Shared learning shapes human performance: Transfer effects in task sharing.

Abstract

We investigated whether performing a task with a co-actor shapes the way a subsequent task is performed. In four experiments participants were administered a Simon task after practicing a spatial compatibility task with an incompatible S-R mapping. In Experiment 1 they performed both tasks alongside another person; in Experiment 2 they performed the spatial compatibility task alone, responding to only one stimulus position, and the Simon task with another person; in Experiment 3, they performed the spatial compatibility task with another person and the Simon task alone; finally, in Experiment 4, they performed the spatial compatibility task alone and the Simon task with another person. The incompatible practice eliminated the Simon effect in Experiments 1 and 4. These results indicate that when a task is distributed between two participants with each one performing a different part of it, they tend to represent the whole task rather than their own part of it. This experience can influence the way a subsequent task is performed, as long as this latter occurs in a social context.

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Shared learning shapes human performance: Transfer effects in
task sharing
Nadia Milanese, Cristina Iani*, Sandro Rubichi
Università di Modena e Reggio Emilia, Italy
a r t i c l ei n f o
Article history:
Received 2 September 2009
Revised 1 March 2010
Accepted 10 March 2010
Keywords:
Spatial compatibility
Simon effect
Social cognition
Learning
Incidental learning
a b s t r a c t
We investigated whether performing a task with a co-actor shapes the way a subsequent
task is performed. In four experiments participants were administered a Simon task after
practicing a spatial compatibility task with an incompatible S-R mapping. In Experiment
1 they performed both tasks alongside another person; in Experiment 2 they performed
the spatial compatibility task alone, responding to only one stimulus position, and the
Simon task with another person; in Experiment 3, they performed the spatial compatibility
task with another person and the Simon task alone; finally, in Experiment 4, they per-
formed the spatial compatibility task alone and the Simon task with another person. The
incompatible practice eliminated the Simon effect in Experiments 1 and 4. These results
indicate that when a task is distributed between two participants with each one perform-
ing a different part of it, they tend to represent the whole task rather than their own part of
it. This experience can influence the way a subsequent task is performed, as long as this
latter occurs in a social context.
? 2010 Elsevier B.V. All rights reserved.
1. Introduction
Many everyday activities require interaction with other
people. While some of these interactions involve little or
no interpersonal coordination, others clearly put to the test
our coordination abilities. If we think of a situation like
moving together with another person a heavy piece of fur-
niture up a curvy staircase, it is clear that efficient perfor-
mance requires an understanding of what the other is
doing in order to predict his or her future actions and to
behave accordingly. As recent studies suggest, our ability
to understand others and to coordinate with them depends
on the creation of shared task representations, that is rep-
resentations integrating current and predicted self and
other’s actions (cf. Sebanz, Bekkering, & Knoblich, 2006;
see also Tomasello, Carpenter, Call, Behne, & Moll, 2005).
These shared representations emerge in a variety of situa-
tions involving jointly acting individuals even when con-
sidering theother’sactions
suggesting that human cognition is biased toward joint ac-
tion (e.g., Atmaca, Sebanz, Prinz, & Knoblich, 2008; Hom-
mel, Colzato, & van den Wildenber, 2009; Sebanz,
Knoblich, & Prinz, 2003, 2005; Sebanz, Knoblich, Prinz, &
Wascher, 2006; Sebanz, Rebbechi, Knoblich, Prinz, & Frith,
2007; Tsai, Kuo, Hung, & Tzeng, 2008; Welsh, Higgins, Ray,
& Weeks, 2007).
Social interactions play an important role in learning
too. Indeed, our ability to perform novel tasks depends
on the application of knowledge previously acquired
through learning, which often occurs through social inter-
action (e.g., Vygotsky, 1978). Given these considerations,
we believe it is of particular interest to investigate the rela-
tionship between learning and performance in individual
and social contexts. This requires an investigation into
whether learning derived from social interactions may be
transferred to distinct but similar tasks performed either
in social or individual contexts and whether individual
isnotnecessary,thus
0010-0277/$ - see front matter ? 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.cognition.2010.03.010
* Corresponding author at: Dipartimento di Scienze Sociali, Cognitive e
Quantitative, Università di Modena e Reggio Emilia, Via Allegri, 9, 42121
Reggio Emilia, Italy.
