Natural
Inter-
actions
Theoretical & Motor Aspects
So how have philosophers’ attempted to answer these questions?
The key device is the use of examples and contrast cases.
To illustrate, suppose a scientist and a philosopher walk into the park.
They see two sisters cycling to school together.
This is a paradigm example of joint action.
The scientist immediately asks, How are their actions coordinated?
The philosopher objects: There’s more to joint action than mere coordination.
We know this because
in another park there are two strangers who happen to be cycling the same route side-by-side.
And although the strangers are not engaged in joint action---their’s are a parallel but
merely individual actions---, their actions do need to be exquisitely coordinated if they
are not to collide.
Bratman offers a counterexample to something related to the Simple View \citep[see][]{Bratman:1992mi,bratman:2014_book}.
Suppose that you and I each intend that we, you and I, go to New York together.
But your plan is to point a gun at me and bundle me into the boot (or trunk) of your
car.
Then you intend that we go to New York together, but in a way that doesn't
depend on my intentions. As you see things, I'm going to New York with you whether
I like it or not. Does this provide the basis for an objection to the Simple View?
Bratman’s ‘mafia case’
Michael Bratman offers a counterexample to something related to the Simple View.
Suppose that you and I each intend that we, you and I, go to New York together.
But your plan is to point a gun at me and bundle me into the boot (or trunk) of your
car.
Then you intend that we go to New York together, but in a way that doesn't
depend on my intentions. As you see things, I'm going to New York with you whether
I like it or not. This doesn't seem like the basis for shared agency.
After all, your plan involves me being abducted.
But it is still a case in which we each intend that we go to New York together and we do.
So, apparently, the conditions of the Simple View are met (or almost met) and yet there is
no shared agency.
***BRATMAN's DIAGNOSIS - have to intend to do it by way of the other’s intentions.
This is what is wrong in mafia case.
Shared agency means connecting with each other as agents, not merely as bodies
Bratman’s brilliant idea for avoiding this sort of problem is to suggest that we don’t just each intend the action but rather we each intend to act by way of the other's intentions.
We can put this by saying that our intentions must interlock: mine specify yours and yours mind.
Now this appeal to interlocking intentions enables Bratman to avoid counterexamples like the Tarantino walkers; if I intend that we walk by way of your intention that we walk, I suppose can't rationally also point a gun at you and coerce you to walk.
‘each agent does not just intend that the group perform the […] joint action.
‘Rather, each agent intends as well that the group perform this joint action in accordance with subplans (of the intentions in favor of the joint action) that mesh’
(Bratman 1992: 332)
`each agent does not just intend that the group perform the […] joint action. Rather, each agent intends as well that the group perform this joint action in accordance with subplans (of the intentions in favor of the joint action) that mesh' \citep[p.\ 332]{Bratman:1992mi}.
Our plans are \emph{interconnected} just if facts about your plans feature in mine and conversely.
‘shared intentional [i.e.\ collective] agency consists, at bottom, in interconnected planning agency of the participants’ \citep{Bratman:2011fk}.
One feature of Bratman’s account is that you can be engaging in a joint action even if
you merely see the other’s intentions as opportunities to exploit and constraints to work around.
As long as you know about, and go along with, the other’s intentions, there is
joint action.
Many, like Gilbert find this unacceptable
common goal
A common goal is is a single goal to which the
agents’ actions are directed.
[Can illustrate common vs collective goal with current political situation in
which the actions of bitter rivals may have a common goal but no collective goal
(unlike the political allies).]
This is still not enough. To see why, suppose that
the strangers’ actions are no longer coordinated and they are walking
different routes to their gate, but that
each stranger is concerned that
the Marseille flight should leave on time. As each sees it, the only thing she can
do to this end is to walk to the gate. Her actions are therefore directed to the
same goal as the other’s: to ensure the Marseille flight leaves on time.
So there is one goal to which each of their actions are directed; that is, a common
goal. I suspect we still haven’t captured what talk of a ‘we mode’ aims at.
Kourtis et al, 2012
Kourtis et al, 2012
Kourtis et al, 2012
Kourtis et al (2014, figure 1c)
I think we're a long way from having a large body of converging evidence for this conjecture,
but there is some that points in this direction.
One of the most relevant experiments is this one by \citet{kourtis:2014_attention}.
They contrasted a simple joint action involving two agents clinking glasses.
The CNV is a signal of motor preparation for action which is time-locked to action onset.
In previous research, Kourtis et al show (i) that the CNV occurs when joint action
partners act, suggesting that when acting together we represent others' actions motorically
as well as our own \cite{kourtis:2012_predictive};
and
(ii) (roughly) a stronger CNV occurs in relation to actions of others one is engaged in joint action than
in relation to actions of others one is merely observing \cite{kourtis:2010_favoritism}.
Kourtis et al hypothesised that in actions like clinking glasses,
A single outcome represented is motorically,
which triggers planning-like processes
concerning all the agents' actions.
This leads to the prediction that the CNV in joint action will resemble that occurring in
bimanual action more than that occuring in unimanual action.
Kourtis et al (2014, figure 4a)
... and this is exactly what they found.
