Reaction time and probability on isolated terms

The reaction-time probability effect on isolated trials was found to be asymmetrical in an experiment on 64 college students. There was a large drop in RT for a high-probability probe trial embedded in a block of low-probability trials, but a much smaller rise for a low-probability trial embedded in high-probability trials. Thus, low- but not high-probability responses seem to be influenced by characteristics of the trial block. If the basis of the probability effect were the strategic placement of the criterion for response initiation, symmetrical results should have been obtained. A motivational account which accords with the present data is that the subject is ordinarily willing to prepare but is averse to doing so in some (not entirely specified) low-probability circumstances.     

Efficacy of self-instructional training for reducing children''s anxiety in an evaluative situation

Fifty-six fourth-grade children were categorized as either high or low in trait anxiety and then assigned to a self-instruction treatment, minimal-treatment, or no-treatment control condition. At both pretest and posttest, the subjects recited a memorized poem while being videotaped with the expectation that they would be judged on their performance. State anxiety measures, a behavior rating of anxiety, a measure of performance accuracy and the time involved in reciting a poem were obtained at both pretest and posttest. Contrary to expectation, the self-instructional training resulted in subjects' exhibiting greater signs of behavioral anxiety, subjects' hurrying through the task (taking less time to recite the poem) and high trait-anxiety subjects' reporting more state anxiety while anticipating reciting the poem. Correlational analyses indicated that trait anxiety was significantly related to the measures of state anxiety and the behavior rating of anxiety but not to performance accuracy.     

An information processing system for the psychiatric emergency room

An information processing system for a psychiatric emergency room is described. Several studies are presented that show the utility of the system. In the first study, variables involved in diagnosis are explicated. The second study attempts to determine the characteristics that distinguish recidivists from nonrecidivists at an emergency room. The third study attempts to find patient variables related to success in short-term treatment programs. The final study is aimed at discovering whether there are psychopathological effects related to the use of inhalants. Together, these studies show the potential of a mental health information system for learning more about the nature of mental disorders and their treatment.     

The relation between proximity and brightness similarity in dot patterns

The Gestalt studies demonstrated the tendency to visually organize dots on the basis of similarity, proximity, and global properties such as closure, good continuation, and symmetry. The particular organization imposed on a collection of dots is thus determined by many factors, some local, some global. We discuss computational reasons for expecting the initial stages of grouping to be achieved by processes with purely local support. In the case of dot patterns, the expectation is that neighboring dots are grouped as a function of proximity and similarity of contrast, by processes that are independent of the overall organization and the various global factors. We describe experiments that suggest a purely local relationship between proximity and brightness similarity in perceptual grouping.     

Surface tilt (the direction of slant): A neglected psychophysical variable

Surface slant (the angle between the line of sight and the surface normal) is an important psychophysical variable. However, slant angle captures only one of the two degrees of freedom of surface orientation, the other being thedirection of slant. Slant direction, measured in the image plane, coincides with the direction of the gradient of distance from viewer to surface and, equivalently, with the direction the surface normal would point if projected onto the image plane. Since slant direction may be quantified by the tilt of the projected normal (which ranges over 360 deg in the frontal plane), it is referred to here assurface tilt. (Note that slant angle is measured perpendicular to the image plane, whereas tilt angle is measured in the image plane.) Compared with slant angle’s popularity as a psychophysical variable, the attention paid to surface tilt seems undeservedly scant. Experiments that demonstrate a technique for measuring apparent surface tilt are reported. The experimental stimuli were oblique crosses and parallelograms, which suggest oriented planes in 3-D. The apparent tilt of the plane might be probed by orienting a needle in 3-D so as to appear normal, projecting the normal onto the image plane, and measuring its direction (e.g., relative to the horizontal). It is shown to be preferable, however, to merely rotate a line segment in 2-D, superimposed on the display, until it appears normal to the perceived surface. The apparent surface tilt recorded in these experiments corresponded closely to that predicted by assuming the 3-D configurations consist of equal-length lines and perpendicular intersections.     

