ArticlePDF Available

Hofsten, C.: Developmental changes in the organization of prereaching movements. Developmental Psychology 20(3), 378-388

Authors:

Abstract

Examined how the kind and amount of prereaching activity change with age during the period preceding successful grasping of objects. 23 infants were tested at 3-wk intervals from the 1st week of life to 16 wks of age. 12 Ss were also seen at 19 wks of age. At each session, the S was presented with an object moving slowly in different ways in front of him or her. In the middle of each session there was also a 1-min period with no object present. Results show that the amount of prereaching declined at 7 wks and that this decrease was contingent on the presence of the object. Ss did not seem to lose interest in the object at this age, but attending to the object inhibited prereaching activity in some way. The form of prereaching also changed at 7 wks, with the fist clenched during the forward extension of the arm. After this age, the amount of prereaching activity again increased and the hand opened during the forward extension, but only when the S looked at the object. (20 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Developmental Psychology
1984,
Vol 20, No 3. 378-388Copyright 1984 by the
American Psychological Association, lnc
Developmental Changes in the Organization of
Prereaching Movements
Claes von Hofsten
University of Uppsala, Uppsala, Sweden
How does the kind and amount of prereaching activity change with age during the
period preceding successful grasping of objects, that is, during the first 4 months
oflife? This question was studied longitudinally in 23 infants. They were seen every
third week from the first week of life to 16 weeks of age. Twelve of the infants
were also seen at 19 weeks of
age.
At each session the subject was presented with
an object moving slowly in different ways in front of him or her. In the middle of
each session there was also a
1-minute
period with no object present. The results
show that the amount of prereaching goes down at 7 weeks and that this decrease
is contingent on the presence of the object. The infant does not seem to lose interest
in the object at this age, but attending to the object inhibits prereaching activity
in some way. The form of prereaching changes at this age, too. Instead of opening
the hand during the forward extension of the arm the hand will be fisted. After
this age, the amount of prereaching activity will go up again and the hand will
start opening during the forward extension, but only when the infant looks at the
object.
A neonate, placed on its back in a horizontal
or semiupright position will, if it is alert and
has support for trunk and head, engage in
rather extensive spontaneous movements of
its arms and hands. These movements show
a specific patterning, for example, the forward
extension of the arm is often accompanied by
an opening of the hand (von Hofsten, 1982;
Trevarthen, 1974). This synergistic extension
of arm and hand contrasts with the passive
traction reflex where the arm is extended for-
ward by pulling it at the wrist (Twitchell, 1965).
In the latter
case,
all muscles will flex, including
those of the fingers, that is. the hand will get
fisted. Fisted hands are rare in spontaneous
forward extensions of the arm. DiFranco,
Funds for this investigation were provided by grants to
the author from the Swedish Council for Research in the
Humanities and Social Sciences.
I
wish to thank the mothers and nurses at Ringblomman,
Akademiska Sjukhuset, Uppsala, Sweden, for their helpful
cooperation.
I
also
wish to
thank Annica Lindgren-Rydberg
for her experimental assistance, patient scoring of vid-
eotapes, and computation of
data.
Finally, I am indebted
to Herbert L Pick, Jr for his useful comments on the
manuscript
Requests for reprints should be sent to Claes von Hof-
sten,
Department of Psychology, University of Uppsala,
Box 227, S-75104 Uppsala, Sweden.
Muir, and Dodwell (1978) found that only 8%
of neonates arm movements could be so de-
scribed.
That the arm movements of the neonate
may come under visual control has been re-
vealed through careful analysis of the aiming
of arm movements in three-dimensional space
(von Hofsten, 1982). It was found that these
movements, performed while the infant fixated
an object, were aimed closer to that object
than movements performed while the infant
looked elsewhere or closed her eyes. However,
the aiming was not very precise. Furthermore,
the infant never grasped the object and rarely
touched it. The fact that some aspects of
reaching, like the oriented movements of the
arm, may be controlled by vision in the ne-
onate but not others, like the catching, grasp-
ing, and manipulative movements of the hand,
makes it justified to call this activity pre-
reaching (Trevarthen, 1974).
The questions asked in the present article
concern the way in which prereaching move-
ments change with age during the period pre-
ceding successful grasping of objects, that is,
during the first 4 months oflife. Such changes
may carry information about restructurings
or reorganizations of the reaching activity and,
thus,
also about developmental changes in the
378
DEVELOPMENTAL CHANGES OF PREREACHING MOVEMENTS379
maturing nervous system. Two types of sug-
gestions of developmental discontinuity will
be considered.
Amount of Activity
A classical hypothesis states that neonatal
motor activity should disappear before reap-
pearing again in a more mature form
(McGraw, 1943). The described sequence is
said to be due to the takeover of behavior by
cortical centers. When this happens, the cen-
ters previously regulating the behavior will first
be brought under control by inhibition before
excitatory connections are formed. From that
standpoint, Humphrey (1969) argued that
prereaching activity should disappear shortly
after birth. Existing data (Cunningham, 1979;
McDonnell, 1979; Trevarthen, 1974) do not
support a hypothesis of complete disappear-
ance,
but the activity might well diminish.
There is, to my knowledge, no study of the
complete age range that has looked at amount
of activity.
However, even if the amount of prereaching
diminishes during some period, this does not
necessarily mean that Humphrey's assump-
tions are right. There are at least two other
ways of explaining such an effect. Bower (1974)
believed in such a decrease in activity but
thought that it was due to the fact that neonatal
prereaching is seldom successful. In other
words, the activity will be temporarily extin-
guished from lack of reinforcement. Another
way to explain a decrease in activity is in terms
of the focus of activity. There is an extensive
social development during the second and the
third month of life with, for instance, the ap-
pearance of the smile. It is quite possible that
the emerging social activity will, for a while,
make the infant less focused on objects and
prereaching. It should be noted that only
Humphrey's (1969) account for an eventual
decrease in amount of prereaching postulates
any reorganization of these. The two alter-
native explanations are both based on as-
sumptions of changes in the behavioral bias
of the infant.
Kind of Activity
Prereaching activity may remain throughout
the period but change in a qualitative and dis-
continuous way. In a series of
articles,
Moun-
oud (Mounoud, 1976, 1981; Mounoud &
Vinter, 1981) has argued that the coordinated,
prestructured movement patterns of the ne-
onate become dissociated into isolated activ-
ities during the second and third month of
life.
