Collective Goals and Motor Representations

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Collective Goals and Motor Representations

Motor representations concern not only bodily configurations and movements but also more distal outcomes such as the grasping of a mug or the pressing of a switch \citep{butterfill:2012_intention,hamilton:2008_action,cattaneo:2009_representation}.

Some motor processes are planning-like in that they involve deriving means by which the outcomes could be brought about and in that they involve coordinating subplans \citep{jeannerod_motor_2006,zhang:2007_planning}.

Motor processes concerning actions others will perform occur in observing others act \citep{Gangitano:2001ft}---and even in observing several others act jointly \citep{manera:2013_time}---and enables us to anticipate their actions \citep{ambrosini:2011_grasping,aglioti_action_2008}.

In joint action, motor processes concerning actions another will perform can occur \citep{kourtis:2012_predictive, meyer:2011_joint}, and can inform planning for one's own actions \citep{vesper:2012_jumping,novembre:2013_motor,loehr:2011_temporal}.

In some joint actions, the agents have a single representation of the whole action (not only separate representations of each agent's part) \citep{tsai:2011_groop_effect,loehr:2013_monitoring,Menoret:2013fk}, and may each make a plan for both their actions \citep{meyer:2013_higher-order,kourtis:2014_attention}.

An interagential structure of motor representation: \begin{enumerate} \item there is an outcome to which a joint action could be collectively directed and in each agent there is a motor representation of this outcome; \item these motor representations trigger planning-like processes in each agent which result in plan-like hierarchies of motor representations; \item the plan-like hierarchy in each agent involves motor representations concerning another's actions as well as her own; \item the plan-like hierarchies of motor representations in the agents nonaccidentally match. \end{enumerate}

\section{Motor Representation}

A \emph{goal} is an outcome to which an action is directed.

Motor representations represent goals such as the grasping of an egg or the pressing of a switch. These are outcomes which might, on different occasions, involve very different bodily configurations and joint displacements (see \citealp{rizzolatti_functional_2010} for a selective review).

Motor representations trigger processes which are planning-like insofar as they involve (a) computing means from representations of ends; and (b) satisfying relational constraints on actions.

Recall how Ayesha takes a glass and holds it up while Beatrice pours prosecco; and unfortunately the prosecco misses the glass, soaking Zachs’s trousers. Ayesha might say, truthfully, ‘The collective goal of our actions was not to soak Zach's trousers in sparkling wine but only to fill this glass.’ What could make Ayesha’s statement true?

As this illustrates, some actions involving multiple agents are purposive in the sense that

among all their actual and possible consequences,

there are outcomes to which they are directed

and the actions are collectively directed to this outcome

so it is not just a matter of each individual action being directed to this outcome.

In such cases we can say that the actions have a collective goal.

As what Ayesha and Beatrice are doing---filling a glass together---is a paradigm case of joint action, it might seem natural to answer the question by invoking a notion of shared (or `collective') intention. Suppose Ayesha and Beatrice have a shared intention that they fill the glass. Then, on many accounts of shared intention,

the shared intention involves each of them intending that they, Ayesha and Beatrice, fill the glass; or each of them being in some other state which picks out this outcome.

The shared intention also provides for the coordination of their actions (so that, for example, Beatrice doesn't start pouring until Ayesha is holding the glass under the bottle). And coordination of this type would normally facilitate occurrences of the type of outcome intended. In this way, invoking a notion of shared intention provides one answer to our question about what it is for some actions to be collectively directed to an outcome.

Are there also ways of answering the question which involve psychological structures other than shared intention? In this paper we shall draw on recent discoveries about how multiple agents coordinate their actions to argue that the collective directedness of some actions to an outcome can be explained in terms of a particular interagential structure of motor representations. Our actions having collective goals is not always only a matter of what we intend: sometimes it constitutively involves motor representation.

What about the Simple View Revised?

At this point I want to return to considering Simple View Revised. So far I haven’t offered an objection directly to this view.

Simple View

Two or more agents perform an intentional joint action
exactly when there is an act-type, φ, such that
each agent intends that
they, these agents, φ together
and their intentions are appropriately related to their actions.

Simple View Revised

... and

we engage in parallel planning;

for each of us, the intention that we, you and I, φ together leads to action via our contribution to the parallel planning

(where the intention, the planning and the action are all appropriately related).

