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Reach on sound: A key to object permanence in visually impaired children
Elisa Fazzi a,, Sabrina Giovanna Signorini b, Monica Bomba a, Antonella Luparia b,Jose Lanners c, Umberto Balottin d
a Unit of Child Neurology and Psychiatry, Spedali Civili, Mother and Child Department, University of Brescia, Italyb Unit of Child Neurology and Psychiatry and Child Neuro-ophthalmology, IRCCS C. Mondino Foundation, University of Pavia, Pavia, Italyc Fondazione Robert Hollman, Cannero Riviera (VB), Italyd Unit of Child Neurology and Psychiatry, IRCCS C. Mondino Foundation, University of Pavia, Pavia, Italy
a b s t r a c ta r t i c l e i n f o
Article history:
Received 24 September 2010
Received in revised form 16 January 2011
Accepted 18 January 2011
Keywords:
Visually impaired children
Object permanence
Reach on sound
Cognitive development
Background: The capacity to reach an object presented through sound clue indicates, in the blind child, the
acquisition of object permanence and gives information over his/her cognitive development.
Aim: To assess cognitive development in congenitally blind children with or without multiple disabilities.
Study design: Cohort study.
Subjects: Thirty-seven congenitally blind subjects (17 with associated multiple disabilities, 20 mainly blind)
were enrolled.
Outcome measures: We used Bigelow's protocol to evaluate reach on sound capacity over time (at 6, 12, 18,
24, and 36 months), and a battery of clinical, neurophysiological and cognitive instruments to assess clinical
features.
Results: Tasks n.1 to 5 were acquired by most of the mainly blind children by 12 months of age. Task 6
coincided with a drop in performance, and the acquisition of the subsequent tasks showed a less
agehomogeneous pattern. In blind children with multiple disabilities, task acquisition rates were lower, with
the curves dipping in relation to the more complex tasks.
Conclusions: The mainly blind subjects managed to overcome Fraiberg's conceptual problem i.e., they
acquired the ability to attribute an external object with identity and substance even when it manifested its
presence through sound only and thus developed the ability to reach an object presented through sound.Instead, most of the blind children with multiple disabilities presented poor performances on the reach on
sound protocol and were unable, before 36 months of age, to develop the strategies needed to resolve
Fraiberg's conceptual problem.
2011 Elsevier Ireland Ltd. All rights reserved.
1. Introduction
In the construction of sensorimotor intelligence, vision is the most
important sense [13]. Vision allows the child to develop an
awareness of his external world: it is through vision that the child
learns to know and recognise his mother's face and acquires object
permanence and the earliest notions of causality.
The sensorimotor development of the blind child [46] differs
from the pattern that emerges in the normally-sighted child due to
the presence, in the former, of specific neuromotor and cognitive
difficulties [711]. In accordance with other authors, the mobility that
normally follows each postural achievement is considerably delayed
in blind children without multiple disabilities. A visual function deficit
implies difficulties developing an awareness of physical causality, of
spatial relations and, above all, of object permanence [4].
Fraiberg [12,13] maintains that the capacity to reach an object that
is presented through sound is, in the blind child, the behavioural
indicator of the acquisition of object permanence. Also in the
normally-sighted child, sound plays a developing role in the
construction of the object; since Piaget's stage 4, sound becomes a
more and more powerful cue in directing the child's active search for
the object [14]. While locomotion plays a necessary facilitative role in
the development of object permanence [15], motor achievements are
in turn supported by the progressive construction of the object
through sound. In a previous study we reported that the onset of self-
initiated mobility in blind children is related to the demonstration of
each child's ability to reach out and take an object presented by sound
clue alone. In particular, we observed that all of the subjects of our
group of blind children learned to walk independently only after
gaining the ability to find their bearings when guided by a sound [9].
Our survey provided further confirmation of the findings of Fraiberg
Early Human Development 87 (2011) 289296
Corresponding author. Tel.: +39 0303995724; fax: +39 0303995723.
E-mail address: elisa.fazzi@gmail.com (E. Fazzi).
