# McGregor, Baltieri & Buckley, 2015: A Minimal Active Inference Agent

**URL:** <http://discourse.iapct.org/t/mcgregor-baltieri-buckley-2015-a-minimal-active-inference-agent/6856>\
**Category:** CSG2016\
**Created:** [May 8, 2016, 1:46pm UTC](http://discourse.iapct.org/t/mcgregor-baltieri-buckley-2015-a-minimal-active-inference-agent/6856 "2016-05-08T13:46:58Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Matti](http://discourse.iapct.org/user_avatar/discourse.iapct.org/matti/32/3066_2.png) [@Matti](http://discourse.iapct.org/u/Matti)\
**Post date:** [May 8, 2016, 1:46pm UTC](http://discourse.iapct.org/t/mcgregor-baltieri-buckley-2015-a-minimal-active-inference-agent/6856/1 "2016-05-08T13:46:58Z")

</div>

[From MK (2016.05.08.1545 CET)]

Readable intro re predictions vs intentions.

> **···**
>
> ----
> 
> McGregor, Baltieri & Buckley, 2015: A Minimal Active Inference Agent  
> arXiv:1503.04187 [cs.AI]  
> [http://arxiv.org/abs/1503.04187](http://arxiv.org/abs/1503.04187)
> 
> 1 Introduction
> 
> Active inference is the name given by Karl Friston to a process  
> of an agent’s simultaneously co-constrained inference regarding the world  
> combined and directed actions to change it, understood specifically as the  
> minimisation of an information-theoretic quantity describing the instantaneous  
> relation of a system to its "typical" sensory environment.
> 
> According to proponents of active inference, all mechanical implementation of  
> cognitive behaviour (including both the active and inferential aspects of  
> cognition) can be reduced to the minimisation of a single informational "free  
> energy" quantity; moreover, this quantity can be assigned an interpretation  
> using cognitive concepts resembling beliefs and intentions.
> 
> This theory has attracted a great deal of attention (both positive and  
> negative), since it claims to unify a wide variety of principles in cognitive  
> science, machine learning and neuroscience. However, a clear and balanced  
> discussions of the framework’s strengths and weaknesses is still lacking.
> 
> We suspect that one of the barriers preventing a wider understanding of the  
> theory is the language which been used to describe it. The language is  
> technically dense, using terms like ’surprise’, ’generative’, ’ensemble’,  
> ’variational’ and can seem to beg philosophical questions in a way which is not  
> strictly mandated by the formalism of the active inference theory. For instance,  
> the framework is frequently characterised as claiming that cognitive agents act  
> so as to "confirm their predictions", or "minimise their surprise"; we will see  
> that alternative interpretations exist for the same formal assertions.
> 
> Furthermore one of the central strengths of the formalism is its potential to  
> unite an understanding of action and perception within a single  
> unified framework  
> [13]. However understanding the exact implications of this will likely require  
> the utilisation of agent based approaches which to date have largely been  
> absent.
> 
> This paper aims to clarify the foundations of the active inference or  
> "free-energy" framework in terms which can be understood by a wide audience. We  
> start by giving a brief conceptual overview of the information Free-Energy (IFE)  
> principle and active inference in an intuitive language.
> 
> [...]
> 
> One of the most interesting aspects of the active inference framework is that  
> two things which we generally regard as quite distinct are given the same formal  
> treatment: on the one hand, beliefs or predictions about sensory input and the  
> external world which underlies it, and on the other hand intentions regarding  
> the outcomes of our actions. In this sense, active inference blurs the  
> distinction between a prediction and an intention; both are treated as  
> conceptions-of-the-future, with the main difference being in what physical  
> variables change most when the reality turns out to be different from the  
> expectation [13].
> 
> Although the free-energy literature uses the terms "prediction" and  
> "expectation" interchangeably for this concept, it seems that only the verb  
> "expect" in English really captures the ambiguity between intention and  
> prediction which the active inference framework rests upon. It is unfortunate  
> that the word "expectation" also has a technical meaning which is relevant to  
> active inference, i.e. the mean of a probability distribution. Hence, we propose  
> the term "expectance" to refer to the superclass of probabilistic beliefs and  
> desires implicit in the active inference framework.
> 
> In this language, active inference asserts that agents constantly behave so as  
> to reduce the discrepancy between their expectances and reality; the resolution  
> of discrepancy by changing internal variables is known as "updating one’s  
> predictions", while the resolution of discrepancy by changing reality is known  
> as "acting on one’s environment".
> 
> Crucially, under active inference both of those dynamics are always occurring  
> simultaneously. It is not necessary to pre-judge which of those dynamics will  
> predominate by calling the expectance a "prediction" or an "intention" in  
> advance of observing the outcome. The typical presentation of active inference  
> states that agents behave so as to make their "predictions" come true. We  
> believe this wording erases the distinction between internal and external  
> resolution of expectance violation, in an unhelpful way. Intuitively, if an  
> agent "predicts" its arm to move to the left, and the arm instead stays in  
> place, we would expect it to change internally so as to make different  
> predictions; no action on the world would be presupposed by the discrepancy. On  
> the other hand, if the agent "intends" its arm to move to the left, and the arm  
> instead stays in place, we would expect it to exert a greater force on its arm  
> by contracting the relevant muscles.
> 
> Of course, it is entirely possible that the agent could begin by attempting to  
> move its arm and, in doing so, learn that its range of movement is restricted by  
> external forces. The expectance violation can be resolved by coming to a halfway  
> point in which the agent "updates its predictions" to reflect the fact that its  
> movement is restricted, "modifies its intentions" to be consistent with what is  
> achievable, and "acts on the world" by moving within its available range. Such  
> an equilibrium can emerge naturally from a continuous-time process where  
> informational free energy is minimised along distinct internal dimensions  
> simultaneously. ...
> 
> ----
> 
> M

