Parametrized preference structures and some geometrical interpretation

Order structures such as linear orders, semiorders and interval orders are often used to model preferences in decision-making problems. In this paper we introduce a family of preference structures where the mutual indifference threshold belongs to a specific family parametrized by extended reals α. This family includes interval orders (α=1), tangent circle orders (α=0) and a new preference structure called ‘diamond order’ (α=−∞). All these preference relations present an asymmetric part which is shown to be always quasi-transitive and to be transitive for α > 1. Diamond orders present ‘forbidden configurations’ which can occur in the case of tangent circle orders. © 1997 John Wiley & Sons, Ltd.     

Effects of visual roll on steering control and gaze behavior in a motorcycle simulator

The goal of this study was to examine the effects of visual roll tilt on gaze and riding behavior when negotiating a bend using a motorcycle simulator. To this end, experienced motorcyclists rode along a track with a series of right and left turns whilst the degree of visual roll tilt was manipulated in three different conditions. Gaze behavior was analyzed by using the tangent point as a dynamic spatial reference; the deviation of gaze to this particular point was computed in both the horizontal and vertical directions. Steering control was assessed in terms of the lateral positioning, steering stability and number of lane departures. In the no-roll condition, the motorcyclists tracked a steering point on the road ahead, which was compatible with the hypothesis of “steer where you look” behavior. In the roll condition, our results revealed that the horizontal distribution of gaze points relative to the tangent point was preserved. However, significantly more fixations were made further ahead of the tangent point in the vertical direction. This modification of visual behavior was coupled with a degradation in steering stability and an offset in lateral positioning, which sometimes led to lane departures. These results are discussed with regard to models of visual control of steering for bend negotiation.     

Behavioural adaptation or constraint? The effect of curve proximity on driving behaviour

Horizontal curves are typically associated with increased crash risk when compared with straight roads, but recent analyses have suggested that having more frequent sharp curves decreases the relative crash risk posed by each curve. Here, 90 drivers completed a simulated rural drive with either high proximity (160 m straight tangent between curves) or low proximity (1200 m tangent) curves. Curve proximity had a significant effect on approach speeds, with drivers in the high proximity curve drive showing significantly lower mean and maximum approach speeds before entering the curve. However, they also showed an unexpected tendency to higher speeds while negotiating the curve itself. The current study provides direct empirical evidence that driving behaviour on approach to a given curve is significantly affected by the proximity of other curves, and therefore highlights the need to factor in the characteristics of the road on approach to the curve, as well as the features of the curve itself when assessing risk.     

Planarity and segmentation in stereoscopic matching

The matching of stereograms which contain periodic patterns suggests ways in which the stereo correspondence problem may be solved in human vision. The stereograms seem to be segmented by coarse-scale features. Within each segment a set of matches approximating a plane is chosen. In regions with periodic patterns there may be many such planar sets, and the disparity of coarse-scale features seems to guide the choice of a particular set. This emphasis on planarity may reflect the occurrence of correlation-like operations in cortical neurons. An attractive possibility is that segmentation effectively delimits areas of the visual field within which disparities are likely to be slow changing (eg local tangent planes to surfaces) so that the correlation sums evaluated in a segment can give the best estimate of depth. A mechanism of this kind cannot account for all of stereo matching, since not all visual objects are well described by ensembles of planes. But it is likely to be a component of the matching system which is particularly important where images are 'noisy' and averaging is needed to extract reliable disparities.     

Boundaries,journals and counselling psychology: Stephen Palmer interviews Kasia Szymanska

You have just retired from editing Counselling Psychology Review, the in-house journal of the British Psychological Society, Division of Counselling Psychology. It seems an appropriate moment to interview you for Counselling Psychology Quarterly. In this interview I want to focus on a topic I know you are interested in, client-therapist boundary issues, and your experience editing the journal. But I'd like to start off at a slight tangent. What encouraged you to go into counselling psychology as a profession?     

