Suicidal Behaviors in Surviving Monozygotic and Dizygotic Co‐Twins: Is the Nature of the Co‐Twin's Cause of Death a Factor?

Genetically informative samples can address hereditary and experiential influences on suicide‐related behaviors. The frequency of suicide‐related behaviors was compared in twins from two survivor groups: (1) those whose co‐twins' deaths were suicides (monozygotic [MZ]: n = 47; dizygotic [DZ]: n = 31), and (2) those whose co‐twins' deaths were nonsuicides (MZ: n = 347; DZ: n = 170). The frequency of suicide attempts among suicide survivors was significantly higher in MZ than DZ twins, while the frequency of suicide attempts among nonsuicide twin survivors did not differ between MZ and DZ twins. Twin concordance for suicide attempts more likely reflects a genetic predisposition than a behavioral reaction to the loss.     

Single-Stage Prediction Models Do Not Explain the Magnitude of Syntactic Disambiguation Difficulty

The disambiguation of a syntactically ambiguous sentence in favor of a less preferred parse can lead to slower reading at the disambiguation point. This phenomenon, referred to as a garden-path effect, has motivated models in which readers initially maintain only a subset of the possible parses of the sentence, and subsequently require time-consuming reanalysis to reconstruct a discarded parse. A more recent proposal argues that the garden-path effect can be reduced to surprisal arising in a fully parallel parser: words consistent with the initially dispreferred but ultimately correct parse are simply less predictable than those consistent with the incorrect parse. Since predictability has pervasive effects in reading far beyond garden-path sentences, this account, which dispenses with reanalysis mechanisms, is more parsimonious. Crucially, it predicts a linear effect of surprisal: the garden-path effect is expected to be proportional to the difference in word surprisal between the ultimately correct and ultimately incorrect interpretations. To test this prediction, we used recurrent neural network language models to estimate word-by-word surprisal for three temporarily ambiguous constructions. We then estimated the slowdown attributed to each bit of surprisal from human self-paced reading times, and used that quantity to predict syntactic disambiguation difficulty. Surprisal successfully predicted the existence of garden-path effects, but drastically underpredicted their magnitude, and failed to predict their relative severity across constructions. We conclude that a full explanation of syntactic disambiguation difficulty may require recovery mechanisms beyond predictability.     

Posttraumatic Stress Disorder Symptom Clusters and Acquired Capability for Suicide: A Reexamination Using DSM-5 Criteria

This study used the interpersonal–psychological theory of suicide to explore the relationships among DSM-5 posttraumatic stress disorder (PTSD) symptom clusters derived from the six-factor anhedonia model and facets of acquired capability for suicide (ACS). In a sample of 373 trauma-exposed undergraduates, most PTSD symptom clusters were negatively associated with facets of ACS in bivariate correlations, but the anhedonia cluster was positively associated with ACS in regression models. Structure coefficients and commonality analysis indicated that anhedonia served as a suppressor variable for the other symptom clusters. Our findings further elucidate the complex relationship between specific PTSD symptom clusters and ACS.     

Perceptions of the parent-adolescent relationship: a longitudinal investigation

A self-report measure of conflict and aspects of warmth in the parent-child relationship was completed by 1,330 11-year-old twins, 1,176 of whom completed the inventory again 3 years later. On average, adolescents' perceptions of the quality of the parent-child relationship declined consistently and moderately between age 11 and age 14. Conflict with parents increased, whereas all aspects of warmth decreased; changes were significantly greater for girls than boys. Variances increased with age, primarily because of increases in the magnitude of genetic effects. Heritability estimates ranged from .09 to .31 at intake and .35 to .45 at follow-up and tended to be higher for boys than girls. Changes in the parent-child relationship are interpreted as reflecting genotype-environment correlation processes whereby adolescents increasingly influence their relationships with their parents.     

Multiply controlled verbal operants: an analysis and extension to the picture exchange communication system

This paper presents Skinner's (1957) analysis of verbal behavior as a framework for understanding language acquisition in children with autism. We describe Skinner's analysis of pure and impure verbal operants and illustrate how this analysis may be applied to the design of communication training programs. The picture exchange communication system (PECS) is a training program influenced by Skinner's framework. We describe the training sequence associated with PECS and illustrate how this sequence may establish multiply controlled verbal behavior in children with autism. We conclude with an examination of how Skinner's framework may apply to other communication modalities and training strategies.     

Identifying shared environmental contributions to early substance use: the respective roles of peers and parents

Although behavior genetic studies have suggested that early substance use is primarily environmentally mediated, no study has sought to identify the specific sources of environmental variance. Using data obtained from multiple informants, this study assessed the contributions of peer deviance and parent-child relationship problems to substance use in 14-year-old male and female twins (N = 1,403) drawn from the Minnesota Twin Family Study (MTFS). All three phenotypes were influenced primarily by shared environmental variance (average c(2) =.51), as was the overlap among them. Moreover, peer deviance and parent-child relationship problems accounted for approximately 77% of the variance in early substance use. Findings also indicated that peer deviance, but not parent-child relationship problems, accounted uniquely for variance in early substance use.     

Hostility and facial affect recognition: effects of a cold pressor stressor on accuracy and cardiovascular reactivity

The effects of hostility and a cold pressor stressor on the accuracy of facial affect perception were examined in the present experiment. A mechanism whereby physiological arousal level is mediated by systems which also mediate accuracy of an individual’s interpretation of affective cues is described. Right-handed participants were classified as high hostile (N=28) or low hostile (N=28) using the Cook Medley Hostility Scale. The high-hostile group met joint selection criteria. Only high-hostile participants who showed cardiovascular reactivity to the cold pressor, with systolic BP change exceeding the group mean were included. Groups were further subdivided into cold pressor and non-cold pressor test conditions. It was predicted that high-hostile men, relative to low-hostile men, would show decreased perceptual accuracy when presented with happy, angry, and neutral facial configurations within the left visual field (LVF). Results indicated that high-hostile men were less accurate than low-hostile men in the LVF. Further, pre-stress accuracy scores in the high-hostile men were similar to the post-stress accuracy scores of the low-hostile men. The lateralization of affective function and the role of physiological arousal in affective facial perception are discussed.     

Genetic and Environmental Influences on Psychopathy Trait Dimensions in a Community Sample of Male Twins

Psychopathy appears to be comprised of two broad dimensions: impulsivity/antisocial behavior and interpersonal detachment/callousness. This study examined the extent to which variance in these 2 psychopathy trait dimensions was associated with common or unique genetic, shared, and nonshared environmental factors in two independent samples of reared together 16–18-year-old male twins. One sample included 142 monozygotic (MZ) and 70 dizygotic (DZ) pairs; the other sample included 128 MZ and 58 DZ pairs. Boys completed the Minnesota Temperament Inventory (MTI), a 19-item measure that contains separate subscales: Antisocial and Detachment. Variance in the Antisocial and Detachment scales was associated with additive genetic factors and neither scale was associated with shared environmental factors. As expected, the bivariate biometric analysis suggested genetic influence on the covariance of the scales. The results are consistent with theoretical models of psychopathy that posit some independence in the etiology of the two major trait dimensions of psychopathy.