Nonlinear principal components analysis: introduction and application

The authors provide a didactic treatment of nonlinear (categorical) principal components analysis (PCA). This method is the nonlinear equivalent of standard PCA and reduces the observed variables to a number of uncorrelated principal components. The most important advantages of nonlinear over linear PCA are that it incorporates nominal and ordinal variables and that it can handle and discover nonlinear relationships between variables. Also, nonlinear PCA can deal with variables at their appropriate measurement level; for example, it can treat Likert-type scales ordinally instead of numerically. Every observed value of a variable can be referred to as a category. While performing PCA, nonlinear PCA converts every category to a numeric value, in accordance with the variable's analysis level, using optimal quantification. The authors discuss how optimal quantification is carried out, what analysis levels are, which decisions have to be made when applying nonlinear PCA, and how the results can be interpreted. The strengths and limitations of the method are discussed. An example applying nonlinear PCA to empirical data using the program CATPCA (J. J. Meulman, W. J. Heiser, & SPSS, 2004) is provided.     

Effects of motivations and gender on adolescents' self-disclosure in online chatting.

This study investigated the effect of motivations for online chatting and gender factors in self-disclosure in adolescents' online chatting. Participants were 260 high school students (128 female, 132 male) who participated in online chatting. The results revealed that self-disclosure in online chatting differed by motivation, but gender was not a significant variable for explaining self-disclosure.     

Fear Extinction to an Out-Group Face: The Role of Target Gender

ABSTRACT— Conditioning studies on humans and other primates show that fear responses acquired toward danger-relevant stimuli, such as snakes, resist extinction, whereas responses toward danger-irrelevant stimuli, such as birds, are more readily extinguished. Similar evolved biases may extend to human groups, as recent research demonstrates that a conditioned fear response to faces of persons of a social out-group resists extinction, whereas fear toward a social in-group is more readily extinguished. Here, we provide an important extension to previous work by demonstrating that this fear-extinction bias occurs solely when the exemplars are male. These results underscore the importance of considering how gender of the target stimulus affects psychological and physiological responses to out-group threat.     

Internet addiction among Norwegian adults: a stratified probability sample study

Most Norwegians are Internet users. We conducted a stratified probability sample study (Norway, 2007, age-group 16–74 years, N = 3,399, response rate 35.3%, 87.1% Internet users) to assess the prevalence of Internet addiction and at-risk Internet use by the Young Diagnostic Questionnaire (YDQ). The prevalence of Internet addiction (YDQ score 5–8) was 1.0% and an additional 5.2% were at-risk Internet users (YDQ score 3–4). Internet addiction and at-risk Internet use was strongly dependent on gender and age with highest prevalences among young males (16–29 years 4.1% and 19.0%, 30–39 years 3.3% and 10.7%). Logistic regression showed that male gender, young age, university level education, and an unsatisfactory financial situation were factors positively associated with "problematic Internet use" (at-risk and addicted use combined). Time spent on the Internet and prevalence of self-reported sleeping disorders, depression, and other psychological impairments increased linearly with YDQ score. Problematic Internet use clearly affects the lives of many people.     

Overt naming fMRI pre- and post-TMS: Two nonfluent aphasia patients, with and without improved naming post-TMS

Two chronic, nonfluent aphasia patients participated in overt naming fMRI scans, pre- and post-a series of repetitive transcranial magnetic stimulation (rTMS) treatments as part of a TMS study to improve naming. Each patient received 10, 1-Hz rTMS treatments to suppress a part of R pars triangularis. P1 was a ‘good responder’ with improved naming and phrase length; P2 was a ‘poor responder’ without improved naming.Pre-TMS (10 years poststroke), P1 had significant activation in R and L sensorimotor cortex, R IFG, and in both L and R SMA during overt naming fMRI (28% pictures named). At 3 mo. post-TMS (42% named), P1 showed continued activation in R and L sensorimotor cortex, R IFG, and in R and L SMA. At 16 mo. post-TMS (58% named), he also showed significant activation in R and L sensorimotor cortex mouth and R IFG. He now showed a significant increase in activation in the L SMA compared to pre-TMS and at 3 mo. post-TMS (p < .02; p < .05, respectively). At 16 mo. there was also greater activation in L than R SMA (p < .08). At 46 mo. post-TMS (42% named), this new LH pattern of activation continued. He improved on the Boston Naming Test from 11 pictures named pre-TMS, to scores ranging from 14 to 18 pictures, post-TMS (2–43 mo. post-TMS). His longest phrase length (Cookie Theft picture) improved from three words pre-TMS, to 5–6 words post-TMS.Pre-TMS (1.5 years poststroke), P2 had significant activation in R IFG (3% pictures named). At 3 and 6 mo. post-TMS, there was no longer significant activation in R IFG, but significant activation was present in R sensorimotor cortex. On all three fMRI scans, P2 had significant activation in both the L and R SMA. There was no new, lasting perilesional LH activation across sessions for this patient. Over time, there was little or no change in his activation. His naming remained only at 1–2 pictures during all three fMRI scans. His BNT score and longest phrase length remained at one word, post-TMS.Lesion site may play a role in each patient’s fMRI activation pattern and response to TMS treatment. P2, the poor responder, had an atypical frontal lesion in the L motor and premotor cortex that extended high, near brain vertex, with deep white matter lesion near L SMA. P2 also had frontal lesion in the posterior middle frontal gyrus, an area important for naming (Duffau et al., 2003); P1 did not. Additionally, P2 had lesion inferior and posterior to Wernicke’s area, in parts of BA 21 and 37, whereas P1 did not.The fMRI data of our patient who had good response following TMS support the notion that restoration of the LH language network is linked in part, to better recovery of naming and phrase length in nonfluent aphasia.     

