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online handout

Motor Mindreading?

[email protected] & [email protected]

Cecilia’s talk is about narrowing down the potential functions of mirror neurons and stepping back from some of the wildest ideas about their roles in our lives.
My aim in this talk is to complement hers by suggesting that there may be a further function for mirror neurons.
Building on the her agreement that mirror neurons may be involved in tracking others’ actions, I want to suggest that there is a case for the view that they are also involved in tracking others’ mental states.
Let me start with a little bit of tidying up, that I think will be entirely uncontrovesial.

‘“mirror” areas [...] encode concrete representations of observed actions

(e.g.,the action involved in opening a particular bottle)

rather than abstract, higher level representations

(e.g., the goal “to open”; Wurm & Caramazza, span 2019; Wurm & Lingnau, 2015).’

(Heyes & Catmur, 2022, p. 155)

Wurm & Lingnau (2015, p. figure 1, part)

but ...

mirror activation contingent on correctness of the action

NB: effect observed in pianists but not in non-pianists who were trained to detect the errors

Candidi, Maria Sacheli, Mega, & Aglioti (2014, p. figure 1)

Point here is just that mirror activation contingent on correctness of the action.
But if had more time could also say that the timing issue is important (and Wurm & Lingnau (2015) are not getting at timing) because Candidi distinguish early mirror responses (not sensitive to correctness) from later mirror responses.
Good review and commentry in (Naish, Houston-Price, Bremner, & Holmes, 2014)
[Cecelia might argue that there’s low spatial resolution. But the muscle-specific responses indicate that motor processes are certainly involved. Can also counter that low temporal resolution of fMRI may be a limiting factor]
[figure text] ‘Figure 3. The left panel of the figure shows the significant interaction of response and muscle factors where the facilitation of corticospinal excitability found for Hit trials was restricted to APB and did not expand to the other muscles. The right panel of the figure shows the significant interaction between response and time factors in pianists where the facilitation of the corticospinal excitability during Hit trials was absent 100 ms, was clearly significant 300 ms, and was still present as a strong trend 700 ms after error observation. Mean ± standard error mean (SEM).’

Some markers of motor representation ...

1. are unaffected by variations in kinematic features but not goals

Cattaneo, Sandrini, & Schwarzbach (2010) showed participants ‘adapting movies’ of an action and then asked them to judge same/different for a test picture. TMS applied to PMv, IPL and STS for controls.
Results: In experiment 1, shorter RTs when TMS to PMv and IPL regardless of whether effector in test picture was some or different as in the adapting movie.
Results: In experiment 2, shorter RTs when TMS to STS but only if same effector used; TMS to PMV reduces RTs for both effectors (see Figure 4).

2. are affected by variations in goals but not kinematic features

Villiger, Chandrasekharan, & Welsh (2010): TMS-enhanced MEPs measures.
Target muscle is the flexor pollicis brevis (FPB) in the arm, which would be involved in lifting the egg-like object.
Findings are that MEPs are significantly lower when the object is present compared to when it is absent. (This is a bit counterintuitive: explained by inhibition required.)
Incidentally, ‘the observed direction of the modulation was not consistent with previous TMS literature. Specifically, MEP amplitudes were significantly lower in the Object-Present than in the Object-Absent conditions (Fig. 2), suggesting that there was an inhibitory effect of object manipulation on the activity of M1 during action observation.’
Cretu, Ruddy, Germann, & Wenderoth (2019) present some results that extend Villiger et al. (2010)’s also using TMS-enhanced MEPs and occulsion. By presenting an informative cue to the type of grasp, Cretu et al. (2019) show that you can get the MEP-effect even without any kinematic information. They compared precision-grip (PG) and whole-hand grip (WHG) stimuli, measuring MEPs from two corresponding muscles. See figure 4 (to understand the results) and figure 6 (main findings). (Not using Cretu et al. (2019) here because they do not actually vary whether or not the target object is present so not as good an illustration as Villiger et al., 2010.)

concrete vs abstract ?

lexically concrete

Motor representations in action observation carry information about opening this bottle not that one (Wurm & Lingnau, 2015).

kinematically abstract

Motor representations carry information about goals such as opening (Rizzolatti & Sinigaglia, 2016),

and about correctness (Naish et al., 2014).

-- concrete actions, not lexical action categories

-- distal goals, not kinemtic features

?

Two degrees of abstractness.

concrete vs abstract ?

lexically concrete

Motor representations in action observation carry information about opening this bottle not that one (Wurm & Lingnau, 2015).

kinematically abstract

Motor representations carry information about goals such as opening (Rizzolatti & Sinigaglia, 2016),

and about correctness (Naish et al., 2014).

-- concrete actions, not lexical action categories

-- distal goals, not kinemtic features

?