Psychophysical judgment of curvatures

In this study we explored psychophysical judgments (magnitude estimation) of the curvature of visual lines. Prior research has lacked a rigorous definition of curvature, but here it was defined as the reverse of the ray of the osculating circle tangent to the curve in the given point. Four different functions were evaluated: hyperbole, sinusoid, parabola, and a cubic function. Using the method of magnitude estimation to judge 20 exemplar curves from each of the families, three respondents made a total of 1440 estimations each. Responses to all four families of curves were fit well by Stevens' power function with an exponent less than 1. One application of this research is the use of such curves as variables in assessing illusions of curvature.     

The information for catching fly balls: judging and intercepting virtual balls in a CAVE

Visually guided action implies the existence of information as well as a control law relating that information to movement. For ball catching, the Chapman Strategy--keeping constant the rate of change of the tangent of the elevation angle (d(tan(alpha))/dt)--leads a catcher to the right location at the right time to intercept a fly ball. Previous studies showed the ability to detect the information and the consistency of running patterns with the use of the strategy. However, only direct manipulation of information can show its use. Participants were asked to intercept virtual balls in a Cave Automated Virtual Environment (CAVE) or to judge whether balls would pass behind or in front of them. Catchers in the CAVE successfully intercepted virtual balls with their forehead. Furthermore, the timing of judgments was related to the patterns of changing d(tan(alpha))/dt. The advantages and disadvantages of a CAVE as a tool for studying interceptive action are discussed.     

The Poggendorff illusion: Amputations,rotations, and other perturbations

Studies of the Poggendorff illusion (a transversal interrupted by parallel lines) showed that illusory effects increased linearly with increasing separation between the parallels, increased in inverse proportion to the tangent of the angle of intersection between transversal and parallels, decreased whenever line segments (other than a transversal segment) were omitted, decreasing to zero when the segment of a parallel forming the obtuse angle with the transversal was omitted, and varied systematically with the tilt of the whole display, approaching zero when the transversal was oriented in a horizontal or vertical position. Hypothesis: The Poggendorff illusion involves at least three kinds of effects on the perceived orientation of a segment: distortion by other segments (especially a segment intersecting at an obtuse angle), stability of vertical and Horizontal orientations, and assimilation towards vertical or horizontal.     

Investigating the effectiveness of perceptual treatments on a crest vertical curve: A driving simulator study

Rural roads are characterized by a high percentage of run-off-the-road accidents and head-on collisions, mainly caused by inappropriate speeds and failure to maintain a proper lateral position along the roadway alignment. Among several road safety treatments, low-cost perceptual measures are considered an effective tool, as they generally increase the risk perceived by drivers, or even alter the drivers’ speed perception, and consequently tempting them to decrease their speeds. Their effectiveness has been widely recognized in a number of studies, especially with respect to road intersections and curves.The overall aim of this study is to investigate the effects of different perceptual treatments on driving speed, along a crest vertical curve of an existing two-lane rural road, in order to identify the most effective measure to reduce speed and define its subsequent implementation in the field. Three perceptual treatments were tested using a driving simulator: white peripheral transverse bars, red peripheral transverse bars and optical speed bars, with each one being painted along the approaching tangent to the crest vertical curve. The effects of these speed-reducing measures were investigated using a sample of forty-four participants, by comparing the driving speeds with those recorded under a baseline condition (without a treatment); these were also used to validate the driving simulator’s speed measurements with those found in the field. Moreover, subjective measures were collected, consisting of the driver’s static evaluation of the desired speed, risk perception and markings comprehension, based on screen shot pictures that represented the simulated configurations of the treatments.The findings demonstrated an overall effectiveness of the perceptual treatments, although only the red peripheral transverse bars were found to significantly reduce the driving speeds (−6 km/h). The analysis of the questionnaire yielded interesting information and demonstrated the importance of performing driving simulation tests for evaluating the effectiveness of perceptual treatments.Finally, the results confirmed the enormous potential of using driving simulators to pinpoint a number of speed-reducing measures, and consequently select the most effective one that reduces cost and promotes safety before its actual implementation in the field.     