Relationship between heart rate variability and cognitive function during threat of shock

The aim of the present study was to investigate the relationship between resting heart rate variability (HRV) and cognitive functions during threat of shock. A Continuous Performance Task and a Working Memory Task were used to measure cognitive functions. Sixty-five male participants from the Royal Norwegian Navy participated. HRV was measured during baseline, test conditions and recovery. Participants were randomly assigned into non-threat and threat groups. Based on the median split of the high frequency (HF) spectral power, groups were divided into two additional groups. Overall, the high HRV participants showed superior performance on cognitive tasks independent of non-threat or threat conditions. During threat condition the low HRV group showed improved performance. Thus, individuals with high HRV were more stress tolerant and resilient in the face of environmental changes. The results from the study might have implications with regard to performance in operational settings, but also for other fields of psychological research such as individual differences, anxiety and coping.     

Screening for drugs in oral fluid: Illicit drug use and drug driving in a sample of urban and regional Queensland motorists

Police services in a number of Australian states and overseas jurisdictions have begun to implement or consider random road-side drug testing of drivers. This paper outlines research conducted to provide an estimate of the extent of drug driving in a sample of Queensland drivers in regional, rural and metropolitan areas. Oral fluid samples were collected from 2657 Queensland motorists and screened for illicit substances including cannabis (delta 9 tetrahydrocannibinol [THC]), amphetamines, ecstasy, and cocaine. Overall, 3.8% of the sample (n = 101) screened positive for at least one illicit substance, although multiple drugs were identified in a sample of 23 respondents. The most common drugs detected in oral fluid were ecstasy (n = 53), and cannabis (n = 46) followed by amphetamines (n = 23). A key finding was that cannabis was confirmed as the most common self-reported drug combined with driving and that individuals who tested positive to any drug through oral fluid analysis were also more likely to report the highest frequency of drug driving. Furthermore, a comparison between drug vs. drink driving detection rates for one region of the study, revealed a higher detection rate for drug driving (3.8%) vs. drink driving (0.8%). This research provides evidence that drug driving is relatively prevalent on Queensland roads, and may in fact be more common than drink driving. This paper will further outline the study findings’ and present possible directions for future drug driving research.     

Exploring Internet Motives and Life Satisfaction Among Hungarian and Israeli Medical Students, Living in Hungary

Objective Using the Internet can influence psychological well-being, for instance life satisfaction has been negatively related to Internet uses. The first aim of this study was to compare the motives for Internet use and life satisfaction. The second aim was to explore nation- and gender-based differences in Internet uses. Method The questionnaires related to Internet motives and life satisfaction, and were filled out by 300 medical students, including 150 Israeli students (75 females, 75 males) and 150 Hungarian students (75 females, 75 males). Results In the Israeli and Hungarian sample, the entertainment motive was rated the highest while the escape motive was rated the lowest. There were significant differences between the Israeli male and female students in arousal and information-seeking, while for the Hungarian male and female students there were significant differences for pass time. Life satisfaction was higher in the Israeli sample. In both samples it was shown that the higher the life satisfaction was, the less likely the students were to use the Internet for companionship purposes. Again in both samples, a higher life satisfaction predicted less frequent use of the Internet for the social interaction motives.     

Contextual influences on interpersonal complementarity

The influence of context on interpersonal complementarity was examined using an event-contingent recording procedure. Setting and role status moderated the relation between how a person behaved and how the other person behaved. Individuals were more likely to respond with agreeable behavior to agreeableness in others when not at work than when at work and when in a high status work role relative to a low status work role. Reciprocity between dominance and submissiveness was found in work settings but not in nonwork settings. Individuals were more likely to reciprocate more submissive behavior by the other person with more dominant behavior and more likely to reciprocate more dominant behavior by the other person with relatively more submissive behavior when in a higher status work role relative to lower status work roles. Results were interpreted in terms of the influence of decreased structure and shared goals on increasing interpersonal complementarity.     

Visions and Realities: Supervisee Perspectives of Multicultural Supervision

This article provides an overview of the experiences of 4 psychologists‐in‐training as supervisees in multicultural supervision relationships. Grounded in the supervision and multicultural literature, this article helps both supervisors and supervisees to (a) understand supervisees' needs and perspectives for culturally integrated supervision and (b) discuss multicultural issues during supervision. Recommendations are provided to facilitate the development of effective multicultural supervision. Este artículo muestra un resumen de las experiencias de 4 psicológos‐en‐entrenamiento bajo supervisión en relaciones de supervisión multiculturales. En base a la literatura multicultural y de supervisión, este artículo ayuda a supervisores y supervisados a (a) entender las necesidades de los supervisados y sus perspectivas hacia temas que integran la cultura en la supervisión, y (b) a discutir temas multiculturales durante la supervisión. Se proveen recomendaciones para facilitar el desarrollo de supervisión multicultural eficaz.