cell (the main sheet of the test), a blank 16-cell sheet, and 16 cardboard pieces, each with a picture of the main test sheet. The way to do the Kim Karad test is that the main cardboard sheet is shown to the participants for 1 minute, and then the person has to remember and place the pieces he has, as he saw them. The examinee is then asked to correct his or her work compared to the main sheet, then this step is repeated a second time, and the person has to correct his or her work again. In the last step (which is the main step and the score is calculated), the participants are asked to set the blank sheet of the test as before, without seeing the main sheet. The examiner calculates the test score in the last step. This test can assess short-term, medium-term and long-term visual memory. The reliability coefficient of this test is acceptable (0.81) (31). Also, other studies have estimated the validity of this test using the retesting method, which reported the criterion-related validity coefficient of 0.5 and the validity coefficient of 0.62 at the significance level of 0.01 (32).
    Working Memory Rehabilitation: working memory rehabilitation is a program designed based on Dehn's working auditory memory intervention program and includes 4 major techniques includes: elaborative rehearsal, semantic rehearsal, chunking, and paraphrasing (33). The program designed in 18 sessions (each sessions 60-minute), which are shown in Table 1.
Data collection
    Initially, in the pretest phase, both the Wechsler Memory Span Test and Kim Karad Visual Memory Test were performed on both groups. Then, the working memory rehabilitation was performed on the experimental group in 18 sessions (each sessions 60-minute) over 6 weeks but control group received nothing. After the rehabilitation sessions, posttest was held. In the posttest phase, the experimental group and the control group performed the Wechsler Memory Span Test and Kim Karad Visual Memory Test again.
Ethical considerations
    This research has a code of ethics from Urmia University of Medical Sciences with the ID of IR.UMSU.REC.1398.142 and the clinical trial code of IRCT201909100447737N1. In this study, ethical considerations such as professional competence, respectful and honest treatment,  individual rights, human dignity, confidentiality, non-exploitation of participants, avoidance of harming others and non-distortion of information were regarded.
Data analysis
    The data were analyzed using descriptive (mean and standard deviation) and inferential statistics (multivariate analysis of covariance or MANCOVA) by SPSS 22.00.
 
Results
    The study included 30 elderly people whose mean age was 75.3 ± 5.2, 77.7% were single (without a spouse, divorced or deceased), 22.2% married (with a live spouse) and their education was as follows: 85% middle school, 15% high school diploma and undergraduate.
    As Table 2 shows, the mean and standard deviation of posttest visual memory of the working memory rehabilitation group in the short-term was 12.00 (1.2), in medium-term  was 10.80 (1.03) and in the long-term was 12.33 (0.93).
    As table 3 shows, the mean and standard deviation of the posttest memory span of the working memory rehabilitation group was 11.66 (1.44) in direct span and 9.66 (1.24) was reverse span.
    The results of table 4 showed that the value of the Wilks' lambda test was 0.034 for the visual memory variable and 0.088 for the memory span, which were significant at the level of 0.001 (p < 0.001). The smaller the value of the Wilks' lambda test than 1, the more significant the difference between the groups is.
Homogeneity of variances
    The results of Levene's test showed that the difference in variances between the two groups in the score components of the consistent card, inconsistent card and interference from the variable of the Stroop test and response error, deletion response, correct response and reaction time from the Continuous Performance Test  were not significant. Based on these results, the assumption of homogeneity of variances in the above variables in the studied groups was confirmed. This test was not significant for any of the variables, in other words, the variances were equal in both population. As a result, the use of parametric tests was unrestricted.
    The results of table 5 showed that there was a significant difference between the elderly in the experimental and control groups in visual memory at the level of 0.001 (p < 0.001). In other words, the visual memory of the experimental group differed after performing the working memory rehabilitation. There was also a significant difference between the elderly in the experimental and control groups in memory span at the level of 0.001 (p < 0.001). In other words, the memory span of the experimental group differed after performing working memory rehabilitation

