Brain and Cognition 44, 455–469 (2000)
doi:10.1006/brcg.1999.1205, available online at http://www.idealibrary.com on
Timing and Force Components in Bilateral Transfer
of Learning
Luis Augusto Teixeira
School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
Published online August 18, 2000
Bilateral transfer of perceptual and motor components in movement control was
investigated through two experiments. In Experiment 1 a simple anticipatory timing
task was practiced with either the preferred or the nonpreferred hand. After a short
resting interval an additional set of trials was performed with the contralateral hand.
In Experiment 2, the same experimental design was used to investigate bilateral
transfer of fine force control in a wrist-flexion movement. Analysis of the results
showed that bilateral transfer of learning took place for both anticipatory timing and
force control, with more noticeable transfer of training for the former. Asymmetry in
transfer was found for force control, with significant transfer only in the preferredto-nonpreferred direction. Transfer of anticipatory timing occurred similarly in both
directions. These results indicated anticipatory timing as a powerful component for
bilateral transfer, while force control showed to be more dependent on practice with
the specific muscular system.  2000 Academic Press
INTRODUCTION
Acquisition of motor skills involves two complimentary sides that determine the extent to which new movements can be performed proficiently: the
specificity and the generalizability of learning. Experimental evidence has
pointed out that some conditions of practice lead to specificity of learning
so that remarkable decrease in performance is seen when the sensory information available during acquisition is modified (Proteau, Marteniuk, & Lévesque, 1992; Teixeira, 1995). On the other hand, different kinds of transfer
of learning are known to occur after the acquisition of a motor task, ranging
from transfer of relational to specific parameters of control (see Young &
Schmidt, 1987, for review). Completely specific acquisition of motor skills
or perfect transfer of learning, however, rarely are observed, as in most instances there are some components that are incorporated by a new control
assembly and other ones that need to be specifically learned from the requireAddress correspondence and reprint requests to Luis Augusto Teixeira, Escola de Educação
Fı́sica e Esporte, Av. Prof. Mello Moraes, 65, Universidade de São Paulo, Butantã, S.P., Brazil
05508-900. E-mail: lateixei@usp.br.
455
0278-2626/00 $35.00
Copyright  2000 by Academic Press
All rights of reproduction in any form reserved.
456
LUIS AUGUSTO TEIXEIRA
ments of the new task. Studies on bilateral transfer of learning have usually
shown an advantage of previous practice with the homologous contralateral
limb in tasks such as drawing/writing (Hicks, 1974; Parlow & Kinsbourne,
1989; Thut et al., 1996), tactual recognition (Parlow & Kinsbourne, 1990;
Sathian & Zangaladze, 1998), pointing under displaced vision (Choe &
Welsh, 1974; Elliott & Roy, 1981; Kalil & Freedman, 1966), pursuit tracking
(Hicks, Gualtieri, & Schroeder, 1983), mirror tracing (Cook, 1933a, 1933b),
and maze tracking (Milisen & Riper, 1939; Wieg, 1932). These investigations have revealed an increased proficiency in performance with a resting
body segment after practice with the contralateral homologous limb, but few
investigations have provided information about what control parameters are
effectively transferred to the contralateral side of the body.
Considering transfer of learning in general, temporization of movements
has been shown to be relatively independent of the effector system used to
produce the response. Franz, Zelaznik, and Smith (1992) showed that intraindividual variability in repetitive timing tasks is significantly correlated between movements made with the index finger, forearm, and jaw, pointing
out a common element responsible for movement synchronization (see also
Keele, Pokorni, Corcos, & Ivry, 1985). Additionally, Matos, Teixeira, Lomônaco, Lima, and Sañudo (1997) have shown the transfer of anticipatory timing between tasks involving different levels of movement complexity. Because transfer of learning was observed to take place from a simple (button
pressing) to a complex (hitting a foam ball with a racquet) anticipatory timing
task as well as in the opposite direction, this study suggested anticipatory
timing to be a generalizable element in movement control.
On the other hand, transfer of learning in tasks characterized by reduced
perceptual and strong motor components has shown to be less pronounced
than in tasks that require greater perceptual resources. Karni et al. (1995)
analyzed cortical and behavioral modifications during learning a serial fingertapping task and in subsequent transfer-tapping tasks performed with either
the same or the contralateral hand. The results indicated that learning led to
an increased cortical map only for the practiced motor task, and neither transfer to different tapping sequences performed with the same hand nor transfer
between hands for the same sequence were found. Similar specificity of
learning has been found by Teixeira (1992, 1993) in investigations on bilateral transfer of learning when a task requiring fine force control was used.