For instance, in the case of prereaching,
the movements of the arm and the hand should
no longer be coordinated. The decomposition
of activity is said to be a necessary part of an
adaptive restructuring
process.
The constituent
elements or local programs are elaborated in-
dividually before they enter into new com-
positions of behavioral organization. Through
this process, the activities of the infant and
the properties of reality acquire meaning that
will enable the infant to control her actions
better.
Observations by Trevarthen (1974) and
others (Cunningham, 1979; White, Castle, &
Held, 1964) suggest that the extension synergy
of neonatal prereaching is broken up in the
second and third month of life. Trevarthen
(1974) found that during this period there is
a loss of fluency in the extension movements
of the fingers. "The grasp movement may be
lost, while vigorous, usually jerking arm ex-
tensions are made as the object is intensely
fixated"
(p.
577). However, Trevarthen has an-
other explanation of the phenomena than
Mounoud. He believed (Trevarthen, Murray,
& Hubley, 1981) that the observed blocking
of hand opening depends on a proportionally
much greater growth of the proximal limb-
control system than of the distal-hand control
system during the first months of life.
In the present longitudinal study, which
covers the whole prereaching period, amount
as well as type of prereaching activity was
measured.
Method
Subjects
Nine male and 14 female infants completed the lon-
gitudinal program. The first recording of
each
infant was
made at a clinic in Uppsala, Sweden, to which mothers
can go from the delivery ward with their newborns on the
third day after delivery They usually stay 5 days. At the
clinic, which is of rooming-in type, the mothers rest and
learn to nurse and breast-feed their infants. Staying at the
clime is cost-free. The mothers represent a
fair cross
section
of the Uppsala population. At
the
time of
the
study,
between
8 and 11 mothers were simultaneously attending
the
clinic.
380CLAES VON HOFSTEN
Only those infants with Apgar scores between 8 and
10,
who were born at a concepuonal age between 38 and
42 weeks, and had a birth weight between 2750 and 4500
g were considered for the longitudinal program All the
subjects were born between January 4 and February 9,
1980.
Two of the infants were monozygotic twins (G.Ji
and G.Ma.).
Stimulus
The object presented to the infants was a spherical tuft
made of a bright red, blue, and yellow yarn. It was hanging
down from the end of a 70 cm long horizontal hollow rod
attached via a felt coupling to the perpendicular shaft of
an electric motor with variable speed and direction Thus,
the object moved along a horizontal circular path of 140
cm diameter. During testing the motor was placed straight
behind the infant. The attached rod moved above the in-
fant's head, and the object hung down at the height of the
infant's eyes, at a nearest distance of approximately 12
cm from them (see Figure 1)
Experimental
Conditions
In the experiment the object either moved back and
forth in front of the infant between a position about 25
cm to the left and 25 cm to the right or remained stationary
straight ahead The motion of the object was either smooth
or irregular. The irregularity of the motion was created
by having an experimenter starting and stopping the motor
about once a second When in continuous motion the
object had a velocity of either 3.2 cm or 6.4 cm per sec
The irregularly moving object covered only about half the
distance of the smoothly moving object in 1 s
The chair A chair was constructed from sketches pro-
vided by Trevarthen (1979), it can be seen in Figure 1.
The chair allowed free movement of the infant's arms
while supporting the head and trunk. A 13-cm-wide band
of linen was laced around the infant's chest, just under
the armpits, to hold him or her securely The inclination
of the chair was 50°.
Recording arrangements To allow three-dimensional
analysis of the hand movements, the situation was recorded
by two SONY AVC-3250 CE video cameras placed as
shown in Figure 1, with the axis of one camera parallel
to the axis of the infant's body (50° inclination) and the
axis of the other camera perpendicular to the first one
Procedure
The experiment was divided into two blocks that were
identical, with the exception of object velocity. In one of
the blocks the lower object velocity was used and in the
other the higher. Between the two blocks, there was a 1-
minute period during which the object was absent.1 Which
block to present first was randomly determined
In each block the object passed six times in front of
the infant. The object moved alternatively from the left
to the right and from the right to the left. Starting direction
was randomly determined. The sequence of movements
was always the same. The first time the object passed in
front of the infant it moved smoothly and the second time
Figure 1 Experimental situation.
it moved irregularly At the third passage it moved smoothly
until straight ahead, where it stopped for about 30 s before
continuing its interrupted motion. In the middle of the
stopping period, the object was shaken gently for about
10 s After this sequence of motions another identical se-
quence of smooth, irregular, and stopping motions followed
This time the directions of the motions were reversed.
Thus,
in each block, the object made four smooth-motion
passages in front of the infant (2 complete and 2 inter-
rupted) and two irregular-motion passages As the irreg-
ularly moving object only covered half the distance of the
smooth-moving one per time unit, the exposure time for
the two types of motions were about the same The ex-
posure time for each type of motion was 60 s in the slow-
velocity block and 30 s in the fast-velocity block In each
of the two blocks the object remained stationary straight
ahead, for a total period of 60 s
The longitudinal program At the first session the in-
fants were between 4 and 8 days old (Mdn = 6 days). After
the first session the infants were seen every third week
until age 16 weeks Fourteen of the infants were also seen
at 19 weeks The remaining 9 infants joined the study too
late to be included in the final session. Summer vacation
had already started then Ten infants missed one of the
first six sessions, two at 1 week, one at 4 weeks, two at 7
and 10 weeks, and three at 16 weeks.
1 The original plan was to present a static object in front
of the infant during the middle
1-minute
period. However,
as it was impossible to keep the object totally stationary,
this condition was replaced by the object-absent condition
but only after the investigation had started. Thus, five
infants were, at the first recording, presented with a "sta-
tionary" object at the middle
1-minute
period.