1. motor goal tracking

2. motor mindreading

The Background

Kovács Effect (Kovács, Téglás, & Endress, 2010)

Low, Edwards, & Butterfill (2020, p. figure 1, part) based on Kovács et al. (2010)

Low et al. (2020, p. figure 1, part) based on Kovács et al. (2010)

Low et al. (2020, p. figure 1, part) based on Kovács et al. (2010)

Low et al. (2020, p. figure 1, part) based on Kovács et al. (2010)

Low et al. (2020, p. figure 1, part) based on Kovács et al. (2010)

The Question

Why do others’ false beliefs ever have an effect on your own actions?

Also---a second question---, if this *is* fast mindreading, what kinds of process underpin it? (We know something about broad architectural features and maybe even about minimal models of mind; but we don’t have much of a theory about the processes it involves yet.)
Inspiration: Action anticipation can influence reaction times.
NB: In this experiment, participants had to imitate a reach-to-grasp movement which was modelled for them before the go-stimulus (the mug) appeared.
WHat is measured? Movement initiation times. (NB not response times.)

Costantini et al, 2010 figure 1b

Anticipation associated with other people’s action possibilities can also influence your movement initiation times.

Costantini et al, 2011 figures 3,4

Why do others’ false beliefs ever have an effect on your own actions?

Maybe it’s because others’ false beliefs influence whether you anticipate them performing certain actions, and those anticipations in turn influence your reaction times.

Conjecture: ???

Prediction: constraining others’ action possibilities will reduce task-irrelevant effects of their false beliefs on your reaction times.

It’s easy enough to understand the prediction; the conjecture that yields it is a bit harder to specify. So allow me to do this slowly ...

The Model

Outcomes such as reaching for and grasping of a cup can be represented motorically.
As a body of research on mirror neurons and motor simulation more generally demonstrates, motor representations of outcomes can generate expectations concerning another agent’s behaviour
These expectations are plausibly compared with the behavior that is actually observed.
And we conjecture that the result of this comparison modulates the strength of the motor representation of the outcome.
Within limits, this modulation will ensures that an outcome represented motorically is likely to be a goal of the observed action.
In this way, motor representations enable goal tracking.
So far we have nothing about belief-tracking. Where could that come in?
Jason’s pilot indicates that belief-tracking, which I suppose involves representing registrations, can influence behavioural expectations. But how?
In principle, we might imagine that the belief-tracking process results in a second, independent behavioural expectation.
While we cannot rule this possibility out, it seems to add theoretical complexity.
After all, belief-tracking depend so on goal-tracking in this way: you can only track another’s mental states by tracking their actions. We therefore need the goal-tracking process to provide input to the belief-tracking process.
But if the goal-tracking process ignores the belief-tracking process, then false beliefs would cause it to make systematic errors about the goals of actions. Since these errors would feed into the belief-tracking process, it would seem that this process too should go wrong whenever there is a false belief. But then there would be no point in tracking beliefs at all.
Our proposal is therefore different: the belief-tracking process influences the process by which the behavioural expectation is generated. The representation of registration means that behavioural expectation is generated as if things were as they are registered as being, rather than as they actually are. Put colourfully, another’s registration can change the world as seen by your motor system. (This might be why Katheryn has repeatedly found altercentric intereference effects of belief on motor actions.)
This picture has a radical implication about the nature of the automatic belief-tracking processes. It implies that those belief-tracking processes must interface directly with motor processes. This requires, in turn, that automatic belief-tracking represents objects and outcomes in the same format as the motor representations do. Motor processes and belief-tracking must share a common representational format.
Although lots of details are not specified by the picture, its is does make readily testable predictions. For one thing, it implies that limits on what can be represented motorically are also limits on automatic belief-tracking.

The Model’s Predictions

The picture also generates a prediction that has been tested: where a goal-tracking response is underpinned by motor simulation, the goal-tracking will manifest sensitivity to the observed agent’s beliefs. If Jason’s preliminary findings hold up, they will provide evidence that the prediction is correct.
So far, the picture is neutral about the timing of the effect. In order to better understand the link between belief-tracking and goal-tracking, it would be helpful to have information about the timings of these processes. In particular, it would be good to know whether the observed agent’s beliefs influence goal-tracking from the earliest point at which it can be observed, or whether there is a period during which goal-tracking processes are unaffected by the agent’s beliefs. In making this kind of discovery possible, Jason’s paradigm should enable us to understand more about how belief-tracking processes are linked (or not) to goal-tracking processes.

1. In motor mindreading only, goal-tracking will manifest sensitivity to agents’ beliefs.

2. In motor mindreading only, physically constraining protagonists (or participants) will impair belief tracking.

I will show you the good news first.

Some Evidence

mixed

Low et al. (2020, p. figure 1, part) based on Kovács et al. (2010)

Low et al. (2020, p. figure 1, part) based on Kovács et al. (2010)

Low et al. (2020, p. figure 1, part) based on Kovács et al. (2010)

Low et al. (2020, p. figure 1, part) based on Kovács et al. (2010)

Low et al. (2020, p. figure 2)

Nice replication, which is mildly interesting because we used a movie clips with real people rather than smurfs.
The loose sheet control works great: same Kovacs effect.
Any trace of which is just gone with the mumified figure. Now response times are just a function of the participants’ own beliefs.

