The analysis of zero-inflated count data: beyond zero-inflated Poisson regression

Infrequent count data in psychological research are commonly modelled using zero-inflated Poisson regression. This model can be viewed as a latent mixture of an "always-zero" component and a Poisson component. Hurdle models are an alternative class of two-component models that are seldom used in psychological research, but clearly separate the zero counts and the non-zero counts by using a left-truncated count model for the latter. In this tutorial we revisit both classes of models, and discuss model comparisons and the interpretation of their parameters. As illustrated with an example from relational psychology, both types of models can easily be fitted using the R-package pscl.     

The sexual responses of sexual sadists

On average, rapists show greater relative genital responses to rape stories than do nonrapists in the laboratory. It has been suggested that this robust group difference is explained by the fact that many rapists are sexually sadistic. It is not clear, however, what the critical cues underlying rapists' genital responses are, because rape stories used in previous research include a mix of sadistic cues of violence and victim injury as well as cues of victim resistance and nonconsent. The present study was conducted to identify the critical cues producing self-identified sadists' sexual responses, and thereby to test sexual sadism as an explanation of rapists' arousal pattern. The present study was also conducted to develop a new phallometric test for sexual sadism for research and clinical applications, given evidence of poor diagnostic reliability and validity. Eighteen self-identified male sadists, 22 men with some sadistic interests who did not meet all of our sadist criteria, and 23 nonsadists (all recruited from the community) were compared in their genital and subjective responses to a new set of stories that disentangle violence/injury cues from resistance/nonconsent cues. The three groups differed in both their genital and subjective responses: using indices of relative responding, sadists responded significantly more to cues of violence/injury than nonsadists and men with some sadistic interests. The group difference for cues of nonconsent was not significant. The results suggest that sexual sadism primarily involves arousal to violence/injury in a sexual context rather than resistance/nonconsent. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Culture and the distinctiveness motive: constructing identity in individualistic and collectivistic contexts

The motive to attain a distinctive identity is sometimes thought to be stronger in, or even specific to, those socialized into individualistic cultures. Using data from 4,751 participants in 21 cultural groups (18 nations and 3 regions), we tested this prediction against our alternative view that culture would moderate the ways in which people achieve feelings of distinctiveness, rather than influence the strength of their motivation to do so. We measured the distinctiveness motive using an indirect technique to avoid cultural response biases. Analyses showed that the distinctiveness motive was not weaker-and, if anything, was stronger-in more collectivistic nations. However, individualism-collectivism was found to moderate the ways in which feelings of distinctiveness were constructed: Distinctiveness was associated more closely with difference and separateness in more individualistic cultures and was associated more closely with social position in more collectivistic cultures. Multilevel analysis confirmed that it is the prevailing beliefs and values in an individual's context, rather than the individual's own beliefs and values, that account for these differences.     

Use of a driving simulator to assess performance under adverse weather conditions in adults with albinism

Participants with albinism have reduced vision and nystagmus with reduced foveation times. This prospective study evaluated driving in 12 participants with albinism and 12 matched controls. Participants drove a vehicle simulator through a virtual rural course in sunny and foggy conditions. Under sunny conditions, participants with albinism showed a narrower preferred minimum safety boundary during car-following tasks than did controls, but there was no difference under foggy conditions. Their driving did not differ significantly from that of controls when approaching a stop sign or when choosing gap size between oncoming vehicles when crossing an intersection. However, when compared to control drivers, participants with albinism had a decreased minimum safety boundary for car-following that should be included in counseling regarding driving safety.     

The Politics of Judicial Public Reason: Secular Interests and Religious Rights

This paper seeks a better understanding of the role of public reason in alimenting or defusing religious conflicts by looking at how courts apply it in deciding cases arising out of them. Recent scholarship and judicial decisions suggest, paradoxically, that courts can be biased towards either the secular or the religious. This risks alienating both religious majorities and religious and secular minorities. Judicial public reason is uniquely equipped to protect minorities, and its costs to religious majorities may be mitigated by accepting religious morality and identity claims in the political and legislative realm. Despite the political fragilities of judicial public reason, it is not intrinsically hostile to religious claims. It ought in fact to be fully equipped to recognize the equality and religious freedom rights that religious groups and individuals might assert in pursuing exemptions from general secular laws. Judicial public reason does have the potential to defuse religious conflicts, however much it falls short in practice.     

