Extending the Explanandum for Predictive Processing A Commentary on Andy Clark Michael Madary In this commentary, I suggest that the predictive processing framework (PP) might Commentator be applicable to areas beyond those identified by Clark In particular, PP may be relevant for our understanding of perceptual content, consciousness, and for ap! Michael Madary plied cognitive neuroscience My main claim for each area is as follows: madary*uni-main+ de #) PP urges an organism-relative conception of perceptual content $) Historical a priori accounts of the structure of perceptual e&perience con! ,ohannes -utenberg!.niversit/t verge with results from PP Main+, -ermany ') (here are a number of areas in which PP can find important practical ap! plications, including education, public policy, and social interaction (arget Author Keywords Andy Clark Anticipation ) Applied cognitive neuroscience ) Consciousness ) Perception ) Per! Andy Clark* ed ac uk ceptual content ) Phenomenology ) Predictive processing .niversity of Edinburgh Edinburgh, .nited 1ingdom 0ditors (homas Met+inger met+inger *uni!main+ de ,ohannes -utenberg!.niversit/t Main+, -ermany ,ennifer M 2indt 3ennifer windt*monash edu Monash .niversity Melbourne, Australia 1 Introduction An understandable reaction to the predictive one's case. hope to avoid this danger by being processing framework (PP) is to think that it is clear upfront that my goal is not to convince too ambitious (Hohwy this collection). My sug- the skeptic of the attraction of PP. cannot im- gestion in this commentary is the opposite. prove on $lark (and others" see below) in that will argue that PP can be fruitfully applied to regard. nstead" investigate the following !ues- areas of in!uiry that have so far received little" tion( if some version of PP (again" see below) is if any" attention from the proponents of PP. true" then what are the larger implications for Perhaps we can e#tend the e#planandum even human self-understanding) My answer to this further than Andy Clark has recommended. !uestion covers three topics. *irst will engage %here is a certain rhetorical danger to the with $lark's discussion of perceptual processing position am urging. &ne should not oversell from sections + and 2.+ of his article. %here Madary, M ($4#5) 0&tending the 0&planandum for Predictive Processing ! A Commentary on Andy Clark In ( Met+inger 6 , M 2indt (0ds) Open MIND: 7(C) 8rankfurt am Main" MI9: -roup doi" #4 #554$;<7='<5=574'#' 1 | ## www open!mind net will sketch how PP's reversal of the traditional erature there is an emerging !uestion about model of perceptual processing may have signi- whether to understand PP as internalist or e#- ficant implications for the way in which we un- ternalist regarding the vehicles of mental states derstand perceptual content" which is a core is- (Hohwy ,/+;)< take no position either way sue in the philosophy of psychology. n the here" but see footnote ,. &verall" my remarks second section will turn to another area of are motivated by $lark's e#position of PP" but philosophical concern( consciousness. Historic- they should be applicable to other approaches ally" consciousness research has had a rocky re- and interpretations as well. lationship with the sciences of the mind. hope to point towards the possibility of a rapproche- 2 A new conception of perceptual content ment. n the final section of the commentary" will !uickly touch on some practical matters. f $lark has emphasi1ed the way in which PP de- PP is true" then there are important con- parts from the standard picture in perceptual se!uences for the way in which we approach psychology" and from =avid Marr's (+72,) topics in education" public policy" and social in- model of visual processing in particular (pp. +> teraction. 9). According to the standard account" the flow My goal is to indicate possible areas in of information is ?bottom-up"@ as perceptual which $lark's article (and related themes) systems construct increasingly sophisticated might serve as a foundation for future directions representations based on the information trans- of research. My main claims are as follows" duced at the periphery. According to PP" per- numbered according to each section( ception involves the active prediction of the up- coming sensory input" ?top-down.