E-mail address: cristina.iani@unimore.it (C. Iani).
Cognition 116 (2010) 15–22
Contents lists available at ScienceDirect
Cognition
journal homepage: www.elsevier.com/locate/COGNIT

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learning may transfer to performance in social contexts as
well.
As regards individual performance, there are clear indi-
cations of transfer of learning in tasks investigating spatial
correspondence effects. Spatial correspondence effects are
evident in choice-reaction tasks in which the stimulus ap-
pears in a right or left location and the response is produced
manually (for a review see Proctor and Vu (2006)). In the
spatial stimulus–response compatibility task, the response
is selected on the basis of stimulus location. In compatible
mappings participants are instructed to respond with the
key that is located on the same side of the stimulus,
whereas in incompatible mappings the instructions are re-
versed. In the Simon task, the task-relevant stimulus fea-
ture is non-spatial (e.g., shape or color), and subjects
respond with assigned right and left keys (Simon & Rudell,
1967). Thus, there are trials in which stimulus and response
locations correspond (i.e., corresponding S-R pairings) and
trials in which they do not (i.e., non-corresponding pair-
ings). In both tasks, performance is usually faster and more
accurate when there is spatial correspondence between
stimulus and response (i.e., when the mapping is compati-
ble for the spatial SRC task and when stimulusand response
locations correspond for the Simon task) than when there is
not (i.e., when the mapping is incompatible for the spatial
SRC task and when stimulus and response locations do
not correspond for the Simon task).
ByusingthetransferparadigmdevelopedbyProctorand
Lu(1999),ithasbeenshownthatwhenparticipantsperform
aspatialcompatibilitytaskinwhichtheyarerequiredtore-
spondtostimuluslocationbyemittingaspatiallyincompat-
ible response (i.e., responding to the left stimulus with the
right key and vice versa) and then transfer to a Simon task,
the Simon effect is reduced, absent of even reversed, that
is,reactiontimesfornon-correspondingresponsesarefaster
thanthoseforcorrespondingresponses(Iani,Rubichi,Gher-
ri, & Nicoletti, 2009; Proctor & Lu, 1999; Tagliabue, Zorzi,
Umiltà,&Bassignani,2000).Thisisthoughttooccurbecause
responding for a certain amount of trials with a spatially
incompatible mapping strengthen the non-corresponding
associationbetweenastimulusandaresponsetotheextent
that this association continues to affect performance even
whenthetaskischangedandtheresponseshouldnolonger
be emitted on the basis of a spatial stimulus feature (cf.
Tagliabue et al., 2000).
Notably, the Simon task has proven to be a good candi-
date task to investigate the emergence of shared represen-
tations. In a pioneer study by Sebanz et al. (2003),
participants were shown photographs of a centrally pre-
sented right hand pointing to the right, to the left, or
straight, with the instruction to press one of two lateral-
ized keys according to the color of a ring appearing on
the index finger. They were required to perform the task
either alone or paired with another participant. When they
performed the task individually, responses were faster
when the pointing direction of the hand spatially corre-
sponded to the required response. Hence, the direction
conveyed by the stimulus influenced the response even if
task irrelevant. Interestingly, the advantage for corre-
sponding trials (i.e., Simon effect) was absent when each
participant performed the task alone with the instruction
to respond to only one color, but was present when partic-
ipants performed the task alongside another participant,
each responding to only one color. The occurrence of the
Simon effect in the latter condition was taken as evidence
that each participant represented the other’s action and
integrated this representation in action planning.
In the present study the transfer paradigm described
above was used to assess whether performing a task with
a co-actor shapes the way a subsequent task is performed.