Theory and therapy in stuttering: A complex relationship

There are many treatments currently available for stuttering, for both children and adults. These range from direct interventions intended to reduce the severity and/or frequency of the speech behaviors of stuttering, to those intended to alleviate the anxiety and other mental health issues that can accompany the disorder. However, as there are little supporting data for many of these treatments, there is little consensus about which to use. Another way to evaluate stuttering treatments is to explore the extent to which they address the cause of the disorder. However, the cause of stuttering is not yet known. In this theoretical paper, a 3-factor causal model is presented, to which the mechanisms thought to be driving different treatments are then aligned. The model is innovative, in that it attempts to explain moments of stuttering. It is argued that all causal factors must be operating at each moment of stuttering. The model is intended as a new way of looking at cause, and how treatments may address cause. It is hoped this will stimulate discussion and lead to further lines of inquiry.Educational objectives: The reader will be able to: (a) describe the P&A 3-factor causal model of moments of stuttering; (b) state how indirect direct stuttering treatments relate to cause, according to the P&A model; (c) describe how direct stuttering treatments relate to cause, according to the P&A model; (d) state the purpose of cognitive behavior therapy; and (e) describe at least one suggestion for further research arising from the P&A model.     

The effect of mother–infant skin-to-skin contact on infants’ response to the Still Face Task from newborn to three months of age

The effect of mother–infant skin-to-skin contact on infants’ developing social expectations for maternal behavior was investigated longitudinally over infants’ first 3 months. Infants with and without skin-to-skin contact engaged with their mothers in the Still Face Task at ages 1 week, 1 month, 2 months, and 3 months. Infants with skin-to-skin contact began responding to changes in their mothers’ behavior with their affect at 1 month; infants without skin-to-skin contact did so at 2 months. At 3 months, infants with skin-to-skin contact increased their non-distress vocalizations during the still face phase, suggesting social bidding to their mothers. Skin-to-skin contact accelerated infants’ social expectations for their mothers’ behavior and enhanced infants’ awareness of themselves as active agents in social interactions.     

What makes labour and birth traumatic? A survey of intrapartum 'hotspots'

Evidence suggests between 1% and 6% of women develop post-traumatic stress disorder (PTSD) after childbirth. 'Hotspots' are moments of extreme distress during traumatising events that are implicated in symptoms of PTSD. This cross-sectional internet survey of hotspots examined (1) the content of intrapartum hotspots and (2) whether particular events, cognitions or emotions during hotspots are related to PTSD. Women (N?=?675) who experienced a difficult or traumatic birth completed a questionnaire composed of a validated measure of PTSD, questions concerning the existence of hotspots, and a newly developed measure of emotions and cognitions during hotspots. The majority of women (67.4%) reported at least one hotspot during birth and 52.9% had re-experiencing symptoms of these hotspots. Women were more likely to have PTSD if hotspots involved fear and lack of control (odds ratio (OR) 1.30, 95% CI 1.17-1.43) or intrapartum dissociation (OR 1.12, 95% CI 1.05-1.19). Risk of PTSD was higher if hotspots concerned interpersonal difficulties (OR 4.34, 95% CI 2.15-8.77) or obstetric complications (OR 3.35, 95% CI 1.64-6.87) compared to complications with the baby.     

Documenting the Adverse Impact of Résumé Screening: Degree of ethnic identification matters

We investigated the adverse impact of résumé screening, taking into account the intersectionality of minority characteristics. A correspondence audit test showed hiring discrimination depended on the strength of applicants' ethnic identification. The odds for rejection were 4–6 times higher for résumés with ethnic minority identifiers (Arab names; Arab affiliations) when compared with ethnic majority identifiers (Dutch names; Dutch affiliations). Sex moderated the ethnicity effect but the particular effect (ethnic prominence; double jeopardy against women or men) depended on the type and degree of ethnic identification, lending support for a within‐category approach to study ethnic prejudice. The four‐fifths rule resulted in similar findings. Theoretical implications regarding the intersectional effects of minority characteristics and practical implications regarding ways to avert adverse impact during résumé screening are discussed.