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Effects of Brain Injury and Age on Prospective Memory Self-Rating and Performance Roseann Hannoo, Peter Adams, Scott Harrington, Caroline Fries-Dias, and Martin T. Gipson University of the Pacific ABSTRACT. The purposes of this study were (1) to assess internal consistency and test-retest reliability of the Prospective Memory Questionnaire (PMQ) developed by Hannon and associates; (2) to compare PMQ self-ratings of adults with brain injury versus younger and older noninjured adults; (3) to develop short-term and long-term tasks for measuring actual prospective memory performance; and (4) to study the relationship between scores on the PMQ and the prospective memory tasks. Internal consistency of the PMQ was .92 and test-retest reliability was .88. Groups differed significantly on only one PMQ subscale. Actual prospective memory performance was significantly worse for adults with brain injury and older adults than for younger adults on two of the three sets of summary measures. PMQ self-ratings were significantly but weakly correlated with short-term task performance, but not with long-term task performance. Implications of the findings for assessment and treatment of prospective memory impairment are discussed. Prospective memory (the ability to remember to perform future actions) is one of the least investigated types of memory in normal adults (Harris, 1984), elderly adults (Dobbs &Rule, 1987), and adults with brain injury (Mateer, Sohlberg, & Crinean, 1987). All three of these groups, however, describe prospective memory as one of their most significant areas of memory deficit. While a significant literature exists on self-rating of memory generally (Herrmann, 1982, 1984) and there are many types of clinical instruments for assessing memory, standardized self-rating instruments and clinical measures of prospective memory are poorly developed. Such instruments are important in the rehabilitation of deficits in prospective memory in individuals with brain-injury or advanced age, REHABILITATION PSYCHOLOGY Vol. 40, No. 4, 1995 O 1995 by the Division of Rehabilitation Psychology of the American Psychological Association Published by Springer Publishing Company, Inc., 536 Broadway, New York, NY 10012 289 Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol og ic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly . 290 Hannon et al. both for initial assessment and for monitoring effectiveness of treatment. Since people's beliefs about their own memory abilities, whether accurate or inaccu- rate, infl uence their behavior, the relationship between self-rating of prospec- tive memory abilities and actual performance must be studied to frilly understand memory functioning. Hannon and colleagues (1990) developed the Prospective Memory Questionnaire (PMQ) with 74 behaviorally anchored items rated on a 9-point Likert-type scale. Subscales were rationally and theoretically developed based on prior research to measure five dimensions of prospective memory: Long-Term Episodic Tasks, Short- Term Episodic Tasks, Long-Term Habitual Tasks, Short-Term Habitual Tasks, and Techniques to Assist Recall. The questionnaire was administered to 361 subjects (291 college students, 19 community college students with brain injury, 14 rehabilitation center clients with brain injury, and 37 alcoholics) for its initial validation. Coefficient alpha was .93 for the PMQ total score, and ranged from .80 to. 90 for the subscales (except for Long-Term Habitual which was .60), confi rming the value of the subscales. A factor analysis separated the items into five factors, four of which corresponded largely to the subscales designed for the PMQ (all but Long-Term Habitual). The PMQ was reduced to 63 items based on this factor analysis, with Long-Term Episodic, Short-Term Habitual, and Technique scales retained, and a new Internally Cued scale (which included most of the original Short-Term Habitual items) added. Nine items with the lowest item-total correla- tions with any of the scales were dropped. An unpublished follow-up study was performed in which the PMQ with 63 items was administered to 214 subjects (197 college students, 17 community college adults with brain injury). Coefficient alpha was .90 for the PMQ total score, and ranged from .81 to .88 for the subscales. Based on factor analysis of these results, the 52-item PMQ used in the present study was developed. The purposes of the present study were (1) to further develop the PMQ, including internal consistency and test-retest reliability; (2) to compare PMQ self-ratings of adults with brain injury with older and younger adults; (3) to develop a set of tasks for measuring actual prospective memory performance; and (4) to study the relation- ship between scores on the PMQ and the