Combining cues while avoiding perceptual conflicts

A common assumption in cue combination models is that small discrepancies between cues are due to the limited resolution of the individual cues. Whenever this assumption holds, information from the separate cues can best be combined to give a single, more accurate estimate of the property of interest. We examined whether information about the discrepancy itself is lost when this is done. In our experiments, subjects were required to combine cues to match certain properties while avoiding perceptual conflicts. In part 1, they combined expansion and change in disparity to estimate motion in depth; and in part 2, they combined perspective and binocular disparities to estimate slant. We compared the pattern in the way that subjects set the two cues with the patterns predicted by models of cue combination with and without a loss of information about the discrepancy. From this comparison we conclude that little information about the discrepancies between cues is lost when the cues are combined.     

Spatial but not temporal cueing influences the mislocalisation of a target flashed during smooth pursuit

Human subjects misjudge the position of a target that is flashed during a pursuit eye movement. Their judgments are biased in the direction in which the eyes are moving. We investigated whether this bias can be reduced by making the appearance of the flash more predictable. In the normal condition, subjects pursued a moving target that flashed somewhere along its trajectory. After the presentation, they indicated where they had seen the flash. The mislocalisations in this condition were compared to mislocalisations in conditions in which the subjects were given information about when or where the flash would come. This information consisted of giving two warning flashes spaced at equal intervals before the target flash, of giving two warning beeps spaced at equal intervals before the target flash, or of showing the same stimulus twice. Showing the same stimulus twice significantly reduced the mislocalisation. The other conditions did not. We interpret this as indicating that it is not predictability as such that influences the performance, but the fact that the target appears at a spatially cued position. This was supported by a second experiment, in which we examined whether subjects make smaller misjudgments when they have to determine the distance between a target flashed during pursuit and a reference seen previously, than when they have to determine the distance between the flashed target and a reference seen afterwards. This was indeed the case, presumably because the reference provided a spatial cue for the flash when it was presented first. We conclude that a spatial cue reduces the mislocalisation of targets that are flashed during pursuit eye movements. The cue does not have to be exactly at the same position as the flash.     

Should observed overconfidence be dismissed as a statistical artifact? Critique of Erev, Wallsten, and Budescu (1994)

I. Erev, T. S. Wallsten, and D. V. Budescu (1994) showed that the same probability judgment data can reveal both apparent overconfidence and underconfidence, depending on how the data are analyzed. To explain this seeming paradox, I. Erev et al. proposed a general model of judgment in which overt responses are related to underlying "true judgments" that are perturbed by error. A central conclusion of their work is that observed over- and underconfidence can be split into two components: (a) "true" over- and underconfidence and (b) "artifactual" over- and underconfidence due to error in judgment. It is argued in the present article that decomposing over- and underconfidence into true and artifactual components is inappropriate. The mistake stems from giving primacy to ambiguously defined model constructions (true judgments) over observed data.     

Psychometrically matched visual-processing tasks in schizophrenia spectrum disorders

Patients with schizophrenia show deficits in visual perception and working memory, but the relationship between these deficits has not been characterized with psychometrically matched tasks. The authors administered 2 visual discrimination and 6 recognition tasks to 43 schizophrenia spectrum patients and 22 nonpsychiatric subjects. When performing difficulty-matched tasks, spectrum subjects showed more severe impairments for motion compared with form processing. When tasks were matched on true score variance, spectrum subjects exhibited worse performance on both form and motion discrimination, and a differential deficit in motion recognition with a short display duration and long interstimulus interval. These results provide evidence of differential deficits in visual processing in schizophrenia that appear to be dependent on the temporal characteristics of the tasks.     

Natural Law, Motives, and Freedom of the Will

In this paper I piece together a Wittegnsteinian view of the topics indicated in my title, contrasting it with the views of Bertrand Russell and Donald Davidson - two philosophers who, in words from the Blue Book , seem "constantly to see the method of science before their eyes." I conclude that Wittegnstein helps us understand something those philosphers tend to overlook: that "freedom of the will" gets its meaning not in a belief to be assessed by evidence but, on the contrary, in the expression of a way of living and assessing life that limits the role of "assessing beliefs by evidence."     

IDEOLOGICAL FORMATIONS OF WITNESSING THE HOLOCAUST IN WARTIME DIARIES OF JAROSŁAW IWASZKIEWICZ AND MARIA DĄBROWSKA

The Polish writers Jaros?aw Iwaszkiewicz (1894–1980) and Maria D?browska (1889–1965) spent the years of brutal German occupation in Warsaw. Both witnessed the establishment of the Ghetto, the 1942 deportations, and the 1943 Uprising, as well as the attempts of the Jewish fugitives to hide on the “Aryan side” of the city. Yet their war diaries reveal contrasting attitudes toward the destruction of the Jews. Whereas D?browska projected indifference by practically ignoring the evolving genocide, Iwaszkiewicz expressed dismay and compassion. Iwaszkiewicz and his wife Anna engaged in rescuing Jews while D?browska showed no sympathy for the Jewish plight. Such polarized responses to the Holocaust by individuals who were contemporaries, fellow writers, and prominent members of the intellectual elite of Warsaw raise questions about the nature of witnessing and responding to atrocities. This essay posits that the differences in these writers' attitudes toward the genocide of the Polish Jews were indelibly tied to the ideological systems that shaped their self-identities.     

Curved movement paths and the Hering illusion: Positions or directions?

When trying to move in a straight line to a target, participants produce movement paths that are slightly (but systematically) curved. Is this because perceived space is curved, or because the direction to the target is systematically misjudged? We used a simple model to investigate whether continuous use of an incorrect judgement of the direction to the target could explain the curvature. The model predicted the asymmetries that were found experimentally when moving across a background of radiating lines (the Hering illusion). The magnitude of the curvature in participants' movements was correlated with their sensitivity to the illusion when judging a moving dot's path, but not with their sensitivity when judging the straightness of a line. We conclude that a misjudgement of direction causes participants to perceive a straight path of a moving dot as curved and to produce curved movement paths.