In these studies, Teixeira employed a task of propelling a small plastic disk
with the index finger from a home position to a horizontal target on a smooth
surface and analyzed the gain in performance with the contralateral hand
after practice. The results indicated no significant improvement for the contralateral hand in comparison to a condition without any previous practice.
In general, these results are indicative that bilateral transfer of learning is
task specific, with potential of transfer apparently being a function of the
main control components required for proficient performance. Another as-
TRANSFER OF TIMING AND FORCE
457
pect of bilateral transfer of learning related to the specificity of the task is
the direction of transfer. In the cross-activation model (Parlow & Kinsbourne, 1989), direction of bilateral transfer of learning has been proposed to
be related to relative cerebral specialization of function. When the dominant
neuromotor system is used, ‘‘engrams’’ are formed in both cerebral hemispheres, while the use of the nondominant neuromotor system leads to the
formation of a single-sided engram in the nondominant hemisphere. As a
corollary, bilateral transfer is hypothesized to take place from the dominant
to the nondominant system but not in the opposite direction. Because the
left cerebral hemisphere is supposed to play the main role in the sequential
organization of movements and the right hemisphere to be the main responsible for visuospatial analysis (Goodale, 1990), the direction of transfer would
be determined by the main component required for the control of action. In
the callosal access model (Taylor & Heilman, 1980), on the other hand, it
has been proposed the formation of a neural representation only in the dominant left hemisphere. When the dominant side of the body is used there
is a direct access to this representation. When a nondominant limb is used,
control activities of the nondominant hemisphere are carried out with the
leading participation of the dominant contralateral hemisphere through
the corpus callosum. Thus, as a function of bilateral cerebral activation in
the performance with the nondominant (but not with the dominant) limb,
transfer of learning from the nondominant to dominant hand is expected to
take place.
The research strategy employed here to investigate the issues raised above
was to select a task composed of strong perceptual and weak effector components (Experiment 1) and then of the opposite characteristics, i.e., strong
effector and weak perceptual components (Experiment 2) and to analyze the
amount of bilateral transfer of learning after practicing one of these tasks
with either the preferred or the nonpreferred hand.
EXPERIMENT 1
In Experiment 1 a strong perceptual/weak effector component task was
used to assess the bilateral transferability of learning. The task selected to
represent this category involved pressing a switch coincidentally with the
end of the displacement of a luminous stimulus. The main skill developed
during the acquisition of this task was to make a simple movement in a
narrow temporal window; that is, to learn to anticipate the correct time to
produce the response to make two events occur simultaneously. Utilization
of the contralateral hand after the task acquisition was expected to lead to
a similar level of performance in relation to the practiced hand, since this
short and simple movement requires a minimum of both spatial and force
accuracy. As the perceptual component was maintained unchanged in the
transfer condition, one could expect to find a high index of bilateral transfer
to the untrained hand.
458
LUIS AUGUSTO TEIXEIRA
Method
Subjects. University students (n ⫽ 40), ages 18 to 33 years old (M ⫽ 22 years), volunteered
to participate in this study. Thirty-seven subjects declared right-handedness for fine motor
skills and three of them declared left-handedness.
Apparatus and task. A commercial Bassin Anticipation Timer (Lafayette Instrument) was
used to produce the displacement of a luminous signal in the direction of the subject. This
apparatus is made up of a metallic runway 152 cm long, which holds 32 light-emitting diodes
(LEDs) arranged in line on its mid-longitudinal axis. Adjacent LEDs are spaced by intervals
of 4.5 cm, which gives rise to a displacement distance of 144 cm. The sequenced lightening
of the LEDs produce the perception of a single stimulus moving from one end of the runway
to the other. The runway was placed on the mid-sagittal plane in a horizontal position a few
centimeters from the subject, with the stimulus moving toward the subject at a constant velocity
of 4.4 m/s. At the end of the runway there was a manual switch, which was to be pressed
with the thumb coincidentally with the lightening of the last LED of the sequence. The performance was analyzed as a function of the unsigned temporal difference between the synchronizatory movement and the actual arrival of the luminous stimulus at the criterion position
(absolute error) and consistency of response (variable error).