0378-3782/$ see front matter 2011 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.earlhumdev.2011.01.032
Contents lists available at ScienceDirect
Early Human Development
j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / e a r l h u m d ev
http://dx.doi.org/10.1016/j.earlhumdev.2011.01.032http://dx.doi.org/10.1016/j.earlhumdev.2011.01.032http://dx.doi.org/10.1016/j.earlhumdev.2011.01.032mailto:elisa.fazzi@gmail.comhttp://dx.doi.org/10.1016/j.earlhumdev.2011.01.032http://www.sciencedirect.com/science/journal/03783782http://www.sciencedirect.com/science/journal/03783782http://dx.doi.org/10.1016/j.earlhumdev.2011.01.032mailto:elisa.fazzi@gmail.comhttp://dx.doi.org/10.1016/j.earlhumdev.2011.01.0327/27/2019 Alcance de Sonido Clave Permanencia Del Objeto en Ciegos
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and Bigelow who demonstrated that reach on sound is the crucial
moment in terms of the blind child's access to the world of
representation, as well as being an activity that indicates the child's
readiness to achieve locomotion.
To deepen this aspect, Freiberg affirms that the blind child must be
able to overcome a conceptual problem in order to acquire thereach on sound capacity [13]: since, for the blind child, objects do
not possess the sensory and perceptible qualities which make them
recognisable to sighted children, in order to conceive of grasping anobject with a sound, he/she must manage without the merely visual
information relating to that object and form a mental image of it
[14,15]. From Fraiberg's descriptions [12,13], the acquisition of this
ability emerges as a significant moment in the development of the
blind child, being at once a condition of and a catalyst for all his
subsequent development. This is why it is particularly important to
promote reach on sound in theblindchild: it represents the solution
to Fraiberg's conceptual problem, guaranteeing the attribution of
substance even to objects that are presented exclusively through
sound.
The importance of reach on sound is analysed by Bigelow [14
16], who has developed an 11-item protocol specifically designed to
investigate the sequential development, in blind children, of the
ability to seek and reach objects presented through sound and tactile
clues. The progressive acquisition and mastering of these items appear
to be related to a growing awareness of object permanence in the
absence of sight. Furthermore, Bigelow establishes a correlation
between the Piaget's stages in the acquisition of object permanence
and the stages in the acquisition of reach on sound, suggesting that
the eleventasks in the reach on sound protocol reflect theprocess of
the acquisition of sensorimotor intelligence, and thus represent a
measure of cognitive development. In the presence of multiple
developmental disabilities this process of acquisition is likely to be
altered.
We set out to evaluate the development of the reach on sound
function in a sample of congenitally blind children without and with
other neuromotor and/or cognitive disabilities, paying particular
attention to differences and/or similarities in their acquisition of this
ability.
2. Methods
2.1. Sample description
The study sample was made up of 37 congenitally blind children,
consecutively referred to the Centre of Child Neuro-ophthalmology at
the C. Mondino Institute of Neurology in Pavia (Italy) for diagnostic
and therapeutic assessment. The Institutional Ethical Committee
approved the research project. The parents of all the enrolled children
signed an informed consent form in order to participate to the study.
Congenital blindness was diagnosed according to the International
Classification of Functioning, Disability and Health ICF [17];
cerebral visual impairment was defined according to Good [18,19].
2.2. Procedure
Visual impairment was assessed on the basis of clinical behaviour
(absence of any response to light or minimal perception of light, or
visual acuity less than 0.02, as evaluated using Teller Acuity Cards
[20]), and a neuro-ophthalmological assessment according to previ-
ous records [21]. In addition,all thesubjectsunderwent a neurological
examination and neurophysiological investigations (VEPs, BAEPs and
EEG) in order to establish whether their blindness was isolated or
associated with other neuromotor or sensory disabilities. The socio-
demographic and clinical features of the sample are detailed in
Table 1.
All the 37 subjects underwent the assessment of developmental
level through the administration of The ReynellZinkin Scales:
Developmental Scales for Young Visually Handicapped Children
[22]. For this study, we used the total scores and the cut-offs proposed
by the authors to qualify normal mental development, slight and
severe mental delay. Mental development was assessed at the follow-
up session of 12 months of age.On the basis of the results of the clinical and instrumental
examinations the subjects were divided into two groups (see Table 1):
Group I of blind children (10 males and 10 females) with a normal
mental development at the ReynellZinkin Scales and without
associated motor handicaps or focal signs at the neurological
examination. For brevity, we will call these subjects as mainly
blind; they are, indeed, children in which blindness, at the
moment of the evaluation, is the outstanding problem; the termmainly is used in order to not exclude the possibility of a future
development of a neuropsychological problem, but this kind of
handicap wasn't present at the evaluation time. We presume that,
in the first years of life, prior cognitive hitches might be present
but not yet describable.
