On the perception of shape from shading.

The extraction of three-dimensional shape from shading is one of the most perceptually compelling, yet poorly understood, aspects of visual perception. In this paper, we report several new experiments on the manner in which the perception of shape from shading interacts with other visual processes such as perceptual grouping, preattentive search ("pop-out"), and motion perception. Our specific findings are as follows: (1) The extraction of shape from shading information incorporates at least two "assumptions" or constraints--first, that there is a single light source illuminating the whole scene, and second, that the light is shining from "above" in relation to retinal coordinates. (2) Tokens defined by shading can serve as a basis for perceptual grouping and segregation. (3) Reaction time for detecting a single convex shape does not increase with the number of items in the display. This "pop-out" effect must be based on shading rather than on differences in luminance polarity, since neither left-right differences nor step changes in luminance resulted in pop-out. (4) When the subjects were experienced, there were no search asymmetries for convex as opposed to concave tokens, but when the subjects were naive, cavities were much easier to detect than convex shapes. (5) The extraction of shape from shading can also provide an input to motion perception. And finally, (6) the assumption of "overhead illumination" that leads to perceptual grouping depends primarily on retinal rather than on "phenomenal" or gravitational coordinates. Taken collectively, these findings imply that the extraction of shape from shading is an "early" visual process that occurs prior to perceptual grouping, motion perception, and vestibular (as well as "cognitive") correction for head tilt. Hence, there may be neural elements very early in visual processing that are specialized for the extraction of shape from shading.     

Differences in lingual vibrotactile threshold shifts during magnitude-estimation scaling between normal-speaking children and children with articulation problems.

The purpose of this study was to investigate differences in function of the tactile sensory system between groups of normal-speaking children and children with articulation problems. This task was accomplished by studying possible tactile threshold shifts occurring during magnitude-estimation scaling of vibratory stimuli presented to the dorsal surface of the tongue. 10 normal-speaking children (M age = 7.8 yr.) and 9 children with articulation problems (M age = 7.5 yr.) participated. The normal-speaking children and articulatory defective children performed differently on the magnitude-estimation scaling task in which threshold was allowed to return to baseline after each stimulus presentation. These two groups of children also showed dissimilar threshold shifts for the suprathreshold intensities employed in the magnitude-estimation scaling.     

Effects of noise on sleep inertia as a function of circadian placement of a one-hour nap.

The purpose of the present study was to analyse the arousing effects of noise on sleep inertia as a function of circadian placement of a one-hour nap. In a first experiment, we measured the effects of sleep inertia in a neutral acoustic environment after a one-hour nap placed either at 0100 or 0400 on response time during a spatial memory test. In a second experiment were analysed the effects of an intense continuous noise on sleep inertia. The results showed that noise produced a total abolition of sleep inertia after an early nap (0000 to 0100). This may be due to the arousing effect of noise; however, results are less clear after a late nap 0300 to 0400 as noise seems to be ineffective. This result is discussed in terms of either a function of time-of-day effect or of prior sleep intensity. Moreover, our data suggest a possible interaction of noise with partial sleep deprivation leading to a slight deleterious effect those subjects who did not sleep at all.     

Imputation of missing categorical data by maximizing internal consistency

This paper suggests a method to supplant missing categorical data by reasonable replacements. These replacements will maximize the consistency of the completed data as measured by Guttman's squared correlation ratio. The text outlines a solution of the optimization problem, describes relationships with the relevant psychometric theory, and studies some properties of the method in detail. The main result is that the average correlation should be at least 0.50 before the method becomes practical. At that point, the technique gives reasonable results up to 10–15% missing data.We thank Anneke Bloemhoff of NIPG-TNO for compiling and making the Dutch Life Style Survey data available to use, and Chantal Houée and Thérèse Bardaine, IUT, Vannes, France, exchange students under the COMETT program of the EC, for computational assistance. We also thank Donald Rubin, the Editors and several anonymous reviewers for constructive suggestions.     

Did Pearson reject the Neyman-Pearson philosophy of statistics?