Design and procedures. Subjects sat facing the apparatus, which was positioned on a workbench, aligning the mid-sagittal axis of their bodies with the line formed by LEDs on the
runway. After assessing subjects’ preferred hand by verbally inquiring about the preferred
hand used to perform fine motor tasks such as writing and painting, they were familiarized
with the task and experimental procedures by performing three trials in the condition of the
following practice. Immediately after familiarization, 60 practice trials were performed in a
single series, with intertrial intervals of approximately 7 s. On each trial a verbal warning
signal was followed by the lightening of the first LED of the runway (for 1 s), and then the
luminous stimulus began to move toward the subject. The subject’s practice hand was kept
in a constant place, positioned on the workbench beside the last LED of the sequence.
Subjects were pseudorandomly assigned to one of two groups, maintaining the number of
subjects and the number of males and females equivalent between them. One group carried out
practice trials with their preferred hand. After this acquisition phase, they remained engaged on
a cognitive task for 10 min and then performed five trials with the nonpreferred hand (P-NP
group). The other group underwent the opposite treatment, practicing with the nonpreferred
hand and being transferred to the preferred hand (NP-P group). Knowledge of results was
provided both during acquisition and transfer by verbally informing the subject with the directional timing error (in milliseconds) after every trial.
RESULTS AND DISCUSSION
Absolute error in the acquisition were grouped in blocks of six trials and
analyzed through a two-way 2 (Group) ⫻ 10 (Block) ANOVA with repeated
measures on the second factor. The results showed only a significant main
effect for Block [F(9, 342) ⫽ 7.73, p ⬍ .0001], indicating improvement in
accuracy during acquisition. Absence of a significant main effect for Group
[F(1, 38) ⫽ .35, p ⬎ .1] and interaction [F(9, 342) ⫽ 1.13, p ⬎ .1] showed
equivalent levels of accuracy and homogeneous improvement throughout
acquisition in the performance with the preferred and nonpreferred hand (Fig.
1).
In the comparison between transfer and control trials, a descriptive analysis was made by calculating the index of transfer, based on the proportional
TRANSFER OF TIMING AND FORCE
459
FIG. 1. Temporal absolute error for blocks of six trials during the acquisition phase for
the preferred (P) and nonpreferred (NP) hands.
gain in performance in the transfer condition in relation to the opposite
group’s initial five acquisition trials (same hand, intergroup comparison) and
the index of performance decline, representing the proportional deterioration
of performance from the last five acquisition trials in relation to transfer
(different hand, intragroup comparison). For the preferred hand, the experimental condition had a 36% gain in performance, while its index of performance decline was 27% (Fig. 2a). A similar index of transfer was achieved
with the nonpreferred hand, in which there was a 41% gain in relation to
the control condition and an index of decline equal to 29% (Fig. 2b).
Further inferential analysis was conducted for accuracy scores through a
three-way 2 (Group) ⫻ 3 (Phase: beginning of acquisition ⫻ end of acquisition ⫻ transfer) ⫻ 5 (Trial) ANOVA with repeated measures on the last two
factors. The results indicated significant main effects for Phase [F(2, 76) ⫽
30.61, p ⬍ .001] and Trial [F(4, 152) ⫽ 6.81, p ⬍ .001]. Significant interactions were observed for Group ⫻ Phase [F(2, 76) ⫽ 4.08, p ⬍ .05],
Group ⫻ Trial [F(4, 152) ⫽ 2.67, p ⬍ .05], and Phase ⫻ Trial [F(8, 304) ⫽
3.07, p ⬍ .005]. Newman–Keuls post hoc procedures pointed out significant
superior performance of the experimental conditions over their controls, i.e.,
in the comparison between transfer trials of one group with initial trials of
the other group, except for the last trial when similar performance was observed. These results were due to a significant improvement of performance
throughout trials in the beginning of acquisition while no significant modifications in temporal accuracy were observed for transfer trials. Additionally,
in the analysis of the transition from acquisition to transfer no significant
differences were found, which indicates no disruption in performance by the
transfer task.
Analysis of variable error was conducted through a two-way 2 (Group) ⫻
3 (Phase) ANOVA with repeated measures on the second factor. The results
460
LUIS AUGUSTO TEIXEIRA
FIG. 2. Temporal absolute error for the initial trials of the P-NP group (P-Bgn), final
(NP-End) and transfer (P-Exp) trials of the NP-P group (a), initial trials of the NP-P group
(NP- Bgn), and final (P-End) and transfer (NP-Exp) trials of the P-NP group (b).
indicated only significant main effects for Phase [F(2, 76) ⫽ 24.61, p ⬍
.001]. Post hoc comparisons pointed out significant differences between beginning of acquisition and the other two phases, with no difference between
end of acquisition and transfer. These results showed that consistency developed by both groups during practice was maintained in the transfer trials,
resulting in a reduced variability of performance in relation to the beginning
of acquisition (Fig. 3).
