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 anincidence 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° 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.     

Die Psychotherapeutenausbildung aus Sicht der Teilnehmer

Background

A survey was performed to assess the current situation in education and to identify critical issues 10 years after the inception of the German law regulating the education of psychological psychotherapists and child and adolescent psychotherapists. The study reports the results of a nationwide survey of German psychological psychotherapists and child and adolescent psychotherapists currently in training. The aim of the survey was to evaluate the individual sections of training, desired alterations and structural and financial conditions.

Methods

All trainees were contacted via the training institutes and the umbrella organizations. A total of 3,223 trainees participated and answered questions mainly using an online questionnaire.

Results

Most respondents practiced their training part-time and in most cases the trainees thought that the training would last longer than initially expected. The practical training was rated most poorly, whereas practical education and individual supervision were rated as most useful. The survey revealed deficits concerning the evaluation of the quality of several components of the training.

Conclusions

From the perspective of the trainees there is a necessity to modify the financial conditions of the training. This result has been considered in the recommendations of a research expertise on psychotherapy training and should stimulate further research.     

Consumption experience of impulse buying in Indonesia: Emotional arousal and hedonistic considerations

Two studies focused on impulsive purchase experiences. Feelings, considerations and ratings of purchase impulsiveness were measured with respect to a recent purchase by means of interviews immediately after the purchase in the shopping environment (Study 1) and through shopping diaries (Study 2). Feelings and considerations were measured by open-ended questions, which yielded a wide range of responses in each category. These responses were subjected to multidimensional scaling. The results demonstrated a high versus low arousal dimension of positive emotions and a hedonic versus utilitarian dimension of considerations. Emotions and considerations were predicted by general impulse-buying tendency, and were related to the experience of impulsive purchases. In Study 2, impulse buying tendency was measured 2 months earlier. Structural equation modelling confirmed a model in which general impulse buying tendency predicts the feelings and considerations in the purchase environment, which in turn, determine the experience of making an impulsive purchase.     

Psychological and demographic correlates of career patterns

Recent years have witnessed a growing diversity of career patterns, resulting from the relative decline of stable employment. In the present study of 1368 employed and self-employed German adults career pattern diversity was assessed using nine pictograms. The goal was to identify psychological and demographic correlates of these patterns and to answer the question of whether they differed for participants from the former (communist) East and the capitalist West. Findings indicated that upward-pointing career patterns still connected to extrinsic criteria such as income and job security. With regard to psychological correlates, upward patterns connected to lower work-related demands imposed by social change and a higher level of personal and social resources. Only in the West, upward patterns related to male gender and high education, reflecting more traditional access to upwardly mobile career opportunities.     

Salient features in 3-D haptic shape perception

Shape is an important cue for recognizing an object by touch. Several features, such as edges, curvature, surface area, and aspect ratio, are associated with 3-D shape. To investigate the saliency of 3-D shape features, we developed a haptic search task. The target and distractor items consisted of shapes (cube, sphere, tetrahedron, cylinder, and ellipsoid) that differed in several of these features. Exploratory movements were left as unconstrained as possible. Our results show that this type of haptic search task can be performed very efficiently (25 msec/item) and that edges and vertices are the most salient features. Furthermore, very salient local features, such as edges, can also be perceived through enclosure, an exploratory procedure usually associated with global shape. Since the subjects had to answer as quickly as possible, this suggests that speed may be a factor in selecting the appropriate exploratory procedure.     

Haptic identification of curved surfaces

In two experiments, the active haptic identification of three-dimensional mathematically welldefined objects is investigated. The objects, quadric surfaces, are defined in terms of the shape index, a quantity describing the shape, and curvedness, a quantity describing overall curvature. Both shape index and curvedness are found to have a significant influence on haptic shape identification . Concave surfaces lead to a larger spread in responses than convex ones. Hyperbolic surfaces show a slight tendency to be identified with more difficulty than elliptic ones. Surfaces with a high curvedness are identified more easily than those with a low curvedness. Results from experiments with constant and with random curvedness are indistinguishable . It is concluded that shape index and curvedness are psychophysically not confounded.     

Sich verlieben und die große Liebe

Although romantic love plays an important role for many people, empirical studies on romantic love have only been carried out recently. This article describes the results of a questionnaire on romantic love completed by 606 volunteers. The results show that nearly everyone has had the personal experience of falling in love at least once. According to the reports in the questionnaire, men and women do not differ with respect to the frequency and to the velocity with which they fall in love. Women, however, more often believe that their respective partner has fallen in love at a relatively early stage, whilst men believe that their respective partner has fallen in love only later. Both men and women exhibit distinct physical and emotional phenomena when they have fallen in love – women more pronouncedly than men. The quality of the relationship between men and women appears to be better if the partners have initially fallen in love with each other. From the point of view of couple therapy, the quality and quantity of being in love appear to be less important than the methods of coping with it, i.e. accepting that the initial romantic love period may not stay forever but must be replaced by another type of love, or accepting that a couple can also have a highly satisfactory relationship, although there was no initial period of romantic love.     

The visual contour in depth

We asked subjects to match points on the surface of a smooth three-dimensional (3-D) shape with points on the surface of another object that was geometrically identical to the first object but was placed in a different pose, was differently textured, and was differently shaded. In all cases, the fiducial point was on the rim of one of the objects (i.e., the boundary of the visible region of the surface), whereas the matching point was well within the silhouette of the other object. This allowed us to draw (preliminary) conclusions concerning the way monocular human observers are able to handle the neighborhood of the rim, where the local slant assumes arbitrarily high values. All experiments were done in real space with real objects (no computer-simulated scenes), the points being indicated with laser beam illumination. The subject was given control over the direction of the laser beams and was thus able to perform the task by adjustment from the vantage position. We studied both consistency (whether the subject’s judgments were invariant against changes of relative pose) and veridicality (whether the depth of the visual contour as calculated from the settings agreed with the true distance as measured by mechanical means). Subjects caught much of the 3-D structure of the contour but did deviate appreciably and apparently idiosyncratically from the true geometry.     

Detection of spatial discontinuities in first-order optical flow fields

We investigated the extent to which the human visual system can detect discontinuities in firstorder optical flow fields. We constructed two types of spatial discontinuities: a circular split field with a straight edge and a disk with annular surround. We used two different first-order optical flow components: an expansion and a rotation. We found an intriguing difference in the detection thresholds for straight and circular discontinuities. Whereas straight discontinuities yielded thresholds of 10%— 50% difference in expansion or rotation, circular discontinuities could, at first, only be detected at extreme differences (>>100%). After a learning period, thresholds for such stimuli decreased, but they remained significantly higher than thresholds for the straight edge. Thresholds rose for stimuli that formed a gradual transition between a circular and a straight edge, and they decreased with increasing eccentricity of the circular discontinuity. Results suggest that symmetry in the stimulus, defined by the coincidence of the center of expansion or rotation and the center of the circular discontinuity, was responsible for the difference in thresholds for circular and straight discontinuities.