DEVELOPMENTAL CHANGES OF PREREACHING MOVEMENTS381
Results
For each infant and session, every arm
movement extending forward more than 7.5
cm from the frontoparallel plane tangential to
the body of the infant was scored from the
videotape, except those originating from Moro
reflexes or startles and those associated with
yawning, sneezing, or sudden forward head
movements. The task was rather simple as the
7.5 cm borderline was clearly indicated on the
TV screen. There was one problem with the
older infants. They sometimes tracked the
moving object with their extended arms and
hovered around the stationary object. In such
cases,
two movements were scored if the for-
ward extension exceeded 4 s, three movements
if the forward extension exceeded 8 s, and so
forth. The intracoder reliability for this task
was 0.94. Three infants scored no forward ex-
tensions at all for the first three sessions of the
study. They were omitted from further data
treatment for that reason. For the remaining
20 infants, 1,954 forward extensions were
scored altogether.
Each forward extension was further scored
with respect to the looking behavior of the
infant and the posture and movement of the
hand. The following four categories of looking
behavior were used.
1.
Fixation (F). The infant directed his or
her eyes toward the target area. If the object
moved, the infant changed gaze in accordance
with the motion of the object.
2.
Nonfixation (NF). The eyes were opened
but the infant was not looking at the object.
3.
Eyes closed (CL) The eyes were closed.
4.
Indeterminate gaze (IG) The eyes were
opened, and the object was within the infant's
field of
view,
but it was uncertain whether the
infant was looking at the object or not.
The behavior of the hand was scored in one
of the following four categories:
1.
Fisted (f). All the fingers were fully
flexed before and during the reach.
2.
Half-open (ho). The fingers were semi-
flexed before and during the reach.
3.
Open before (o). The fingers were ex-
tended before the reach started.
4.
Opening during
(od).
Two or more digits
clearly extended during the forward extension
of the arm.
Table 1
Mean Number of Forward Extensions per Subject
When the Object Is Present and Absent
Distributed Over Age and Types
of Looking Behavior
Object present
Age Object
(weeks) n F IG NF + CL Total absent
1
4
7
10
13
16
19
18"
13"
19
18
18
20
17
12
25
2 1
3.8
1.2
7 1
9.7
18.3
36 6
09
09
1.1
0.8
1.9
10
1.2
0.3
7.7
88
4 1
3.5
2.3
14
1.8
2.0
11.2
11.8
9.1
5.6
11 3
12.0
21.2
38 9
1.9
2.1
2.2
1.7
1.0
1.7
2.3
Note F = fixation, IG = intermediate gaze, NF = non-
fixation, CL = closed eyes, n = number of subjects.
*
At one week of
age,
only 13 of the 18 subjects received
the object-absent condition Therefore, two sets of means
have been calculated, one for the whole group and one
for those who received the object-absent condition.
Reliability of scoring was evaluated in two
ways.
The forward extensions of the three
youngest age groups were classified indepen-
dently by two observers. Interobserver reli-
ability was found to be 0.91 for looking be-
havior and 0.92 for hand behavior. Intraob-
server reliability for the main coder (A.R.),
measured for four randomly chosen infants of
each of the four oldest age groups, was above
0.90 for all the scored properties.
Number of Forward Extensions
The distribution of forward extensions over
age and looking behavior is shown in Table 1.
In Table 1 movements while not fixating the
object (NF) and movements while the eyes
were closed (CL) are pooled. Eyes closed while
reaching was very rare except at the first week.
The number of such cases at that age was 76.
At the remaining six sessions, the total number
of closed-eye reaches was on the average of
only 4 per session.
Table 1 shows that the number of forward
extensions increases considerably during the
last three sessions. Before that, the number of
movements stays rather stable. The decrease
at 7 weeks is not statistically significant. How-
ever, the number of movements while fixated
382CLAES VON HOFSTEN
gives a different picture for the first four ses-
sions.
These movements increase in number
from the first to the second session (t = 2.15,
p < .05) after which there is a considerable
decrease up to the third session (t = 3.34, p <
.01).
From there on the number of movements
while fixated increases steadily up to the last
session.
Finally, it can be observed from Table
1
that
the number of movements in the object-absent
condition stays pretty much the same over age.
An analysis of variance (ANOVA) showed that
there was no systematic effect of age in this
condition, F{6, 110) < 1.
In Table 2 the total number of reaches as
well as the number of fixated ones are shown
for each subject and session. The upper part
(subjects with
B
as first initial) of Table 2 shows
the results of the 8 boys and the lower part
(subjects with G as first initial) the results of
the 12 girls of the study. The individual dif-
ferences are great. One subject (G.N.) made
only one fixated reach before 19 weeks of
age,
and one subject made as many as 121. How-
ever, there are also consistencies between sub-
jects.
Fourteen of the 18 subjects who partic-
ipated at 7 weeks showed a decrease in the
number of fixated movements. Eleven subjects
had no fixated movements at all at 7 weeks
compared to 3 subjects at 4 weeks. The in-
crease in reaching after 7 weeks is rather dra-
matic for most infants. Generally, it occurs
after a period of practically no reaching. At
the session when the number of reaches per-
formed by the infant starts to increase, the
number of forward extensions goes up from,
on the average, 4.5 to 21.7 movements per
session. However, as can be seen from Table
2,
this increase in reaching activity starts at
different ages for different infants. For 8 infants
it occurred at 10 weeks of age, for 6 infants
at 13 weeks of age, for 5 infants at 16 weeks
of age and for one infant at 19 weeks of age.
The effect of the different experimental
conditions on amount of prereaching activity
for different ages is shown in Figure 2.
In Figure 2 the smooth and irregular mo-
tions of the target have been pooled for each
velocity conditions. The differences in fre-
quency of reaching between these two types
of motions were small and unsystematic. Fig-
ure 2 shows that the decrease in reaching ac-
Table 2
Total Number of Movements and Number of Fixated Movements for Each Subject
and Age (in Parentheses)
Subject
BT.
B.F.
B.S.
B.M.
B.B.
B.W.
B.A.
B.G.
G.E.
G.N.
G.M.
G.L.
G.Mo.
G.Ka.
G.Ha.
G.Li.
G.Ni.
GJu.
GJi.
G.Ma.
