Extraction of relief from visual motion

We quantified the ability of human subjects to discriminate the relative distance of two points from a slanted plane when viewing the projected velocities of this scene (orthographic projection). The relative distance from a plane (called relief) is a 3-D property that is invariant under linear (affine) transformations. As such, relief canin principle be extracted from the instantaneous projected velocity field; a metric representation, which requires the extraction of visual acceleration, is not required. The stimulus consisted of a slanted planeP (specified by three points) and two pointsQ ₁ andQ ₂ that are non-coplanar withP. This configuration of points oscillated rigidly around the vertical axis. We have measured thesystematic error andaccuracy with which human subjects estimate the relative distance of pointsQ ₁ andQ ₂ from planeP as a function of the slant of_P. The systematic error varies with slant: it is low for small slant values, reaches a maximum for medium slant values, and drops again for high slant values. The accuracy covaries with the systematic error and is thus high for small and large slant values and low for medium slant values. These results are successfully modeled by a simple relief-from-motion computation based on local estimates of projected velocities. The data are well predicted by assuming (1) a measurement error in velocity estimation that varies proportionally to velocity (Weber’s law) and (2) an eccentricity-dependent underestimation of velocity.     

Children’s reading skills: A comparison of traditional and computerized assessment

Student’s ability to read computer text was investigated by comparing reading performance on decoding and phonetics tests of the Woodcock-Johnson (Revised) Tests of Achievement, Forms A and B. Fifty-one students completed one form of the reading tests through the traditional administration method and a second form using computer administration. Initial form and administration order were counterbalanced. Coefficients of equivalence of .91 and .86 were obtained for traditional and computer administration methods of the two tests. The results are interpreted as indicating that computer-administered reading tests can assess the same domains as traditional measures, and that they may become increasingly important in the complete assessment of functional reading skills.     

Aggressivity,inattention, hyperactivity,and impulsivity in boys at high and low risk for substance abuse

Aggressivity, inattention, hyperactivity, and impulsivity are cardinal dimensions of externalizing behavior problems of childhood. They are diagnostic and clinical features of childhood disorders, and are thought to be linked to the subsequent development of adult disorders such as substance abuse (SA). Little is known, however, about the convergent and discriminant validity of these four constructs. We used multiple measures to develop indices of aggressivity, inattention, hyperactivity, and impulsivity in a sample of 10- to 12-year-old boys (N=183) with and without a family history of SA. Data were taken from mother reports, child reports, teacher reports, and laboratory tasks. The study aims were (1) to test the convergent and discriminant validity of aggressivity, inattention, hyperactivity, and impulsivity; (2) to examine whether the data were consistent with a model specifying the four constructs as indicators of one superordinate factor; and (3) to differentiate boys with and without a family history of SA in construct scores. The results supported the convergent and discriminant validity of the four constructs. Although discriminable, the constructs covaried strongly and were consistent with a model specifying them as indicators of a single superordinate factor. Boys with a family history of substance abuse scored higher than control boys on aggressivity, inattention, and impulsivity scores, but the groups did not differ on hyperactivity scores. The results are discussed in terms of the role of childhood behavior problems in vulnerability to SA.This work was supported by the National Institute on Drug Abuse grant No. DA 05605.     

Temporal coordination of alternative and simultaneous aiming movements of constrained timing structure

Two experiments are reported addressing the preparation and initiation of movements with equal or unequal timing properties for both hands. Temporal coordination was examined in two movement tasks: one in which both hands performed the movements simultaneously (simultaneous aiming task) and one in which only one alternative of two possible movements was executed (choice aiming task). For each task a different group of subjects was used. Besides the timing relationships between both movements, the effects of preparation interval (1, 3, and 5 s), the average velocity (7, 14, 17.5, and 70 cm/s), the presence of advance information about the required velocity of the movement(s), and practice were investigated. Based on the common- and the specific-timing notions, distinct hypotheses were tested as to the effects of the variables on the temporal coordination as revealed by reaction time. A main result was that the effects of timing differences between the hands was task specific. For the choice task the data are in agreement with the common-timing notion of coordination, i. e., only one timing demand at a time can be prepared, whereas in the simultaneous task evidence was obtained for the specific-timing notion, i. e., independent preparation and initiation of different timing properties for the hands. However, it is argued that the results of the choice task probably do not reflect a general inability to prepare movements of different timing requirements for both hands, but is related to a task-specific strategy of selective preparation.     

