Using a virtual reality system to study balance and walking in a virtual outdoor environment: a pilot study.

Falls and fall-related injuries are a major problem for elderly persons. Most falls occur during walking and turning, and the risk of falling increases when attention is diverted to something besides walking. It is often difficult to standardize methods for testing balance and fall tendency in a clinically relevant setting. We describe the development of a system using a virtual environment (VE) to assess how attention demanding and unexpected events influence a person's capacity to control balance and movement. The hardware in the system consists of a head-mounted display (HMD), a magnetic tracker system, and two SGI computers. The software consists of the image generation of the VE and the management and visualization of motion tracking data. In a preliminary pilot study eight subjects (age 23-80) participated. Each subject walked on a normal floor and was visually presented a familiar outdoor environment in the HMD. They were exposed to different unexpected events, such as a virtual snowfall and tilting of the VE. Disturbances of balance and walking patterns such as changes in speed, stride length and balance reactions like slipping were observed. Two subjects experienced symptoms of cyber sickness with a SSQ score above 25 points. Walking with sensors only did not affect walking time, but in VE the subjects generally walked more slowly. Virtual tilting of the environment had an impact on balance performance during walking. This effect was not observed while the test subjects were walking in a virtual snowfall. The model needs further development but may hold a potential for clinical use.     

Police officers' views of effective interview tactics with suspects: The effects of weight of case evidence and discomfort with ambiguity

This study examined the effects of case‐specific facts and individual discomfort with ambiguity (DA) on investigators' beliefs concerning effective interviewing tactics for suspects. Violent crime investigators (n = 30) responded to a questionnaire including the Need for Closure Scale (NFCS) and ratings of the importance of 39 interrogation tactics in two hypothetical interrogations with a homicide suspect, where the evidence consisted of either technical evidence or soft information. Twenty tactics were analysed with a multidimensional scaling procedure which confirmed two discrete interviewing themes: humane and dominant. More tactics, both dominant and humane, were rated as important if the evidence was soft compared with technical. In the soft evidence condition, investigators who were high on DA rated both types of tactics as more important than did low‐DA investigators. In the technical evidence condition, no such difference emerged. Copyright © 2008 John Wiley & Sons, Ltd.     

Stability and change in work values among male and female nurses and engineers

Gender related changes of work values were analyzed in a longitudinal questionnaire study of 173 male and 48 female engineers and 353 female and 31 male nurses at three measurement occasions covering about four and half years from the end of their vocational education. At all occasions, Social relations were rated as more important by women than by men and Altruism was given higher ratings by the nurses than by the engineers. Within both occupations women's mean Altruism ratings were higher than men's mean ratings, and in all groups except male engineers the mean ratings dropped between the three occasions. Women's ratings of Benefits and career and Influence were strengthened in both occupations, thereby eliminating an initial gender difference. The stability of work values is discussed in terms of challenges and norms in working life.     

Suppressing permutations or rigid planar rotations: A remedy against nonoptimal varimax rotations

Varimax rotation consists of iteratively rotating pairs of columns of a matrix to a maximal sum (over columns) of variances of squared elements of the matrix. Without loss of optimality, the two rotated columns can be permuted and/or reflected. Although permutations and reflections are harmless for each planar rotation per se, they can be harmful in Varimax rotation. Specifically, they often give rise to the phenomenon that certain pairs of columns are consistently skipped in the iterative process, whence Varimax will be terminated at a nonstationary point. The skipping phenomenon is demonstrated, and it is shown how to prevent it.The author is obliged to Henk Kiers for commenting on a previous draft.     

Mood and belief-value correlation

This is an investigation of belief-value distortion as measured by the correlation between sets of beliefs and values for a given attitude object. Correlations were computed for each subject separately. Initial mood levels and mood changes subsequent to ratings of attitudes to nuclear power were investigated in the first two studies. In Study 1 mood changes were positively correlated with attitude. In Study 2, mood levels were positively correlated both with attitude, optimism, and tendency towards extreme belief-value correlations (belief-value distortion). In a third study, attitudes were studied both towards nuclear power and alcohol. There were no clear relations between the two fields of contents. Mood changes were small and inconsistent. However, tendency to act correlated with both optimism and belief-value distortion, also with the level of attitude kept constant. A model relating mood, optimism, belief-value distortion, and action is suggested.     

On Green's best linear composites with a specified structure,and oblique estimates of factor scores

Green solved the problem of least-squares estimation of several criteria subject to the constraint that the estimates have an arbitrary fixed covariance or correlation matrix. In the present paper an omission in Green's proof is discussed and resolved. Furthermore, it is shown that some recently published solutions for estimating oblique factor scores are special cases of Green's solution for the case of fixed covariance matrices.     

Factor analysis of dichotomized variables

An approach for multiple factor analysis of dichotomized variables is presented. It is based on the distribution of the first and second order joint probabilities of the binary scored items. The estimator is based on the generalized least squares principle. Standard errors and a test of the fit of the model is given.