A note on sequent calculi intermediate between LJ and LK

We prove that every finitely axiomatizable extension of Heyting's intuitionistic logic has a corresponding cut-free Gentzen-type formulation. It is shown how one can use this result to find the corresponding normalizable natural deduction system and to give a criterion for separability of considered logic. Obviously, the question how to obtain an effective definition of a sequent calculus which corresponds to a concrete logic remains a separate problem for every logic.     

Theories and inter‐theory relations in Bošković

During 1745–1755 Bo?kovi? explicitly used the concept of scientific theory in three cases: the theory of forces existing in nature, the theory of transformations of geometric loci, and the theory of infinitesimals. The theory first mentioned became the famous theory of natural philosophy in 1758, the second was published in the third volume of his mathematical textbook Elementorum Universae Matheseos (1754), and the third theory was never completed, though Bo?kovi? repeatedly announced it from 1741 on. The treatment of continuity and infinity in natural philosophy, geometry and infinitesimal analysis brought about inter‐theory relations in Bo?kovi?'s work during his Roman period. The two constructed theories of Bo?kovi?, the theory of forces and the theory of geometric transformations, directly influenced the idea for the construction of his third theory. These written theories refer to understanding and effective application of continuity and infinity in natural philosophy and geometry, and this task, according to Bo?kovi?, requires methodological support from the theory of infinitesimals.     

An ethnomethodological clarification of Husserl's concepts of “regressive inquiry” and “Galilean physics” by means of discovering praxioms

This paper offers an ethnomethodological clarification of Husserl's concepts of Galilean physics and regressive inquiry. It employs the reader's textual-practical operationalization of these concepts. With the use of a simple optical prism as a perspicuous case of a scientific instrument, the reader will be asked and instructed to make a self-reflexive inquiry into the practical contingencies of the prismatic field of reflection. The reader will discover that the geometric structures of the reflective field of the prism is an achievement and formalization of the reader's own operatlonalizations. I named these discoverable discovering operationspraxioms or practical axioms — the pre-scientific contingencies of the geometric structures of prismatic reflection.I would like to thank Mike Lynch, Eric Livingston, George Psathas and Shelley Schweizer-Bjelic for their comments.     

They do what they are told to do: the influence of instruction on (chess) expert perception-commentary on linhares and brum (2007)

Linhares and Brum (2007) argue that they provide evidence for analogy as the main principle behind experts' acquisition of perceptual knowledge. However, the methodology they used—asking players to pair positions using abstract similarity—raises the possibility that the task reflects more the effect of directional instructions than the principles underlying the acquisition of knowledge. Here we replicate and extend Linhares and Brum's experiment and show that the matching task they used is inadequate for drawing any conclusions about the nature of experts' perception. When expert chess players were instructed to match problems based on similarities at the abstract level (analogy), they produced more abstract pairs than pairs based on concrete similarity. However, the same experts produced more concrete pairs than abstract ones when instructed to match the problems based on concrete similarity. Asking experts to match problems using explicit instructions is not an appropriate way to show the importance of either analogy or similarity in the acquisition of expert knowledge. Experts simply do what they are told to do.     

The effect of the observer vantage point on perceived distortions in linear perspective images

Some features of linear perspective images may look distorted. Such distortions appear in two drawings by Jan Vredeman de Vries involving perceived elliptical, instead of circular, pillars and tilted, instead of upright, columns. Distortions may be due to factors intrinsic to the images, such as violations of the so-called Perkins's laws, or factors extrinsic to them, such as observing the images from positions different from their center of projection. When the correct projection centers for the two drawings were reconstructed, it was found that they were very close to the images and, therefore, practically unattainable in normal observation. In two experiments, enlarged versions of images were used as stimuli, making the positions of the projection centers attainable for observers. When observed from the correct positions, the perceived distortions disappeared or were greatly diminished. Distortions perceived from other positions were smaller than would be predicted by geometrical analyses, possibly due to flatness cues in the images. The results are relevant for the practical purposes of creating faithful impressions of 3-D spaces using 2-D images.     

Is pictorial perception robust? The effect of the observer vantage point on the perceived depth structure of linear-perspective images

Every image of a scene produced in accord with the rules of linear perspective has an associated projection centre. Only if observed from that position does the image provide the stimulus which is equivalent to the one provided by the original scene. According to the perspective-transformation hypothesis, observing the image from other vantage points should result in specific transformations of the structure of the conveyed scene, whereas according to the vantage-point compensation hypothesis it should have little effect. Geometrical analyses illustrating the transformation theory are presented. An experiment is reported to confront the two theories. The results provide little support for the compensation theory and are generally in accord with the transformation theory, but also show systematic deviations from it, possibly due to cue conflict and asymmetry of visual angles.     

Creation of visual long-term memory

Currently, it is not known by which mechanisms novel visual representations are stored in long-term memory (LTM). Here we report evidence that visual working memory (WM) plays an important role in the formation of visual LTM. By varying exposure times and perceptual difficulty of the stimuli, we find that the rate-limiting factor constraining storage in LTM is the amount of information that can be simultaneously kept in WM, whereas the time needed to store this information into LTM is constant irrespective of the size of the WM content. These results support the hypothesis that visual WM serves as a gate for the storage of information into LTM.