Overall, these results indicated that anticipatory timing performance transfers bilaterally in a symmetric way. Comparing the gain of the contralateral
nonpracticed hand over the control condition without previous practice, both
P-NP and NP-P groups showed a significant improved performance. Considering the intergroup index of transfer, the similarity between the proportional
gain in relation to initial trials for both groups indicates that bilateral transfer
was rather symmetric, with the same amount of transfer from the preferred
to nonpreferred hand as in the opposite direction. Low intragroup indexes
of performance decline and absence of significant differences in the transition from acquisition to transfer, both in accuracy and consistency, pointed
TRANSFER OF TIMING AND FORCE
FIG. 3.
trials.
461
Temporal variable error for P-NP and NP-P groups in the initial, final, and transfer
out a powerful bilateral transfer. Such findings reveal the subjects’ capacity
to maintain similar levels of performance in the transfer to the contralateral
homologous effector system in relation to the end of acquisition.
In agreement with previous findings (Franz et al., 1992; Keele et al., 1985;
Matos et al., 1997), the results presented here support the proposition of
timing as a motor function relatively independent of the effector system,
which can be incorporated into different sensorimotor maps without necessity of specific practice with a particular limb in order to maintain the level
of performance achieved in the acquisition of a primary timing task. Additionally, such bilateral transfer achievement was observed on the very first
trials, indicating that incorporation of the timing component by the contralateral hand structure of control was remarkably efficient.
EXPERIMENT 2
Experiment 2 was designed to test transferability of learning in a task with
strong effector and weak perceptual components. As tasks involving control
of force in a stable environment are representative of this category of skills,
the task consisted of launching a cursor through a linear runway to a specified
target position. Because the launching of the cursor was made with a wristflexion movement, good performance at this task required refined control
over the force produced to propel the cursor with the preferred or nonpreferred hand, without considerable load on perceptual abilities. As the main
requirement for accurate performance at this task is controlled application
of force with manual muscular groups, a limited bilateral transfer of learning
was expected to be found.
462
LUIS AUGUSTO TEIXEIRA
Method
Subjects. University students (n ⫽ 40), ages 18 to 28 years old (M ⫽ 21 years), participated
as subjects in this experiment. Thirty-seven subjects asserted preference for the right hand to
perform fine motor skills and three used the left hand. None of these subjects participated in
Experiment 1.
Apparatus and task. A commercial Linear Positioning Apparatus (Lafayette Instrument)
was used to produce a force-control task. This instrument is composed of a 1-m-long tubular
runway supported by a wooden frame, with a parallel scale in millimeters. A low-friction
moving cursor can be displaced along this runway. Its position is shown on a digital display,
indicating the discrepancy between the intended and the actual end position. At both ends of
this runway there are cursor displacement limiters, which can be fixed at desired points along
the runway to determine the start position of the movement.
To yield a task requiring force control, subjects were asked to launch the cursor to a target
50 cm away from the initial position, using a wrist/fingers-flexion movement. Right-hand
movements were made from the right to the left side, while left-hand movements were performed in the opposite direction. The cursor was contacted with the index and middle fingers,
and the movement was initiated with the elbow and wrist lined up with the shoulder on the
sagittal plane. In this initial position, the wrist and fingers were kept hyperextended in order
to assume a favorable angle to propel the cursor. During the movement the elbow was maintained static and flexed at approximately 120° and the propelling of the cursor was performed
by flexing in a continuous way the wrist and the two fingers contacting the cursor.
Design and procedures. The experimental design was similar to that used in Experiment
1. Subjects were pseudorandomly assigned either to the P-NP group (i.e., practicing the task
with the preferred hand and transferring to the nonpreferred hand) or to the NP-P group (practicing with the nonpreferred hand and transferring to the preferred hand).
After determining subjects’ preferred hand for fine motor skills through verbal inquiry, they
sat facing the apparatus. They had their shoulder, corresponding to their practice hand, aligned
with the start position of the cursor. A limiter was used to establish the initial position for a
distance of 50 cm from the target place. The target was indicated by a vertical arrow right
under the criterion position along the runway. To prevent a whole-arm movement, a vertical
paddle was positioned close to the wrist, limiting the movement in the direction of the target.