prospective memory tasks. METHOD Participants Participants were 114 younger adults (community college and state university students, M age = 28.4, SD = 8.6), 27 older adults (healthy retirement home residents, M age = 73.4, SD = 19.9), and 15 adults with brain injury (community college students, A/age = 31.8, SD=9.2). Adults with brain injury had experienced a significant head trauma (all were unconscious following the injury and most were Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol og ic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly . Prospective Memory Self-Rating and Performance 291 in a coma), and were 1 to 20 years post injury (Md= 3 years). They were enrolled in a special program for students with acquired brain injury, and were asked by the program director if they would like to participate in this study. Older adults were asked to participate by the social/recreation director of the retirement home where they resided. Younger adults and adults with brain injury did not differ signifi- cantly in age (note Ms and SDs above). Groups did not differ significantly in education, tf(6,N= 148) = 8.47, p > .05 (education was measured categorically and most participants checked high school graduate or attended college, no degree). Procedure All participants were tested in group sessions, with 5 to 25 participants per group. To test short-term prospective memory (tasks to be completed within 5 min.), four tasks were administered: 5 min. associative cue task, 2 min. associative cue task, 5 min. time cue task, 2 min. time cue task (types of tasks modeled on Sohlberg & Mateer, 1989). The required response for each task was to initial the response sheet in accordance with the specific associative or time cue instructions. Task problems were presented by slide projector every 15 sec. Tasks were designed to make it difficult for participants to constantly rehearse and keep track of the associative or time cue for a given task, which made the tasks more comparable to real world situations. Tasks were designed so that most participants could accurately complete the basic task requirements which did not involve prospective memory. Tasks are described below, and were presented in the order described: 1.5 min. associative cue task - Items from the WechslerAdult Intelligence Test- Revised Information subtest were presented every 15 sec. Participants were told to write their answers on a numbered response sheet, and to write their initials to the right of their answer when they came to the first question regarding an animal (the associative cue). 2. 2 min. associative cue task - Participants were shown a word fragment every 15 sec and asked to fill in the missing letters to form a word. They were told to write their initials to the right of their answer when they came to the first item for which a color was the correct response (the associative cue). 3.5 min. time cue task - Participants were shown a word every 15 sec. and asked to write the opposite of the word. They were told to write their initials to the right of their answer exactly 5 min. after the first word was presented. 4. 2 min. time cue task - Participants were shown a simple addition problem every 15 sec. and asked to write the answer. They were told to write their initials to the right of their answer exactly 2 min. after the first problem was presented. The score for each task was 0 if there were no initials on the response sheet, 1 if initials were present but in the wrong place, and 2 if the initials were present in the right place. The mean of the scores for the four short-term tasks was used as the short-term task score in the data analysis. Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol og ic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly . 292 Hannon et al. Following these four tasks, participants completed the Symbol Digit Modalities Test (SDMT, Smith, 1982), modified for group presentation, as a measure of attention and concentration. The PMQ was completed next (see Table 1 for subscales and sample items). This questionnaire was revised and shortened to 52 items based on the previously described work by Hannon et al. (1990), and contained four subscales: Long-Term Episodic, Short-Term Habitual, Internally Cued, and Techniques to Assist Memory (higher scores indicate poorer performance on the PMQ total score and on the subscale scores). To assess test-retest reliability, 72 participants were readministered the PMQ 10-14 days later (these participants were selected based on availability, and represented all three participant groups). To test long-term prospective memory (tasks to be completed hours or days later), participants were given two questionnaires to return by mail, the Beck Depression Inventory (BDI; Beck, 1978), and a shortened version of the Neurop- sychological Symptom