To this aim, we ran four experiments in which participants
were administered a Simon task after practicing a spatial
compatibility task with an incompatible S-R mapping
(see Fig. 1). In Experiment 1 they performed both tasks
alongside another person; in Experiment 2, they performed
the spatial compatibility task alone, responding to only one
stimulus position and the Simon task with another person;
in Experiment 3, they performed the spatial compatibility
task with another person and the Simon task alone; finally,
in Experiment 4, they performed the spatial compatibility
task alone and the Simon task with another person. The
use of the transfer paradigm will allow us to test whether
shared practice shapes performance in a subsequent task.
Specifically, if joint prior practice modulates subsequent
BaselinePracticeTransfer
Exp. 1
Exp. 2
Exp. 3
Exp. 4
Fig. 1. Schematic representation of the experimental conditions used in
the four experiments. The participant responding to the red stimulus is
depicted in dark grey, while the participant responding to the green
stimulus is depicted in light grey. (For interpretation of the references to
colours in this figure legend, the reader is referred to the web version of
this paper.)
16
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performance, we should find a reduction or an elimination
of the Simon effect, similarly to what occurs in individual
settings. Furthermore, this paradigm will allow us to test
if joint practice can influence individual performance and
if individual practice can influence joint performance.
2. Experiment 1
The aim of the present experiment was to assess
whether a practice performed alongside another person
can modulate performance in a subsequent Simon task.
To this end, participants were required to perform a joint
Simon task before and after performing a joint practice
with a spatially incompatible mapping between stimulus
and response.
2.1. Methods
2.1.1. Participants
Sixteen students (seven males; four left-handed; age
range: 19–25 years) of the University of Modena and Reg-
gio Emilia took part in Experiment 1 for either a financial
reward (8 Euros) or partial fulfillment of course credit.
They had normal or corrected-to normal vision and were
naïve as to the purpose of the experiment. Once recruited,
they were randomly paired.
2.1.2. Apparatus and stimuli
Stimuli in the spatial compatibility task were white
solid squares, whereas stimuli in the Simon task were red
or green solid squares (4.5 ? 4.5 cm). They were presented
on a color screen controlled by an IBM computer, 9.5 cm to
the left or to the right of a central fixation cross (1 ? 1 cm).
In both tasks, responses were executed by pressing the ‘‘z”
or ‘‘-” key of a standard Italian keyboard with the left or
right index finger, respectively. Viewing distance was
about 60 cm.
2.1.3. Design and procedure
The experiment consisted of three consecutive sessions
separated by a 5-min interval: a baseline session, a practice
session and a transfer session. In the baseline and transfer
sessions participants were administered a Simon task,
whereas in the practice session they were administered a
spatial compatibility task with an incompatible S-R
mapping.
Both Simon and spatial compatibility tasks were per-
formed jointly with participants sitting side-by-side in
front of the same computer screen. In the spatial compat-
ibility task, each participant was instructed to respond to
only one stimulus location by pressing the contralateral
key. Hence the participant sitting on the right chair re-
sponded to left stimuli with the right key, whereas the par-
ticipant sitting on the left chair responded to right stimuli
with the left key. In the Simon task, each participant was
instructed to respond to only one stimulus color. For half
of the pairs, the participant sitting on the right chair was
instructed to press the right key to the red stimulus
whereas the participant sitting on the left chair was in-
structed to respond with the left key to the green stimulus.
The other half experienced the opposite mapping.
In both tasks, a trial began with the presentation of the
fixation cross at the center of a black background. After 1 s
the stimulus appeared to the right or to the left of fixation.
In the Simon task, the stimulus remained visible for 800 ms
and maximum time allowed for a response was 1 s. In the
spatial compatibility task the stimulus remained visible for
600 ms and maximum time allowed for a response was
350
375
400
425
450
r e f sna r Te n i l esaB
Session
RT (ms)
C
NC
Baseline Practice Transfer
*
Fig. 2. Mean reaction times (ms) for the baseline and transfer sessions of Experiment 1 as a function of stimulus–response correspondence. Bars indicate
standard errors of the means. Asterisks denote significant differences. C = corresponding; NC = non-corresponding.