Group II of children (7 males and 10 females) with associatedhandicaps (16 with cerebral visual impairment and 1 with Jubert
syndrome). There was clinical evidence of cerebral palsy with
developmental delay in 88% of the Group II subjects and of
developmental delay only in the remaining 12% (p=0.000; see
Table 1).
No child in either group showed hearing impairment at the BAEPs.
The subjects in Group I were first assessed at a mean age of
9.1 months (SD=5.1; range=424) and those in Group II at a mean
age of 10.8 months (SD=8.2; range=628). They were followed up
through longitudinal controls every three months for the period
ranging from the 6th to the 36th month of age, with all the children in
the two groups reaching the last follow up at 36 months. Infants were
tested individually, in the presence of their mother, in a dedicated
room in our Institution, by a familiar experimenter (always the same
Table 1
Socio-demographic and clinical features of the two groups.
Gr ou p 1 G roup 2 p
n= 20 n = 17
Gender: male n(%) 10(50%) 7(41.2%) n.s.
Gestational age: mean(S.D.) 38.9(0.8) 36.8(1.0) n.s.
Born: n(%) n.s.
At term 17(85%) 8(47.1%)
Moderately preterm 2(10%) 5(29.4%)
Severely preterm 1(5%) 4(23.5%)
Visual damage: n(%) n.s.
Complete bilateral blindn ess 10(50%) 9(52.9% )
Light perception 10(50%) 8(47.1%)
Type of visual damage: n(%)
Disord er s of ext er na l p art s of the eye 1( 5% ) 0
Retinal disorders
Leber's congenital amaurosis 12(60%) 0
Joubert syndrome 0 1(5.9%)
Retinal haemorrhage 1(5%) 0
Retinopathy of prematurity 1(5%) 0
Retinal dysplasia 1(5%) 0
Cerebral visual impairment 0 16(94.1%)
Optic atrophy 3(15%) 0
Norrie disease 1(5%) 0
Cognitive level (ReynellZinkin Scales): n(%) 0.000
Normal 20(100%) 0
Slight mental delay 0 4(23.5%)Severe mental delay 0 13(76.5%)
n.s. = not significant.
S.D. = standard deviation.
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operator in all the control-sessions). Each follow up comprised an
interview with the parents, a neurological examination, ascertain-
ment of the achievement, or otherwise, of the main gross motor
milestones, a video-recording to explore the child's spontaneous
behaviour in the presence of the mother. The latter was performed
during a separate fifteen minute session of observation of both the
baby and his/her mother staying together.
2.3. Reach on sound protocol
In this study we focused on the ability to reach objects presented
through sound clue. This ability was evaluated through the Bigelowreach on sound protocol [16], the eleven tasks of which are
described briefly in Table 2. The sequence of tasks set out in the
protocol parallels the process of the acquisition of object permanence,
each task belonging, according to Piagetian thought, to a specific stage
in this process (Table 3).
In accordance with Bigelow's indications [16], the procedure was
explained to the mother, who was asked not to give any specific cues
to the child during the tasks. Nevertheless the mother was asked to
paraphrase the experimenter's verbalizations when appropriate or
necessary to elicit the best possible response from the child. The
infant was on the floor in a sitting position (with or without back
support, accordingly with the age and the motor development of the
subject).
Each task was tried to be presented for a minimum of 3 trials in
each session, with the exception of Tasks 1, 3, 5 and 7. We used
Bigelow's criterion for mastery to consider a task successful when
50% or more of the trials were correct at a certain follow-up time and
also at the subsequent control. The task was judged successful if the
infant reached directly to the toy used as the target and contacted it
without any scanning or groping movements. Reaches directly in the
direction of the toy or its sound which did not result in the child
securing the toy were also judged to be successful if the reaches were
off target by approximately 5 cm or less. Exceptions to this second
criterion for success were when the child had continuous tactile
contact with the toy (Task 1), there was continuous movement of acontinuously sounding toy (Task 4),or there were based on thechild's
first response to the trial presentation. All the tasks were presented in
the order described in Table 2 in all the follow-up sessions. The
children's responses to the tasks were scored from videotapes of the
sessions.
2.4. Reach on sound tools and targets
The stimulus toys used were the ones of the experimenter's and
were the same for all the subjects. Moreover, we asked the mother to
bring one or two familiar child's toys in order to optimise the
children's response to the tasks. As indicated by Bigelow's protocol
[16], mechanical-sounding toys (such as a buzzing robot or a music
box), manually operated sound toys (such as a hand bell and a giraffe
squeeze toy), and toys without sound (like a doll and a rubber ball)
were used. The children's toys used as targets were squeeze toys,
rattles, and stuffed sounding animals.