Ramenzoni et al, 2014 figure 1
Importantly there is converging evidence for the involvement of motor representation concerning
a partner’s action in joint action from studies which use behavioural measures ...
Joint performance is better when observing joint actors; individual performance when observing
individual actors.
Ramenzoni et al, 2014 figure 1
Ramenzoni et al, 2014 figure 1
della Gatta et al, ‘Drawn Together’ Cognition 2017
So once again we are forced to ask,
What are those motor representations doing here?
Sacheli et al, 2018 figure 2 (part)
Sacheli et al, 2018 figure 5
[Skip -- just in case anyone asks]
Sacheli et al, 2018 figure 3
Let me start by stepping back and consider an individual action.
An agent moves a mug from one place to another, passing in from her left hand to her right hand half way [*demonstrate].
It’s a familiar idea that motor representations of outcomes resemble intentions in that they can trigger processes which are like planning in some respects.
These processes are like planning in that they involve starting with representations of relatively distal outcomes and gradually filling in details, resulting in a structure of motor representations that can be hierarchically arranged by the means-end relation \citep{bekkering:2000_imitation,grafton:2007_evidence}.
Processes triggered by motor representations of outcomes are also planning-like in that they involve selecting means for actions to be performed now in ways that anticipate future actions \citep{jeannerod_motor_2006,zhang:2007_planning,rosenbaum:2012_cognition}.
Now in this action of moving a mug, there is a need, even for the single agent, to coordinate the exchange between her two hands.
(If her action is fluid,
she may proactively adjust her left hand in advance of the mug’s being lifted by her right hand \citep[compare][]{diedrichsen:2003_anticipatory,hugon:1982_anticipatory, lum:1992_feedforward}.)
How could such tight coordination be achieved?
Part of the answer involves the fact that motor representations and processes concerning the actions involving each hand are not entirely independent of each other.
Rather there is a plan-like structure of motor representation for the whole action and motor representations concerning actions involving each hand are components of this larger plan-like structure.
It is in part because they are components of a larger plan-like structure that the movements of one hand constrain and are constrained by the movements of the other hand.
Earlier we considered what is involved in performing an ordinary, individual action, where an agent moves a mug from one place to another passing it between her hands half-way.
Compare this individual action with the same action performed by two agents as a joint action.
One agent takes the mug and passes it to the other, who then places it.
The joint action is like the individual action in several respects.
First, the goal to which the joint action is directed is the same, namely to move the mug from here to there.
Second, there is a similar coordination problem---the agents’ two hands have to meet.
And, third, the evidence we have mentioned suggests that in joint action, motor representations and processes occur in each agent much like those that would occur if this agent were performing the whole action alone.
Why would this be helpful?
Suppose the agents' planning-like motor processes are similar enough that, in this context, they will reliably produce approximately the same plan-like structures of motor representations.
Then having a single planning-like motor process for the whole joint action in each agent means that
\begin{enumerate}
\item in each agent there is a plan-like structure of motor representations concerning each of the others’ actions,
\item each agent's plan-like structure concerning another's actions is approximately the same as any other agent's plan-like structure concerning those actions,
\item each agent's plan-like structure concerning her own actions is constrained by her plan-like structures concerning the other’s actions.
\end{enumerate}
So each agent’s plan-like structure of motor representations concerning her own actions is indirectly constrained by the other agents' plan-like structures concerning their own actions
by virtue of being directly constrained by her plan-like structures concerning their actions.
In this way it is possible to use ordinary planning-like motor processes to achieve coordination in joint action.
What enables the two or more agents' plan-like structures of motor representations to mesh is not that they represent each other's plans but that they processes motorically each other's actions and their own as parts of a single action.
So how does the joint action differ from the corresponding individual action?
There are at least two differences.
First, we now have two plan-like structures of motor representations because in each agent there is a planning-like motor process concerning the whole action.
These two structures of motor representations have to be identical or similar enough that the differences don’t matter for the coordination of the agents’ actions---let us abbreviate this by saying that they have to \emph{match}.
The need for matching planning-like structures is not specific to joint action;
it is also required where one agent observing another is able to predict her actions thanks to planning-like motor processes concerning the other’s actions (we mentioned evidence that this occurs above).
A second difference between the joint action and the individual action is this.
In joint action there are planning-like motor processes in each agent concerning some actions which she will not eventually perform.
There must therefore be something that prevents part but not all of the planning-like motor process leading all the way to action.
Exactly how this selective prevention works is an open question.
We expect bodily and environmental constraints are often relevant.
There may also be differences in how others’ actions are processed motorically \citep[compare][]{novembre:2012_distinguishing}.
\footnote{\citep[p.\ 2901]{novembre:2012_distinguishing}: 'in the context of a joint action—the motor control system is particularly sensitive to the identity of the agent (self or other) of a represented action and that (social) contextual information is one means for achieving this distinction'}
And inhibition could be involved too \citep[compare][]{sebanz:2006_twin_peaks}.
My proposal, then, is this.
In both practical reasoning and motorically, sometimes agents are able to achieve coordination
for joint action not by representing each others’ plans but
by treating each other's actions and their own as if they were parts of a single action.
This is the fundamental idea behind co-representation, as I see it.
conclusion
In conclusion, ...