Subjects were given three familiarization trials to assess their comprehension of the task
and procedures. Afterward they began the acquisition phase, in which after every trial the
experimenter recorded the discrepancy between the criterion and the actual final position of
the propelled cursor and signaled to the subject to return the cursor to the initial position using
their opposite hand. In order to prevent fatigue in the proximal muscles of the arm, the subjects
were instructed to uphold their practicing arm on the table supporting the apparatus in the
intertrial intervals.
Because intrinsic knowledge of results was available from the apparatus scale during movement execution and cursor displacement, no augmented feedback was given. The 60 acquisition trials were performed in sequence with intertrial intervals of 7–8 s. After an active resting
interval (the same activity as for Experiment 1), subjects changed their position in relation to
the apparatus to perform five transfer trials. In the transfer task they had their shoulder, elbow,
and hand of the resting arm lined up with the contralateral initial position and performed the
50-cm launching task with the opposite hand, also with the displacement of their wrist in the
direction of the target limited by a paddle.
Results and Discussion
The results were analyzed in the same way as for Experiment 1, using
spatial accuracy (absolute error) and consistency (variable error) as depen-
TRANSFER OF TIMING AND FORCE
463
FIG. 4. Spatial absolute error for blocks of six trials during the acquisition phase for the
preferred (P) and nonpreferred (NP) hands.
dent variables. The two-way 2 (Group) ⫻ 10 (Block) ANOVA with repeated
measures on the second factor, employed for analysis of absolute error in
the acquisition phase, revealed only a significant main effect for Block [F(9,
342) ⫽ 27.44, p ⬍ .0001], indicating a homogeneous improvement in accuracy for both P-NP and NP-P groups (Fig. 4).
The index of transfer showed an advantage of 11% for the experimental
preferred hand in relation to its control, and an index of decline of 115% in
relation to the performance with the contralateral practice hand in the end
of acquisition (Fig. 5a). The experimental nonpreferred hand achieved an
index of transfer equal to 35% and an index of performance decline of 65%
(Fig. 5b).
The three-way 2 (Group) ⫻ 3 (Phase) x 5 (Trial) ANOVA with repeated
measures on the last two factors for absolute error indicated significant main
effects for Phase [F(2, 76) ⫽ 33.35, p ⬍ .001] and Trial [F(4, 152) ⫽ 8.76,
p ⬍ .001]. Significant interactions were found for Group ⫻ Phase [F(2, 76) ⫽
4.08, p ⬍ .05], Phase ⫻ Trial [F(8, 304) ⫽ 2.86, p ⬍ .05], and Group ⫻
Phase ⫻ Trial [F(8, 304) ⫽ 2.21, p ⬍ .05]. Newman–Keuls procedures
indicated that a significant gain in transfer compared to initial acquisition
trials took place only on the first trial for the P-NP condition, while no significant gain was found for the NP-P group. In the comparison between end
of acquisition and transfer, significant decline of performance was observed
only on the first trial in the NP-P condition, while no significant differences
were observed in the opposite direction of transfer. The combined effect of
transfer for the P-NP group and decline of performance for the NP-P group
on the first trial of transfer led to a significantly superior performance with
the nonpreferred hand on this trial, while no significant between-hand differences were found afterward. Additionally, there were no between-trial significant differences in the performance with the nonpreferred hand in the
464
LUIS AUGUSTO TEIXEIRA
FIG. 5. Spatial absolute error for the initial trials of the P-NP group (P-Bgn), final (NPEnd) and transfer (P-Exp) trials of the NP-P group (a), initial trials of the NP-P group (NPBgn), and final (P-End) and transfer (NP-Exp) trials of the P-NP group (b).
transfer phase, which indicates stability of performance. Differently, the experimental preferred hand showed a similar pattern in relation to beginning of
acquisition, with significant improvement of performance throughout trials.
Analysis of variable error, conducted through a two-way 2 (Group) ⫻ 3
(Phase) ANOVA with repeated measures on the second factor, indicated only
a significant main effect for Phase [F(2, 76) ⫽ 24.61, p ⬍ .0001]. Posthoc contrasts indicated that all comparisons were significant, revealing an
increased consistency of performance in transfer compared to initial trials
in spite of the decline in the transition from acquisition to transfer (Fig.6).