The Mathematical Event: Mapping the Axiomatic and the Problematic in School Mathematics

Traditional philosophy of mathematics has been concerned with the nature of mathematical objects rather than events. This traditional focus on reified objects is reflected in dominant theories of learning mathematics whereby the learner is meant to acquire familiarity with ideal mathematical objects, such as number, polygon, or tangent. I argue that the concept of event—rather than object—better captures the vitality of mathematics, and offers new ways of thinking about mathematics education. In this paper I draw on two different but related theories of event articulated in the philosophies of Alain Badiou and Gilles Deleuze to argue that the central activity of ‘problem solving’ in mathematics education should be recast in terms of a problematic of events.     

Converting between measures of slope of the psychometric function.

The psychometric function's slope provides information about the reliability of psychophysical threshold estimates. Furthermore, knowing the slope allows one to compare, across studies, thresholds that were obtained at different performance criterion levels. Unfortunately, the empirical validation of psychometric function slope estimates is hindered by the bewildering variety of slope measures that are in use. The present article provides conversion formulas for the most popular cases, including the logistic, Weibull, Quick, cumulative normal, and hyperbolic tangent functions as analytic representations, in both linear and log coordinates and to different log bases, the practical decilog unit, the empirically based interquartile range measure of slope, and slope in a d' representation of performance.     

Guilt by association?

Recent evolutionary perspectives on guilt tend to focus on how guilt functions as a means for the individual to self-regulate behavior and as a mechanism for reinforcing cooperative tendencies. While these accounts highlight important dimensions of guilt and provide important insights into its evolutionary emergence, they pay scant attention to the large empirical literature on its maladaptive effects on individuals. This paper considers the nature of guilt, explores its biological function, and provides an evolutionary perspective on whether it is an individual-level or group selected trait. After surveying philosophical and psychological analyses of guilt, we consider which psychological mechanisms underlie the capacity to experience and act from guilt and whether they point to an emergence of guilt in early humans or to guilt having a longer phylogenetic history. Because guilt is a characteristically social emotion, we then examine its contemporary role in social and legal contexts, which may provide clues to its original biological function. Finally, we provide the outlines of two evolutionary explanations for guilt. We argue that group selection may have promoted the capacity to experience guilt, but that under certain conditions there may have been a positive individual selection force as well.     

Converting between measures of slope of the psychometric function

The psychometric function’s slope provides information about the reliability of psychophysical threshold estimates. Furthermore, knowing the slope allows one to compare, across studies, thresholds that were obtained at different performance criterion levels. Unfortunately, the empirical validation of psychometric function slope estimates is hindered by the bewildering variety of slope measures that are in use. The present article provides conversion formulas for the most popular cases, including the logistic, Weibull, Quick, cumulative normal, and hyperbolic tangent functions as analytic representations, in both linear and log coordinates and to different log bases, the practical decilog unit, the empirically based interquartile range measure of slope, and slope in a? representation of performance.     

Display organization and the detection of horizontal line segments

Observers searched for a horizontal line segment through displays containing varying numbers of elements differing from the target and from each other in terms of orientation. These elements were always positioned on imaginary concentric circles centered in the middle of the display. They were allocated to these positions either randomly or in such a way that their orientation was equal to that of the tangent to the circle at that position. The search for the target line appeared to proceed spatially in parallel with the latter class of displays, and serially with the former. These findings are explained and discussed within the context of the attentive-preattentive dichotomy that characterizes spatial vision.     