Parallel planning means that the Simple View Revised provides one explanation of how it is that our actions could have a collective goal. [for later: link between iasmr and parallel planning (same structure)]

Few discussions of joint action have considered the existence of Very Small Scale Shared Agency ...

Very Small Scale
Shared Agency

A \emph{very small scale action} is one that is typically distantly related as a descendent by the means-end relation to the actions which are sometimes described as ‘small scale’ actions, such as playing a sonata, cooking a meal or painting a house \citep[e.g.][p.~8]{bratman:2014_book}.

There are very small scale joint actions like playing a chord together in the course of playing a duet, clinking glasses in the course of toasting our success, or plassing a plate between us in the course of doing the washing up together.

Small Scale
Shared Agency

Very Small Scale
Shared Agency

Playing a piano duet

Playing a chord together

Toasting our success together

Clinking glasses

Washing up together

Passing a plate between us

Philosophers have rarely considered such very small scale joint actions. But at least some such cases seem to involve exercising shared agency no less than larger scale activities like painting a house together.

But very small scale joint actions create a challenge to views like Gilbert’s.

Those views hinge on the roles of intention and practical reasoning.

But in at least some cases, very small scale joint actions are not a consequence of practical reasoning concerning those particular actions, nor need they involve intentions which specify outcomes to which the very small scale joint actions are directed. There is simply no need for practical reasoning, or intention, in many such cases. This is particularly obvious if you think about very small scale joint actions which occur in the context of larger scale activities, such as our playing a chord in the course of playing a piano duet.

Of course, there is no principled bar to having intentions concerning the goals of such very small scale actions (as far as I know), and such intentions may sometimes exist. But in very small scale cases of acting together, intentions and practical reasoning are often superfluous and sometimes absent.

Despite this, these very small scale interactions appear to involve exercises of shared agency no less than small scale activities such as playing a piano duet.

For very small scale cases, in virtue of what might they have collective goals?

motor representations represent outcomes and trigger planning-like processes

Let me mention some almost uncontroversial facts about motor representations and their action-coordinating role.

Suppose you are a cook who needs to take an egg from its box, crack it and put it (except for the shell) into a bowl ready for beating into a carbonara sauce. Even for such mundane, routine actions, the constraints on adequate performance can vary significantly depending on subtle variations in context. For example, the position of a hot pan may require altering the trajectory along which the egg is transported, or time pressures may mean that the action must be performed unusually swiftly on this occasion. Further, many of the constraints on performance involve relations between actions occurring at different times. To illustrate, how tightly you need to grip the egg now depends, among other things, on the forces to which you will subject the egg in lifting it later. It turns out that people reliably grip objects such as eggs just tightly enough across a range of conditions in which the optimal tightness of grip varies. This indicates (along with much other evidence) that information about the cook’s anticipated future hand and arm movements appropriately influences how tightly she initially grips the egg (compare \citealp{kawato:1999_internal}). This anticipatory control of grasp, like several other features of action performance (\citealp[see][chapter 1]{rosenbaum:2010_human} for more examples), is not plausibly a consequence of mindless physiology, nor of intention and practical reasoning. This is one reason for postulating motor representations, which characteristically play a role in coordinating sequences of very small scale actions such as grasping an egg in order to lift it.

The scale of an actual action can be defined in terms of means-end relations. Given two actions which are related as means to ends by the processes and representations involved in their performance, the first is smaller in scale than the second just if the first is a means to the second. Generalising, we associate the scale of an actual action with the depth of the hierarchy of outcomes that are related to it by the transitive closure of the means-ends relation. Then, generalising further, a repeatable action (something that different agents might do independently on several occasions) is associated with a scale characteristic of the things people do when they perform that action. Given that actions such as cooking a meal or painting a house count as small-scale actions, actions such as grasping an egg or dipping a brush into a can of paint are very-small scale. Note that we do not stipulate a tight link between the very small scale and the motoric. In some cases intentions may play a role in coordinating sequences of very small scale purposive actions, and in some cases motor representations may concern actions which are not very small scale. The claim we wish to consider is only that, often enough, explaining the coordination of sequences of very small scale actions appears to involve representations but not, or not only, intentions. To a first approximation, \emph{motor representation} is a label for such representations.% \footnote{% Much more to be said about what motor representations are; for instance, see \citet{butterfill:2012_intention} for the view that motor representations can be distinguished by representational format. }