The toys used in the intermittent sound task (see Task 10 and 11)
were manually operated sound toys which were manipulated to
produce a sound approximately every 2 s.
A metal screen, 44 cm square cloths, and small pillows were used
as coverings for the stimulus objects in the cover object task 6.
2.5. Statistical analysis
Continuous variables were expressed as mean and standard
deviation (SD), and were compared using the parametric T-test.Categorical variables have been presented as counts and percentages
and compared with the test. A pb0.05 was considered statistically
significant.
The statistical analysis was performed using the statistical package
SPSS 13.0 (SPSS Inc. Corp., USA).
Table 2
Reach on sound protocol.
Task n. Tasks' description
1 Reaching of a non-sonorous object that touches the child's body
( continuous tactile stimulation in the absence of sonorous information)
2 Reaching of a sonorous object that wasfi
rst touched and then taken away while continuing to make a sound( tactile stimulation initially, followed by continuous sonorous stimulation)
3 Reaching of a sonorous object in a fixed position
( continuous auditory stimulation in the absence of tactile information)
4 Reaching of a moving sonorous object moved in a horizontal 180 arc around the head
( continuous auditory stimulation in the absence of tactile information)
5 Reaching of a s onorous o bject and of a no n-so norous object that the child has dropped (obse rva tion al test)
6 Reaching of a sonorous object concealed by a screen
7 Reaching of a sonorous object that designs a vertical arc
( continuous auditory stimulation in the absence of tactile information)
8 Reaching of a n on-sonorous object taken out of the child's hands an d positi oned in a s et poin t close to hi m
( discontinuous tactile stimulation in the absence of sonorous clues)
9 R eac hing of a sonor ous obj ec t p ulled aw ay f rom t he c hild a nd m oved in a horizont al a rc to one sid e while c ontinu ing to sou nd
( continuous auditory stimulation)
10 Reaching of an intermittently sounding object that designs a horizontal arc
( discontinuous auditory stimulation in the absence of tactile information)
11 Reaching of an object that sounds intermittently at fixed points in space
( discontinuous auditory stimulation in the absence of tactile information)
Table 3
Correlation between the 11 tasks in the reach on sound protocol and the stages in the
development of object permanence according to Piaget [16].
Reach on sound
task n.
Piaget stages Age of
acquisition
(months)
1 III: Start of object permanence 4/58/9
From 2 to 7 IV: Active searching for the object that has
disappeared but without taking into account its
series of visible movements
8/911
8 Transitional stage
From 9 to 10 V:The child nowtakesinto account the seriesof
visible movements of the object, but not yet its
invisible movements
11/1218
Completed protocol VI: The child has acquired the concept of object
permanence
1824
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3. Results
As regards the neuromotor development (Table 4), at the last
follow-up visit, the children in Group I showed a homogeneous
profile:all thesubjectshad acquired good head control, andthe sitting
and standing positions. Independent walking was achieved by 19 of
the Group I subjects (95%) by the end of the follow up, at a mean age
of 19 months (SD=8.7), at which stage the one remaining subject
(5%) had achieved only assisted gait. Of the 20 subjects in Group I, 9
didn't crawl (45%). Of the 11 remaining subjects, 4 (36.4%) achievedcrawling at a normal time, 3 (27.3%) crawled at the same time as
walking, 3 (27.3%) crawled after learning to walk independently and
one crawled but was not walking at 36 months.
A very different neuromotor profile, characterised by failure to
achieve, or markedly delayed achievement of, almost all the functions,
both postural and locomotor, emerged in the blind children with
associated multiple disabilities: four children (23%) did not achieve
postural control, seven (42%) acquired only control of the head (at a
mean age of 15 months), four children (23%) achieved the sitting
position at the mean age of 24 months, and two children (12%)
affected by a less severe form of cerebral palsy were able to stand at
the mean age of 26 months. Therefore, none of the Group II children
had acquired the ability to walk by the age of 36 months, when the
follow-up period ended.As regards the acquisition of prehension (Table 4), all the blind
children (100%) of Group I achieved bimanual grasp and (index)fingerthumb grasp at the mean ages of 6 and18 months respectively.
Like the acquisition of neuromotor functions, development of
manipulatory function was also found to be deficient in the blind
children with associatedhandicaps: prehension was absent in 65% (11
children) of the Group II and present, although inadequate (poorly
functional attempts that did not result in the complete grasping of the
object) in 12% of the cases (two children). Only 4 of the Group II
subjects(22%) acquiredbimanualgrasp, at the meanage of 24 months.
