Concerning the determination of trait variability

An analytic technique for the study of trait variability is presented. An expression for the average variance from test to test and an expression for the variance of these variances are derived in terms of the number of tests and the intercorrelations between them, and limiting cases are examined. The question of the true relationship between the nature of the distribution of test scores in a sample ofN persons and the nature of the distribution ofn traits in a single individual is discussed, and other problems are introduced.     

FIT: An iterative parameter-estimation function in LISP

A nested parameter-estimation program (FIT), written in LISP, is described. FIT searches an n-dimensional parameter space for the set of parameter values associated with either a minimum or a maximum criterion score. The range of the parameters is cut in half on each iteration. Two versions of FIT, one suitable for use on large, mainframe systems and the other designed for small microprocessors, appear in the appendices.     

Human spatial orientation in the pitch dimension

Two experiments were conducted. In Experiment I, each of eight Ss attempted to place himself at 13 different goal orientations between prone and supine. Deviations of achieved body pitch angles from goal orientations were determined. In Experiment II, each of eight Ss attempted to align a visual target with his morphological horizon while he was placed at each of the 13 goal orientations. Changes in settings of the target were examined. Results indicate that Ss underestimate body pitch when they are tilted less than 60 deg backward or forward from the vertical, overestimate body pitch when they are nearly prone, and accurately estimate body pitch when they are nearly supine. In contrast, Ss set the visual target maximally above the morphological horizon when they are tilted 30 deg forward from the vertical. The findings are discussed in terms of common and different physiological mechanisms that may underlie judgments of these types.     

Directional information and apparent movement

The number of alternative directions that a point of light can take in the apparent movement produced by the successive exposure of two points of light may be considered its directional information. The present experiment is concerned with the relationship between such directional information and the threshold between apparent movement and apparent successiveness, the original hypothesis being that the greater the directional information, the higher the threshold of movement. In fact, contrary results were obtained. Thresholds were obtained under conditions where movement could occur in either eight directions or only in two directions, better and more persistent movement being found under the former conditions. But this result is obtained only when one measures thresholds by an ascending method: increasing the time separation between light points from optimal movement to successiveness. An hypothesis is proposed to explain the findings stated in terms of “attentional disarticulation”.     

Distance discrimination in a simulated space environment

The just noticeable difference (JND) for distance was investigated by a paired-comparisons method using successive comparisons. The research utilized an optically simulated large target located in a textureless environment at distances along the saggital plane out to 12, 800 ft. The value of ΔD/D varied from less than 3% at 200 ft to about 7% at 12, 800 ft. The results confirmed a power function relationship between distance threshold and observation distance.     

Identifying rotated letter-like symbols

Previous research has shown that the identification of rotated alphanumeric symbols seems to be performed via the extraction of critical features encoded invariant to the symbol’s orientation. The present research argued that the use of such feature extraction processes might be a function of, first, a subject’s familiarity with the symbols, and second, the number of symbols from which a presented symbol is sampled. Earlier research has used highly over learned alphanumerics, in sets of six symbols; this practice is argued here as being seemingly conducive to feature extraction. In two experiments, the generality of a feature extraction interpretation, in contrast to one of mental rotation, was tested by having subjects previously trained to relative high- vs. low-familiarity criteria identify novel symbols in conditions in which a presented symbol was 1 of either 5 or 20 possibilities. Identification response times were found to be constant across all nonstandard orientations of presented symbols, irrespective of symbol familiarity or symbol set size. The findings support the generalization of a feature extraction interpretation to varying numbers of novel symbols of varying familiarity.     

Cross-Lagged Relationships Between Insomnia and Posttraumatic Stress Disorder in Treatment-Receiving Veterans

Insomnia is a risk factor for the development of posttraumatic stress disorder (PTSD) while it is also plausible that PTSD symptoms can maintain insomnia symptoms. The present study examined longitudinal bidirectional relationships between insomnia and PTSD symptoms in treatment-seeking veterans. Participants were 693 ex-serving members of the Australian Defence Force who participated in an accredited, hospital-based outpatient PTSD program. Participants completed self-reported assessments of PTSD and insomnia symptoms at four time points: intake, discharge, 3-month, and 9-months posttreatment follow-up.Cross-lagged pathway analyses indicated significant bi-directional pathways between insomnia symptoms and PTSD symptoms at most time points. A final cross-lagged model between insomnia symptoms and the PTSD symptom clusters indicated that the PTSD symptom paths on insomnia symptoms, between intake and discharge, were attributable to reexperiencing PTSD symptoms. In contrast, across posttreatment follow-up time points there were significant paths of insomnia symptoms on all PTSD symptom clusters except from insomnia at 3-months to avoidance symptom at 9-months. PTSD symptoms and insomnia symptoms have bidirectional associations over time that may lead to the mutual maintenance or exacerbation of each condition following PTSD treatment. Where residual insomnia symptoms are present post-treatment, a sleep-focussed intervention is indicated and a sequenced approach to treatment recommended.     

The effectiveness of unitization in mitigating age-related relational learning impairments depends on existing cognitive status

Binding relations among items in the transverse patterning (TP) task is dependent on the integrity of the hippocampus and its extended network. Older adults have impaired TP learning, corresponding to age-related reductions in hippocampal volumes. Unitization is a training strategy that can mitigate TP impairments in amnesia by reducing reliance on hippocampal-dependent relational binding and increasing reliance on fused representations. Here we examined whether healthy older adults and those showing early signs of cognitive decline would also benefit from unitization. Although both groups of older adults had neuropsychological performance within the healthy range, their TP learning differed both under standard and unitized training conditions. Healthy older adults with impaired TP learning under standard training benefited from unitized training. Older adults who failed the Montreal Cognitive Assessment (MoCA) showed greater impairments under standard conditions, and showed no evidence of improvement with unitization. These individuals’ failures to benefit from unitization may be a consequence of early deficits not seen in older adults who pass the MoCA.     

Attitudes toward religious diversity among American exemplars of Christian virtue

An important concern within contemporary Western societies is how religious adherents view and engage religious diversity. This study attempts to further understandings regarding religious diversity in contemporary society through the accounts of American Christian religious exemplars whose religious identification spans the conservative evangelical, liberal Protestant and Roman Catholic traditions. Ninety‐six in‐depth interviews were conducted with individuals recognized by their congregational leadership as exemplifying Christian virtues and thereby Christian commitment. Weak denominational allegiances, accompanied by salient identification with broad Christian religious traditions were found. Mainline/liberal Christians tended to identify conservative/evangelical Christians as ‘others’, while conservative/evangelical Christians identified Mormons as ‘others.’ Also, a shift in attitudes toward Catholics was found among Protestants, and attitudes toward non‐Christian religions were respectfully civil across a range of theological understanding of these religions. The implications of these findings for religious identity in contemporary society are explored with particular attention to religious diversity.