Low et al. (2020, p. figure 3)

The Model’s Predictions

1. In motor mindreading only, goal-tracking will manifest sensitivity to agents’ beliefs.

2. In motor mindreading only, physically constraining protagonists (or participants) will impair belief tracking.

What about constraining participants (rather than the agent)? Cannot constrain participants with the Kovacs-paradigm (because depends on RTs and might not work if you switched from manual responses). So Pieter Six, who is a just-finished PhD student supervised by Jason Low and myself adapted a different paradigm involving anticipatory looking ...

Six (2022, p. figure 11)

‘participants in the movement-restricted group were required to hold on to the elastic band at the start of every experimental block.’ (Six, 2022, p. 98)
[Six (2022, p. 95) Experiment 1: ‘predictive gaze behaviour was modulated by the false belief state of the agent’] So far, so good. [In Experiment 1, we had no response to the videos required but there was a visual detection task - press a key when one of the cups turns purple, which we expected would help to keep people attentive and ‘disguise the real purpose of the expeirment’.]
The basic finding that false belief states modulate predictive gaze behaviour was partially replicated in Experiment 2, (although differently from Experiment 1, ‘In the false belief condition, we saw that anticipatory looking times generally sat around chance level.’ but this could be due to some technical difficulties with the equipment?) [Ask Pieter: I think the attention check still involved a keypress, which the participant could do with the elastic band?]
However the motor mindreading prediction was not supported: ‘Our crucial manipulation in this experiment was the addition of a group that was motor-restricted and therefore unable to grasp for a cup, which should in principle attenuate motor simulation and action prediction. This, however, was not the case.’ (Six, 2022, p. 111)
[Also Six (2022, p. Experiment 3) did not find evidence that false belief states modulate predictive gaze behaviour. I think this may be because we asked participants to predict the action on each trial (‘Unlike previous experiments, this experiment featured a question prompt (“on which side of the screen will the hand appear?”) after each trial upon participants were asked to respond vocally with “left” or “right”.’) Notably, DLTS and explicit behavioural predictions were tightly correlated; this suggests to me that asking the question may have altered which processes moved the eyes.]

The Model’s Predictions

1. In motor mindreading only, goal-tracking will manifest sensitivity to agents’ beliefs.

2. In motor mindreading only, physically constraining protagonists (or participants) will impair belief tracking.

OK, let’s go back to constraining the agent’s action possibilities since we had more luck with that ...

Zani, Butterfill, & Low (2020)

What if we bind the protagonist?

‘The fact that the mediolateral difference between true belief condition and false belief condition disappears when manipulating the agent’s ability to move (i.e., TBT = FBT) is suggestive of an attenuation of participants’ ability to motorically represent the goal of the observed action. However, the lack of a significant effect within conditions (i.e., TBU = TBT; FBU = FBT) also indicates that the effect of constraint on the ability to generate motor predictions about observed belief based actions is not conclusive.’ (Zani PhD, forthcoming)
[On Experiment 2:] ‘In the true belief condition, we again saw a clear effect of hand preshaping on anticipatory looking times. In the false belief condition, we saw that anticipatory looking times generally sat around chance level. Although less clear-cut than results in the first experiment, this still entails that overall looking scores were not completely driven by hand preshaping, at least suggesting an impact of the opposing belief state of the agent.’ (Six, 2022, p. 111)
Sinigaglia, Quarona, Riva, & Butterfill (2021)
sourceparadigmmeasurewho bound?as predicted?
Low &c, 2020Kovacs’ SmurfRTagentY
Six, 2022 Exp. 2Six’ Cupslooking timeparticipantN
Zani, forthcoming Exp. 2Buttelmann/ helpingleaningagentsuggestive
Sinigaglia, Quarona &c, in prepKovacs’ SmurfRTagentunknown
When I chose my title, Motor Mindreading, Jason, Pieter, Gio and I in the land of milk and honey. We couldn’t run an experiment without confirming your predictions.
Since then I think it is fair to say that we seem to have taken a long walk in the desert.
So I cannot report that we have established the existence of motor mindreading. Not yet. But the desert is beautiful in its way, and so I remain hopeful that there will be more experiments which add to the evidence we already have.
Let’s see.

If there is fast mindreading,
what kind of processes might it involve?

This is significant because, as I said, we know very little about the kind processes which are involved in mindreading.
To say that they are ‘fast’ or ‘automatic’ is only to identify a very general architectural feature.
What is needed now, though, are conjectures about the particular kinds of processes that might be involved. If the motor conjecture turns out to be wrong (and for the record I do not think it will, I am still betting on it), what alternative kinds of process might be involved in mindreading?

Motor Mindreading?

[email protected] & [email protected]

For now my conclusion is simple.
Cecilia’s talk is about selecting the most successful of older theories about mirror neurons’ functions and stepping back from some of the wildest ideas about their roles in our lives.
This ground clearing is important because it provides the perfect environment for the next generation of wild conjectures about the roles of mirror neurons. ... like the idea that they can play a role in some forms of mindreading.