No member of this group acquired (index) fingerthumb grasp.
As regards mental development (Table 1), evaluated through
administration of the ReynellZinkin Scales [22], all the subjects of the
Group I showed normal development. In Group II, on the other hand,
mentaldevelopment seemedto be more impaired,with 23%(4 subjects)
presenting slight mental delay and 77% (13 subjects) severe mental
delay.As regards the acquisition of the items in the reach on sound
protocol, 70% (14 children) of the Group I subjects had completed the
protocol by the age of 36 months, as opposed to just 6% (one child) of
the Group II subjects. Fig. 1 shows the percentage of acquisition at
36 months at each task in the two groups. At each task, the statistical
difference between the groups is highly significant (pb0.001). In
particular, in Group I, one child (5%) had achieved all the tasks at
12 months, 4 children (20%) at 18 months, two children (10%) at
24 months, and seven children (35%) at 36 months of age. A further
15% of the Group I subjects (3 children) achieved all the items except
task n. 6, which the only two Group II children who completed a
reasonable proportion of the protocol (12% of Group II) also failed to
achieve. The remaining 15% of the Group I subjects (3 children)
achieved only the first few tasks in the protocol. These three children
were all affected by Leber congenital amaurosis and were character-
ised by behavioural and relational problems. Fig. 2 illustrates the
percentages of the Group I children who, at each of the ages
considered (6, 12, 18, 24, and 36 months), had mastered the various
tasks. It emerges that tasks n. 1 to 5 were acquired by most of Group I
children by the age of 12 months, whereas acquisition of the
subsequent tasks shows a less age-homogeneous pattern, partly as a
result of the greater difficulty of these tasks, a drop in performance
coinciding, indeed, with task n. 6. This drop in performance was also
seen in the Group II subjects (Fig. 3): in this group the overall trend
was similar to that observed in Group I (illustrated in Fig. 2) but the
task acquisition rates (percentages) were lower, with the curves
dipping in relation to the more complex tasks. Furthermore, at the
ages of 6 and 12 months, none of the Group II children had acquired
task n. 4 or above. Conversely, as illustrated in Fig. 2, zero acquisitionrates were recorded in the Group I subjects only at 6 months of age
and, even then, only in relation to the very last tasks in the protocol.
In Group II, two children (12% of the sample) achieved the first
three items, one child (6%) only the first task, and eleven children
(64%) none of the tasks. Of these eleven subjects, nine (52%) showed
reactions indicating alertness, and two (12%) no reaction.
In this group, only one child (6%) completed the protocol and the 2
children (12%) completed a reasonable proportion of the tasks
Table 4
Gross motor and fine motor abilities.
Group I Group II
No psychomotor acquisition 0 4 (23%)
Head control 20 (100%) 7 (42%)
Sitting 20 (100%) 4 (23%)
Standing 20 (100%) 2 (12%)
Walking supported 1 (5%) 0
Walking independently 19 (95%) 0
No prehension 0 11 (65%)Attempts at prehension 20 (100%) 2 (12%)
Bimanual grasp 20 (100%) 4 (23%)
Fingerthumb grasp 20 (100%) 0
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Task 1 Task 2 Task 3 Task 4 Task 5 Task 6 Task 7 Task 8 Task 9 Task10
Task11
Group 1 Group 2
Fig. 1. Percentage of acquired tasks at 36 months in the two groups. All the differences are highly significant (p= 0.000).
292 E. Fazzi et al. / Early Human Development 87 (2011) 289 296
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administered; these subjects were all characterised by cerebral visual
impairment, cerebral palsy, and a slight mental delay. When
observing the acquisition of the main gross motor milestones, these
subjects were three of the less compromised in Group II. Only two
other subjects, who didn't complete the reach on sound protocol,
were characterised by a less profound psychomotor delay: one was
the subject affected by Jubert syndrome and the other one had a
severe mental delay at the ReynellZinkin Scales. Of the other 12
children who didn't complete the reach on sound protocol, one had a
severe psychomotor delay (he could stand seated autonomously just
1 2 3 4 5 6 7 8 9 10 11
6 months
18 months
36 months0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
TASK
6 months 12 months 18 months 24 months 36 months
6 months 20% 25% 15% 5% 5% 0% 5% 0% 0% 0% 0%
12 months 85% 85% 80% 55% 50% 5% 45% 15% 25% 20% 15%
18 months 95% 90% 85% 65% 65% 25% 75% 35% 60% 45% 30%
24 months 100% 95% 90% 80% 70% 35% 80% 45% 60% 50% 40%
36 months 100% 95% 95% 85% 85% 70% 85% 85% 75% 75% 75%
1 2 3 4 5 6 7 8 9 10 11
Fig. 2. Acquisition of reach on sound function in Group I.
