Roberto Casati

The copycat solution to the shadow correspondence problem

Cast shadows (henceforth simply ‘shadows’) depicted in artworks can fulfil some of their perceptual roles, such as helping the retrieval of 3-D structure and of relative positions of objects, without having to be geometrically or physically accurate. The visual system displays a wide tolerance for shadows that are mostly inaccurate, at times making use of the scarce accurate but relevant information that can still be retrieved from them. However, the extent of the tolerable inaccuracy is at present still unexplored. I propose that inaccuracy can be not only totally acceptable but in some cases is even likely to be preferable to accuracy if the main perceptual role of shadows is to help locate in a scene the objects that cast them. I examined a small but effective historical corpus of pictorial endeavours, from which it appears that in some cases painters have used a copycat strategy for drawing the terminator of a shadow, ie they have produced a replica of the visible profile of the caster, which in the norm yields an impossible shadow. The copycat strategy is perceptually effective for solving the correspondence problem of associating a shadow with its caster; copycatting can be more effective than other solutions, including the depiction of the geometrically correct shadow, and is complementary to coarser solutions to the correspondence problem. These phenomena provide insight into the computations effectively used by the brain to deal with space perception. In particular, the brain is not relying on some sort of simplified physical model of the world, for the shadows produced by the copycat effect would correspond to a more complicated physical situation than the one encountered in real life.

Mirror and canonical neurons are not constitutive of aesthetic response

Still missing from the open field of the cognitive study of art are mid-level hypotheses that are both aesthetically specific (as opposed to general claims, e.g. about emotions) and functionally interfaced with psychological findings. Consider the notion of ‘drawing style’, central to art history and the philosophy of art. One crucial issue is whether the style of a draughtsman is inherited from other draughtsmen (see ref. [2xArt and Illusion: A Study in the Psychology of Pictorial Representation. Gombrich, E.H. See all References][2] for a positive answer). Activation of the MNS might enable the observer of a drawing to retrieve some dynamic components of the gesture of the draughtsman. This in turn might influence the drawing acts of the observer (see ref. [3xRepresenting the dynamics of a static form. Freyd, J.J. Mem. Cognit. 1983; 11: 342–346Crossref | PubMed | Scopus (45)See all References][3] for an experiment showing that the direction of the drawing movement can be recovered when perceiving a line). A productive mid-level hypothesis would be that drawing style relies on the dynamics of the hand of the draughtsman and that MNS subserves both style inheritance and recognition, by observers, of such influence between draughtsmen. This claim generates both new distinctions relevant for the philosophy of art and testable hypotheses for neuropsychology. One of them is that experience in drawing production improves the ability to detect influences between draughtsmen (see ref. [4xSeeing or doing? Influence of visual and motor familiarity in action observation. Calvo-Merino, B. et al. Curr. Biol. 2006; 16: 1905–1910Abstract | Full Text | Full Text PDF | PubMed | Scopus (499)See all References][4] for related work on dancers).

The cognitive science of holes and cast shadows

Owing to their peculiar nature of ‘quasi-objects’ or ‘negative objects’ (absences with a shape), shadows and holes are a promising source of insight about the representation of physical objects in cognition. In philosophy, informal conceptual analysis has uncovered interesting common features. (i) Both holes and cast shadows (henceforth simply ‘shadows’) are dependent features; they cannot exist without objects hosting or casting them. Both shadows and holes are somewhere between being regions of space and fully-fledged material objects: they are (ii) similar enough to bounded regions of space in that they have a location, a shape, a size, and are as immaterial as space is, but are (iii) more object-like as they can persist over time and move [1].

The Shadow Knows: A Primer on the Informational Structure of Cast Shadows

I list relevant properties of cast shadows that the visual system could exploit (although it may not exploit). The study concerns the various types of information that can be extracted from shadows by systems that are significantly like ours (including embodied artificial systems) in an environment that is significantly like ours.

Micro‐credits in scientific publishing

– New technologies allow for efficient dissemination of scientific knowledge objects (SKOs). Yet they are likely to transform SKOs as well. The aim of this paper is to propose a way to structure SKOs that allows for both a clear individuation of the main scientific contributions and a fine‐grained structure of credits and evaluation., – The authors review and analyze existing practices of structuring SKOs in different disciplines., – Provisionally considering the published paper as an atomic SKO, possible subatomic structures of SKOs are investigated. It is hypothesized that SKOs are meant to satisfy two separated but interdependent sets of constraints, one related to the contribution the SKO makes to the body of knowledge, and another related to the contribution the SKO makes to the reputation of its authors. It is hypothesized that existing SKO structures are not optimal for satisfying both sets of constraints at once., – A broader analysis may be needed that covers the totality of existing practices., – Guidelines are offered. This paper, including the present abstract, is an example of what the scientific paper of tomorrow could be like., – The paper proposes better apportioning of scientific credits and evaluation; substantive evolution of the academic publishing and credit attribution models., – The idea that the communication and evaluation function of a SKO are differently reflected in their structure is novel. The proposed fine‐grained credit attribution system is novel. The molecular/atomic/sub‐atomic distinction is a new way to fix the terminology.

Counting the holes

Argle claimed that holes supervene on their material hosts, and that every truth about holes boils down to a truth about perforated things. This may well be right, assuming holes are perforations. But we still need an explicit theory of holes to do justice to the ordinary way of counting holes--or so says Cargle.

Does topological perception rest on a misconception about topology

In this article I assess some results that purport to show the existence of a type of ‘topological perception’, i.e., perceptually based classification of topological features. Striking findings about perception in insects appear to imply that (1) configural, global properties can be considered as primitive perceptual features, and (2) topological features in particular are interesting as they are amenable to formal treatment. I discuss four interrelated questions that bear on any interpretation of findings about the perception of topological properties: what exactly are topological properties, what makes them global, in what sense the quoted findings makes them primitive, and what are the hopes of a formal theory of perception based upon them. I suggest that mathematical topology is not the correct model for cognition topological properties, hence that some other formalism ought to be used—a form of “internalized topology.” However, once the principles of this type of topology are spelled out, they may not be as globalistic as one may have expected.

False beliefs and naive beliefs: They can be good for you

Naive physics beliefs can be systematically mistaken. They provide a useful test-bed because they are common, and also because their existence must rely on some adaptive advantage, within a given context. In the second part of the commentary we also ask questions about when a whole family of misbeliefs should be considered together as a single phenomenon.

The availability of large size from shadow: looking for hidden assumptions.

Size-from-shadow arguments requires tinkering in many a case as the geometry of the situation is often not determinate. I then make a remark about the availability of indications about size in perceptual content.

I trabocchetti della rappresentazione spaziale

(buchi, even-ti, unità geografiche) che costituiscono un buon banco di prova per la meto