Biomedical subjects

Paul van Schaik

Publications and source records attributed to Paul van Schaik.

5 recordsLinked to original sources

PubMed2006

A factor analysis of the Wechsler Adult Intelligence Scale 3rd Edition (WAIS-III) in a low IQ sample.

OBJECTIVES: Previous factor analytic studies of the WAIS, WAIS-R and WAIS-III used standardization samples, (representing the general population), clinical populations (e.g. psychiatric) and 'non-clinical' groups (e.g. older adults). These studies endorsed the reliability of the scales in such samples and supported theoretical models of intelligence. The WAIS-III (1997) includes four Indexes based on factor analysis, which provide clinically useful information to practitioners, but have not been validated in a low IQ population. However, the WAIS-III is often administered to individuals with suspected or proven low IQ, as it offers service providers, legislators and the Department of Health with a reliable measure of IQ. The aim of this study was to investigate the factor structure of the WAIS-III in a low IQ sample. METHODS: WAIS-III data was collected from assessments carried out in routine clinical practice from individuals with a full scale IQ of 74 or below (n=105). The data were subjected to factor analysis, using two types of factor analysis: principal axis factoring and principal components analysis. Orthogonal and oblique rotations were applied to the analyses. RESULTS: Only one robust solution could be extracted. This contained two factors, analogous to traditional verbal and performance sub-scales. CONCLUSIONS: This study does not support the four-factor solution which underlies WAIS-III index scores in a low IQ population.

Adolescent↗

PubMed2006

Information, social support and anxiety before gastrointestinal endoscopy.

OBJECTIVES: To examine Lazarus and Folkman's (1984) stress theory regarding the effects of the stress mediators information and perceived social support on anxiety (as the stress response) regarding gastrointestinal (GI) endoscopy (as the stressor) in male and female patients of various age groups. DESIGN: Non-experimental design. METHODS: Structured interviews were conducted with 113 hospital out-patients about to undergo GI endoscopy. Participants indicated their perceptions of how much support and how much clear and useful information they had received from both their general practitioner (GP) and a patient information leaflet developed in collaboration with health psychologists as well as their perceptions of how much social support they had obtained from other patients, family and friends. Anxiety was measured with a population-specific trait and state adaptation of the Hospital anxiety and depression scale (HADS-A). RESULTS: Psychometric exploration of the HADS-A revealed a single general anxiety factor. The reliability of this factor was high, with Cronbach's alpha=0.91. The majority of the sample experienced high anxiety levels. Gender, but not age, differences emerged, showing females to be more anxious than males, F(1, 84)=5.68, p<.05. A regression model built on stress theory was tested, with anxiety as the dependent variable and 11 predictor variables. The model was significant with R(2)=0.452, F(11, 47)=3.522 and p=0.001. CONCLUSIONS: The clarity, but not the amount, of information and social support from important others, but not GPs, were both mediating the stress experience of the patients by reducing their perceived anxiety.

Adolescent↗

PubMed2005

Influence of illness script components and medical practice on medical decision making.

Illness scripts are knowledge structures composed of consequences, enabling conditions, and faults. The effects of illness script components--consequences and enabling conditions--and physician factors on referral decisions for gastrointestinal disorders were investigated. The hypothesis that consequences and enabling conditions increase the likelihood of referral was confirmed and several interactions between consequences and enabling conditions were found. The hypothesis that physician factors moderate the effect of enabling conditions was also confirmed, but (contrary to illness script theory) evidence was also found for moderation of consequences. Both enabling conditions and consequences were found to be moderated by physician factors to a larger extent than previously assumed by illness script theory.

Adult↗

PubMed2004

Presence within a mixed reality environment.

Mixed reality environments represent a new approach to creating technology-mediated experiences. However, there is a lack of empirical research investigating users' actual experience. The aim of the current exploratory, non-experimental study was to establish levels of and identify factors associated with presence, within the framework of Schubert et al.'s model of presence. Using questionnaire and interview methods, the experience of the final performance of the Desert Rain mixed reality environment was investigated. Levels of general and spatial presence were relatively high, but levels of involvement and realness were not. Overall, intrinsic motivation, confidence and intention to re-visit Desert Rain were high. However, age was negatively associated with both spatial presence and confidence to play. Furthermore, various problems in navigating the environment were identified. Results are discussed in terms of Schubert's model and other theoretical perspectives. Implications for system design are presented.

Adolescent↗

PubMed2003

Developing a virtual reality-based methodology for people with dementia: a feasibility study.

The aim of this study was to examine the feasibility of virtual reality (VR) technology for use by persons with dementia (PWD). Data were obtained directly from six PWD regarding their experiences with a virtual environment (VE) of a large outdoor park. A user-centered method was developed to assess: (a) presence; (b) user inputs; (c) display quality; (d) simulation fidelity; and (e) overall system usability. The extent to which PWD could perform four functional activities in the VE was also investigated (e.g., mailing a letter). In addition, physical and psychological well-being of PWD while interacting with the VE was assessed objectively by recording heart rate during the VR sessions and subjectively with discrete questionnaire items and real-time prompts. Symptom profiles associated with simulator sickness were assessed with an adapted version of the Simulator Sickness Questionnaire. The study found that PWD to some extent experienced presence; perceived that objects were realistic and moved naturally; generally felt in control of the interaction; and demonstrated little difficulty using a joystick for navigation. The study also demonstrated that VR is an appropriate medium for assessing functional behavior within the context of an ecologically valid VE. PWD did not experience any significant increase in symptoms associated with simulator sickness, or detriments to their psychological and physical well-being. These findings demonstrated that it is feasible to work in VEs with PWD.

Aged↗