---

<div class="post-metadata">

**Author:** ![wmansell](http://discourse.iapct.org/user_avatar/discourse.iapct.org/wmansell/32/36_2.png) [@wmansell](http://discourse.iapct.org/u/wmansell)\
**Post date:** [May 9, 2016, 9:31am UTC](http://discourse.iapct.org/t/mcgregor-baltieri-buckley-2015-a-minimal-active-inference-agent/6856/2 "2016-05-09T09:31:59Z")

</div>

These guys need to be shown PCT, pointed out the phenomenon of control, and shown that the formalism modelling it within PCT is much less ambiguous!  
Warren

> **···**
>
> > On 8 May 2016, at 14:46, MK \<perceptualposts@gmail.com\> wrote:
> > 
> > [From MK (2016.05.08.1545 CET)]
> > 
> > Readable intro re predictions vs intentions.
> > 
> > ----
> > 
> > McGregor, Baltieri & Buckley, 2015: A Minimal Active Inference Agent  
> > arXiv:1503.04187 [cs.AI]  
> > [[1503.04187] A Minimal Active Inference Agent](http://arxiv.org/abs/1503.04187)
> > 
> > 1 Introduction
> > 
> > Active inference is the name given by Karl Friston to a process  
> > of an agent’s simultaneously co-constrained inference regarding the world  
> > combined and directed actions to change it, understood specifically as the  
> > minimisation of an information-theoretic quantity describing the instantaneous  
> > relation of a system to its "typical" sensory environment.
> > 
> > According to proponents of active inference, all mechanical implementation of  
> > cognitive behaviour (including both the active and inferential aspects of  
> > cognition) can be reduced to the minimisation of a single informational "free  
> > energy" quantity; moreover, this quantity can be assigned an interpretation  
> > using cognitive concepts resembling beliefs and intentions.
> > 
> > This theory has attracted a great deal of attention (both positive and  
> > negative), since it claims to unify a wide variety of principles in cognitive  
> > science, machine learning and neuroscience. However, a clear and balanced  
> > discussions of the framework’s strengths and weaknesses is still lacking.
> > 
> > We suspect that one of the barriers preventing a wider understanding of the  
> > theory is the language which been used to describe it. The language is  
> > technically dense, using terms like ’surprise’, ’generative’, ’ensemble’,  
> > ’variational’ and can seem to beg philosophical questions in a way which is not  
> > strictly mandated by the formalism of the active inference theory. For instance,  
> > the framework is frequently characterised as claiming that cognitive agents act  
> > so as to "confirm their predictions", or "minimise their surprise"; we will see  
> > that alternative interpretations exist for the same formal assertions.
> > 
> > Furthermore one of the central strengths of the formalism is its potential to  
> > unite an understanding of action and perception within a single  
> > unified framework  
> > [13]. However understanding the exact implications of this will likely require  
> > the utilisation of agent based approaches which to date have largely been  
> > absent.
> > 
> > This paper aims to clarify the foundations of the active inference or  
> > "free-energy" framework in terms which can be understood by a wide audience. We  
> > start by giving a brief conceptual overview of the information Free-Energy (IFE)  
> > principle and active inference in an intuitive language.
> > 
> > [...]
> > 