Total
1
4(0)
10(2)
2(0)
8(2)
30(4)
17(5)
8(1)
11
(2)
8(1)
37(2)
10(3)
24(6)
9(5)
20(6)
5(2)
2(0)
6(2)
14(2)
225
(45)
4
26(5)
15(9)
14(5)
19(3)
16(9)
17(5)
25
(10)
4(0)
4(1)
1(0)
10(5)
2(2)
4(2)
6(1)
10(5)
4(4)
21(5)
8(2)
6(0)
212
(73)
7
4(0)
17(4)
8(0)
8(4)
0(0)
17(0)
0(0)
14(4)
21(0)
3(0)
12(2)
0(0)
0(0)
4(0)
6(2)
14(2)
3(0)
9(4)
140
(22)
Age
(weeks)
10
29(11)
25(15)
8(1)
2(2)
19(11)
28(17)
9(1)
0(0)
2(0)
0(0)
0(0)
0(0)
34
(24)
4(1)
34(27)
4(4)
13(7)
23(7)
234(128)
13
10(5)
9(9)
1(0)
20(12)
18(8)
43
(39)
0(0)
6(0)
1(0)
0(0)
0(0)
22(16)
8(8)
4(4)
12(9)
1(0)
25(16)
3(0)
18(3)
58
(54)
259(193)
16
13(5)
12(6)
40(39)
31
(29)
3(0)
58
(55)
13(11)
10(4)
2(2)
18(14)
40(40)
12(5)
16(9)
19(13)
17(9)
23
(23)
63
(47)
390(311)
19
35
(33)
20(18)
78
(73)
87
(80)
19(13)
59
(54)
24
(16)
4(3)
76
(74)
14
(10)
77
(65)
1(0)
494
(439)
Total
86
(26)
88
(45)
73
(45)
123
(85)
106
(50)
258
(194)
133
(102)
62
(22)
37(3)
73
(55)
85
(27)
56
(38)
72
(54)
58
(35)
129(101)
93
(50)
133
(100)
57
(22)
68
(37)
164(110)
1954(1211)
DEVELOPMENTAL CHANGES OF PREREACHING MOVEMENTS383
tivity at 7 weeks is contingent upon the pres-
ence of the object, as there is no decrease in
the frequency of movements during the object-
absent interval at that age. The 7-week session
is the only one in the study where the reaching
activity in the object-absent condition is higher
than in the other conditions (/ = 2.11, p <
.05).
Furthermore, Figure 2 shows that the
Stop condition elicited more reaches per min-
ute than the motion conditions at all ages from
4 weeks on and that the slow motion elicited
more reaches than the fast one, at least from
10 weeks on. A means
ANOVA
(Kirk, 1968)
showed that the main effect of object motion
was statistically significant, F\2, 12) = 7.57,
p < 0.01. The Stop condition should not be
confused with a static-object condition. It is,
rather, a transfer from translatory motion to
jiggling motion. This change in event seems
to be an efficient elicitor of reaches.
As shown by the present data, forward-ex-
tended arm movements does not cease alto-
gether when the infant does not look at the
object or when the object is not in front of
the infant. Rather, there seems to be some
base-level activity that is independent of con-
dition. To appreciate the effect of different
types of object conditions on the reaching ac-
' REACHES/MIN.
5
STOP
SLOW
FAST
NO OBJECT
(BASELINE)
10131619
AGE(WEEKS)
Figure 2 Number of forward extensions per minute for the fast, slow, and stop conditions of the experiment
as a function of
age.
BASE is the number of forward extensions per minute m the no-object condition.
384CLAES
VON
HOFSTEN
Table 3
Estimated Percentage Time Spent Looking at the Object and Frequency of Reaching During That
Period for the Motion Conditions and the Stop Condition at Each Age Level
Condition
Motion
% fixation
Reaches/min
Stop
%
fixation
Reaches/min
- Base level
Reaches/min
N
1
17
2.2
27
2.1
1.9
13
4
50.9
69
2.2
2.1
19
7
69.1
66
1.1
2.2
18
Age (weeks)
10
51
2.0
78
3.1
1.6
18
13
56
2.6
71
3.9
1.0
20
16
68
4.0
82
6.2
1.7
17
19
75
7.6
92
10.1
2.3
12
Note The base level of reaching at the object-absent condition is also shown for each age level.
tivity of the infant, reaching activity should
be related to this base level. An estimation of
the base-level activity is given by the frequency
of reaching in the object-absent period.
However, just to compare the overall fre-
quency of reaching in an object condition with
the base frequency in the object-absent con-
dition would not do justice to the effect of the
object on reaching frequency. This follows
from the fact that the infant does not look at
the object all the time when it is present. To
get a better estimation of how the object affects
reaching, we need to know the relative time
spent looking at the object in each condition.
The present study did not measure looking
time directly, but we do know for each reach
whether or not the infant looked at the object.
If we assume that the base-level activity during
an unattended period of an object condition
is the same as the base-level activity during
the object-absent condition, we can calculate,
for each condition, the amount of time spent
looking at the object. Dividing the number of
nonfixated reaches in a condition with the
base-level frequency will give us the amount
of time not looking at the object in that con-
dition. The remaining time would then be the
estimated looking time. In Table 3 the cal-
culated proportion time spent looking at the
object and the frequency of reaching during
this time is shown for the motion conditions
and the Stop condition at each age level. At
the youngest age level the figures in Table 3
are only based on data from the 13 infants
who were presented with the object-absent
condition. Table 3 suggests that the infant
spends more time looking at the object and
reaches more frequently for it in the Stop con-
dition than in the motion conditions. Second,
looking seems to increase monotonically with
age.
Third and most important, Table 3 sug-
gests that reaching activity while the infant
watches the object decreases from being
slightly above base level in the neonate to being
well below base level activity in the 7-week
old. At that age, looking at the object almost
inhibits reaching completely. After 7 weeks of
age,
reaching while watching the object rises
monotonically. Already at 10 weeks the fre-
quency is above base level.
Type of Movements
The results of the analysis of hand posture
and hand movement during reaching are
shown in Figures 3,4, and 5. The three figures
show the proportion of reaches where the hand
was fisted (f), open before (o), and opening
during (od) the forward extension of the arm
for the fixated (F) as well as the nonfixated
reaches (NF) at each age level.
Figure 3 shows that the proportion of fisted
reaches increases dramatically at 7 weeks of
age.
After this age, the proportion of fisted
reaches decreases again. An
ANOVA
was per-
formed on the data of Figure
3.
The individual
scores were thereby treated as replications. As
8 of the subjects were missing in the last ses-
sion, the analysis was only based on the first
six sessions. Missing data were either inter-
DEVELOPMENTAL CHANGES OF PREREACHING MOVEMENTS385
polated (7 cases) or extrapolated (3
cases).
