A Preliminary Study Investigating How People with Mild Intellectual Disabilities Perform on the Rivermead Behavioural Memory Test

A Preliminary Study Investigating HowPeople with Mild Intellectual DisabilitiesPerform on the Rivermead BehaviouralMemory Test

Claire MartinPsychology Department, Box 338, Fulbourn Hospital, Cambridge CB1 5EF, UK

Jenny WestLocal Health Partnerships NHS Trust, Learning Disabilities Service, Stourmead House,

Kedington, Suffolk CB9 7PA, UK

Chris CullNorwich Community Health Partnership NHS Trust, Learning Disabilities Directorate,

Little Plumstead Hospital, Norwich NR13 5EW, UK

Malcolm AdamsJoint Course Organiser, Clinical Psychology Doctorate, Health Practice Unit, University

of East Anglia, Norwich NR4 7TJ, UK

Paper accepted June 2000

Twenty participants with mild intellectual disabilities (IQ� 55±75) completed the Rivermead

Behavioural Memory Test (RBMT; adult version). There was a signi®cant difference in perfor-

mance across the 12 subtests, with the tests relying on verbal memory (e.g. story recall) proving

the most dif®cult and those depending on visual memory (e.g. picture recognition) the easiest.

There was also a negative correlation between age and RBMT scores. It is concluded that the

RBMT is a suitable test to use with this population; it provides useful clinical information, but

as the test currently stands, identi®cation of speci®c memory impairments may not be possible.

Introduction

Memory skills are crucial for effective day-to-day functioning, but within the ®eld of

intellectual disabilities, there are no clinical tests to assess memory function and no

way of determining the presence of signi®cant memory impairment.

The few studies which do exist have used the Rivermead Behavioural Memory Test

(RBMT) which has norms for ages 5±96 years (the child version has norms for ages 5±

10 years and uses more age-appropriate subtests), and has been developed for people

with brain damage, the elderly and `normal' subjects. Wilson & Ivani-Chalian (1995)

tested people with Down's syndrome on the child version (RBMT-C; Aldrich & Wilson

1991) and found that the story recall subtest was particularly hard. Hon et al. (1998)

also used the RBMT-C with older adults with Down's syndrome (aged between 30 and

Journal of Applied Research in Intellectual Disabilities 2000, 13, 186±193

= 2000 BILD Publications186

65 years), and found that name learning, face recognition and remembering an appoint-

ment were the most dif®cult subtests. No such data has been collected for people with

intellectual disabilities in general or using the adult version of the test.

The present study was undertaken in order to explore how people with mild intellec-

tual disabilities perform on the RBMT. The authors used the adult version, which is

more age appropriate. Such information will be useful both clinically to provide some

indication of reasonable expectations of memory functions in people with intellectual

disabilities and academically to contribute to knowledge of everyday memory func-

tioning generally.

Method

Design

The main analysis employed a within-subjects design.

Participants

People who ful®lled the criteria for mild intellectual disabilities (IQ� 55±75; Alves et al.

1991) were recruited from existing caseloads in a UK clinical psychology service for

adults with learning disabilities aged 18 years and over.

People over 60 years of age were excluded to minimize the potential effects of age, as

were those with a history of head injury and people with Down's syndrome over the

age of 35 years because of the possibility of dementia (Holland & Oliver 1995).

Materials

All participants completed the Wechsler Adult Intelligence Scale ± Revised (WAIS-R;

Wechsler 1986) and the RBMT (Wilson et al. 1985). The WAIS-R is a measure of general

ability using 12 subtests which yield Verbal, Performance and Full-Scale IQ scores. The

RBMT was developed in order to assess the real-life memory capacities of individuals

who had sustained brain damage. The 12 subtests were designed as analogues of

everyday memory situations, as follows: Name Learning, in which the name of an

unfamiliar person in a photograph has to be recalled; Story Recall, in which a brief

news-report-style passage is presented orally, the contents of which have to be recalled

immediately and 20 min after presentation; Face Recognition, in which ®ve pictures of

faces are presented and then have to be identi®ed from a series of 10; Picture Recogni-

tion tests recognition of 10 outline drawings of common objects when presented with