1 2 3 4 5 6 7 8 9 10 11
6 months
18 months
36 months0%
20%
40%
60%
80%
100%
TASK
6 months 12 months 18 months 24 months 36 months
6 months 0% 6% 0% 0% 0% 0% 0% 0% 0% 0% 0%
12 months 11% 12% 11% 0% 0% 0% 0% 0% 0% 0% 0%
18 months 11% 12% 11% 11% 11% 0% 11% 6% 11% 0% 0%
24 months 22% 30% 22% 17% 22% 0% 17% 17% 17% 11% 11%
36 months 28% 30% 22% 17% 22% 6% 17% 17% 17% 11% 11%
1 2 3 4 5 6 7 8 9 10 11
Fig. 3. Acquisition of
reach on sound
function in Group II.
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for a few seconds at the age of 4 years) with a slight mental delay at
the developmental scales, two had a less serious psychomotor delay
(one reached the assisted gait at 20 months, one was able to stand at
23 months) and a severe mental delay at the Reynell Zinkin Scales, 9
had both an important psychomotor and mental delay.
Task n. 1 was the only one that all the members of the Group I had
completed by the age of 24 months (see Fig. 2). Moreover, children in
Group I mastered the tasks in sequence, except for tasks 6 and 8 that
were achieved at 36 months of age by the major part of the subjects,meanwhile the tasks n. 7, 9, and 10 were reached earlier.
4. Discussion
We found that the blind child's acquisition of the reach on sound
function shows a characteristic pattern. Most of the children observed
had completed the Bigelow protocol tasks by the age of 36 months,
but from the age of 12 months onwards a peculiar trend seemed to
emerge, characterised by a reduced frequency of achievement on
tasks n. 6 and n. 8 that persisted at follow ups conducted at the ages of
18 and 24 months, with a recovery of these performances not
appearing until the age of 36 months. Tasks n. 6 and n. 8 seemed to
be particularly complex for the blind child, given that they both
present a discontinuity of the tactile stimulus. In task n. 6, the
presence of a cover that hides the object, impeding tactile immediate
recognition and representing a new, unknown tactile substrate that
has to be recognised as a cover, seems to confound the subjects,
slowing the mastering of this task. In task n. 8, the difficulty is
represented by the presence of a discontinuous tactile stimulation in
the absence of sonorous clues. It seems that the discontinuity of the
tactile stimulus represents a specific difficulty for the mastering of the
tasks by the blind children. It is only a few months after acquisition of
the ability to walk independently through space, and thus after the
mean age of two years, that a child learns to know his external world
and develops the strategies needed to overcome these particular
challenges. This would also explain whyonly a smallpercentage of the
Group II children managed to complete the protocol, and in particular
to acquire tasks n. 6 and 8: the presence of a motor and/or cognitive
deficit challenges the child not so much by impeding his execution ofthe task, as by denying him the possibility of moving and gaining
experience of his external world, and thus of finding a solution to
Fraiberg's conceptual problem. In particular, we observed that
walking in Group 1 begun when the first 45 tasks at the reach on
sound protocol were achieved. This observation is in accord with
Bigelow's observations of three blind boys [14]. Children begun to
walk after they entered Piaget's stage IV.Independentgait seemsto be
favoured by the appearance of the child's active searching for the
object, activity that walking seems to support itself. This finding is in
accordance with the hypothesis that the relationship between object
knowledge and the advancement in locomotive skills is facilitative
also in the blind child [14], as it is proposed to be for the sighted
children [23]. Moreover, as observed in a recentstudy [9], congenitally
blind children rarely crawled before walking independently and oftenmissed out this stage altogether. In this aspect, they are similar to
shufflers or scooters who slide on their buttocks rather than crawl.
Even though the motor responses needed in order to perform task
n. 1 are the same as those required for task n. 3, from our results it
would appear that blind children find task n. 3 more difficult to
achieve than task n.1. Thus it might be deduced that a task involving a
continuous tactile stimulus is simpler to perform than one in which it
is the sonorous information that is continuous: in short, tactile tasks
are easier to perform, as suggested by Bigelow's findings [16].
