It is well established that digit span increases in a systematic way throughout childhood (Chi, 1977; Dempster, 1981; Samuel, 1978) and that it is sensitive to the.
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Brifish JOYTMIDeuelopmenfal Pgcbology
(1989). 1, 377-380
Printed in Greaf Britain
377
01989 The British Psychological Society
Differential course of development of spatial and verbal memory span: A normative study Elizabeth B. Isaacs* The WolfJDnCentre, Institute of Child Health, UniverJig of London, ?O Guiyord Street, London W C I N l E H , UK
Faraneh Vargha-Khadem The Woyson Centre, Institute of Child Health, Universig of London and Department of Psychological Medicine, Hospital for Sick Children, Great Ormond Street, London
Children ranging from 7 to 15 were given memory span tests for both digits and blocks, each consisting of forward and backward recall components. Both types of span showed developmental increases. Digit span performance was influenced by order of recall but block span was insensitive to this variable.
It is well established that digit span increases in a systematic way throughout childhood (Chi, 1977; Dempster, 1981; Samuel, 1978) and that it is sensitive to the order of report, with more items recalled forward than backward (Case, Kurland & Goldberg, 1982; Rude1 & Denckla, 1974). Several studies (Grossi, Orsini, Monelti & DiMichele, 1979; Orsini, Schiappi & Grossi, 1980) have examined the development of block span but only up to the age of 10 and only using forward report. The present study was carried out to compare the development of forward and backward digit and block spans in children from 7 to 15, the age range over which digit span is known to increase. As well as providing normative data, such a comparison could be of importance in the context of theories of memory which postulate distinct verbal and visuospatial short-term memory systems (Baddeley, 1986; Baddeley & Lieberman, 1980).
Method SubjettJ A total of 288 children t o o k part in this study; 32 children (16 males, 16 females) were tested at each of the nine age levels between 7 and 15 inclusive. In an effort to make the sample as representative as possible, half of the children in each group attended schools in an inner London borough (four primary, two secondary), and the other half attended schools in an outer London borough (three primary, four *Requests for reprints.
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Elixabetb B. Zsaacs and Faraneb Vargba-Kbadem
secondary). The outer borough had a higher proportion of professional residents and a higher socioeconomic profile than the inner one. The headteacher in each school was asked to select children representing the total range of ability and it was the experimenters’ impression that this condition was fulfilled.
MateriaIs D&it ~ p n Both . parts of the Digit Span subtest of the WISC-R. Digits Forward and Digits Backward, were used (Wechsler, 1982).
Blork spun. The Corsi Blocks (Corsi, 1972) were used to measure rpatial short-term memory. The subjects were presented with a wooden board measuring 9 x 11 into which were glued nine cubes with a 14 in side, arranged in a non-symmetrical pattern. The entire apparatus was painted black with no distinguishing marks except for small numbers which faced the experimenter but were invisible to the subject (see Fig. 1).
Figure 1. The Corsi Block Span apparatus.
Procednre All subjects were tested individually during normal school hours. Equal numbers of subjects were given either Digit Span or Block Span first. Digit Span was administered according to standard instructions (Wechsler, 1982). For Block Span, subjects were told to watch as the experimenter touched a sequence of blocks at the rate of one per second and then to touch the blocks either in forward or backward order. The WISC-R Digit Span sequences were used and the testing procedure was the same as that for Digit Span. The longest string of digits or blocks which the child recalled correctly on at least one occasion was considered to be the measure of memory span.
Results Table 1 presents the means and standard deviations by age group for each of the four measures: Digits Forward (DF), Digits Backward (DB), Blocks Forward (BF) and Blocks Backward (BB).
Spatial and verbal memory span
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Table 1. Means and standard deviations (in parentheses) of the number of items recalled Age ( n = 32) Measure
DF DB BF BB
7
8
9
10
11
12
13
14
15
5.2 (0.8) 3.2 (0.6) 4.1 (0.8) 3.9 (1.2)
5.7 (1.1) 3.6 (1.0) 4.7 (0.9) 4.5 (1.2)
5.8 (1.1) 3.8 (1.1) 4.7 (0.8) 4.7 (1.3)
6.1 (1.4) 3.8 (1.3) 5.3 (0.9) 4.6 (1.1)
6.1 (1.3) 4.5 (1.5) 5.3 (0.7) 5.1 (0.9)
5.8 (1.5) 4.3 (1.1) 5.4 (0.8) 5.0 (0.8)
6.2 (1.3) 4.4 (1.4) 5.4 (1.0) 5.4 (0.9)
6.3 (1.1) 4.0 (1.1) 5.4 (0.9) 5.2 (1.1)
6.7 (1.2) 4.8 (1.1) 5.6 (0.9) 5.5 (1.0)
~~~~~~~~~~
~
~~
~
Ky. D F = Digits Forward; DB=Digits Backward; BF=BIocks Forward; BB= Blocks Backward.
Changes with age All four measures of memory span increased with age. One-way analyses of variance showed a significant effect of age for each measure (DF: F = 5.59,d.f.= 8, 279,
P
