Dyslectic and normally-reading children : 1. Exploration of a
letter-search test for screening purposes : 2. Follow- up and
further exploration in 4 weak and 4 normal readers on letter,
word and number recognition
Citation for published version (APA):
Legein, C. P., & Bouma, H. (1977). Dyslectic and normally-reading children : 1. Exploration of a letter-search test
for screening purposes : 2. Follow- up and further exploration in 4 weak and 4 normal readers on letter, word
and number recognition. Documenta Ophthalmologica, 42(2), 391-396. https://doi.org/10.1007/BF02742254
DOI:
10.1007/BF02742254
Document status and date:
Published: 01/01/1977
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Documenta Ophthalmologica 42,2 : 391 - 396, 1977
DYSLECTIC AND N O R M A L L Y - R E A D I N G CHILDREN
I. EXPLORATION O F A LETTER-SEARCH TEST FOR SCREENING PURPOSES
II. FOLLOW-UP AND F U R T H E R E X P L O R A T I O N IN 4 WEAK AND 4 N O R M A L READERS ON LETTER, WORD AND NUMBER
RECOGNITION
CH.P. LEGEIN & H. BOUMA
(Eindhoven)
INTRODUCTION
The results obtained last year from the examination of 20 dyslectic and 20 normally reading children (Bourna, Legein & Van Rens, 1974; Bouma & Legein, 1976) encouraged us to continue this study into two directions.
Firstly a follow-up study o f all 40 subjects to get an idea o f the course o f these perceptual processes. Secondly a further exploration of possible defec- tive processes in visual recognition. This paper will report b o t h on the follow-up study and on the further exploration in four dyslectic and four normally reading children selected from the above mentioned groups.
Partly summarizing last year's results we found:
1. A backwardness in reading-level for all dyslectic children by at least two years;
2. in the tachistoscopic experiments a significantly lower recognition-score for the dyslectic group with reference to embedded letters and for words especially in parafoveal presentation.
LETTER-SEARCH TEST
F o r the purpose o f bridging the gap between tachistoscopic recognition and ordinary reading we developed a search experiment in which letters e (target letters) within words or letterstrings o f 8 letters had to be marked.
As to the n u m b e r of errors, the dyslectic group missed twice as much target-letters as the control-group and b o t h groups missed more target- letters in the words than in the l e t t e r strings (Table 1).
Table 1. Percent error-scores in letter search test. Large scores: total errors; small scores: after correction for skipped lines.
w o r d s
d y s l . c o n t r .
3 6
2314
13
strings
2 6
1512
9
many lines occurred in which n o t a single target letter was marked. This could be an indication that they just skipped full lines probably due to an insufficient control of the eye-movement towards the new line. We made a correction for these, probably n o t inspected, lines, also indicated in Table I. The general tendency is that more target-letters are missed in the second part of the words and letterstrings; and that the first, fourth and fifth letter- position are at an advantage. Many errors are made at the last few letter- positions in the letterstrings by both groups, and also in words by the dyslectic group.
Since both groups made more errors in the word-test than in the string- test this is indicative of them using knowledge of wordforrns to a certain extent. The specificity of this knowledge has n o t yet been investigated. In conclusion this test puts attention to a probably insufficient eyecontrol on the part of dyslectic children which, together with strong parafoveal inter- ference effects influences their scores. A new version of the test might separate these effects.
FOLLOW-UP
In the tachistoscopic part of the examination there was hardly any change in the high foveal recognition scores of both groups (Table 2). In parafoveal scores, however, there was a definite improvement in particular for words in the dyslectic group.
Table 2. 1975 Average correct recognition-scores (~) of single letters /a/; embedded letters/xax/; words/wrd/. Between brackets are the 1974 scores of the same children.
f o v e a l dysl. contr. / a / 96 (96) 94 (99) /xax/ 72 (68) 9 4 (os) /wrd/ 78 (73) 100 (lOO) p a r a f o v e a l dysl. contr. 91 (m) 9 8 (ge) 28 (+o) 53 (54) S4 ( ~ ) 71 (co)
As to the reading-level of the
eight subjects
(Fig. I) we conclude that the dyslectic children especially made progress and for them a fair correlation between improved reading level and better parafoveal recognition of words is shown (Fig. 2).FURTHER EXPLORATION
Further exploration was done o n foveal recognition of common words (frequency of usage in printed Dutch about 1 : I0,000) of larger lengths (l = 6, 7 and 8). Six words of each length were presented (exposure-time 100 msec). In the dyslectic group the scores for these long words are de- finitely lower than for the shorter words, whereas for the normal groups the scores remained perfect. The scores for word lengths l = 3 - 5 of these subjects have also been included (Table 3).