Only
the main effect of
age
was found to be
signif-
icant, F(5, 218) = 6.94, p = 0.01.
Figure 4 shows that the reaches where the
hand is opened before the movement starts
decreases in frequency up to 7 weeks of age
and then increases. There are no systematic
differences between fixated and nonfixated
reaches in this respect. An ANOVA was per-
formed on the data of Figure 4. As in the
previous case, the individual scores were
treated as replications, and the last session was
deleted from the analysis. The main effect of
age was found to be significant, F\5, 218) =
10.5,
p = 0.01.
Finally, Figure 5 shows that the number of
reaches where the hand is opened during the
forward extension decreases up to 7 weeks of
age.
After that there is an increase for the fix-
ated reaches but not for the nonfixated ones.
It should also be noted that, at each age, there
are more fixated open-during-reaches than
nonfixated ones. An
ANOVA
was performed on
the data of Figure 5. The procedure was as in
the two previous cases. The main effect of fix-
ation was found to be significant, F{1, 218) =
12.61,
p = 0.01, as well as the interaction be-
tween fixation and age, ^5, 218) = 3.77, p =
0.01.
The main effect of age was significant,
F\5,
218) = 2.95,/> = 0.05.
A note on laterality At all age levels there
were more right-hand than left-hand move-
ments. The percentage of right-hand move-
ments was 72, 63, 82, 67, 63, and 55 at 1, 4,
7,10,13,16, and
19
weeks of
age,
respectively.
Seven infants used the right hand more than
the left one throughout the study, but none
used the left hand more throughout the study.
A
% fisted
50.
1101316
AGE(weeks)
Figure 3 Percentage of fixated movements (F) and nonfixated movements (NF) at which the hand is fisted
for the different age levels of the study.
386CLAES VON HOFSTEN
At the most, the left hand dominated in half
the sessions. This happened in three cases.
Discussion
The present investigation gives evidence of
substantial changes in the pattern of prereach-
ing around 2 months of age. These changes
affect the amount as well as the form of reach-
ing. The amount of reaching goes down and
the hand starts to get fisted instead of opened
during the forward extension of the arm as at
earlier age levels. The decline in reaching does
not seem to have anything to do with loss of
interest in the task. According to the calculated
looking times, the fixation of the object seems
to increase during the same age period. The
data, rather, indicate that the actual looking
at the object inhibits, in some way, the exe-
cution of forward-extended arm movements.
One way to explain this effect is in terms of
a change in state of the infant. The excitement
caused by looking at the target might inhibit
the forward extension of the arm. Such an
explanation fits with McGuire and Turkewitz's
(1979) application of Schneirla's approach-
withdrawal theory to infant behavior. This
theory states that if the intensity of the stimulus
in some dimensions exceeds some critical value
the infant will tend to withdraw from it instead
of approach it. However, the approach-with-
drawal theory would also predict that the in-
fant would look away from a too-intense stim-
ulus,
but this does not seem to happen in the
present situation. Rather, the object seems to
be intensely fixated (Trevarthen, 1974).
Another possibility is that, in the excited 2-
month-old infant, not only the agonist but also
the antagonist muscles will be activated and
consequently block the movement. Gatev
(1972) found that arm movements in the 1-
to 2-month-old infant usually begin without
antagonist inhibition.
The two explanations presented above may
account for some aspects of the changes in
'
>
% open before
50
1 4 7 10 13 16 19
AGE (weeks )
Figure
4 Percentage of fixated movements (F) and nonfixated movements (NF) at which the hand is opened
before the forward extension starts for the different age levels of the study.
DEVELOPMENTAL CHANGES OF PREREACHING MOVEMENTS387
prereaching pattern occurring at 2 months of
age,
but neither of them can account for the
fact that the form of movement is changed
whether the object is fixated or not. The ex-
tension synergy, the forward extension of the
arm, and the opening of the hand are broken
up.
At 2 months of age the hand was fully
flexed during the extension of the arm. It is
indeed difficult to explain this development in
other terms than organizational changes in the
prereaching pattern
itself.
At one level the things happening at 2
months of age indicate important changes in
the organization of the nervous system. It has
been well established (Kuypers, 1962, 1964)
that at least two separable systems are re-
sponsible for the control of the upper limb;
one "proximal" motor system organized
mainly on brainstem level and responsible for
the gross movements of the arm and hand and
one "distal" motor system organized cortically
and responsible for the fine coordination of
the hand. The dissociation between arm and
hand movements at 2 months of age and the
inhibition of directed reaching may indicate
that the cortically "distal" motor system has
started functioning but is not yet synchronized
with the proximal motor system. Conse-
quently, coordination is adversely affected. It
may also be as Trevarthen et al. (1981) have
suggested that both systems are functioning
earlier but that, during the first month, the
proximal control system grows more than the
distal and that this is the cause of incoordi-
nation.
The discussion of "distal" and "proximal"
motor systems and their role in development
of reaching has certain affinities with Mc-
Graw's (1943) discussion of the neuro-mus-
cular maturation of the human infant. In both
cases there is a notion of increased cortical
involvement with age. However, in McGraw's
model there are also some explicit statements
describing how this comes about. The rather
well-organized but reflexive behavior of the
newborn is said to disappear through the pro-
opening during
50
19
AGE(weeks)
Figure
5 Percentage of fixated movements (F) and nonnxated movements (NF) at which the hand is opening
during the forward extension for the different age levels of the study.
388CLAES VON HOFSTEN
cess of inhibition before reappearing again in
a more mature and cortically organized form.
The inhibition should cause the behavior not
only to decrease in amount but also to become
disorganized in form. This is in general agree-
ment with the present results. However, some
of McGraw's studies have also more direct
relevance for the discussion of the development
of arm and hand control. For instance, she
studied the ability of an infant to hold itself
suspended by the force of a hand grip. In the
newborn this behavior is a flexion synergy by
which the infant by 4 weeks of age can hold
itself suspended on the average almost half a
minute. However, at 7 to 10 weeks of age the
suspension time has decreased to 6 s on the
average indicating a breaking up of the flexion
synergy that in time parallels the breaking up
of extension synergy observed in the present
study.