N. Milanese et al./Cognition 116 (2010) 15–22
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1200 ms. In both task, a response terminated the trial and
the inter-trial-interval was 1 s.
Both baseline and transfer sessions consisted of 12
practice trials and 160 experimental trials that were di-
vided into two blocks of 80 trials each. The practice session
consisted of 12 practice trials and 300 experimental trials
that were divided into three blocks of 100 trials each.
2.2. Results and discussion
Here and in the following experiments we report only
the data for the Simon task (baseline and transfer sessions).
Correct RTs and arcsin-transformed error rates were
submitted to repeated-measures ANOVAs with session
(baseline vs. transfer) and correspondence (corresponding
vs. non-corresponding) as within-subject factors. The RTs
analysis revealed main effects of session, F(1, 15) = 11.33,
p < .01, g2
and correspondence,
p < .03, g2
(373 ms) than in the baseline (390 ms) session, and in cor-
responding (379 ms) than in non-corresponding (385 ms)
trials. Most important, there was a significant interaction
between the two factors indicating that the Simon effect
differed in the two sessions, F(1, 15) = 13.36, p < .01,
g2
14-ms Simon effect observed in the baseline session was
significant, while a null effect (?0.6 ms) was evident in
the transfer session.
The error rate was 1% in the baseline session and 1.6% in
the transfer session. The analysis revealed no main effects
or interactions. Hence, a spatially incompatible practice
performed jointly influences subsequent performance on
the joint Simon task.
p= .43,
p= .30. Participants were faster in the transfer
F(1, 15) = 6.37,
p= .47 (see Fig. 2). Post-hoc analyses confirmed that the
3. Experiment 2
The aim of the present experiment was to assess
whether the joint Simon effect can be modulated by an
individually- performed go-nogo practice with an incom-
patible mapping. In other words, we evaluated whether
the practice task used in Experiment 1 modulates joint
Simon task performance even when practice is performed
by a single individual. To this end, participants were
required to perform a joint Simon task before and after
performing a spatially incompatible practice in which they
responded to only one stimulus position. The finding of a
modulation would mean that practice of a specific incom-
patible stimulus–response link per se is responsible for the
modulation observed in Experiment 1.
3.1. Participants
Sixteen new students (eight males; four left-handers;
age range = 19–27 years) took part in Experiment 2. They
were selected as in Experiment 1.
3.2. Apparatus, stimuli and procedure
Apparatus, stimuli and procedure were the same as
Experiment 1 except for the followings.
During the practice session participants performed a
go-nogo spatial compatibility task by themselves, with
the instruction to respond to only one stimulus position
with the contralateral key. Half of the participants
responded to left stimuli with the right key, whereas the
other half responded to right stimuli with the left key.
During both baseline and transfer sessions participants
performed a Simon task jointly.
3.3. Results
Responses were comparable in the baseline and transfer
sessions, F < 1. Responses were faster in corresponding
(374 ms) than in non-corresponding
F(1, 15) = 19.69, p < .01, g2
evident in the baseline session did not differ from the 9-
ms effect evident in the transfer session, as indicated by
the non-significant interaction between session and corre-
spondence, F < 1 (see Fig. 3).
Errors were comparable in the baseline (1.2%) and
transfer (1.3%) sessions, F < 1. Errors tended to be fewer
in corresponding (0.6%) than in non-corresponding (1.9%)
trials, F(1, 15) = 3.91, p = .07. The same pattern was evident
in both sessions, as indicated by the lack of an interaction
between correspondence and session, F < 1.
These results allow us to conclude that when the partic-
ipants practice a specific stimulus–response link by them-
selves and then transfer to a joint Simon task, no transfer of
learning occurs.
The following experiments are aimed at assessing
whether a joint practice can influence subsequent individual
performance(Experiment3)andwhetherindividualpractice
can influence subsequent joint performance (Experiment 4).
(383 ms) trials,
p= .57. The 10-ms Simon effect
4. Experiment 3
The aim of the present experiment was to assess
whether shared prior practice modulates the way a single
individual performs a subsequent Simon task. To this end,
participants were required to perform alone a Simon task
before and after performing a joint practice with a spatially
incompatible mapping between stimulus and response.