I document some of the main evidence showing that E. S. Pearson rejected the key features of the behavioral-decision philosophy that became associated with the Neyman-Pearson Theory of statistics (NPT). I argue that NPT principles arose not out of behavioral aims, where the concern is solely with behaving correctly sufficiently often in some long run, but out of the epistemological aim of learning about causes of experimental results (e.g., distinguishing genuine from spurious effects). The view Pearson did hold gives a deeper understanding of NPT tests than their typical formulation as accept-reject routines, against which criticisms of NPT are really directed. The Pearsonian view that emerges suggests how NPT tests may avoid these criticisms while still retaining what is central to these methods: the control of error probabilities.A portion of this research was carried out during tenure of a National Endowment for the Humanities Summer Stipend Fellowship; I gratefully acknowledge that support. A version of this paper was presented at the 1987 meeting of the Society for Exact Philosophy. This paper benefited from discussions and communications with George Barnard and Isaac Levi. I thank Harlan Miller for helpful comments on earlier drafts.     

An automated test development of parallel tests from a seed test

Binary programming models are presented to generate parallel tests from an itembank. The parallel tests are created to match item for item an existing seed test and match user supplied taxonomic specifications. The taxonomic specifications may be either obtained from the seed test or from some other user requirement. An algorithm is presented along with computational results to indicate the overall efficiency of the process. Empirical findings based on an itembank for the Arithmetic Reasoning section of the Armed Services Vocational Aptitude Battery are given.The Office of Naval Research, Program in Cognitive Science, N00014-87-C-0696 partially supported the work of Douglas H. Jones. The Rutgers Research Resource Committee of the Graduate School of Management partially supported the work of Douglas H. Jones and Ing-Long Wu. A Thomas and Betts research fellowship partially supported the work of Ing-Long Wu. The Human Resources Laboratory, United States Air Force, partially supported the work of Ronald Armstrong. The authors benefited from conversations with Dr. Wayne Shore, Operational Technologies, San Antonio, Texas. The order of authors' names is alphabetical and denotes equal authorship.     

Common attitudes about the effect of positive and negative mood on task related motivation]

Several theories on emotion and mood have stressed the close relationship between emotion and motivation. However, assumptions on mood contingent motivations have mainly been studied in the field of social behavior, and there are only few studies concerned with mood contingent task motivations, an area in which nit is possible to distinguish between two motivational sets, the deliberative and the implemented mind set. Assuming that positive mood is associated with a stronger task-oriented deliberative mind set, and that negative mood is associated with a stronger self-oriented deliberative mind set, and that implemented mind set should be intrinsically task-oriented during positive mood and instrumentally task-oriented during negative mood. The present paper is concerned with these assumptions from a subjective perspective: The respondents were asked about their lay perceptions of mood influences (positive, elated versus negative, sad mood) on task related motivations. In study I the respondents (N = 40) were asked about their deliberative mind sets during positive versus negative mood and about their general perceptions of mood influences on performance. In study II the respondents (N = 58) were requested to imagine situations which elicit positive, negative or neutral mood, and then to answer questions on deliberative and implemented mind sets during these states; they also hat to answer a general question about mood influences on task performance. Both quantitative and qualitative measures are used in these studies. The findings support the above general notions, and they additionally show that in the respondents' opinions negative mood effects are more variable than positive mood effects; further, that there are quite a few individual differences in assumed mood effects on task-related motivation.     

The correlation between coping with stress and blood pressure reaction]

This study explored the relationship between individual strategies of coping and blood pressure responses during and after mental stress. Blood pressure behavior was measured noninvasively and continuously before, during and after a mental stress situation in 27 normotensive subjects. Coping strategies were assessed with the Stressverarbeitungsfragebogen (SVF; coping with stress inventory). Two extreme groups were formed on the basis of the scores in the SVF. Results were: (a) Individuals who used coping strategies characterized by controlling the situation directly and constructively, in contrast to probands not using these strategies, exhibited lower blood pressure during the stress situation and a faster return to baseline levels after cessation of stress. (b) Subjects using a coping behavior characterized by the use of defense mechanisms such as suppression and denial, also showed lower blood pressure during stress but a significantly delayed return to baseline levels of blood pressure after stress was concluded.