At a more functional level of description,
Mounoud's (Mounoud, 1976,
1981;
Mounoud
& Vinter, 1981) model of senso-motor devel-
opment fits the obtained results quite well.
The breakdown of the extension synergy of
forward extended arm movements at 2 months
of age can be seen as the dissociation of a
prestructured movement pattern. It is paral-
leled by the breakdown of coordination be-
tween auditory perception and head move-
ments in the orientation toward a sound source
(Field, Muir, Pilon, Sinclair, & Dodwell, 1980).
When, after 2 months of age the hand starts
to open again during the forward extension of
the arm, it only occurred when the infant fix-
ated the object. The opening of the hand is
not, any longer, just a part of an extension
synergy and an orientation reaction but a
meaningful adaptive behavior in
itself.
The
hand now starts to open as a preparation for
manipulating of the object.
References
Bower, T. G. R. Development in infancy (1974) San Fran-
cisco.
Freeman
Cunningham, C. C (1979) Aspects of early development
in Down Syndrome infants Unpublished doctoral dis-
sertation, University of Manchester, Manchester, En-
gland.
DiFranco, D., Muir, D. W., & Dodwell, P. C. (1978)
Reaching in very young infants.
Perception,
7,
385-392.
Field, J., Muir, D., Pilon, R., Sinclair, M., & Dodwell, P.
(1980).
Infants' orientation to lateral sound from birth
to three months Child Development, 51, 295-298.
Gatev, V. (1972) Role of inhibition in the development
of motor co-ordination in early childhood. Develop-
mental Medicine and Child
Neurology,
14,
336-341.
Hofsten, C. von. (1982). Eye-hand coordination in the
newborn. Developmental
Psychology,
18,
450-461.
Humphrey, T. (1969). Postnatal repetition of human pre-
natal activity sequences with some suggestions of their
neuroanatomical basis. In R J Robinson (Ed.) Brain
and
early
behaviour.
Development in the fetus and infant
(pp 43-84). London' Academic Press.
Kuypers, H G. J M. (1962). Corticospinal connections
Postnatal development in the Rhesus monkey Science.
138. 678-680
Kuypers, H G. J. M (1964) The descending pathways
to the spinal cord, their anatomy and function. In J.
C Eccles, & J C. Shade, (Eds.), Organization of the
spinal cord Amsterdam: Elsevier.
McDonnell. P (1979) Patterns of eye-hand coordination
in the first year of life Canadian Journal of Psychology,
33,
253-267.
McGraw, M. B (1943). The neuro-muscular maturation
of the human infant New York: Columbia University
Press
McGuire. I.,
&
Turkewitz, G (1979). Approach-withdrawal
theory and the study of infant development In M Bort-
ner (Ed ), Cognitive growth and development Essays in
memory of Herbert Birch (pp 57-84) New York' Brun-
ner/Mazel
Mounoud. P (1976). Revolutionary periods in early de-
velopment. Archives de Psychologic XLIV, 171, 103
114
Mounoud. P
(1981,
October). L'evolulion des conduttes
de prehension comme illustration dun model du de-
veloppement Paper presented at the seventeeth Joumees
d'Etudes de l'Association de Psychology Scientifique
de Langue Francaise (APSLF) Grenoble, France
Mounoud, P., & Vinter, A (1981). Tire-a-part: Represen-
tation and sensonmotor development. In G Butterworth
(Ed ), Infancy and epistemology An evaluation of
Pi-
aget's theory (pp 200-235) Brighton, Susex: Harvester
Press
Trevarthen, C (1974). The psychobiology of speech de-
velopment In E H Lenneberg (Ed ), Language and
brain Developmental aspects Neurosciences Research
Program Bulletin (pp 570-585), 12
Trevarthen, C (1979). Sketches of chair (Available from
C Trevarthen. Department of Psychology, University
of Edinburgh. 7 George Square, Edinburgh EH8 9YL,
Scotland.)
Trevarthen, C, Murray, L.,
&
Hubley,
P.
(1981) Psychology
of infants lnJ.A Davies&J Dobbing(Eds ), Scientific
foundations of paediatrics (2nd ed.; pp 211-274). Lon-
don William Hememann Medical Books.
Twitchell, T. E. (1965). The automatic grasping responses
of infants. Neuropsychologia, 3, 247-259
White, B. L., Castle. P, & Held, R. (1964). Observations
on the development of visually directed reaching Child
Development, 35, 349-364.
Received August 30, 1982
Revision received November 30, 1982
... Reaching behavior is observed in newborn infants [162], who start producing brief forward extensions of their hand-arm towards nearby objects after the primitive reflex phase. Several examples of this can be found in the literature: Von Hofsten [163], [164] reported an increase in object-oriented extensions of the hand in the first two months after birth. Fiorentino [165] and Shirley [166] mentioned that infants begin to reach using both arms. ...
... Savastano and Nolfi [120], [121] have also studied infant development using an iCub robot [182] simulating the developmental sequence of reaching, through vision and neuro-motor development (changes over the J Ƥ and Ȿ Ƥ matrices), in a fourteen-DOF simulation of the iCub. The iCub is trained and tested in a manner that corresponds to the method used by Thelen [183] and von Hofsten [163], in which the infant is supported in an upright position while a nearby object is presented within reach. Three main conclusions have been drawn from their results. ...
Preprint
Full-text available
Humans and animals undergo morphological development processes from infancy to adulthood that have been shown to facilitate learning. However, most of the work on developmental robotics considers fixed morphologies, addressing only the development of the cognitive system of the robots. This paper aims to provide a survey of the work that is being carried out within the relatively new field of morphological development in robots. In particular, it contemplates morphological development as the changes that occur in the properties of the joints, links and sensors of a robot during its lifetime and focuses on the work carried out by different authors to try to determine their influence on robot learning. To this end, walking, reaching, grasping and vocalization have been identified as the four most representative tasks addressed in the field, clustering the work of the different authors around them. The approach followed is multidisciplinary, discussing the relationships among developmental robotics, embodied artificial intelligence and developmental psychology in humans in general, as well as for each of the tasks, and providing an overview of the many avenues of research that are still open in this field.
... In a reach-to-grasp task, autistic individuals did not rhythmically coordinate the reaching of the arm and the opening of the fingers in a fluid intentional flow -instead they performed one act and then the other separately (Mari et al., 2003). In contrast, TD children coordinated intentional sequences of arm and hand actions fluently in "pre-reaching" and gesturing from early infancy, to achieve coherent goals distal in time and action space (von Hofsten, 1984). ...