What do motor representations represent? An initially attractive, conservative view would be that they represent bodily configurations and joint displacements, or perhaps sequences of these, only. However there is now a significant body of evidence that some motor representations do not specify particular sequences of bodily configurations and joint displacements, but rather represent outcomes such as the grasping of an egg or the pressing of a switch. These are outcomes which might, on different occasions, involve very different bodily configurations and joint displacements (see \citealp{rizzolatti_functional_2010} for a selective review).

Such outcomes are abstract relative to bodily configurations and joint displacements in that there are many different ways of achieving them.

Motor representations make very small scale actions the actions they are. Which very small scale action you are performing or attempting to perform---for example, which phoneme you are articulating or attempting to articulate---is a matter of which outcomes are specified by the motor representations controlling your action.

Relatedly, motor representations can trigger processes which are like planning in some respects. These processes are planning-like in that they involve starting with representations of relatively distal outcomes and gradually filling in details, resulting in motor representations that can be hierarchically arranged by the means-end relation \citep{bekkering:2000_imitation,grafton:2007_evidence}. Some processes triggered by motor representations are also planning-like in that they involve meeting constraints on the selection of means by which to bring about one outcome that arise from the need to select means by which, later, to bring about another outcome \citep{jeannerod_motor_2006, zhang:2007_planning, rosenbaum:2012_cognition}.

Conjecture :
collective goals are represented motorically

\begin{enumerate} \item There is one outcome which each agent represents motorically, and \item in each agent this representation triggers planning-like processes \item concerning all the agents’ actions, with the result that \item coordination of their actions is facilitated. \end{enumerate}

Let me explain what this amounts to.

I.e. sometimes, when two or more actions involving multiple agents are, or need to be, coordinated:

Each represents a single outcome motorically, and
in each agent this representation triggers planning-like processes
concerning all the agents’ actions, with the result that
coordination of their actions is facilitated.

Each represents a single outcome motorically, and
in each agent this representation triggers planning-like processes
concerning all the agents’ actions, with the result that
coordination of their actions is facilitated.

What do we need? (i) Evidence that a single outcome to which all the actions are directed is represented motorically.

(ii) Evidence that this triggers planning-like processes,

(iii) where these concern all the agents' actions,

and (iv) the existence of such representations facilitates coordination of the agents' actions.

\section{Kourtis et al (2014)}

Garbarini et al, 2014 figure 3 (part)

To test this conjecture, Corrado Sinigaglia and I teamed up with Francesco della Gatta, Francesca Garbarini and Marco Rabuffetti. We adapted a bimanual paradigm, the circle-line drawing paradigm, which has been extensively employed for investigating bimanual interference (Franz et al, 1991).

When people have to simultaneously perform noncongruent movements, such as drawing lines with one hand while drawing circles with the other hand, each movement interferes with the other and line trajectories tend to become ovalized. This “ovalization” has been described as a \textbf{bimanual coupling effect}, suggesting that motor representations for drawing circles can affect motor representations for drawing lines (Garbarini et al. 2012; 2013a; 2015a; 2015b; Garbarini and Pia 2013; Piedimonte et al. 2014).

[repetitive] Suppose a straight line and a circle are being drawn at the same time. The straight line will exhibit ovalization.

This ovalization is not just a consequence of pysiology, for you find much the same ovalization when someone is merely imagining drawing the circle, and in patients with anosognosia for hemiplegia.

Instead, the ovalization is a sign that the goal of drawing the two lines, one straight and the other circular, is being represented motorically.

della Gatta et al, ‘Drawn Together’ Cognition 2017

In the key conditions of our adapted version of the circle-line drawing paradigm, participants were asked to unimanually draw circles with their right hands while observing either lines being unimanually drawn by a confederate (Garbarini et al, 2013b; Garbarini et al, 2016).

We contrasted a Parallel Action task with a Joint Action task. These tasks differed only in the instructions given.

In the Joint Action task participants were instructed to perform the task together with the confederate, as if their two drawing hands gave shape to a single design.