Previous studies on bilateral transfer of force control have failed to show
significant effects in tasks involving fine manual musculature (Teixeira,
1992, 1993). Lack of bilateral transfer of control between distal body segments has been explained by absence of neural interhemispheric projections
between homotopic primary motor and somatosensory areas representing the
hands in the cerebral cortex (Thut et al., 1996). The present results, though,
indicated significant improvement of the nonpreferred hand as a result of
practice with the preferred hand, while the opposite direction of transfer did
not show similar transfer effects. The inferential analysis was complemented
TRANSFER OF TIMING AND FORCE
FIG. 6.
trials.
465
Spatial variable error for P-NP and NP-P groups in the initial, final, and transfer
by indexes of transfer and performance decline by showing that transfer from
the preferred to nonpreferred hand produced a threefold higher index of
transfer and a twofold lower index of performance decline in comparison
with the opposite direction of transfer. Thus, bilateral transfer of force control
was found to be asymmetric, with the main transfer from the preferred to
the nonpreferred hand.
GENERAL DISCUSSION
In principle, bilateral transfer of learning may take place in different ways.
It may occur through transfer of all relevant components for proficient performance or through transfer of only more generalizable, effector independent,
control components. Yet, transfer may be partial, with decline in performance of one or more components in the transfer task, or it may be complete,
so that no alteration in the performance is observed in the transfer to the
contralateral limb for some components. Previous studies have shown that
there is a third element to be considered, i.e., symmetry of transfer, with
several findings of unidirectional transfer of learning either from the dominant to nondominant limb (e.g., Parlow & Kinsbourne, 1989) or in the opposite direction (e.g., Taylor & Heilman, 1980). The present results showed
that both anticipatory timing and force control are transferable components
in motor behavior. Comparison of the results of Experiment 1 and Experiment 2, though, reveals that bilateral transfer of learning occurred in qualitatively different ways for these two components in sensorimotor control.
Transfer of force control between hands was found to be asymmetrical,
reaching a significant level only from the preferred to nonpreferred hand
direction. These results are in accordance with Parlow and Kinsbourne’s
(1989) proposition that bilateral transfer of learning occurs from the dominant to nondominant neuromotor system. Differently, transfer of anticipatory
466
LUIS AUGUSTO TEIXEIRA
timing control showed a symmetric relationship, with both hands benefiting
similarly from previous practice with the contralateral hand, as pointed out
by the index of transfer, as well as demonstrated the same capacity to maintain approximately 70% of the level of performance achieved with the contralateral practiced hand, as was shown by the index of performance decline.
Considered as a whole, these findings demonstrate that amount and symmetry of bilateral transfer of learning are dependent on the main components
involved in movement control for a given task. Most studies on bilateral
transfer of learning have used motor tasks in which there exists a complex
combination of perceptual and motor components, or that even require different parameters of movement control, so that it is difficult to determine what
control components were in fact transferred from one limb to the other. Previous findings by Teixeira (1992, 1993), employing a force-control task, have
shown no significant gain in performance for the contralateral nonpracticed
hand, which suggests acquisition of fine force control to be dependent on
practice specifically with a particular neuromotor system. Somewhat different from these findings, the present results showed that for the wrist-flexion
movement task used here the nonpreferred resting limb benefited from practice with the contralateral homologous limb. Scarce significant differences
in relation to controls and high indexes of performance decline, however,
indicate that the amount of bilateral transfer of force control was limited in
relation to that observed for anticipatory timing.
Such weak transfer of learning of force control may be related to the lack
of neural interhemispheric projections between hand areas in the primary
motor and somatosensory areas in the cerebral cortex (Pandya & Vignolo,
1971), which requires indirect neural pathways for interhemispheric communication between the main cortical areas responsible for controlling distal
muscular systems. This characteristic of the brain architecture may dictate
the increased dependence on specific practice for the acquisition of force
control in manual movements, as observed here. Apparently contradictory
to this is the fact that the anticipatory timing task involved a distal thumb
movement and even so the transfer was rather robust in either direction. The
anticipatory timing task, however, required neither accurate force nor another
form of complex spatial specification, so that the critical aspect for proficient
performance was initiating the movement at the right time. Under such circumstances, alteration of the effector system seems to lead to minimal disturbance on performance. These conclusions are in accordance with previous
findings of significant correlations (Franz et al., 1992; Keele et al., 1985)
and transfer of learning (Matos et al., 1997) between timing tasks of different
levels of complexity in terms of the effector system used, shown by a timing
capacity that can be used bilaterally, independent of the specific limb employed to perform the task.
