Pappus in optical space

Optical space differs from physical space. The structure of optical space has generally been assumed to be metrical. In contradistinction, we do not assume any metric, but only incidence relations (i.e., we assume that optical points and lines exist and that two points define a unique line, and two lines a unique point). (The incidence relations have generally been assumed implicitly by earlier authors.) The condition that makes such an incidence structure into a projective space is the Pappus condition. The Pappus condition describes a projective relation between three collinear triples of points, whose validity can--in principle--be verified empirically. The Pappus condition is a necessary condition for optical space to be a homogeneous space (Lobatchevski hyperbolic or Riemann elliptic space) as assumed by, for example, the well-known Luneburg theory. We test the Pappus condition in a full-cue situation (open field, broad daylight, distances of up to 20 m, visual fields of up to 160 degrees diameter). We found that although optical space is definitely not veridical, even under full-cue conditions, violations of the Pappus condition are the exception. Apparently optical space is not totally different from a homogeneous space, although it is in no way close to Euclidean.     

Seeing beyond the target: environmental context affects distance perception

It is commonly assumed that perceived distance in full-cue, ecologically valid environments is redundantly specified and approximately veridical. However, recent research has called this assumption into question by demonstrating that distance perception varies in different types of environments even under full-cue viewing conditions. We report five experiments that demonstrate an effect of environmental context on perceived distance. We measured perceived distance in two types of environments (indoors and outdoors) with two types of measures (perceptual matching and blindwalking). We found effects of environmental context for both egocentric and exocentric distances. Across conditions, within individual experiments, all viewer-to-target depth-related variables were kept constant. The differences in perceived distance must therefore be explained by variations in the space beyond the target.     

The complement of a point subset in a projective space and a Grassmann space

In a projective space we fix some set of points, a horizon, and investigate the complement of that horizon. We prove, under some assumptions on the size of lines, that the ambient projective space, together with its horizon, both can be recovered in that complement. Then we apply this result to show something similar for Grassmann spaces.     

Perceived size and distance as a perceptual conflict between two processing modes

Three different sized squares were successively presented at the same physical distance under three observational conditions which provided different information about distance in the visual field. The 60 observers in each observational condition were asked to give verbal absolute judgments of perceived size and perceived distance for each of the squares. The results showed that in a full-cue situation a ratio of perceived absolute sizes is equal to that of the corresponding visual angles, with perceived distances appearing equal to each other; in a reduced-cue situation an object of smaller perceived size is judged to be farther away than one of larger perceived size, with the observers tending to assume the two objects as the same object or identically sized objects. These results were analyzed in terms of the perceptual conflict between primary perception and secondary perception.     

拓扑几何在知觉组织与空间概念形成中的运用

陈霖的拓扑知觉理论运用几何性质解释知觉组织,并强调拓扑性质的优先性——拓扑知觉是其他几何知觉的基础,拓扑知觉先于其他几何知觉发生。皮亚杰的拓扑首位理论认为儿童的空间概念发展顺序为先发展拓扑几何概念,之后再发展射影与欧式几何概念。两大理论都运用拓扑性质来解释心理现象,其研究对象、研究方法存在很大不同,但它们在理论结构上具有高度一致性,对几何学在心理学上的运用有非常重要的启示意义。     

Review Of The War Between Mentalism and Behaviorism: On the Accessibility of Mental Processes By William R. Utall.

Uttal's goals in writing this book are (a) to demonstrate that the war between mentalism and behaviorism is unwinnable because both sides are fundamentally flawed and (b) to describe a new version of behaviorism that resolves the conflict. The book is generally well written and contains many interesting and important points, but the goals are not attained because of weaknesses in some of the crucial analyses. For example, key terms such as mind and behavior are not defined; the scientific admissibility of inference is denied for philosophical reasons that are not relevant to inference as actually used; the accessibility of mind is both explicitly denied and implicitly assumed; two kinds of reductionism—between and within domains—are acknowledged but the distinction is not consistently maintained; and the proposed new behaviorism ignores rather than solves the old problems.     

A depth processing theory of the Poggendorff illusion

The Poggendorff illusion is attributed to the processing of the oblique lines of the Poggendorff figure as receding horizontal lines with their inner ends equidistant because of attachment to a frontal plane (defined by the parallel lines of the figure). Collinearity in three-dimensional space is inconsistent with such equidistance; one line must lie on a higher horizontal plane than the other. This necessarily noncollinear resolution of the lines in depth processing (which is inferred irrespective of the O’s consciousness of depth) is assumed to influence apparent projective relationships within the figure, thus accounting for the illusion. Predictions from the theory, involving manipulations of the plane defined by the parallels, were confirmed experimentally. In addition, the theory is shown to account very well for the effects of amputations and rotations of the figure, which other theories of the illusion cannot handle.     