Table 1. Treatment protocol in each working memory rehabilitation session

Session	Topic	Purpose
1st	Pretest	Introduction- purpose expression- performing pretest
2nd	Auditory memory	Learning to remember- remembering a few letters, simple words and numbers after a few seconds- remembering the first or last letter, number or word
3rd	Visual memory	Learning to hide one of the objects- identifying deleted objects- Remembering seen objects- Learning to remember seen objects- Remembering faces- repeating patterns
4th	Practice	Repeating auditory and visual memory exercises,  training remembering in reverse order
5th	Play with pictures	Images and photos are shown to the participant and then asked to retell the colors and directions after 15 seconds.
6th	Follow the instructions	At the same time, several orders are given to the participant and he or she must follow them in order
7th	Show movie	A short film is shown to the participant, and after the film is over, the person has to say in colloquial language what she/he has seen.
8th	Recognition memory	Images of animals, fruits, objects and landscapes are shown to the person and she/he must recognize them after a few seconds.
9th	Practice	An overview of the training content of previous sessions
10th	Recall memory	A short story is read to the person in a few minutes (maximum of 3 minutes) and she/he has to tell that story.
11th	Long-term Memory	The person is asked to restate the events of the previous 24 hours in full detail.
12th	Auditory perception	A polynomial phrase is read to a person and he/she must express its meaning in colloquial language. Then we do the same exercise with two phrases and the person has to express the concepts in order.
13th	Learning list	The person is asked to learn a list of words that have already been prepared and then to remind them. The person must also repeat the sentences given by the instructor (examiner).
14th	Practice	An overview of the training content of previous sessions, playing with word cards and recognizing the word provided among all the cards
15th	Mental review technique	Teaching mental review technique (repeated reading and writing)
16th	Mental review technique	Continuing teaching mental review techniques
17th	Practice	An overview of the training content of previous sessions, playing with word cards
18th	Posttest	Thank and performing posttest

 
Table 2. Mean and standard deviation of the experimental and control group in visual memory in pretest and posttest

Size	Experimental group				Control group
	Pretest		Posttest		Pretest		Posttest
	M	SD	M	SD	M	SD	M	SD
Short	7.00	1.29	12.00	1.20	7.13	0.89	7.33	0.97
Medium	6.70	0.94	10.80	1.03	7.00	1.11	7.30	0.84
Long	9.00	0.96	12.33	0.93	9.50	0.88	9.30	1.11

 
Table 3. Mean and standard deviation of the experimental and control group in memory span in pretest and posttest

Memory span	Experimental group				Control group
	Pretest		Posttest		Pretest		Posttest
	M	SD	M	SD	M	SD	M	SD
Direct	8.33	1.23	11.66	1.44	8.46	1.24	9.33	1.58
Reverse	6.46	1.18	9.66	1.34	6.33	1.29	7.00	1.50

 
 
Table 4. Results of MANCOVA on visual memory and memory span

Test	Variable	Value	F	Hypothesis df	Error df		Sig	Eta
Pillai’s Trace	Visual memory	0.966	219.054	3	23	0.001		0.966
	Memory span	0.912	129.019	2	25	0.001		0.912
Wilk’s Lambda	Visual memory	0.034	219.054	3	23	0.001		0.966
	Memory span	0.088	125.019	2	25	0.001		0.912
Hotelling’s Trace	Visual memory	28.57	219.054	3	23	0.001		0.966
	Memory span	10.322	125.019	2	25	0.001		0.912
Error Largest Root	Visual memory	28.57	219.054	3	23	0.001		0.966
	Memory span	10.322	125.019	2	25	0.001		0.912

 
Table 5. Results of MANCOVA on variables in experimental and control groups

Variables		Sum of Squares	df	Mean Squares	F	Sig	Eta Squared
Visual Memory	Short	157.928	1	157.928	229.511	0.001	0.902
	Medium	91.091	1	91.091	181.908	0.001	0.879
	Long	78.7	1	78.7	104.353	0.001	0.835
Memory Span	Direct	71.079	1	71.079	131.734	0.001	0.835
	Reverse	68.206	1	68.206	93.772	0.001	0.783

 

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