Checklist (NSC; Neuropsychological Status Examination Manual, 1983). (Higher scores indicate more symptoms on both measures.) Participants were verbally instructed to return each questionnaire on a different specified date. They were told to include their name and the date in the upper right hand corner of each questionnaire. The verbal instructions were repeated twice after first instructing participants to pay careful attention. Instructions were given verbally rather than in writing to reduce the chance that a significant other would see written instructions and return the questionnaires for the participant. Partici- pants were told that those who returned both questionnaires on the correct dates would receive one California state lottery ticket, and that 10% of these participants would be selected in a drawing to receive $10 each. Two long-term task scores were developed for data analysis: (a) BDI and NSC questionnaire return mean score, with each questionnaire given 0 for no return, 1 if returned on the wrong date, and 2 if returned on the right date; and (b) name and date correct mean score, with each questionnaire given a score ranging from 0 for no name or date to 4 for both name and date in the upper right hand corner. Scores on these questionnaires were used to explore possible relationships between these measures and scores on the PMQ and on short-term and long-term prospective memory tasks. RESULTS Prospective Memory Questionnaire Coefficient alpha was .92 for the PMQ total, and ranged from .78 to .90 for the subscales. Factor analysis of the 52 items using varimax rotation confirmed the structure of the subscales. For test-retest reliability, r = .88 for the PMQ total and ranged from .64 to .88 for the subscales. One-way ANOVAs with multiple comparisons on the PMQ total and each subscale showed that groups differed significantly on only one subscale, Short-Term Habitual. Participants with a brain Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol og ic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly . Prospective Memory Self-Rating and Performance 293 Table 1. Prospective Memory Questionnaire Subscales and Sample Items Long-Term Episodic Scale—task is to be completed hours or days after cue to perform it and occurs on an irregular schedule I forgot to send a card for a birthday or anniversary. I forgot to return books to the library by the due date. Short-Term Habitual Scale—task is to be completed within a few minutes after cue to perform it and occurs routinely I forgot to lock the door when leaving my apartment or house. I forgot to put a stamp on a letter before mailing it. Internally Cued Scale—task does not have a clear specific external cue I forgot what I wanted to say in the middle of a sentence. I was driving and temporarily forgot where I was going. Techniques to Remember Scale—techniques used to help one remember to perform a prospective memory task / rehearse things in my mind so I will not forget to do them. I make Post-It (sticky note) reminders and place them in obvious places. injury rated themselves significantly more poorly on this subscale than did younger adults, F (2, 150) = 3.60, p < .05. Prospective Memory Tasks and SDMT Internal consistency for the prospective memory tasks was analyzed using the four short-term task scores and the questionnaire return and name and date correct scores for each questionnaire, and coefficient alpha was .76. Three prospective memory measures (short-term task mean score, BDI and NSC questionnaire return mean score, and name/date correct mean score) and the SDMT were analyzed for group differences using one-way ANOVAs (higher scores indicate better perfor- mance on all measures). Means and standard deviations for each group on each measure, as well as Fs and ps for each ANOVA, are presented in Table 2. Groups differed significantly on short-term tasks, on name/date correct, and on the SDMT. Adults with brain injury and older adults performed significantly more poorly than younger adults on all three measures. Groups did not differ significantly on questionnaire return. Correlations All correlations were computed using all participants in order to obtain the most stable estimate for the computed r values (the relatively small n for older adults and for adults with brain injury would produce unstable estimates of the true r for these Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol ogic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly . 294 Hannon et al. Table 2. Means and S tandard Deviations for Each Group on Prospective Memory Tasks and the Symbol Digit Modalities Test (SDMT) Task Younger Short-term tasks M 1.66 SD 0.47 Name/Date correct M 3.60 SD 0.97 Questionnaire return M 1.44 SD 0.71 SDMT M 59.96 SD 11.20 Group Older 0.94 0.65 1.75 1.87 1.61 0.67 36.24 15.10 Brain Injury 0.58 0.51 2.09 1.81 1.29 0.80 31.79 15.10 F 44.65a 25.02b 1.06C 61.55d P <.001 <.001 >.10 <.001 a/w='= 2, 151. *>df= 2,129. cdf= 2,150. adf= 2,146. groups). Intercorrelations of measures of prospective memory performance (short- term and long-term) with PMQ self-ratings, SDMT, and age are presented in Table 3. Short-term task performance was significantly correlated with PMQ self-rating scores (total and subscales, except for Techniques to Remember), r = -. 17 to -.25, showing that higher short-term task scores were related to better (i.e., lower) PMQ self-ratings. These relationships accounted for only a small portion of the variance. Neither measure oflong-term performance (questionnaire return, name/date correct) was significantly correlated in the predicted direction with PMQ self-rating scores. Better short-term task performance was significantly correlated with younger age (r = -.43) and with higher SDMT scores (r - .54). These correlations accounted for substantial portions of the variance (18-29%). Better questionnaire return was significantly correlated with older age (r =. 19), but was not correlated with SDMT. Similar to short-term task performance, better name/date correct was significantly correlated with younger age (r = -.39) and with higher SDMT scores (r = .42). Some interesting relationships ofBDI and NSC scores with PMQ self-ratings and measures of prospective memory performance emerged, and intercorrelations are shown in Table 4. There were positive relationships between PMQ total and BDI scores (r = A1) and NSC scores (r = .48), showing that participants with less favorable PMQ self-ratings (i.e., higher PMQ scores) tended to score higher on depression and on neuropsychological symptoms. Similar correlations occurred for allPMQ subscales except Techniques to Remember. The PMQ total and subscale correlations with BDI and NSC accounted for substantial portions of the variance (13-27%). Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol og ic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly . Prospective Memory Self-Rating and Performance 295 Table 3. Intercorrelations of Measures of Prospective Memory Performance With PMQ Self-Ratings, SDMT, and Age PMQ Total score Long-term episodic Short-term habitual Internally cued Techniques to remember SDMT Age Short-term Tasks -.17* -.19* -.25** -.22** .03 .54** -.43** Questionnaire Return .01 -.06 -.04 -.00 .10 .10 .19* Name/Date Correct .07 .01 -.12 .04 .17* .42** -.39** Note. PMQ= Prospective Memory Questionnaire; SDMT = Symbol Digit Modalities Test *p<-05. **p<.0l. Table 4. Intercorrelations of PMQ Self-Ratings and Measures of Prospective Memory Performance With BDI and NSC Scores BDI NSC PMQ Total score Long-term episodic Short-term habitual Internally cued Techniques to remember Short-term tasks Questionnaire return Name/Date correct .41** .36** .43** .38** .17 -.31** -.21* -.20* .48** .44** .46** .52** .20* -.47** .07 -.14 Note. BDI = Beck Depression Inventory; NSC = Neuropsychological Symptom Checklist; PMQ = Prospective Memory Questionnaire. *p < .05. **p <-01. Better short-term task performance was significantly correlated with lower BDI (r = -.31) and NSC (r = -.47) scores, accounting for 9%-22% of the variance. Better performance on questionnaire return and name/date correct was also significantly correlated with lower BDI scores (-.21 and -.20, respectively), but not withNSC scores. Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol og ic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly . 296 Hannon et al. DISCUSSION Both coefficient alpha and factor analysis results indicate that the PMQ is an internally consistent instrument for measuring self-rating of prospective memory. Test-retest reliability is also sufficiently high. Both adults with brain injury and older adults performed more poorly than younger adults on short-term prospective memory tasks, and adults with brain injury rated themselves more poorly than younger adults on the Short-Term Habitual subscale of the PMQ. Groups did not differ significantly on any other PMQ subscales, and this finding is particularly interesting for the Techniques subscale. Since adults who are older and those with brain injury have more difficulty with short-term tasks, they would be expected to use more techniques to remember. Our findings suggest that individuals most needing such techniques may not use them any more frequently than younger adults do. Rehabilitation strategies which focus on developing such techniques therefore appear to be especially important. The prospective memory performance tasks had reasonable internal consistency for initial development. Adults withbrain injury and older adults performed signifi- cantly more poorly than younger adults on short-term tasks and also on name and date correct on returned