10 distracters; Remembering a Belonging, in which a personal item of the client's is

hidden in their view at the beginning of the test and has to be asked for at the end of

the test; Remembering an Appointment, in which the client is similarly instructed at

the beginning of the test to ask a speci®c question in response to a particular cue at a

point later in the test; Remembering a Route and Remembering a Message involve the

client in following a route and delivering a message card to the correct location both

immediately and 15 min after a demonstration by the tester; and the participant is also

asked 11 questions about Orientation for time, place and person.

The subtests are administered consecutively over a period of 30±40 min and the

requirements of the tasks are explained verbally. Standardized pro®le scores are pro-

= 2000 BILD Publications, Journal of Applied Research in Intellectual Disabilities, 13, 186±193

187Journal of Applied Research in Intellectual Disabilities

duced from raw scores, as described in the manual, and these weight each subtest

equally in relation to the others to provide comparable scores across the test battery.

The RBMT has been found to have high inter-rater reliability and good correlation

between subtests (Wilson et al. 1989). It was validated using normal controls, and com-

pared with existing memory tests (Kotler-Cope 1990), self and relative subjective rat-

ings, and staff checklists.

Procedure

All participants in the present study had completed the WAIS-R and some had also

completed the RBMT as part of standard clinical assessments. Those who had not com-

pleted the RBMT were invited to take part in the study by letter and subsequently

®lled in a consent form. The RBMT was then administered in the standard manner to

all participants (within 18 months of the WAIS-R). The WAIS-R was the ®rst test to be

administered.

Results

Participants

Seven out of the 20 participants were female and 13 were male. The age range of the

subjects was 19±58 years (mean� 31.75 years; SD� 11.82 years). One person had a diag-

nosis of epilepsy and no one had Down's syndrome. Twelve people lived in the com-

munity (either with their parents, alone or in hostels), and the remaining eight subjects

lived in National Health Service or social services residences.

The mean Full-Scale IQ score was 67.55 (SD� 5.22; range� 55±75): seven people

obtained scores between 70 and 75, and only two had scores between 55 and 60.

RBMT

The mean standardized pro®le score (SPS) was 15.30 (SD� 4.99; range� 4±22), the dis-

tribution of which is shown in Figure 1.

A repeated-measures, within-subjects analysis of variance was conducted across all

subtest SPSs. There was a highly signi®cant difference between performance on the 12

subtests (F� 7.04, d.f.� 11, P< 0.001). Figure 2 shows the pro®le of mean standardized

scores by subtest.

It is clear that the most dif®cult subtests across the group were (in order of dif®-

culty): immediate and delayed story recall; remembering a name; remembering to ask

for a belonging; and the orientation questions. These were the subtests which rely pri-

marily on memory for verbal information.

In a post hoc analysis using the Tukey test (which performs pairwise comparisons

across all subtests), there were signi®cant differences in performance (critical value dT

� 0.688 at a� 0.05) between the following subtests: both immediate and delayed story

recall with face recognition; delivering a message; remembering to ask about an

appointment; immediate and delayed route recall; and picture recognition; remember-

ing a name with delivering a message; remembering to ask about an appointment;

immediate and delayed route recall and picture recognition. Thus, performance on

three subtests (i.e. immediate and delayed story recall, and remembering a name) was

188 Journal of Applied Research in Intellectual Disabilities


signi®cantly poorer than performance on almost half of the other subtests. This also

suggests that the verbal subtests of story recall and remembering a name are particu-

larly dif®cult for this population.

Table 1 shows the number of participants who were reaching ¯oor and ceiling raw

score levels for each subtest of the RBMT. Although there is not a clear over- or under-

ability in performance, these results serve as a further illustration that there are some

subtests which prove easier than others (e.g. picture recognition).