> > One of the most interesting aspects of the active inference framework is that  
> > two things which we generally regard as quite distinct are given the same formal  
> > treatment: on the one hand, beliefs or predictions about sensory input and the  
> > external world which underlies it, and on the other hand intentions regarding  
> > the outcomes of our actions. In this sense, active inference blurs the  
> > distinction between a prediction and an intention; both are treated as  
> > conceptions-of-the-future, with the main difference being in what physical  
> > variables change most when the reality turns out to be different from the  
> > expectation [13].
> > 
> > Although the free-energy literature uses the terms "prediction" and  
> > "expectation" interchangeably for this concept, it seems that only the verb  
> > "expect" in English really captures the ambiguity between intention and  
> > prediction which the active inference framework rests upon. It is unfortunate  
> > that the word "expectation" also has a technical meaning which is relevant to  
> > active inference, i.e. the mean of a probability distribution. Hence, we propose  
> > the term "expectance" to refer to the superclass of probabilistic beliefs and  
> > desires implicit in the active inference framework.
> > 
> > In this language, active inference asserts that agents constantly behave so as  
> > to reduce the discrepancy between their expectances and reality; the resolution  
> > of discrepancy by changing internal variables is known as "updating one’s  
> > predictions", while the resolution of discrepancy by changing reality is known  
> > as "acting on one’s environment".
> > 
> > Crucially, under active inference both of those dynamics are always occurring  
> > simultaneously. It is not necessary to pre-judge which of those dynamics will  
> > predominate by calling the expectance a "prediction" or an "intention" in  
> > advance of observing the outcome. The typical presentation of active inference  
> > states that agents behave so as to make their "predictions" come true. We  
> > believe this wording erases the distinction between internal and external  
> > resolution of expectance violation, in an unhelpful way. Intuitively, if an  
> > agent "predicts" its arm to move to the left, and the arm instead stays in  
> > place, we would expect it to change internally so as to make different  
> > predictions; no action on the world would be presupposed by the discrepancy. On  
> > the other hand, if the agent "intends" its arm to move to the left, and the arm  
> > instead stays in place, we would expect it to exert a greater force on its arm  
> > by contracting the relevant muscles.
> > 
> > Of course, it is entirely possible that the agent could begin by attempting to  
> > move its arm and, in doing so, learn that its range of movement is restricted by  
> > external forces. The expectance violation can be resolved by coming to a halfway  
> > point in which the agent "updates its predictions" to reflect the fact that its  
> > movement is restricted, "modifies its intentions" to be consistent with what is  
> > achievable, and "acts on the world" by moving within its available range. Such  
> > an equilibrium can emerge naturally from a continuous-time process where  
> > informational free energy is minimised along distinct internal dimensions  
> > simultaneously. ...
> > 
> > ----
> > 
> > M