questionnaires. Groups did not differ on questionnaire return per se. The relationship between age and performance on different types of prospective memory tasks is not well understood. Some studies have found declining performance withage onmore complex tasks (Einstein, Holland, McDaniel, & Guynn, 1992), butnotwith simpler tasks (DobbsA Rule, 1987; Einstein & McDaniel, 1990). Differentiating the specific types of prospective memory tasks which are sensitive to aging versus those which are not is an important issue for future research. Correlation analyses confirmed the typical finding of low association between self-rating of memory and actual performance (Herrmann, 1982, 1984). Self- rating of prospective memory was significantly but weakly correlated with short- term performance and was not significantly correlated with long-term performance. The three measures of actual performance showed differing sensitivity to other variables (age, SDMT, BDI, and NSC) assessed in this study. Short-term memory had significant relationships in the expected direction to all of these variables, with better short-term memory performance related to younger age, higher SDMT scores, and lower BDI and NSC scores. Short-term tasks were also the only performance measure to correlate significantly with the appropriate PMQscale (Short-Term Habitual). Better name/date correct scores were related to younger age, higher SDMT scores, and lower BDI scores. Better questionnaire return was related to older age and lower BDI scores. Future studies should investigate more closely the relation- ship between prospective memory task performance and attention/concentration, depression, and neurological symptomotology, as the present study suggests that these are important variables and that they most clearly relate to performance on short-term tasks. Since individuals with brain injury also frequently experience depression, ruture research is needed to determine the degree to which poorer short- term prospective memory performance is due to depression versus brain injury. Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol og ic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly . Prospective Memory Self-Rating and Performance 29 7 Further research on prospective memory is needed inboth adults with brain injury and older individuals. The types of tasks which are sensitive to aging and to brain injury must be more clearly delineated. Developing tasks which are more relevant to everyday functioning should also be explored. Using the kinds of measures explored in this study, an assessment could be developed which would allow individuals to compare their self-ratings and their actual performance on a battery of prospective memory tasks. This comparison might improve recognition of impairment and increase motivation for treatment. These measures could also be used to monitor effectiveness of treatment in improving both accurate self-rating and actual perfor- mance. REFERENCES Beck, A. T. (1978). Depression Inventory. Philadelphia: CenterforCognitive Therapy. Dobbs, A. R., & Rule, B. G. (1987). Prospective memory and self-reports of memory abilities in older adults. Canadian Journal of Psychology, 41,209- 222. Einstein, G. O., Holland, L. J., McDaniel, M. A., & Guynn, M. J. (1992). 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Morris (Eds.), Everyday memory actions and absent-mindedness (pp. 134-151). New York: Academic Press. Mateer, C. A., Sohlberg, M. M., & Crinean, J. (1987). Perceptions of memory function in individuals with closed-head injury. Journal of Head Trauma Rehabilitation, 2, 74-84. Neuropsychological status examination manual. (1983). Odessa, FL: Psychological Assessment Resources. Smith, A. (1982). Symbol digit modalities test manual. Los Angeles: Western Psychological Services. Sohlberg, M. M., & Mateer, C. A. (1989). Introduction to cognitive rehabilitation: Theory and practice. New York: Guilford Press. Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol og ic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly . 298 Harmon et al. Acknowledgments. The authors thank Carol L. Dais, San Joaquin Delta College, for her assistance in obtaining data from participants with brain injuries. Offprints. Requests for offprints or for copies of the PMQ should be directed to Roseann Hannon, Department of Psychology, University of the Pacific, Stockton, CA 95211. Submitted: October 1993 Revised: December 1994 Revised: February 1995 Accepted: June 1995 Th is d oc um en t i s c op yr ig ht ed b y th e A m er ic an P sy ch ol og ic al A ss oc ia tio n or o ne o f i ts a lli ed p ub lis he rs . Th is a rti cl e is in te nd ed so le ly fo r t he p er so na l u se o f t he in di vi du al u se r a nd is n ot to b e di ss em in at ed b ro ad ly .
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