The sameapplies to tasks n. 2 and 8. Again, these tasks demandthe
same motor behaviour in order to reach the object, but the first was
seen to be more easily achieved than the second, in which the object
was presented only through discontinuous tactile clues: this suggests
that sound gives to the blind child important information about the
object, such as its location and direction, clues that a purely tactile
stimulus that is discontinuous cannot give him. Indeed, in task n. 8,
the child is deprived of all contact with and information about the
object and this influences his attempts to find it. The fact that a
substantial percentage (40%) of children were able to perform this
task at 36 months could be an indication that the older child, despite
being deprived of tactilesonorous information relating to the object
when it is taken out of his hands, will still seek it, aware that it
continues to exist even though he is no longer able to perceive it. Thechildren's performances on task n. 8, however, demonstrate that
seeking of the target object is favoured by having previously had
tactile contact with it.
Task n. 4 proved to be very difficult to achieve, probably for two
reasons: one was the lack of tactile contact with the moving object (a
further demonstration of the importance of integration of tactile and
auditory information in the blind child's ability to reach and take hold
of an object), and second, the fact that the blind child, in this task, had
to show increased upper limb control andprecision in order to reach a
moving as opposed to a stationary object. The child's ability to locate
an object through sound improves as demonstrated by our findings
relating to the achievement of tasks n. 3, 4 and 7, which do not include
tactile clues. In these three tasks, the child is required to reach a
sonorous object that is first stationary (task n. 3) and that then moves
along the horizontal plane (task n. 4), and subsequently designs a
vertical arc(taskn. 7).Giventhat psychophysically it is easierto locate
sounds in the horizontal than in the vertical plane, the sequence in
which these three abilities are acquired reflects the psychophysical
principles of location by sound.
Tasks n. 5 and 9 require the child to reach a sonorous object that is
sounding in a position different from the one in which it had been
when he lost tactile contact with it. Children attempting these tasks
thus find themselves with contrasting tactile and sound clues, but
regardless of where they heard the sound coming from, our children
nevertheless sought the object in the place where they had lost
contact with it. Thus, even though blind children are able to respond
to sound clues, as shown by their achievement of task n. 2, in more
difficult tasks like these, which introduce contrasting information,
they can be seen to fall back on old reaching strategies guided bytactile clues. Thus we can affirm that sound clues facilitate the
reaching of the object, but only when they do not conflict with
tactile information. Furthermore, task n. 5 was apparently easier for
the children than task n. 9 thanks to their development and
application of behavioural rules for the retrieving of objects they
have allowed to fall from their hands: blind children will quickly learn
that if they drop an object, then they themselves must go down to
get it. Applying this rule, they do not need to postulate a spatial
construct, which, instead, is precisely what they do when the object is
taken from their hands as opposed to accidentally dropped (task n. 9).
At task n. 9, children stopped and entered in a state of quiet listening
to object movements. Their steps and gestures were guided by sound.
Task n. 6, the one most similar to the object permanence tests
administered to sighted children, was the one that all our blindchildren found hardest to achieve. The difficulty of this task lies in the
need to remove a cover that conceals the object, which goes on
sounding, from underneath the cover, for the entire duration of the
task: achievement of this task depends on the ability to separate the
means from the end. According to Piaget's description of the
development of object permanence, this ability is possible at 8
12 months (or the fourth stage of Piaget's model), despite the fact
that, at this age, the child's perceives the object as an extension of his
own action; in the subsequent stage (fifth stage: 1218 months), the
child will comprehend the permanence of the object only if he is able
to conserve a visible map of its movements. The blind child instead
has to rely on sound clues in place of this visual information, and only
a small proportion of our Group I subjects were able to perform the
task at the age of 18 months. Piaget indicates that at the sixth stage
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(1824 months) the child has acquired the concept of the object as
permanent, although the relatively small proportion (35%) of our
children who had achieved task n. 6 by the age of 18 24 months
would seem to highlight the particular importance of visual
information in the building of the concepts of object permanence
and of the permanence of the outside world.
Tasks n. 10 and 11, the ones associated with the fifth stage in the
development of object permanence according to Piaget, were the
abilitieswhoseacquisition wasmost delayed in our children.For blindchildren, objects that sound intermittently are particularly difficult to
reach, given that, when they fall silent, their location becomes
unpredictable; conversely, an intermittently sounding object that is in
motion is easier to locate, because the perception of its movement
allows the blind subject to predict or guess its position even when it
has stopped emitting its sound (task 10).