4.1. Participants
Sixteen new right-handed students (seven males; age
range = 19–23 years) took part in Experiment 3. They were
selected as in Experiment 1.
4.2. Apparatus, stimuli and procedure
Apparatus, stimuli and procedure were the same as
Experiment 1 except for the followings.
During the baseline and transfer sessions participants
performed a standard Simon task by their own, whereas
during the practice session they performed a spatial com-
patibility task jointly. During both baseline and transfer
sessions participants sat back-to-back in front of two
different computers and were instructed to respond to
both stimulus colors with a left or right response.
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4.3. Results
Responses were faster in the transfer session (439 ms)
compared to the baseline session (469 ms), F(1, 15) =
15.55, p < .01, g2
in non-corresponding (467 ms) trials, F(1, 15) = 17.61,
p < .01, g2
baseline session did not differ from the 21-ms effect evi-
dent in the transfer session, as indicated by the non-signif-
icant interaction between session and correspondence,
F(1, 15) = 1.29, p = .27, g2
To assess whether only the specific S-R link practiced by
each participant during the practice session was trans-
ferred to the Simon task, RTs in the transfer session were
analyzed as a function of stimulus position, response posi-
tion and practiced S-R link. No interaction involving S-R
link reached significance, Fs < 1.
Errors were comparable in the baseline (3.5%) and
transfer (4.3%) sessions, F(1, 15) = 2.80, p = .11. The analy-
sis revealed a main effect of correspondence, F(1, 15) =
4.29, p = .05, with fewer errors in corresponding (2.9%)
than in non-corresponding (5%) trials. The same pattern
was evident in both sessions, as indicated by the lack of
an interaction between correspondence and session, F < 1.
Hence, a spatially incompatible practice performed jointly
with another person seems to have no influence on indi-
vidual performance on a subsequent Simon task.
p= .51, and in corresponding (442 ms) than
p= .54. The 29-ms Simon effect evident in the
p= .08 (see Fig. 4).
5. Experiment 4
The aim of the present experiment was to assess
whether an individually-performed prior practice can
modulate the way a subsequent joint Simon task is per-
formed. To this end, participants were required to perform
a joint Simon task before and after performing alone a
practice with a spatially incompatible mapping between
stimulus and response.
5.1. Participants
Sixteen new students (five males; one left-hander; age
range = 22–29 years), selected as in the previous experi-
ments, took part in Experiment 4.
5.2. Apparatus, stimuli and procedure
Apparatus, stimuli and procedure were the same as
Experiment 3 except that during the baseline and transfer
sessions participants performed a joint Simon task,
whereas during the practice session they performed a spa-
tial compatibility task alone, sitting back-to-back in front
of two different computers.
5.3. Results
Responseswerefasterincorresponding(383 ms)thanin
non-corresponding (390 ms) trials, F(1, 15) = 4.29, p = .05,
g2
but interacted with correspondence, F(1, 15) = 6.99, p <
.02, g2
differed in the two sessions. Post-hoc analyses confirmed
that the 10-ms Simon effect observed in the baseline
session was significant, while a null effect (3 ms, n.s.) was
evident in the transfer session.
Errors were comparable in the baseline (0.2%) and
transfer(0.5%)sessions,
F(1, 15) = 1.19,
p= .22. Session did not reach statistical significance, F < 1,
p= .32 (see Fig. 5), indicating that the Simon effect
p = .29.The
350
375
400
425
450
r e f sna r Ten i l e saB
Session
RT (ms)
C
NC
Baseline Practice Transfer
*
*
Fig. 3. Mean reaction times (ms) for the baseline and transfer sessions of Experiment 2 as a function of stimulus–response correspondence. Bars indicate
standard errors of the means. Asterisks denote significant differences. C = corresponding; NC = non-corresponding.