Previous conceptual models on bilateral transfer of learning have proposed
the formation of single-sided ‘‘engrams’’ in the dominant cerebral hemi-
TRANSFER OF TIMING AND FORCE
467
sphere independent of the limb used during practice (Taylor & Heilman,
1980) or in the nondominant hemisphere when the nondominant hand is
employed in the acquisition (Parlow & Kinsbourne, 1989). Additionally,
Laszlo, Baguley, and Bairstow (1970) have proposed the formation of unilateral engrams on the basis of practice with the contralateral limb. All of these
models propose a single direction of bilateral transfer of learning, which
varies as a function of particular explanations for interhemispheric flow of
information.
In light of the present findings, no single model seems to provide a good
fit for all the data. Symmetry between the preferred and nonpreferred hand
observed in the performance on the anticipatory timing task suggests that
the two cerebral hemispheres worked in a quite similar way, without asymmetries in the mode in which the task was acquired or in the amount of
contralateral transfer of learning. Thus, formation of unilateral engrams, or
asymmetrical transfer as a function of hemispheric dominance, turns out to
be an inappropriate general conclusion. A conceptualization put forth to explain current and previous experimental findings is based on the conception
of cerebral hemispheres as composed of a number of neural populations,
which are responsible for specific functions in sensorimotor control. The
assembly and activation of a group of such control units to perform a motor
task in the hemisphere contralateral to the limb employed in the acquisition
leads to activation of homologous units in the opposite hemisphere (cf. Tanji,
Okano, & Sato, 1988). Power of interhemispheric coactivation is thought to
depend on variables like the main sensorimotor components involved in the
control of the movement and the strength of the connections among components of a neural population responsible for controlling a given sensorimotor
operation. As a function of particular structural and anatomical characteristics of homologous limbs acquired throughout life-span development, motor
components used in force control are dependent to some extent on specific
practice with the criterion limb (Teixeira, 1992, 1993). Such practice with
a particular body segment seems to hold an important function in proficient
performance of strengthening the connections between control units and in
molding them to conform with the idiosyncrasies of this particular effector
system. Perceptual components like anticipatory timing, on the other hand,
are capable of achieving better bilateral transfer. The fact that this component
in a global sensorimotor map is a behavioral function that results from the
collective work of a set of processing units, which are widely distributed
throughout large regions in the associative area in both cerebral hemispheres,
renders its connection to different effector systems easier to be implemented.
This feature prevents greater disturbances in the response when transfer to
a different action system is required.
Bilateral transfer of learning, hence, is proposed to be a function of utilization of general-purpose control units and of well-defined neural groups of
sensorimotor control. Similarity of performance between the preferred and
468
LUIS AUGUSTO TEIXEIRA
nonpreferred hand throughout the acquisition phase shows that both hands
have the same potential for achieving refined control over these kinds of
movement. It is hypothesized that asymmetry in bilateral transfer of force
control observed here is due to asymmetric neural architectures established
before the beginning of learning as a result of previous differential usage of
the two hands. As a well-defined global map is expected to produce stronger
coactivation signals between the two cerebral hemispheres, the transfer effect
in tasks requiring refined movement control should be higher from the preferred (more used) to the nonpreferred system. In tasks in which general
purpose units play the main role, like in simple anticipatory timing tasks,
transfer to the homologous contralateral limb can be expected to be stronger
and symmetric, since these functions are relatively independent of a specific
effector system.
REFERENCES
Choe, C. S., & Welsh, R. B. (1974). Variables affecting the intermanual transfer and decay
after prism adaptation. Journal of Experimental Psychology, 102, 1076–1084.
Cook, T. W. (1933a). Studies in cross education: I. Mirror tracing the star-shaped maze. Journal of Experimental Psychology, 16, 144–160.
Cook, T. W. (1933b). Studies in cross education: II. Further experiments in mirror tracing
the star-shaped maze. Journal of Experimental Psychology, 16, 679–700.
Elliott, D., & Roy, E. A. (1981). Interlimb transfer after adaptation to visual displacement:
Patterns predicted from the functional closeness of limb neural control centres. Perception, 10, 383–389.
Franz, E. A., Zelaznik, H. N., & Smith, A. (1992). Evidence of common timing processes in
the control of manual, orofacial, and speech movements. Journal of Motor Behavior, 24,
281–287.