Mirror Neurons,Embodied Simulation,and the Neural Basis of Social Identification

The shared intersubjective space in which we live since birth enables and bootstraps the constitution of the sense of identity we normally entertain with others. Social identification incorporates the domains of action, sensations, affect, and emotions and is underpinned by the activation of shared neural circuits. A common underlying functional mechanism—embodied simulation—mediates our capacity to share the meaning of actions, intentions, feelings, and emotions with others, thus grounding our identification with and connectedness to others. Social identification, empathy, and “we-ness” are the basic ground of our development and being. Embodied simulation provides a model of potential interest not only for our understanding of how interpersonal relations work or might be pathologically disturbed but also for psychoanalysis. The hypothesis is that embodied simulation is at work within the psychoanalytic setting between patient and analyst. The notions of projective identification and the interpersonal dynamic related to transference and countertransference can be viewed as instantiations of the implicit and prelinguistic mechanisms of the embodied simulation-driven mirroring mechanisms here reviewed.     

Why anamorphoses look as they do: an experimental study

The aim of this research was to understand why anamorphic images break up until they are unrecognizable when the observer's eye moves away from the regularization point. An experimental device was set up allowing the anamorphic deformation of images, consisting of a rotating screen on which figures were projected. The point from which subjects observed the screen was far from the projecting point. The projected figures lengthened equally when the screen rotated either clockwise or counterclockwise. On the other hand, the perceptual result was the opposite: in the former case, a rigid figure was seen rotating around its own vertical axis; in the latter case, the same figure was seen elongating or shortening in a non-rigid manner, without rotating. Since we were in a projective condition, the invariance of the cross-ratio was maintained. Therefore, we were in a situation of non-rigidity, in spite of the invariance of the cross-ratio. Three stimuli, white on a black background, were used in experiment 1. They were a segment, three aligned points, and four aligned points. Subjects had to rotate the screen at will and stop it at the point when they saw the transformation of movement from rigid rotation to non-rigid elongation. The results showed that: (i) in spite of being a projective invariant, the cross-ratio is not always a perceptual invariant too; (ii) the threshold screen position between the two motions was located at the position where the modifications of the solid angle subtended to the stimulus assumed a different trend from that of a sinusoid. Two stimuli were used in experiment 2: a continuous segment and one intersected by four vertical lines. The aim was the same as for experiment 1, but subjects had to repeat it from five different points of observation. The results showed that: (1) there was no significant difference depending on type of stimulus, indicating that the computability of the cross-ratio is not a necessary condition for the execution of the task; (2) the more the observer moved away from the projection axis, the more evident the distortion of the stimulus appeared, in accordance with what happens when observing an anamorphosis; (3) when the metamorphosis from rigid motion to elastic motion was seen the visual angle subtended to the stimulus was constant for all distances from the projection axis, in accordance with the hypothesis of rigidity.     

Projective invariance and the kinetic depth effect.

Seven experiments test the assumption that, in the kinetic depth effect, observers have reliable and direct access to the equivalence of shapes in projective geometry. The assumption is implicit in 'inverse optics' approaches to visual form perception. Observers adjusted a comparison shape to match a standard shape; both standard and comparison were portrayed as in continuous rotation in space, using a graphics computer. The shapes were either plane quadrilaterals or solid prisms. The angular difference of the planes of the shapes was varied, as was the dot density of a texture in those planes. Departure from projective equivalence was measured in six studies by measuring the planar analogue of cross ratio, and in a seventh by measuring the cross ratio for points in space. Projective equivalence was not found to be perceived uniformly, except in one experiment that did not involve rotation in depth. Otherwise changes in orientation of up to 180 degrees about a single coordinate axis had no significant effect on matches in shape, while changes in orientation about more than one coordinate axis produced significant effects. The addition of texture and a change in rotation speed did not correct departures from projective equivalence.     

Haptically straight lines

In this research, we set out to investigate haptically perceived space. Large deviations with respect to physical space have already been shown to exist. Here, research on haptic space is continued by investigating straight lines constructed by touch. In four experiments, subjects were asked to produce straight lines between two reference markers that were in the horizontal plane at a fixed distance from each other. Each experiment corresponded to a different task: two different interpolation tasks, an intersection task, and a pointing task. Straight lines had an orientation that was approximately frontoparallel. Subjects used both hands; manipulation was unrestricted. Although we found considerable differences between observers, the overall pattern of results showed that haptically straight lines were generally curved away from the observer. However, in one of the interpolation tasks they corresponded to physically straight lines. In addition, the pointing task generally produced larger deviations than the other three tasks. Taken together, the results show that there is no unique definition of the straight line, a conclusion that questions the viability of the concept of haptic space.     