Dramatic conversation: An exploratory application of Burton's discourse model

The British sociolinguists Sinclair and Coulthard have generated a systematic approach to the analysis of natural conversation using classroom discourse. Burton has articulated an innovative development of this model that she claims is applicable to a broad range of spoken discourse. She focuses on the language of dramatic plays. Her model is explained, and in an attempt to assess its viability, an application to a brief exchange in a Tennessee Williams play and its Italian translation is proposed. Interesting differences between the interactive structures of the two texts are revealed, indicating that Burton's model may be fruitful for the analysis of fictional dialogue. However, theatre talk may differ in as yet unknown ways from natural conversation.     

Prevalence of the extinction burst and its attenuation during treatment

Although extinction has been an effective treatment for a variety of behavior disorders, its use may be associated with several adverse side effects, the most common being an initial increase in the frequency of the target response, called an "extinction burst." We attempted to determine the prevalence of the extinction burst in applied research and its possible attenuation with other operant procedures. An analysis of 113 sets of extinction data indicated that bursting may not be as common as previously assumed (it occurred in 24% of the cases) and may be less likely when extinction is implemented with alternative procedures rather than as the sole intervention (bursting was evident in 12% of the former cases and 36% of the latter).     

Optical trajectories and the informational basis of fly ball catching

D. M. Shaffer and M. K. McBeath (see record 2002-02027-006) plotted the optical trajectories of uncatchable fly balls and concluded that linear optical trajectory is the informational basis of the actions taken to catch these balls. P. McLeod, N. Reed, and Z. Dienes (see record 2002-11140-016) replotted these trajectories in terms of changes in the tangent of optical angle over time and concluded that optical acceleration is the informational basis of fielder actions. Neither of these conclusions is warranted, however, because the optical trajectories of even uncatchable balls confound the information that is the basis of fielder action with the effects of those same actions on these trajectories. To determine the informational basis of fielder action, it is necessary to do the control-theory-based Test for the Controlled Variable, in which the informational basis of catching is found by looking for features of optical trajectories that are protected from experimentally or naturally applied disturbances.     

Holism about value: some help for invariabilists

G.E. Moore’s principle of organic unity holds that the intrinsic value of a whole may differ from the sum of the intrinsic values of its parts. Moore combined this principle with invariabilism about intrinsic value: An item’s intrinsic value depends solely on its bearer’s intrinsic properties, not on which wholes it has membership of. It is often said that invariabilism ought to be rejected in favour of what might be called ‘conditionalism’ about intrinsic value. This paper is an attempt to show how invariabilism might be filled out in ways that allow its proponents to answer their conditionalist opponents. The main point consists in identifying how some amount of extrinsic part-value may contribute to whole-value that is nevertheless intrinsic. This enables an invariabilist to explain how the intrinsic value of a whole may differ from the sum of its intrinsic part-values, without abandoning the Moorean doctrine that intrinsic value supervenes on intrinsic properties (the proposal is nevertheless consistent with the view that invariabilist and conditionalist accounts might exist side by side). I finish with a brief explanation of how the main proposal could help construct invariabilist accounts of particular organic unities, looking beyond the more general argument they have with conditionalists.     

Job as Apologetic: The Role of the Audience

A key to interpreting the Book of Job, following from the general methodology for the human sciences set out by the French sociologist Pierre Bourdieu, is to regard the field in which the text is embedded as the beliefs of its audience rather than its explicit content of story and characters. Bourdieu has shown the extent to which belief and practice involve elements of uncertainty and strategy, allowing inconsistencies to be interpreted as rhetorical effects. Several conclusions follow: the main focus of the Book is honour and wisdom; belief in divine transcendence may be produced as an effect of discontinuity and uncertainty in the narrative; piety may appear as an ideological effect of a pre-monetary economic order; and the principle of temporal retribution is shown to be reinforced by the text. At the same time, the Book is shown to furnish its own critique of conventional piety and to articulate an alternative piety grounded in critique itself. Religion is not purely ideological, for piety is portrayed as a critique of the ideological effects of the symbolic order.