The difficulties encountered by the blind children of Group I in
performing the tasks of the reach on sound protocol did not seem to
be related to the mental development as measured by the Reynell
Zinkin Scales: in fact, all the subjects presented normal scores. The
three subjects of Group I with a Leber syndrome who achieved only
the first tasks of the reach on sound protocol presented relational
difficulties. A particular psychological fragility is described in some
children with Leber syndrome, characterised by withdrawn and
stereotyped behaviour, in the absence of a diagnosis of an autistic
spectrum disorder [24].
In Group II, most of the subjects possessed neither appropriate
manipulatory functions, nor the ability to reach an object presented
through sound; these children tended to use their hands as means of
self-stimulation more than as a means through which to gain
knowledge of the real world around them. These are behavioural
mannerisms that have been frequently described in congenitally blind
children with and without neurodevelopmental disabilities [24,25].
Upon the presentation of a sound stimulus, most of the subjects
demonstrated nothing more than aspecific reactions, indicating
alertness, or remained immobile; at the very most, they might make
some movement indicating excitement. The profile of acquisitions in
this group was found to be discontinuous andlacking in homogeneity,
and the results obtained were markedly low; however, in consideringthese low results it has to be recalled that the presence of motor
disabilities can preclude or render extremely difficult a subject's
attempts to reach thetarget objects. Forthe childrenin Group II, touch
continued to be the preferred sensory channel when seeking, and
attempting to reach,the targetobject,as demonstratedby thefact that
tasks n. 1 and 2 (involving tactile contact with the object) were the
only ones that a reasonable proportion of them were able to achieve;
moreover, these same tasks were also the ones most easily performed
by theGroupI children.The GroupII children,likethe GroupI subjects,
showed a trend of a lower performance on task n. 6. This finding, that
needsto beconfirmed by further studies,seemsto reveala pattern that
could be specific to severe visual impairment, not being influenced by
the presence or absence of an associated motor deficit.
In conclusion, the subjects affected by an isolated visual deficit,despite showing an initial and slight neuromotor developmental
delay, were able to develop good manipulatory skills and subse-
quently to walk independently, thanks in part to their acquisition of
the ability to reach an object presented through sound.
On the basis of theresults emerging from our administration of thereach on sound protocol, we are able to affirm that when comparing
tasks that differed only in the type of sensory information provided
(i.e., only tactile vs only auditory clues), the tactile tasks seemed to
be theones more easilyachieved: in particular, blind babiespresented
an attentional alert to sound, but seemed to prefer touch to orientate
their exploration. In fact, in the first months of life, our children
tended to reach objects that they had previously touched rather than
those that they had merely heard, and in the presence of conflicting
tactile and auditory clues, they responded first to the tactile
information, acquiring only subsequently the ability to use the
auditory information. Only in specific situations they found to
implement behaviours based on precise reaching modalities, like
the ones needed to perform task n. 5. At older ages, when sensorial
discrimination and multisensorial integration are more mature [26],
touch and sound seemed to guide the child in reaching the object in
like manner. The children whose blindness was associated with
psychomotor and/or mental delay presented, in most cases, severe
clinical pictures in which the delay, which usually persisted, alsoresulted in poor performances on the reach on sound protocol: the
subjects in this group rarely achieved, or achieved only with a very
marked delay, the ability to reach an object presented though sound.
The exploratory and learning techniques adopted by these subjects
continued to be rather primitive (the mouth playing a central role)
and their ability to move in space was often impeded by the difficulty
they had separating themselves from environmental points of
reference and contact. Thus, as we demonstrated in a previous
study [9], when the visual deficit is associated with other handicaps,
the result is a clinical situation of extreme gravity due to the fact that
each of the two pathological conditions seems to reinforce the other,
giving rise to severe psychopathological pictures. On the other hand,
the difficulties encountered in both groups (I and II) on task n. 6 (i.e.
reaching of a sonorous object concealed by a cover) may represent a
characteristic pattern of severe visual impairment and highlights the
particular importance of tactile information in exploring the outside
world and reaching the target objects.
In view of the important role that certain acquisitions play in
neuropsychological development, it is crucial that the blind child be
enabled to acquire through hisothersenses theknowledge thathe is not
permitted to acquire through sight. The acquisition ofreach on sound,
representing the solution to Fraiberg's conceptual problem, emerges
as a significant moment in the development of the blind child, being at
once a condition of and a catalyst for all his subsequent development.
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