The role of verbal ability in the processing of complex verbal information

Summary This study investigated the relation between psychometric mental-ability test scores and several reaction-time measures; a simple-reaction task, a choice-reaction task, the Posner and Mitchell (1967) letter-identification task, and a variation of the sentence-verification task. Scores on the Raven Advanced Progressive Matrices and the Verbal Subtest of the Scholastic Aptitude Test (SATV) were obtained. The less complex information-processing tasks replicate earlier studies in which general intelligence was only marginally related to reaction-time measures. The sentence-verification task systematically varied task complexity. Several direct and derived measures from the task were significantly correlated with psychometric mentalability measures. However, even though a number of precautions were taken to ensure that the sentence-verification task assessed purely verbal-processing efficiency, there was little evidence for an important task-specific relation between verification measures and verbal ability. Moreover, despite its relative verbal complexity, sentence verification did not reflect a greater relationship to verbal ability than other tasks did. Overall, the information-processing efficiency measures used in this study suggested a fairly general, rather than a task-specific, relationship to intellectual ability.The research presented in this paper was conducted while the first author was affiliated with the University of Georgia, U. S. A.     

The dynamics of Prägnanz

Summary There is quite wide-spread agreement about the relevance of pattern Pragnanz (Koffka, 1935) with respect to the human interpretation of visual patterns. There is less agreement about whether pattern Pragnanz is based solely on pattern information (static) or also on the history of the perceiver (dynamic). In Van Leeuwen and Van den Hof (1991), experimental data concerning serial patterns are presented within the framework of the dynamic-network approach initiated by Buffart (1986, 1987). These experimental data are claimed to give evidence against the static-coding approach initiated by Leeuwenberg (1969, 1971). In the present paper, however, I show first that Buffart's theoretical basis is incorrect, and that in fact Leeuwenberg's static-coding approach is the basis for the dynamic-network approach. Second, I show that those experimental data rather give evidence in favor of the static-coding approach, by using those same data for a test of the most recent static-coding model (Van der Helm & Leeuwenberg, 1991; Van der Helm, Van Lier, & Leeuwenberg, 1992). Finally, I propose a reconciliation between the two approaches, in the sense that the dynamic-network model could be shaped in such a way that it yields a simulation, and maybe even an enrichment, of the static-coding model.     

Conditional Control of Fluid Consumption in an Occasion Setting Paradigm Is Independent of Pavlovian Associations

Drug states, flavors, and contextual cues were each trained as conditional discriminative stimuli to control a saccharin-LiCl association. In transfer tests, drug states transferred control over consumption to other flavored solutions and to food. Contexts and flavors transferred control only to other flavored solutions. Pavlovian control groups given direct pairings of context-LiCl or flavor-LiCl did not show reliable transfer. However, these control groups did show greater or the same aversion to the specific context or flavor predicting LiCl compared to the context or flavor discrimination groups. The dissociation of the discrimination and Pavlovian groups on transfer versus preference tests suggests that performance on the occasion setting task cannot be due to simple excitation or learning about a unique compound cue. Data from extinction procedures provide further support for the dissociation between simple excitation and occasion setting.     

CONSTRUCT ACCESSIBILITY AND THE MISATTRIBUTION OF AROUSAL:

Abstract— Schachter and Singer (1962) showed that people search the immediate environment for emotionally relevant cues to label and interpret unexplained physiological arousal We investigated how unobtrusively activated cognitions and physiological arousal interact to produce emotional experience when the immediate environment is devoid of relevant cues Subjects were primed with positive, negative, or neutral concepts They then either exercised or sat still and, either immediately or after a delay, rated their emotional state Consistent with what Schachter and Singer found, subjects in the exercise, delayed-rating condition, who lacked an obvious explanation for their arousal, made the most extreme affective self-ratings, which were consistent with the valence of the primed concepts These subjects apparently interpreted their residual arousal in terms of the primed concepts Subjects in the exercise, immediate-rating condition, who had an explanation for their arousal (i e, the exercise), were not influenced by the primes Subjects in the no-exercise condition showed typical priming effects, with prime-consistent self-ratings that decayed over time Implications for emotion formation, misattnbution of arousal, and cognition are discussed     

Client Cognitive Responses as a Function of Quality of Counselor Verbal Responses

This study examined the relationship between high and low quality counselor responses in four response modes and client cognitions. Twenty-one university students participated in two sessions of brief counseling that included high and low quality counselor responses in paraphrasing, questioning, reflection of feeling, and self-disclosure. After each counseling session, participants used Kagan's (1975) interpersonal process recall method to report their cognitions in response to these counselor responses. Results indicated that the participants had more favorable cognitions toward the counselor associated with high quality counselor paraphrasing and reflection of feeling responses. Participants' cognitions directed toward themselves did not differ in response to any of the four high and low quality counselor responses. Implications of the results are discussed.