Table 3. Correct foveal word recognition scores for various wordlengths.
dysl. contr.
f = 3
77
100
f = 4
77
100
~=s
8 0
100
f : 6
42
100
f=7
38
100
f=8
33
96
Forty, randomly composed, digit strings (length l = 1, 2, 3, 4) were foveaUy presented (100 msec exposure time). Table 4 gives the results for both groups and it is obvious that, as from l = 3, dyslectics have far more diffi- culties than children which read normally. We tested numers of two digits parafoveally (eccentricity = 1 ~ and found that both groups had rather high scores: dyslectics 8270 and controls 9470. A foveal recognition experiment of numbers was also done using both a normal ( I 0 0 msec) and a prolonged presentation time (500 msec). Table 4 shows an increase of correct scores. This probably indicates that the short-term memory capacity is n o t an essential limiting factor in these experiments.
7
"1- 6 Z ~ s @~ 4
"10 P 32
grade / / / / / / / " "s/
//ysexc
1 , i r l L , i I i I 9 I 5 6 7 8 9 10 11 12 13 14 yrs. a g eFig. 1. Follow-up of reading level 1974 (small symbols)-1975 (large symbols).
1-0
%- +1 n ~O i--0
3
"5
dvslexic /
~ . - l l l
control
o
g o
" O I I I I I I1
2
3
4
5
6 grade 7
reading level (TANGHE)
Fig. 2. Follow-up of parafoveal word-recognition and of reading level 1974 (small symboIs)-1975 (large symbols),
Table 4. Correct foveal number scores for various lengths (1) at two stimulus durations. f - - 1
'f= 2
f : 3
1 / = 4/=5
dysl.
lOO ms soo ms 9 5 9 5 6 8 9 1 3 8 7 0 - 3 0contr.
Ioo m s soo ms 1 0 0 - I O 0 - 9 5 1 0 0 9 8 9 2 - 6 5Nevertheless the short term memory function (rehearsal) seems worse in the dyslectic group as is indicated by testing this function as well by audi- tory presentation of digit-strings (l = 3,4,5) with a pronounciating speed of 2 numbers per second. Table 5 shows the results and indicates a low score for the dyslectic group in repeating long digit-strings (l = 5). In conclusion the lower scores ,obtained in visual presentation of. numbers then seem due to perceptual factors rather than to short-term memory dysfunction.
Table 5. Auditory presentation of digit-strings. Correct scores for various lengths.
dysl. contr.
I = 3
100
100
f : 4
80
88
f - 5
42
80
CONCLUSION
As to the research on dyslexia the conclusion then seems to be that eye control, perception and recognition of letters and words, and storage pro- cesses should be studied n o t just in isolation b u t also in their mutual de- pendence on one another. This conclusion links up with the n o t i o n that dyslexia stems from many different adverse factors.
the resulting difficulties are moreover n o t confined to the reading of text, but are clearly present in the recognition of numbers. Indeed, dyslexia is a syndrome. We have hopes that the understanding of the underlaying phe- n o m e n a of dyslexia may proceed equally fast as the understanding of normal reading processes, which, in the literature as well as at IPO (Institute for Perception Research), is a subject of renewed interest.
REFERENCES
Bouma, H., Legein, Ch.P. & Van Rens, A.L.M. Visual recognition by dyslexic children. IPO Annual Progress Report 9: 104-109 (1974).
Bouma, H. & Legein, Ch.P. Foveal and parafoveal recognition of letters and words by dyslexics and by average readers. Neuropsych. (in press) 1976.
Authors' address:
Institute for Perception Research, IPO P.O. Box 513