Goodale, M. A. (1990). Brain asymmetries in the control of reaching. In M. A. Goodale (Ed.),
Vision and action: The control of grasping. Norwood, NJ, Ablex. Pp. 14–32.
Hicks, R. E. (1974). Asymmetry of bilateral transfer. American Journal of Psychology, 87,
667–674.
Hicks, R. E., Gualtieri, C. T., & Schroeder, S. R. (1983). Cognitive and motor components
of bilateral transfer. American Journal of Psychology, 96, 223–228.
Kalil, R. E., & Freedman, S. J. (1966). Intermanual transfer of compensation for displaced
vision. Perceptual and Motor Skills, 22, 123–126.
Karni, A., Meyer, G., Jezzard, P., Adams, M. M., Turner, R., & Ungerleider, L. G. (1995).
Functional MRI evidence for adult motor cortex plasticity during skill learning. Nature,
377, 155–158.
Keele, S. W., Pokorny, R. A., Corcos, D. M., & Ivry, R. (1985). Do perception and motor
production share common time mechanisms? A correlational analysis. Acta Psychologica,
60, 173–191.
Laszlo, J. I., Baguley, R. A., & Bairstow, P. J. (1970). Bilateral transfer in tapping skill in
the absence of peripheral information. Journal of Motor Behavior, 2, 261–271.
Matos, T. C. S., Teixeira, L. A., Lomônaco, F. B., Lima, A. C. P., & Sañudo, A. (1997).
Transfer of learning between anticipatory timing movements with different levels of mo-
TRANSFER OF TIMING AND FORCE
469
tor complexity. Proceedings of the Annual Conference of the Canadian Society for Psychomotor Learning and Sport Psychology, 28, 56.
Milisen, R., & Riper, C. van (1939). Differential transfer of training in a rotary activity. Journal
of Experimental Psychology, 24, 640–648.
Pandya, D. N., & Vignolo, L. A. (1971). Intra- and interhemispheric projections of the precentral, premotor and arcuate areas in the rhesus monkey. Brain Research, 26, 217–233.
Parlow, S. E., & Kinsbourne, M. (1989). Asymmetrical transfer of training between hands:
Implications for interhemisferic communication in normal brain. Brain and Cognition,
11, 98–113.
Parlow, S. E., & Kinsbourne, M. (1990). Asymmetrical transfer of braille acquisition between
hands. Brain and Language, 39, 319–330.
Proteau, L., Marteniuk, R. G., & Lévesque, L. (1992). A sensorimotor basis for motor learning:
Evidence indicating specificity of practice. Quarterly Journal of Experimental Psychology A, 44, 557–575.
Sathian K., & Zangaladze, A. (1998). Perceptual learning in tactile hyperacuity: Complete
intermanual transfer but limited retention. Experimental Brain Research, 118, 131–134.
Tanji, J., Okano, K., & Sato, K. C. (1988). Neuronal activity in cortical motor areas related
to ipsilateral, contralateral, and bilateral digit movements of monkey. Journal of Neurophysiology, 60, 325–343.
Taylor, H. G., & Heilman, K. M. (1980). Left-hemisphere motor dominance in right-handers.
Cortex, 16, 587–603.
Teixeira, L. A. (1992). Transferência de aprendizagem inter-membros: O que é transferido?
[Interlimb transfer of learning: What is transferred?]. Revista Paulista de Educação
Fı́sica, 6, 35–40.
Teixeira, L. A. (1993). Bilateral transfer of learning: The effector side in focus. Journal of
Human Movement Studies, 25, 243–253.
Teixeira, L.A. (1995). Integração visomotora em tarefas sincronizatórias [Visuomotor integration in anticipatory timing tasks]. Unpublished doctoral dissertation, University of São
Paulo, São Paulo, S.P., Brazil.
Thut, G., Cook, N., Regard, M., Leenders, K., Halsband, U., & Landis, T. (1996). Intermanual
transfer of proximal and distal motor engrams in humans. Experimental Brain Research,
108, 321–327.
Wieg, E. L. (1932). Bi-lateral transfer in the motor learning of young children and adults.
Child Development, 3, 247–268.
Young, D. E., & Schmidt, R. A. (1987). Transfer of movement control in motor skill learning.
In S. M. Cornier, & J. D. Hagman (Eds.), Transfer of learning: Contemporary research
and applications. San Diego, Academic Press. Pp. 47–79.