Article
Full-text available
We propose Rhythmic Relating for autism: a system of supports for friends, therapists, parents, and educators; a system which aims to augment bidirectional communication and complement existing therapeutic approaches. We begin by summarizing the developmental significance of social timing and the social-motor-synchrony challenges observed in early autism. Meta-analyses conclude the early primacy of such challenges, yet cite the lack of focused therapies. We identify core relational parameters in support of social-motor-synchrony and systematize these using the communicative musicality constructs: pulse ; quality ; and narrative . Rhythmic Relating aims to augment the clarity, contiguity, and pulse-beat of spontaneous behavior by recruiting rhythmic supports (cues, accents, turbulence) and relatable vitality; facilitating the predictive flow and just-ahead-in-time planning needed for good-enough social timing. From here, we describe possibilities for playful therapeutic interaction, small-step co-regulation, and layered sensorimotor integration. Lastly, we include several clinical case examples demonstrating the use of Rhythmic Relating within four different therapeutic approaches (Dance Movement Therapy, Improvisational Music Therapy, Play Therapy, and Musical Interaction Therapy). These clinical case examples are introduced here and several more are included in the Supplementary Material (Examples of Rhythmic Relating in Practice). A suite of pilot intervention studies is proposed to assess the efficacy of combining Rhythmic Relating with different therapeutic approaches in playful work with individuals with autism. Further experimental hypotheses are outlined, designed to clarify the significance of certain key features of the Rhythmic Relating approach.
... Par exemple, Piek et Carman (1994) et Thelen (1979) ont montré que les patterns de mouvements, indépendamment de la présence ou non d'un objet, sont caractérisés par des unités multiples et que des changements caractéristiques dans l'organisation spatio-temporelle dans les semaines précèdent l'apparition d'un véritable mouvement d'atteinte. D'autres études (von Hofsten, 1982(von Hofsten, , 1984Thelen, et coll., 1996 ;Bhat et coll., 2005 ;Bhat et Galloway, 2006 ;Craighero et coll., 2011) ont montré que le nombre des mouvements dirigés vers l'avant augmente si les nouveau-nés, même de quelques jours, voient un objet devant eux. ...
... A paired comparison procedure was used in Experiment 2 to determine whether graspable cylinders displaying the scales of a Gaboon viper, rosettes from a leopard coat, a commercial Burberry plaid, and a plain surface differed appreciably in attracting the attention of 5-month-old infants whose visuomotor coordination of reaching was undergoing developmental refinement (see von Hofsten, 1984;Rohlfing et al., 2013). ...
Article
Full-text available
Geometrically arranged spots and crosshatched incised lines are frequently portrayed in prehistoric cave and mobiliary art. Two experiments examined the saliency of snake scales and leopard rosettes to infants that are perceptually analogous to these patterns. Experiment 1 examined the investigative behavior of 23 infants at three daycare facilities. Four plastic jars (15×14.5cm) with snake scales, leopard rosettes, geometric plaid, and plain patterns printed on yellowish-orange paper inside were placed individually on the floor on separate days during playtime. Fourteen 7–15-month-old infants approached each jar hesitantly and poked it before handling it for five times, the criterion selected for statistical analyses of poking frequency. The jars with snake scales and leopard rosettes yielded reliably higher poking frequencies than the geometric plaid and plain jars. The second experiment examined the gaze and grasping behavior of 15 infants (spanning 5months of age) seated on the laps of their mothers in front of a table. For paired comparisons, the experimenter pushed two of four upright plastic cylinders (13.5×5.5cm) with virtually the same colored patterns simultaneously toward each infant for 6s. Video recordings indicated that infants gazed significantly longer at the cylinders with snake scales and leopard rosettes than the geometric plaid and plain cylinders prior to grasping them. Logistic regression of gaze duration predicting cylinder choice for grasping indicated that seven of 24 paired comparisons were not significant, all of which involved choices of cylinders with snake scales and leopard rosettes that diverted attention before reaching. Evidence that these biological patterns are salient to infants during an early period of brain development might characterize the integration of subcortical and neocortical visual processes known to be involved in snake recognition. In older individuals, memorable encounters with snakes and leopards coupled with the saliency of snake scales and leopard rosettes possibly biased artistic renditions of similar patterns during prehistoric times.
Article
Several studies have previously investigated the effects of sticky mittens training on reaching and grasping development. However, recent critique casted doubts on the robustness of the motor effect of this training. The current study presents a pre‐registered report that aimed to generalize these effects to Swedish infants. Three‐month‐old infants N = 96, 51 females, mostly White middle class in Uppsala, received daily, parent‐led sticky mittens or observational training for 2 weeks or no training in 2019. Reaching and grasping abilities were assessed before and after training, using motion tracking and a 4‐step reaching task. Sticky mittens training did not facilitate successful reaching. These results indicate that beneficial motor effects of sticky mittens training did not generalize to this sample.
Article
Humans and animals undergo morphological development processes from infancy to adulthood that have been shown to facilitate learning. However, most of the work on developmental robotics considers fixed morphologies, addressing only the development of the cognitive system of the robots. This paper aims to provide a survey of the work that is being carried out within the relatively new field of morphological development in robots. In particular, it contemplates morphological development as the changes that occur in the properties of the joints, links and sensors of a robot during its lifetime and focuses on the work carried out by different authors to try to determine their influence on robot learning. To this end, walking, reaching, grasping and vocalization have been identified as the four most representative tasks addressed in the field, clustering the work of the different authors around them. The approach followed is multidisciplinary, discussing the relationships among developmental robotics, embodied artificial intelligence and developmental psychology in humans in general, as well as for each of the tasks, and providing an overview of the many avenues of research that are still open in this field.