Dissociation between visual perception of allocentric distance and visually directed walking of its extent

Walking without vision to previously viewed targets was compared with visual perception of allocentric distance in two experiments. Experimental evidence had shown that physically equal distances in a sagittal plane on the ground were perceptually underestimated as compared with those in a frontoparallel plane, even under full-cue conditions. In spite of this perceptual anisotropy of space, Loomis et al (1992 Journal of Experimental Psychology. Human Perception and Performance 18 906-921) found that subjects could match both types of distances in a blind-walking task. In experiment 1 of the present study, subjects were required to reproduce the extent of allocentric distance between two targets by either walking towards the targets, or by walking in a direction incompatible with the locations of the targets. The latter condition required subjects to derive an accurate allocentric distance from information based on the perceived locations of the two targets. The walked distance in the two conditions was almost identical whether the two targets were presented in depth (depth-presentation condition) or in the frontoparallel plane (width-presentation condition). The results of a perceptual-matching task showed that the depth distances had to be much greater than the width distances in order to be judged to be equal in length (depth compression). In experiment 2, subjects were required to reproduce the extent of allocentric distance from the viewing point by blindly walking in a direction other than toward the targets. The walked distance in the depth-presentation condition was shorter than that in the width-presentation condition. This anisotropy in motor responses, however, was mainly caused by apparent overestimation of length oriented in width, not by depth compression. In addition, the walked distances were much better scaled than those in experiment 1. These results suggest that the perceptual and motor systems share a common representation of the location of targets, whereas a dissociation in allocentric distance exists between the two systems in full-cue conditions.     

Through the looking glass clearly: accuracy and assumed similarity in well-adjusted individuals' first impressions

Do well-adjusted individuals have particularly accurate insight into what others are like or are they biased, primarily seeing their own characteristics in others? In the current studies, the authors examined how psychologically adjusted individuals tend to see new acquaintances, directly comparing their levels of distinctive accuracy (accurately perceiving others' unique characteristics), normative accuracy (perceiving others as similar to the average person), and assumed similarity (perceiving others as similar to the self). Across two interactive, round-robin studies, well-adjusted individuals, compared with less adjusted individuals, did not perceive new acquaintances' unique characteristics more accurately but did perceive new acquaintances, on average, as similar to the average person, reflecting an accurate understanding of what people generally tend to be like. Furthermore, well-adjusted individuals had a biased tendency to perceive their own unique characteristics in others. Of note, both pre-existing perceiver adjustment and target-specific liking independently predicted greater accuracy and assumed similarity in first impressions. In sum, well-adjusted individuals see through the looking glass clearly: although they erroneously see others as possessing their own unique characteristics, they accurately understand what others generally tend to be like.     

The Meaningfulness of Helping Others: Loren Eiseley's “The Star Thrower”

Freud and Klein describe projective processes—projection, projective identification, and the repetition compulsion—that cause interpersonal distortions not only in the psychotherapy relationship but in adult intimate relationships as well. Winnicott's theory of the use of an object describes a way of relating that is free of the distortions of projection, opening up the possibility of differentiation between intimate partners. Two case examples illustrate how addressing projective processes assisted one patient in extricating herself from a psychologically abusive relationship and helped a couple in treatment to move from object relating to object use. It is argued that the use of these psychoanalytic theories has an important role within a modern relational social work practice.     

Specifying the Concept of Future Generations for Addressing Issues Related to High-Level Radioactive Waste

The nuclear community frequently refers to the concept of “future generations” when discussing the management of high-level radioactive waste. However, this notion is generally not defined. In this context, we have to assume a wide definition of the concept of future generations, conceived as people who will live after the contemporary people are dead. This definition embraces thus each generation following ours, without any restriction in time. The aim of this paper is to show that, in the debate about nuclear waste, this broad notion should be further specified and to clarify the related implications for nuclear waste management policies. Therefore, we provide an ethical analysis of different management strategies for high-level waste in the light of two principles, protection of future generations—based on safety and security—and respect for their choice. This analysis shows that high-level waste management options have different ethical impacts across future generations, depending on whether the memory of the waste and its location is lost, or not. We suggest taking this distinction into account by introducing the notions of “close future generations” and “remote future generations”, which has important implications on nuclear waste management policies insofar as it stresses that a retrievable disposal has fewer benefits than usually assumed.     