@ =eviation 1. PP urges an organism-relative conception of from what is predicted" known as the prediction perceptual content. error, propagates upwards through the hier- 2. Historical a priori accounts of the structure archy until it is e#plained away by the .ayesian of perceptual e#perience converge with res- generative model. ults from PP. Now would like to add that the standard 3. %here are a number of areas in which PP can picture in perceptual psychology has been find important practical applications. widely regarded as complementary to the stand- ard picture in the philosophy of perception (see Before entering into the specific issues" should %ye ,///" for e#ample). &ne central !uestion in add a note about what mean by PP. Here the philosophy of perception is the following: am following the general theoretical framework what is the content of perceptual states) &r, e#pressed in $lark's article as well as in a num- what does perception represent) %he standard ber of other publications ($lark ,/+-0 Hohwy answer, in tune with Marr’s approach" is that ,/+-). %he approach has a number of intellec- perceptual systems represent the e#ternal world" tual roots" including Hermann von Helmholt1 more or less as it really is. As Marr puts it" the (+234) and 5ichard 6regory (+72/). %he main purpose of vision is ?to know what is where by contemporary e#pression of PP perhaps owes looking” (+72,). %his way of thinking about the most to 8arl *riston (,//9" ,//2" ,/+/) and perceptual content is almost a commonplace in his collaborators" also with important develop- the philosophical literature (Lewis +72/" p. ,-70 ments of the generative model by 6eoffrey Hin- *odor +724" $h. ;0 =retske +779" $h. 1). 8ath- ton (,//4). By referring to PP as one general leen Akins has described how the orthodo# con- framework" do not mean to imply that there ception regards the senses as ?servile@ in that are no outstanding issues of disagreement or they report on the environmental stimulus open !uestions within PP. As $lark indicates" ?without fiction or embellishment@ (+773" pp. citing :pratling (,/+-)" there are a number of -9/>-9+). options being developed as to the specific imple- :ince PP overturns the reigning model in mentation of PP. Also, in the philosophical lit- perceptual psychology" one might now ask Madary, M ($4#5) 0&tending the 0&planandum for Predictive Processing ! A Commentary on Andy Clark In ( Met+inger 6 , M 2indt (0ds) Open MIND: 7(C) 8rankfurt am Main" MI9: -roup doi" #4 #554$;<7='<5=574'#' 2 | ## www open!mind net whether it also overturns the reigning model in of representing the world with the single guid- the philosophy of perception. Here are two ini- ing principle of error minimi1ation. tial reasons to think that it does. *irst" accord- %hese two points suggest an understand- ing to PP" there is always an active contribution ing of perceptual content as something that is from the organism, or at least from a part of deeply informed by the specific history and em- the organism. Perceptual states are generated bodiment of the organism. %he content of per- internally and spontaneously by the ongoing dy- ception is a comple# interplay between particu- namics of the generative model. %hose states lar organisms and their particular environments. are constrained by perceptual sampling of the At least on the face of it" this way of consider- world" not driven by input from the world. Per- ing perception suggests new challenges and in- ceptual states are driven by the endogenous teresting new theoretical options for philosoph- activity of the predictive brain. %he relevant ers interested in describing perceptual content. causal history of these states begins" if you will" *or one thing, it suggests that propositional within the brain" rather than from the outside. content as e#pressed using natural language Cach organism’s generative model is uni!ue in (:earle +72-" p. 40) may be ill-suited for the that it has been formed and continuously re- task of describing perceptual content. Natural vised according to the particular traDectory of language does not typically include reports that organism's cycle of action and perception. about prediction-error minimi1ation" nor does it As $lark himself puts it" the forward flow of capture the fine-grained differences in percep- sensory information is always ?relative to spe- tual content that will arise due to slight vari- cific predictions@ (p. 3). %hese considerations ations in the predictions made by different or- make it clear that there can be variation in per- ganisms. %he traditional account of perceptual ceptual content for identical environmental con- content" following Marr, does not include such ditions. Perceivers with different histories will differences" and is thus better disposed to e#- have different predictions (Madary ,/+-" pp. pression using natural language. 342–345). %he degree of variation is an open %hese new challenges for understanding !uestion" but it is reasonable to e#pect vari- perceptual content may offer at the same time a ation. general lesson for understanding all mental con- A second reason to think that PP motiv- tent in a naturalistic manner. Let me e#plain. ates a richer conception of perceptual content is &ne of the main goals in the philosophy of psy- that perception" according to PP" is not simply chology has been to naturali1e intentionality" to in the service of informing the organism ?what give an account of the content of mental states is where.@ &ne main feature of PP is that per- in terms of the natural sciences (in non-mental- ception and action work together in the service istic terms).