Relationship between IQ and RBMT scores

The SPS of the RBMT was correlated (Pearson's r) with IQ scores, but there were no

signi®cant ®ndings.

Figure 1 Distribution of Rivermead Behavioural Memory Test standardized pro®le scores.

Figure 2 Bar chart of mean Rivermead Behavioural Memory Test standardized scores by subtest

(NB maximum score per subtest� 2). For a list of abbreviations, see `Appendix 1'.



Tab

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Relationship between age and RBMT scores

There was a signi®cant negative correlation (Pearson's r) between the age of a partici-

pant and SPS (r�ÿ0.471, P< 0.05), and the orientation (r�ÿ0.59, P< 0.01) and

remembering to deliver a message (r�ÿ0.48, P< 0.05) subtests. Thus, the older the

participant, the poorer the performance on questions of orientation and remembering

to deliver a message.

Discussion

The main ®ndings of the present study were that a clinical sample of people with mild

intellectual disabilities have signi®cantly poorer recall for some subtests of the RBMT

in comparison to others. No signi®cant correlation was found between IQ and overall

RBMT performance. However, there was a signi®cant negative correlation between age

and RBMT performance, such that memory functioning declined as age increased.

It is important to remember that the nature of the present study was preliminary

and the sample size was very small. This was also a clinical sample, the subjects hav-

ing been referred to the clinical psychology service for a variety of reasons, including

cognitive assessment, parenting assessment and challenging behaviours. As such, the

participants may not be representative of the broader population of people with mild

intellectual impairment. Consequently, the present results must be interpreted with

caution. Nonetheless, some interesting issues are raised.

Particularly dif®cult subtests were story recall and remembering a name. These

results are consistent with the ®ndings of Wilson & Ivani-Chalian's (1995) study with

people with Down's syndrome using the RBMT-C, i.e. that story recall is especially dif-

®cult for this population.

The differences between the results obtained in the present study and those reported

by Wilson & Ivani-Chalian (1995) may be partly accounted for by test content. For

example, the apparently superior mean score for people with Down's syndrome on

story recall when compared with the subjects in this study can possibly be explained

by the easier content of the story in the RBMT-C.

The lack of a signi®cant correlation between IQ and overall RBMT performance is

perhaps not surprising given the limited range of IQ values in the small sample.

The negative correlation between age and RBMT score is of particular interest since

the upper age limit of participants was restricted in order to minimize such effects.

This raises the possibility that memory deterioration may occur earlier in those with

intellectual disabilities than in the normal population, particularly in view of the fact

that age effects were not found in the RBMT validation study (Wilson et al. 1985).

However, it is dif®cult to comment further because only two of the participants in the

present study were aged 50 years or older. In addition, two people in this study per-

formed particularly poorly, and these extreme scores may have served to distort the

distribution, resulting in a spurious relationship between age and RBMT scores. None-

theless, it is interesting to note that a signi®cant age effect was also found by Hon et al.

(1998) in their study of adults with Down's syndrome using the RBMT-C.

Because all the participants were able to complete all the subtests of the RBMT

within 30 min, it would seem an appropriate test to use with this population. However,

the range of raw scores is small on some of the subtests (e.g. remembering a name),

providing little room for differentiation within the intellectual disability population. It



should also be remembered that some subtests are performed poorly by most partici-

pants (e.g. remembering to ask for a belonging).

Clinically, the implications of the present study are manifest. The RBMT is a test that

can be used easily with this population. Furthermore, when the apparent contribution

of age to RBMT performance in this population is considered, monitoring ability over

time with this tool becomes possible and may allow for the identi®cation of changes

which could raise the question of dementia.

There is a need for clinicians to consider more carefully how information is conveyed

and how we interpret many of the tests which use verbal information as a primary

means of communication (e.g. the WAIS-R). If, as the present study suggests, part of

the pro®le of abilities of people with mild intellectual disabilities who are in receipt of

clinical services is that memory for verbally presented information is limited, some

form of augmentation may need to be considered. Considering the apparently short

nature of the RBMT story (four full sentences) and the great dif®culty that most people

in the present sample have with this subtest, it may be that day-to-day expectations,

which are often based on communication through language, are potentially too high.