Newtonian Idealism: Matter,Perception, and the Divine Will

This paper investigates Isaac Newton's rather unique account of God's relation to matter. According to this account, corpuscles depend on a substantially omnipresent God endowing quantities of objective space with the qualities of shape, solidity, the unfaltering tendency to move in accord with certain laws, and—significantly—the power to interact with created minds. I argue that there are important similarities and differences between Newton's account of matter and Berkeley's idealism. And while the role played by the divine will might at first appear to be a species of occasionalism, I conclude that there are, for Newton, genuine causal relations between minds and bodies. Ultimately, to fully appreciate this account of the creation and persistence of matter, we must consider not only Newton's metaphysical writings, but also his sensorium theory of mind‐body interaction, his heterodox theological commitments, and the influences of Descartes, More, and Locke.     

The myth of the encoding-retrieval match

Modern memory researchers rely heavily on the encoding-retrieval match, defined as the similarity between coded retrieval cues and previously encoded engrams, to explain variability in retention. The encoding-retrieval match is assumed to be causally and monotonically related to retention, although other factors (such as cue overload) presumably operate in some circumstances. I argue here that the link between the encoding-retrieval match and retention, although generally positive, is essentially correlational rather than causal—much like the link between deep/elaborative processing and retention. Empirically, increasing the functional match between a cue and a target trace can improve, have no effect, or even decrease retention performance depending on the circumstance. We cannot make unequivocal predictions about retention by appealing to the encoding-retrieval match; instead, we should be focusing our attention on the extent to which retrieval cues provide diagnostic information about target occurrence.     

Statistical Learning of Unfamiliar Sounds as Trajectories Through a Perceptual Similarity Space

In typical statistical learning studies, researchers define sequences in terms of the probability of the next item in the sequence given the current item (or items), and they show that high probability sequences are treated as more familiar than low probability sequences. Existing accounts of these phenomena all assume that participants represent statistical regularities more or less as they are defined by the experimenters—as sequential probabilities of symbols in a string. Here we offer an alternative, or possibly supplementary, hypothesis. Specifically, rather than identifying or labeling individual stimuli discretely in order to predict the next item in a sequence, we need only assume that the participant is able to represent the stimuli as evincing particular similarity relations to one another, with sequences represented as trajectories through this similarity space. We present experiments in which this hypothesis makes sharply different predictions from hypotheses based on the assumption that sequences are learned over discrete, labeled stimuli. We also present a series of simulation models that encode stimuli as positions in a continuous two‐dimensional space, and predict the next location from the current location. Although no model captures all of the data presented here, the results of three critical experiments are more consistent with the view that participants represent trajectories through similarity space rather than sequences of discrete labels under particular conditions.     

That’s not my place: The interacting effects of faultlines,subgroup size,and social competence on social loafing behaviour in work groups

Taking a social relations approach to team diversity, we propose that faultlines—hypothetical dividing lines that split a team into relatively homogeneous subgroups—impact the team members’ propensity to exhibit social loafing behaviour. We further propose that this individual-level reaction to the faultline structure of the team can differ among team members, depending on the size of their subgroup and on their individual social competence. We tested the assumptions with a sample of real teams working on an intellective task during which social loafing behaviour was video-coded. In partial support of the hypotheses, generalized mixed models revealed that social loafing behaviour was most common for team members who were part of a team with strong faultlines, who belonged to the larger subgroup in their team, and who exhibited low levels of social competence. The results therefore highlight the benefits of taking a multilevel approach to the effects of faultlines.     

The Regress of Pure Powers Revisited

The paper aims to elucidate in better detail than before the dispute about whether or not dispositional monism—the view that all basic properties are pure powers—entails a vicious infinite regress. Particular focus is on Alexander Bird's and George Molnar's attempts to show that the arguments professing to demonstrate a vicious regress are inconclusive because they presuppose what they aim to prove, notably that powers are for their nature dependent on something else. I argue that Bird and Molnar are mistaken. It is true that dispositional monism is popularly assumed to characterize powers as dependent entities, but this is not what the arguments aim to prove. They merely aim to demonstrate that it would be absurd to assume that all properties are dependent in this way. Finally, it is argued that there is an unresolved tension in Bird's and Molnar's accounts of powers. They characterize them as being for their nature dependent on the manifestations that they are for, and yet ontologically independent of those same manifestations. Until that tension is resolved, their accounts are not equipped to remove the threat of vicious regress.