Article
Perception, action, and intrinsic motivation play an essential role in early development, promoting the creation and refinement of new and more complex forms of behaviors as infants try a range of sensorimotor patterns in their environment. I use the example of infants’ reaching to illustrate how goal-directed action emerges from the intersection of seemingly distinct visual and proprioceptive-tactile-motor spaces that form in the early months following birth. The intersection of these two spaces begins with a casual contingent event involving vision and action: when the hand happens to contact a target. This event, which marks the onset of reaching, provides new behavioral value, reinforces the motor action, and intrinsically motivates infants to attempt to reproduce the behavior. Subsequent repeated cycles of perception and action lead to the exploration of a range of motor responses and a progressive alignment of the visual space with the proprioceptive-tactile-motor space, ultimately fostering the selection and refinement of increasingly successful and refined reaching patterns. Extensive hands-on experience in the environment and learning about the immediate outcomes of actions play a critical role in shaping behavioral development.
Article
Full-text available
Examined in Exp I the number and distribution of arm–hand movements of 14 newborn infants when a slowly moving object was either present or absent. More of the movements performed while the infant fixated the object were forward extended than otherwise. However, there was no difference in the absolute frequency of forward extension between periods when the object was present and when it was absent. In Exp II, the forward extensions of 13 infants were analyzed by a technique that took into consideration the 3-dimensional properties of arm–hand movements. The movements performed while the neonate fixated the object were aimed closer at the object than other movements. The effect was not a function of changes in body posture or head direction accompanying changes in visual direction. It was further shown that fixated movements clustered closer around the object and that the hand slowed down near the object in the best aimed of the fixated movements. It is concluded that there exists in the newborn a rudimentary form of eye–hand coordination, the primary function of which is attentional rather than manipulative. (30 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
Six chapters are included: structural foundations of behavior, neonatal behavior, development of neuromotor activities, some aspects of early sensory development, individual development, maturation and learning. In the first chapter, exact principles and experimental findings are listed, and a list of assumptions which provide a theoretical framework are stated. Throughout the book the author correlates as closely as possible the behavioral data with the neurological data now available. Most space is devoted to neuromotor activities, and diagrams, tables, and graphs are used wherever possible. In discussing maturation and learning, educational hints are systematically presented as conclusions from experimental studies. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
Three kinds of automatic grasping response in the infant are described: (1) the traction response, a flexor synergy of the upper limb elicited by stretch of the shoulder adductors occurs in the neonate; (2) the grasp reflex consisting of flexion-adduction of the fingers and elicited by a contact stimulus to the palm emerges between 1-3 months, while the (3) instinctive grasp reaction, a complex exploratory and prehensile response also elicited by contact stimulus to the hand develops between 4-10 months. These reactions are physiological substrata for increasingly complex forms of "voluntary" prehension which develop as the infant matures.
Article
The traditional reflex-to-voluntary behavior model of development is questioned, and an alternative hypothesis is proposed that reflex functions are distinct from the ontogenetic antecedents of voluntary behavior. An overview of patterns of eye–hand coordination in the 1st yr of life suggests that reflexes and cortically controlled instrumental activity share a parallel course of development, with the latter increasing in frequency and importance as development proceeds. Despite procedural problems in studying neonatal reaching there remains sufficient evidence that hand movements in infants under 8 wks of age are progressively coordinated with visual stimuli. Some new data are presented that show that up to at least 12 wks of age the left hand shows greater activity and orientation to visual stimuli than the right hand, which is contralateral to the dominance of neonatal reflexes. Experiments are reviewed that have studied the emergence of visually guided reaching and its development during the 2nd half of the 1st yr. The evidence is consistent with the hypothesis that this apparently new behavior, clearly distinct from reflexes, is in fact on a continuum with these earlier nonreflexive, instrumental behaviors. (French abstract) (79 ref)
Article
It has been claimed that reaching to visually presented targets is a valid indicator of perceptual capacity in very young infants. In a previous report we failed to replicate the findings on which that claim is based. Here we reanalyze some of the tapes of the first report, using a less restricted criterion for what constitutes a reach, and a much more detailed analysis of the various components of reaching behaviour. A number of components are readily distinguished and reliably observed. Infants of seven to twenty-one days show great individual variation in their reaching, from no such behaviour to a great deal. Certain clusters of the components of reaching can be used to define different reaching "styles". The infants who reached most frequently in our sample all showed a dominant pattern of reaching, which in certain respects appears to be more mature than that of other babies. The finer analysis revealed no differences in the reaching behaviour to objects and pictures of objects, even among the most active reachers.
Article
Head turning to off-centered sound was videotaped monthly in a group of infants during their first 3 months of life. Infants turned reliably toward the sound at birth and at 1 and 3 months of age. They failed to respond reliably at 2 months due to an increase in no-turn responses. Potential explanations for the temporary decline in orientation responses to sound are discussed.
Article
The spinal distribution of the corticospinal fibers was studied experimentally in infant rhesus monkeys (Macaca mulatta) by means of the NautaGygax silver impregnation technique. The findings suggest that the bulk of the direct cortico-motoneuronal connections in the rhesus monkey are established postnatally, during at least the first 8 months of life.
Article
This paper reports the results of a normative study of the development of visually-directed prehension during the first six months of life. Thirty-four normal infants born and reared under relatively uniform conditions in a state hospital were studied. The technique combined detailed longitudinal observations with a standardized testing procedure designed to elicit visual-motor responses including prehension. A sequence of development is described, categorized into eight stages of two weeks each. A number of separate and distinct visual-motor and tactual motor behaviors were found to contribute to this sequence, culminating in the development of visually-directed reaching just prior to 5 months of age.
Article
This chapter discusses the descending pathways to the spinal cord. These pathways can be grouped according to their origin into two categories: (1) those coming from the cerebral cortex and (2) those coming from the brain stem. The cortico-spinal fibers appeared to be derived primarily from the pericruciate cortex in the cat and from the pericentral cortex in the Rhesus monkey. Ablation-degeneration studies in both animals demonstrated that the cortico-spinal fibers are distributed to the nuclei cuneatus and gracilis and to the spinal gray matter. In regard to the latter distribution, the cortical fibers in the cat terminate, primarily, in the nucleus proprius of the dorsal horn, and the intermediate zone. Only a few fibers spill over into the territory of the ventral horn and none are distributed to the motoneuronal cell groups. In the lower brain stem system of fibers that descended throughout the spinal cord via the lateral funiculus, distributed among to the lateral reticular formation and to some cranial motor nuclei. In the spinal cord, the bulk of this system appeared to be directed to the cervical segments, as only few fibers were found in the lumbo-sacral segments despite the damage to the rubro spinal tract.