In the Parallel Action task, participants were given no such instruction so that they could draw in parallel, observing each other but not acting together.

If participants were to follow our instructions, their actions would have the collective goal of drawing a circle and a line in the Joint Action task but not in the Parallel Task.

Our conjecture entails that this collective goal could be represented motorically. Accordingly, we predicted that there should be an interpersonal motor coupling effect. This would result in greater ovalization of the lines drawn in the Joint Action task than in the Parallel Action task ...

And that was actually what we found.

Our hypothesis is that interpersonal motor coupling may occur when an individual is acting unimanually, providing she is acting jointly with another and not merely acting in parallel. This is because in joint action, but not in parallel action, an individual could represent motorically the collective goal of drawing both a circle and a line even if she is actually only drawing a line. Somewhat as in the case of individual bimanual action, so also in joint action: the motor representations of one hand’s drawing can influence the motor representations of the other hand’s drawing. One difference in joint action, of course, is that the hands belong to different individuals.

della Gatta et al, ‘Drawn Together’ Cognition 2017

Parallel

“Look at the screen in front of you. You will see either circles or lines drawn by the experimenter [i.e. confederate] sitting in front of you. Look at them while drawing either a circle or a line. While drawing, please don’t lift the pen from the tablet and try to take advantage of the whole drawing area.”

So far I've been providing some evidence for the conjecture that collective goals are represented motorically.

It’s important to stress that is is only one bit of the evidence. There’s quite a bit more.

Conjecture :
collective goals are represented motorically

I.e. sometimes, when two or more actions involving multiple agents are, or need to be, coordinated:

Each represents a single outcome motorically, and
in each agent this representation triggers planning-like processes
concerning all the agents’ actions, with the result that
coordination of their actions is facilitated.

In particular the evidence I have provided doesn’t address the issue of coordination. There is a little bit of direct evidence for this that I won't mention.

And of course much more evidence would be needed before we could regard the conjecture as established.

In virtue of what do actions involving multiple agents ever have collective goals?

cooperation?

So much for motor representation. How does this relate to cooperation?

Earlier I suggested that

Purposive actions are cooperative to the extent that, for each agent, her performing these actions rather than any other actions depends in part on how good an overall pattern of trade-offs between demandingness and well-suitedness can be achieved for all of the actions.

Now I want to suggest that

Where we each represent a collective goal motorically, our actions will normally be cooperative in this sense.

Why is this true?

Motor representation of collective goal in each of us.

In each of us, the motor representation triggers a process which results in a plan-like structure of motor representations. These motor representations concern all of our actions, yours and mine.

These motor representations are agent-neutral. The motor process constructs the plan-like structure in such a way as to achieve a good pattern of trade offs between demandingness and well-suitedness across all of the actions, yours and mine.

Further, because humans are quite similar motorically, in many situations our motor plans will nonaccidentally match. That is, they will be identical or be such that differences between them do not matter to our coordination.

So the actions you perform will have been selected in part because they enable a good balance of pattern of trade offs between demandingness and well-suitedness across all of our actions, yours and mine. And this is just what cooperation requires.

[ALT: ...]

Because in the sort of parallel-planning triggered by the motor representations in an interagential structure of motor representations, there is no distinction between actions I will perform and actions you will perform.

I am, in effect, just trying to work out the best way to achieve the outcome irrespective of who does what; and so are you; and this is the hallmark of effective cooperation.

To illustrate, consider a case where I grasp a mug and pass it to you. Considering just my action, let’s say it is most comfortable for me to grasp the mug by the handle. But this would force you to grip the mug awkwardly, making the overall awkwardness of our action very high. If our actions are cooperative, I will attempt to reduce the overall awkwardness by grasping the mug in a way that is slightly less awkward for me. And I am likely not to grasp it by the handle \citep{meyer:2013_higher-order}. Instead, I will adopt a more awkward

Where we each represent a collective goal motorically, our actions will normally be cooperative.

Limit: very small scale joint actions

What’s exciting isn’t that all cooperation involves motor representations. It’s that mere motor representation makes any cooperative actions possible at all. Cooperative action isn’t something that depends on terribly sophisticated notions like shared intention or joint commitment. It begins with the motoric.

\textbf{A certain interagential structure of motor representation is among the things which can enable humans to cooperate.}

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