Combining discrepant diagnostic information from multiple sources: Are complex algorithms better than simple ones?

Optimizing methods of combining discrepant diagnostic information from multiple sources is one of the more daunting tasks facing the field of child psychopathology. Several researchers have asserted that complex information-combining schemes, those in which certain information or sources of information are weighted differently from others, are preferable. This study provides theoretical and empirical evidence that simple information-combining schemes, those in which all information from all sources is weighted equally, will as a rule work as well as complex schemes and may even work better. The implications of these findings for diagnostic instrument and algorithm design are discussed. A two-step diagnostic procedure utilizing a simple information-combining scheme is presented.     

Postcriterion overlearning reduces the effectiveness of the method of adjusted learning

One goal of the method of adjusted learning (“dropout procedure”) is to equate the strength of different Items for subsequent retention. Some studies have yielded results in accord with this goal while others have not, with no known reason for the discrepancy. We manipulated the number of postcriterion overlearning trials and found that the adjusted learning procedure was effective in equating items for subsequent retention when learning terminated after one correct response per item but ineffective when postcriterion overlearning trials occurred. This finding is especially important for those versions of the adjusted learning procedure, such as the frequently utilized variant developed by Battig (1965), that incorporate overlearning of the to-be-equated items.     

“Acts of god and man”: Long-term character change in survivors of disasters and the law

Evidence from differing disaster populations indicates enduring effects on mental functioning or character change in survivors. Following the Buffalo Creek Disaster, character changes included psychic constriction, denial, somatization, and survivor guilt. In the legal proceedings following that disaster survivors received compensation for “psychic impairment,” a term devised to cover the long-term effects of the survivor syndrome. Among combatant survivors of the Vietnam War, a common character change included the failure to channel hostile impulses effectively. Crucial for this group has been the role of law to provide a recovery environment conducive to their reentry to society.     

Police intervention in riots: The role of accountability and group norms. A field experiment

This study explores the role of perceived accountability in riot police action. The basic hypothesis is that accountability, provided that non-violent norms are made salient, will lessen the chances of escalation of a conflict between police and demonstrators. Four platoons participated in a field experiment conducted at the Dutch Riot Police Academy, in which they played a riot simulation. In a 2 × 2 design, the effects of accountability and Department on attitudes and norms concerning the action of ‘police’ and ‘demonstrators’ were tested. Measurements were made before and after the simulation. Internal analysis, involving redefined accountability categories, provided support for our hypothesis. That is, perceived accountability proved to be related to a heightened public self-awareness, a less extremely positive evaluation of fellow group members, and less intergroup differentiation. The limitations of an internal analysis are discussed, as well as the importance of the nature of organizational norms and of the accountability forum in predicting the effect of accountability.     

Lightness differences and the perceived segregation of regions and populations

A striking finding reported by Beck, Sutter, and Ivry (1987) was that, in textures composed of regions differentiated by the arrangement (checks and stripes) of two texture elements (light and dark squares), a large lightness difference between the squares could fail to yield segregation between the regions, whereas a smaller lightness difference could sometimes yield strong segregation. In the experiments reported here, we compared the segregation of striped and checked arrangements of light and dark squares into regions with the segregation of two randomly interspersed populations of light and dark squares into subpopuiations. Perceived lightnesses are the same for a given set of squares, whether they are arranged in regions or in intermixed populations. Perceived population segregation is approximately a single-valued function of the lightness differences of the squares, but perceived region segregation is not. The reason for the difference between population segregation and region segregation may be that region segregation is mediated by detectors’ having large oriented receptive fields (large bar detectors) that are sensitive to the fundamental spatial frequency and orientation of the texture region as defined by the arrangement of the squares (Beck et al., 1987; Sutter, Beck, & Graham, 1989). These detectors cannot be responsible for population segregation, because the light and dark squares are distributed randomly throughout these patterns and therefore do not define a consistent arrangement of any particular spatial frequency or orientation. The light and dark squares in the population patterns fall equally on excitatory and inhibitory regions of large bar detectors. A plausible explanation for population segregation is to suppose that the segregation is the result of similarity grouping of the light and dark squares.     

Heart rate—QT interval relationship during postural change and exercise

The QT interval of the electrocardiogram, although often coordinated in an inverse relationship to heart rate, appears from the existing evidence to be regulated by mechanisms separate from those that govern heart rate. The purpose of this inquiry was to explore further the relationship of the two and to test other factors that may contribute to the regulation of QT. Heart rate and QT duration were measured in healthy human subjects during postural change and exercise. The data showed that, while coordinated in an inverse relationship under some circumstances, under others heart rate and QT were discordant, leading to the inference that there is no fixed linkage between the two. Previous work by the authors and other published studies have suggested that ventricular contractility may have more predictable association with QT shortening than do increases in heart rate. Observations of force of ventricular contraction (HI and IJ velocity) as reflected in ballisto-cardiographic tracings were made using each of 12 human subjects as the authors’ own control. The data revealed a highly significant correlation between the velocity measures and QT duration (p<0.01) but not heart rate. These findings led to the conclusion that there is clearly not a fixed relationship between heart rate and QT interval and to the hypothesis that QT may more closely reflect the degree of cardiac contractility.     

Social phobia: Axis I and II correlates

The presence of Axis I and Axis II disorders in 71 social phobic patients was examined. Generalized anxiety disorder was the most common secondary Axis I disorder, followed by simple phobia. Avoidant personality disorder and obsessive-compulsive personality disorder were the most common Axis II diagnoses, and 88% of the sample exhibited features of these 2 personality styles. Subjects with additional Axis I diagnoses were more anxious and depressed than those with no additional Axis I disorder. Social phobics with additional Axis II disorders were more depressed but not more anxious than those with no Axis II diagnosis. Furthermore, those with an additional Axis I disorder had higher scores on measures of neuroticism, interpersonal sensitivity, and agoraphobia. The prevalence and impact of additional Axis I and II disorders on the etiology, maintenance, and treatment outcome for persons with social phobia are discussed.     

Rhythmic heart rate variability (sinus arrhythmia) related to stages of sleep

Evidence that the excursion of rhythmic heart rate variability (sinus arrhythmia) may be manipulated by altering the subject’s state of concentration, prompted a study of effects associated with different stages of sleep. There were 9 healthy subjects, ages 16–69, and one 55-year-old subject (C.P.) with a myocardial infarction history. Awake and during sleep the excursion of heart rate variability was greatest among the younger subjects, decreasing progressively with age. C.P. displayed rhythmic heart rate variability only when asleep. In light sleep (Stages 1 and 2) all subjects, with the exception of the 69-year-old, whose rate remained almost fixed throughout the night, displayed rhythmic heart rate variability, roughly synchronous with respiration. Neither the elderly subjeot nor C.P. entered into deep sleep (Stages 3 and 4). Among the other subjects, deep sleep was marked by a precise correlation between the frequency of respiration and heart rate variability. In REM sleep, however, in all subjects, there was often a total dissociation between respiration and rhythmic heart rate variability. There were periods of no heart rate variability with continuing regular respiration and of rhythmic heart rate variability with spontaneous breath holding. In the presence of heart rate variability during REM, C.P. displayed frequent ectopic beats, but ectopic beats were nearly absent in REM periods characterized by a steady, unvarying heart rate. The range of heart rate variability at rest and during sleep (sinus arrhythmia) reflects the manner in which autonomic activity is brought to bear in regulating the heart beat. The study of the behavior of sinus arrhythmia may offer a way to anticipate the occurrence of dangerous cardiac dysarrhythmias and sudden death, especially during sleep.