It is clinically important to begin to differentiate between impaired and expected

memory functioning in people with intellectual disabilities. However, the results dis-

cussed so far suggest that interpreting the performance of people with intellectual dis-

abilities on this test according to existing criteria is not possible. The results suggest

that those subtests which may provide the best discrimination are those with cut-off

points which are not at (or nearly at) the bottom of the scoring range. In this study,

those tests were: remembering to deliver a message; orientation; picture recognition;

remembering a route; and face recognition.

Clearly, further studies on a larger scale are required to replicate the ®ndings of the

present study, to explore further the relationship between age and RBMT performance,

and to explore the detection of signi®cant memory impairment in this population.

Further studies might also bene®t from differentiating between the performance of

people with different biological/medical diagnoses, particularly where these might

have an effect on memory (e.g. epilepsy; Thompson 1997).

Correspondence

Any correspondence should be directed to Chris Cull, Consultant Clinical Psychologist,

Norwich Community Health Partnership NHS Trust, Learning Disabilities Directorate,

Little Plumstead Hospital, Norwich NR13 5EW, UK.

References

Aldrich F. K. & Wilson B. (1991) Rivermead Behavioural Memory Test for Children (RBMT-C): apreliminary evaluation. British Journal of Clinical Psychology 30, 161±168.

Alves E., Williams C., Stephen I. & Prossner G. (1991) Mental impairment and severe mentalimpairment. The Psychologist August, 373±376.

Holland A. J. & Oliver C. (1995) Down's syndrome and the links with Alzheimer's disease. Journalof Neurology, Neurosurgery and Psychiatry 59, 111±114.

Hon J., Huppert F. A., Holland A. J. & Watson P. (1998) The value of the Rivermead BehaviouralMemory Test (Children's Version) in an epidemiological study of older adults with Down syn-drome. British Journal of Clinical Psychology 37, 15±29.



Kotler-Cope S. (1990) Memory impairment in older adults: the interrelationships between objectiveand subjective clinical and everyday memory assessment. In: Wilson B. A. (1993) Ecologicalvalidity of neuropsychological assessment: Do neuropsychological indexes predict performancein everyday activities? Applied and Preventive Psychology 2, 209±215.

Thompson P. J. (1997) Epilepsy and memory. In: The Clinical Psychologist's Handbook of Epilepsy:Assessment and Management (eds C. Cull & L. H. Goldstein). Routledge, London.

Wechsler D. (1986) Wechsler Adult Intelligence Scale ± Revised. The Psychological Corporation, NY.Wilson B. A., Cockburn J. & Baddeley A. D. (1985) The Rivermead Behavioural Memory Test. Thames

Valley Test Company, Titch®eld.Wilson B., Cockburn J., Baddeley A. & Hiorns R. (1989) The development and validation of a test

battery for detecting and monitoring everyday memory problems. Journal of Clinical and Experi-mental Neuropsychology 11, 855±870.

Wilson B. & Ivani-Chalian R. (1995) Performance of adults with Down's syndrome on the Chil-dren's Version of the Rivermead Behavioural Memory Test: a brief report. British Journal of Clin-ical Psychology 34, 85±88.

Appendix 1

Key to abbreviations

Appt�Remembering to ask about a future appointment

Date�Remembering the date

Faces� Face recognition

Item�Remembering to ask for a hidden item

Mess�Remembering to deliver a message

Name�Remembering a name

Orient�Orientation questions

Pics�Picture Recognition

Route-Imm�Remembering a route (immediate recall)

Route-Del�Remembering a route (delayed recall)

Story-Imm� Story recall (immediate)

Story-Del� Story recall (delayed)



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A Preliminary Study Investigating How People with Mild Intellectual Disabilities Perform on the Rivermead Behavioural Memory Test