MULTIVARIATE ASSESSMENT OF CONFLICT IN DISTRESSED AND NONDISTRESSED MOTHER-ADOLESCENT DYADS

A battery of measures was used to assess conflict between mothers and young adolescents (females and males, 11 to 15 years of age). Two groups of families, one composed of a distressed clinical sample (N = 38), the other a nondistressed normative sample (N = 40), participated. The assessment battery included retrospective judgments, frequency estimates, self-monitored home recording, and tape-recorded discussion of a home problem. Content of assessment measures tapped aspects of parental control, decisionmaking, self-reported interaction behavior, arguments, interaction behavior rated by independent “blind” observers, frequency and anger-intensity of specific problematic issues, and perceptions of positive and negative behaviors of the other family member. Based on univariate analyses, 21 of the 26 defined variables discriminated significantly in the predicted direction. Maternal and adolescent reports of behavior and independent ratings of tape-recorded interaction emerged as strong and consistent discriminators. Stepwise multivariate discriminant analysis provided successful classification of 100% of the families based on the inclusion of nine variables. In a cross-validation sample, 84% of the families were correctly classified. Implications for systematic outcome research as well as clinical application are discussed.     

Transection of direct anterior thalamic afferents from the hippocampus: effects on activity and active avoidance in rats

This investigation demonstrates the importance of the direct hippocampo-anterior thalamic component of the postcommissural fornix in the control of general locomotion and active avoidance. Transection of anterior thalamic afferents from the hippocampal formation (subicular cortex), at the point where they exit from the fornix posterior to the septum, is sufficient to enhance bidirectional active avoidance acquisition and increase general activity. This transection may also interrupt fibers to or from other thalamic nuclei and the anterior septum. However, destruction of connections of the anterior septum with the hippocampus, habenula, and thalamus by transection in the coronal plane anterior to the descending fornix columns, without damage to the subiculothalamic fibers, increases general activity levels without damage to the subiculothalamic fibers, increases general activity levels without affecting active avoidance behavior. The activity increase in this case resembles that seen after septal lesions rather than that seen after hippocampal lesions. Thus, destruction of a single fornix component contributing afferents to the anterior thalamic nuclei reproduces at least part of the hippocampal syndrome. This suggests that these fibers contribute significantly to the control of these behaviors and may mediate active avoidance changes resulting from hippocampal and fornix damage.     

Comparison of observational recordings in vivo, via mirror, and via television

Simultaneous observational recordings were made in vivo, via an observation mirror, and via closed circuit television. Three of nine observers had extensive experience recording behavior in vivo; three had extensive experience recording behavior via mirror; and three had extensive experience recording via television. Observers recorded nine categories of disruptive behavior for children in a special class setting. Frequencies of behavior recorded in vivo, via mirror, and via television differed significantly for only one category, vocalization. There were no significant main effects or interactions involving the observers' previous experience. Occurrence reliability coefficients computed within and between media demonstrated the similarity of observer agreement in all three media. Data collection procedures using an observational mirror or closed circuit television appear to be reasonable alternatives to in vivo observation in circumstances similar to those in the present study.     

Odorant quality perception: a metric individual differences approach

Perceptual spaces, in which similar stimuli are located close to each other and dissimilar stimuli are located far apart, have aided in the understanding of the physiological and psychological bases for sensory quality coding. Differences in perception between individuals should be reflected by differences in the spatial relationships between stimuli. If the dimensionality of the perceptual space is small (e.g., color space), individual differences that reflect specific pathologies are readily apparent from visual inspection. On the other hand, if the dimensionality of the perceptual space is large (as is proposed for odor space), visual inspection alone may not reveal individual differences in quality perception. The present work presents an information-theory-based method for quantifying individual differences in quality perception from perceptual confusion matrices. The ability of this method to quantify individual differences in quality perception is shown in a hypothetical example of specific anosmia. Finally, the method is applied to the examination of intrasubject consistency of odorant quality perception.