Predictive processing (PP) theory of cognition claims that nervous systems continuously try to anticipate their sensory inputs, following the imperative to minimize the mismatch between their predictions and sensory activations. In the process, the internal model of causal dependencies underlying sensory signals is developed and refined. The theory has recently sparked great hopes that it will provide a unifying account of the entirety of human and non-human cognition: In this view, virtually all cognitive processes are guided by the predictive nature of the internal model. In our recent paper (written by myself and Marcin Miłkowski) we argue that this enthusiasm is premature: PP faces serious problems which effectively stunt its development as a scientific theory. The paper was recently published in the journal Cognitive Science and is now available in open access. It is our second criticism of overextending PP (the previous one is a commentary in BBS on Gilead et al. model of abstract thought).
Our skepticism is based on two main observations. In the first part of the paper, we focus on the “theory-implementation gap”, i.e., the gap between an elaborate mathematical apparatus and its interpretation in terms of psychological phenomena or neurobiologically plausible cognitive architectures. While the formalization of PP is quite strict (but also, notably, very diverse, as there are many different PP algorithms), the theoretical interpretation of its core terms seems to be free-for-all. For example, precision—a concept related to the variability of the signal; thus, to the computational “confidence” or “trust” in its reliability—is being identified with many distinct cognitive and psychological phenomena, including subjective feelings of confidence or trust. This observation applies also to other core technical PP terms, such as predictions or beliefs. Explanations based on such identifications are non-informative, as they are based on the fallacy of equivocation—the confusion of several meanings of a single term in an argument. The theory-implementation gap surfaces also in the computational models of psychiatric phenomena, which do not abide by the root commitments of the theory, regarding functioning and structure of the predictive model.
In the second part of the paper, we present arguments that PP models are not validated empirically in a sufficiently rigorous manner. The vast majority of PP modeling work takes the form of theoretical re-descriptions of contemporary models. These accounts neither yield new, testable predictions nor enable new inferences on phenomena being ‘covered’; they simply use generic PP language to rephrase existing models in hypothetical predictive terms. Moreover, PP proponents harness certain argumentative strategies to conceal the limited usefulness of their models which are often defined as “starting points”, to be empirically validated in the ‘foreseeable’ future. However, they almost never are; instead of testing them against viable alternatives or outcomes explicitly incompatible with the theory, proponents of PP succumb to consistency fallacy, taking selected (broadly consistent) evidence as ‘providing support’ for PP. Not only such practices do not corroborate the theory, but, as we show in the article, they also lead to mutually exclusive PP models of the same phenomenon and wishful interpretations of the obtained data (even in cases when they seem to undermine PP).
The upshot is that, as for today, PP is definitely not a great unifying theory it was promised to be and its development is arrested. In particular, it displays two features that unifying theories should not possess: It is heterogenous and unsystematically applied. Numerous diverse interpretations of technical terms result in mutually exclusive accounts of the same phenomena or theoretical and computational models being at odds with theory’s fundamentals. Therefore, PP is either underspecified or contradictory itself, but it is certainly not unifying.
Predictive processing models of psychopathologies are not explanatorily consistent with the present account of abstract thought. These models are based on latent variables probabilistically mapping the structure of the world. As such, they cannot be informed by representational ontology based on mental objects and states. What actually is the case is merely some terminological affinity between subjective and informational uncertainty.
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In his recent book, Daniel Dennett defends a novel account of semantic information in terms of design worth getting (Dennett, 2017). While this is an interesting proposal in itself, my purpose in this commentary is to challenge several of Dennett’s claims. First, he argues that semantic information can be transferred without encoding and storing it. Second, this lack of encoding is what makes semantic information unmeasurable. However, the argument for both these claims, presented by Dennett as an intuition pump, is invalid.
The world is not designed for pickpockets. Despite this, they successfully cope in it, both with their beneficial manipulation of things and with their management of our attention. Of course, my study “What It Is Like to Be a Pickpocket” should not be considered praise for the craft of pickpockets; it is a demonstration of cognitive ecology and the concept of affordance.
There is no doubt that neuroscience research has a lot
to say about the perceptual phenomena used by pickpockets, which to some extent
are also magicians. However, my article is not a story about how one brain
cheats another brain. I am trying to show something more: these thieves are part
of our cultural cognitive ecosystem; therefore, they share with us physical
objects, ways of thinking and cultural practices, all of which they use for
their own purposes. They are good observers and use different heuristics.
What I focus on in this article is the use of various
affordances. The concept of affordance has found application not only in
ecological psychology (Gibson, 1966), but also in the psychology of design
(Norman, 1988), design engineering (Maier & Fadel, 2001), and even in
neuroscience (Cisek, 2017). Unfortunately, this has led not to the integration
of these fields but to differentiated accounts of affordances. In my own
approach to affordances, however, I perform a certain synthesis. By
“affordances” I understand the relational properties of a given agent–environment
system that offers the agent specific opportunities for action or behavior. Therefore,
these are some cognitive shortcuts that are seen as directly possible in the
understanding of design researchers: people can perceive the possibilities of
certain actions with minimal cognitive processing (see, for example, Masoudi et
al., 2019). One should also not forget social affordances. The social dimension
was already taken into account by Gibson himself, who wrote that what another
animal offers to the observer is not only behavior but also social interaction.
Such affordances involve a pair (or more) of animals in one loop of
cooperation, regardless of whether the type of interaction is sexual,
cooperation, or even conversation (1979, pp. 41–42). This social dimension has
also been noticed by design researchers (e.g. Gaver, 1996).
Why did I find the perspective of design research
useful here? Because our perception does not divide the elements of the
environment into “natural/accidental” and “designed”. The
mechanisms of human–environment interaction that are used by researchers and
engineers of design are mechanisms that we use constantly in everyday life.
On the one hand, good design reduces users’ need for
analysis or reflection. Well-made things “make us smart” (see Norman, 1993). On
the other hand, one should not idealize the role of design in our lives as it
often barely works or even does not work at all. The artifacts that surround us
can be badly designed, badly made, or unsuitable for the needs and context of
humans. Their affordances often confuse us, and in these situations we have to
deal with problematic design products. We use various heuristics which are also
A pickpocket is a special type of user of artifacts
and the cultural ecosystem in general. Undoubtedly, he is very fluent in this,
although he acts against social norms and uses some affordances in a different
way than other people.
To show this better, I refer to fragments of the classic film “Pickpocket” by Robert Bresson.
This is, of course, a fairly idealized and sometimes exaggerated example, yet it is very helpful in exposing the socio-cognitive mechanisms of the craft of pickpockets. I use here the suggestive impact of feature films on audiences which is usually absent in the case of video recordings of instructional scenes or scientific experiments. So, although Bresson’s movie cannot be treated as a source of evidence to support my assumptions, it is worth looking at as a kind of screened thought experiment. It is supposed to help us understand from an ecological perspective what it is like to be someone like a pickpocket.
Wachowski, W. M. (2019). What it is like to be a
pickpocket. Culture & Psychology.