N. Milanese et al./Cognition 116 (2010) 15–22
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analysis
F(1, 15) = 5.99, p = .03, with fewer errors in corresponding
(0.6%) than in non-corresponding (0.1%) trials. The same
pattern was evident in both sessions, as indicated by the
revealedamain effect ofcorrespondence,lack of an interaction between correspondence and ses-
sion, F < 1.
These results indicated that a spatially incompatible
practice performed by a single individual influences the
400
425
450
475
500
r e f sn a r Te n i l esaB
Session
RT (ms)
C
NC
BaselinePractice Transfer
*
*
Fig. 4. Mean reaction times (ms) for the baseline and transfer sessions of Experiment 3 as a function of stimulus–response correspondence. Bars indicate
standard errors of the means. Asterisks denote significant differences. C = corresponding; NC = non-corresponding.
350
375
400
425
450
r e f sna r Te n i l esaB
Session
RT (ms)
C
NC
BaselinePractice Transfer
*
Fig. 5. Mean reaction times (ms) for the baseline and transfer sessions of Experiment 4 as a function of stimulus–response correspondence. Bars indicate
standard errors of the means. Asterisks denote significant differences. C = corresponding; NC = non-corresponding.
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subsequent performance on the joint Simon task, eliminat-
ing the Simon effect in RTs.
5.4. Meta-analysis
To note, even though in Experiment 3 the session ? cor-
respondence interaction did not reach statistical signifi-
cance, there was a 8-ms reduction in the size of the
Simon effect from baseline to transfer. This absolute reduc-
tion was smaller than the reduction observed in Experi-
ment 1 but comparable to that observed in Experiment 4.
To further assess whether the session ? correspondence
interaction changed across the three experiments, we com-
puted the difference between mean baseline and transfer
Simon effects divided by the baseline Simon effect for each
subject. Then we performed a repeated-measures ANOVA
on these values with experiment as between-subjects
factor1.
The main effect of experiment approached significance,
F(2, 45) = 2.75,
p = .07, g2
showed that the reduction of the Simon effect from prac-
tice to transfer was comparable in Experiments 1 and 4
(104% vs. 70%). These reductions significantly differed
(ps 6 .05) from the (non-significant) reduction observed
in Experiment 3 (28%). Hence, these results clearly show
that the modulation of the Simon effect by prior practice
occurred only in Experiments 1 and 4.
p= .11.Planned comparisons
6. General discussion
The main aim of the present study was to assess
whether transfer-of-learning effects observed when indi-
viduals perform a task in isolation are evident under task
sharing situations. Previous studies have shown that when
a task is distributed between two agents, each one tends to
integrate the other’s task and actions into his/her action
plan. This is thought to occur because, as suggested by
the ideomotor theory (e.g., Greenwald, 1970), the observa-
tion or even the imagination of an action activates a repre-
sentation in the observer similar to the representation
activated when the same action is actually performed
(e.g., Brass, Bekkering, & Prinz, 2001; Sebanz et al., 2003;
Tsai et al., 2008).
Although the effects of acting jointly with another indi-
vidual on immediate performance are well documented,
there are no studies assessing the influence exerted by
shared practice on subsequent performance. This is a rele-
vant issue because we often learn to perform novel tasks
interacting with other people and then have to transfer
the acquired skills and knowledge to similar tasks we
may perform either alone or together with another person.
Similarly, we may learn to perform a task alone and then
transfer this learning to activities performed with a co-ac-
tor. Knowingwhetherlearning transfersfrom social to indi-
vidual contexts and vice versa may have important
practical implications in several domains and may also help
us to shed light on some open issues regarding the nature
and the boundary conditions of shared representations.
To address this issue, we conducted four experiments in
which participants were required to practice on a spatial
compatibility task with an incompatible S-R mapping and
then transfer to a Simon task. We manipulated the pres-
ence of a co-actor in the practice and/or in the transfer ses-
sions. Our results showed that an incompatible practice
performed with a co-actor eliminated the Simon effect
only when also the Simon task was distributed between
two participants (Experiment 1). No reduction was evident
when a single individual performed a go-nogo incompati-
ble practice before performing a joint Simon task (Experi-
ment2).While anindividually-performed
modulated the way the joint Simon task was performed,
eliminating the joint Simon effect (Experiment 4), a shared
practice did not reduce the Simon effect when the Simon
task was performed by a single participant (Experiment 3).
