The human element in car following models

This commentary distinguishes between the engineering-inspired formalisms used by Brackstone, M., and McDonald, M. (Transportation Research Part F (1999)) and the psychological knowledge of, and assumptions about human behaviour when car following. It outlines a preliminary mathematical model, based on psychological knowledge about car following behaviour by human drivers, which could be applied in traffic engineering, as a means of bringing these two ways of studying car following closer together.     

Moral Responsibility, Determinism, and the Ability to do Otherwise

In his classic paper, The Principle of Alternate Possibilities, Harry Frankfurt presented counterexamples to the principle named in his title: A person is morally responsible for what he has done only if he could have done otherwise. He went on to argue that the falsity of the Principle of Alternate Possibilities (PAP) implied that the debate between the compatibilists and the incompatibilists (as regards determinism and the ability to do otherwise) did not have the significance that both parties had attributed to it -- since moral responsibility could exist even if no one was able to do otherwise. I have argued that even if PAP is false, there are other principles that imply that moral responsibility entails the ability to do otherwise, and that these principles are immune to Frankfurt-style counterexamples. Frankfurt has attempted to show that my arguments for this conclusion fail. This paper is a rejoinder to that reply; I argue that he has failed to show this.     

Color filling-in under steady fixation: behavioral demonstration in monkeys and humans

Color filling-in is a phenomenon in which the color of an object appears to be filled-in by the color of the surrounding field. We have studied the question of whether monkeys perceive color filling-in with near-foveal stimuli under steady fixation. Two monkeys were trained to fixate steadily and to attend to a disk, surrounded by an annulus of the complementary color, in parafoveal vision. Using displays in which the color of the disk was gradually changed to that of the annulus, we trained the animals to signal when they perceived a uniform color field. During the experiment, we introduced a small percentage of trials in which the disk color remained constant, and looked for 'filling-in' responses in these trials. Three human subjects were also tested for comparison. All subjects produced 'filling-in' responses with frequencies that were significantly higher for static disks with blurred borders than for moving disks or disks with sharp borders. This indicates that the monkeys' responses reflected perceptual filling-in, rather than random behavior. The time course of filling-in was similar in monkeys and humans. For the blurred static disks, responses occurred first after 3-4 s of fixation, reaching a probability of 0.2-0.8 by the end of 6 s, depending on the subject.     

Exocentric pointing in three-dimensional space

A study is reported of an exocentric pointing task in all three dimensions, in near space, with only two visible luminous objects--a pointer and a target. The task of the subject was to aim a pointer at a target. The results clearly show that visual space is not isotropic, since every set direction appeared to consist of two independent components--one in the projection onto a frontoparallel plane (tilt), the other in depth (slant). The tilt component shows a general trend across subjects, an oblique effect, and can be judged monocularly. The slant component is symmetrical in the mid-sagittal plane, requires the use of binocular information, and shows considerable differences between subjects. These differences seem to depend on the amount of binocular information used by each subject. There was a remarkably high level of consistency in the exocentric pointing, despite the absence of environmental cues. The within-subject consistency in the settings of the pointer corresponds to a consistency of about 1 min of arc in disparity of its tip, even though the pointer and target are separated by more than 5 deg.     

The Identity Status Approach: In Need of Fundamental Revision and Qualitative Change

This article is a response to the commentaries of Waterman (this issue) and Berzonsky and Adams (this issue) on my review of the identity status field (van Hoof, this issue). The commentaries illustrate that the identity status researchers attribute different meanings to the identity statuses and identity status research; while Waterman finds it difficult to recognize the field in my review, Berzonsky and Adams agree with several of my conclusions. The two commentaries represent two pillars on which the status approach rests. The difference between the review and the commentaries is that the first includes both pillars, whereas each commentary consists primarily of a selective presentation of assumptions and data. This response focuses on two main points of the commentaries: (a) are the statuses sufficiently validated? and (b) to what extent are they suitable for testing developmental identity hypotheses? Using specific examples I show that the line of reasoning in the commentaries and the data proposed in support of these arguments in fact often support the conclusions of my review, for I demonstrate that the statuses are insufficiently validated and that the statuses are unsuitable for measuring identity development. These conclusions call for a fundamental revision of the identity status approach and a qualitative change in identity theory and research. Finally, the alternative approaches presented by Berzonsky and Adams are evaluated with respect to their contribution to an indispensable qualitative change in the identity status field.     

Relative mislocalization of briefly presented stimuli in the retinal periphery

We studied the ability to localize flashed stimuli, using a relative judgment task. When observers are asked to localize the peripheral position of a probe with respect to the midposition of a spatially extended comparison stimulus, they tend to judge the probe as being more toward the periphery than is the midposition of the comparison stimulus. We report seven experiments in which this novel phenomenon was explored. They reveal that the mislocalization occurs only when the probe and the comparison stimulus are presented in succession, independent of whether the probe or the comparison stimulus comes first (Experiment 1). The size of the mislocalization is dependent on the stimulus onset asynchrony (Experiment 2) and on the eccentricity of presentation (Experiment 3). In addition, the illusion also occurs in an absolute judgment task, which links mislocalization with the general tendency to judge peripherally presented stimuli as being more foveal than they actually are (Experiment 4). The last three experiments reveal that relative mislocalization is affected by the amount of spatial extension of the comparison stimulus (Experiment 5) and by its structure (Experiments 6 and 7). This pattern of results allows us to evaluate possible explanations of the illusion and to relate it to comparable tendencies observed in eye movement behavior. It is concluded that the system in charge of the guidance of saccadic eye movements is also the system that provides the metric in perceived visual space.     

Temporal dynamics of anxiety-related attentional bias: is affective context a missing piece of the puzzle?

Previous research has demonstrated that anxious individuals attend to negative emotional information at the expense of other information. This is commonly referred to as attentional bias. The field has historically conceived of this process as relatively static; however, research by [Zvielli, A., Bernstein, A., &; Koster, E. H. W. (2014). Dynamics of attentional bias to threat in anxious adults: Bias towards and/or away? PLoS ONE, 9(8), e104025; Zvielli, A., Bernstein, A., &; Koster, E. H. W. (2015). Temporal dynamics of attentional bias. Clinical Psychological Science, 3(5), 772–788.], and others, challenges this assumption by demonstrating considerable temporal variability in attentional bias amongst anxious individuals. Still, the mechanisms driving these temporal dynamics are less well known. Using a modified dot-probe task, the present study examined the impact of two relevant contextual variables- affective valence and trial repetition. Affective context was instantiated by the presentation of negative versus neutral pictures before each trial, while repetition context was achieved via the presentation of the valenced pictures in either a blocked- or mixed-trial design. Results indicate that individuals with higher trait-anxiety levels were significantly more influenced by blocked presentations of negative affective information, leading to greater temporal fluctuations in attentional bias. Furthermore, our findings provide additional evidence that attentional bias is best conceptualised as dynamic and variable, and that an individual’s affective experience is one factor that regulates attentional bias dynamics. Implications relating to theoretical and methodological factors are discussed.