The results of the present study may provide some
important information on the nature of shared representa-
tions and may help us understand the similarities and dif-
ferences between the representations activated by action
execution and those activated by action observation. It
has been shown that in humans action execution and ac-
tion observation activate partially overlapping areas (e.g.,
Grèzes & Decety, 2001). However, even though there is
growing evidence of the functional similarity between rep-
resentations of self and other’s action, it is still unclear
whether they are completely equivalent. The smaller mag-
nitude of the joint Simon effect compared to the standard
effect seems to suggest that they are somehow different.
The observation that the Simon effect is modulated by a
joint incompatible practice would suggest that a specific S-
R link that a participant is not actually practicing but is
practiced by his/her co-actor is able to exert an influence
on his/her own future behavior in the same way as a link
that has been actually practiced. Hence, it would be plausi-
ble to conclude that shared representations are completely
equivalent to the representations elicited when an agent
performs alone the whole task. Our results showed that
this occurs only under some circumstances. On the one
hand, the finding of a modulation of the Simon effect under
joint action conditions in Experiment 1 supports the view
that shared practice may have the same effects of an indi-
vidually-performed practice. Specifically, similarly to what
occurs with individuals acting in isolation (Iani et al., 2009;
Proctor & Lu, 1999; Tagliabue et al., 2000), a spatially
incompatible practice performed in a social context
strengthens the non-corresponding association between a
stimulus position and its incompatible response and influ-
ences subsequent performance even when stimulus loca-
tion is no longer task relevant. On the other hand, the
results of Experiment 3 demonstrate that these transfer-
of-learning effects are maximal only when both practice
and transfer take place in a social setting. Hence, learning
taking place in either individual or social settings can influ-
ence shared performance in a subsequent task. On the con-
trary, a shared practice has no effect on individual
performance.
practice
1Since the individual Simon effect is numerically larger than the joint
Simon effect, to compare the different conditions, we adjusted the
difference between the Simon effects evident in the baseline and transfer
sessions taking the baseline value as a reference. The obtained values
represent the relative reduction in the size of the effect from baseline to
transfer.
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The lack of transfer-of-learning effects from social to
individual contexts may be explained by the mechanisms
involved in task sharing. When a task is distributed be-
tween two agents, each one tends to represent the other’s
part of the task. However, to emit the correct response at
the right time, they also need to keep their own and the
other’s part of the task separated. Consistent with this idea,
results of Sebanz et al. (2007) showed that acting with an-
other person led to increased brain activity in ventral
mediofrontal cortex, which is thought to be involved in
the distinction between self and other (e.g., Amodio &
Frith, 2006). Hence, performing the whole task does not
completely correspond, at least at a neural level, to per-
forming only part of the task.
At a more general level, we showed the influence of
joint task performance on incidental learning and the
transfer of this learning to subsequent performance. These
results may allow us to better define the relationship be-
tween social learning and performance. According to
Vygotsky’s idea, what makes human beings different from
other species is their ability to learn by interacting with
other people (cf. Tomasello & Carpenter, 2007; Tomasello,
Kruger, & Ratner, 1993). Children learn by observing what
the adult is doing, internalize what is learned and then
transfer the acquired knowledge to individual perfor-
mance. Our results underline the importance of social
learning but allow us to identify some of its boundary con-
ditions and to better define what is learned. Specifically,
they show that under task sharing conditions, the knowl-
edge acquired during the performance of a task is internal-
ized and transferred to a similar task. The finding that a
joint practice influences performance only when also the
transfer task occurs in a social context suggests that what
is transferred is not only what is specifically practiced but
also aspects of the interactive context in which learning
took place.
Acknowledgements
We would like to thank two anonymous Reviewers for
useful comments on an earlier version of the manuscript.
We also wish to thank Luca Ferraro for helping with data
collection for Experiment 2.
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