Gender differences in psychopathy in a Swedish offender sample

In this study we examined gender differences in the PCL:SV employing a variety of statistical methods with two subsets of psychopathic individuals drawn from larger samples of 129 female and 499 male Swedish offenders. The larger samples included forensic psychiatric patients, forensic psychiatric evaluees and criminal offenders. We found gender differences in antisocial behavior, as defined in factor 2 of the PCL:SV, with female psychopaths (PCL:SV>or=18) displaying significantly more lying, deceitfulness and lack of control, while male psychopaths were more antisocial as measured by the PCL:SV. We conclude that it might be meaningful to use gender specific definitions in the assessment of psychopathy or, alternatively, slightly revise the diagnostic tools. Our results support the use of the three-factor model of the PCL-R and PCL:SV introduced by Cooke and Michie (2001) in female populations.     

Reliability and Validity Evaluation of the Psychopathy Checklist: Screening Version (PCL:SV) in Swedish correctional and forensic psychiatric samples

This study evaluated the structural reliability, construct-related validity, and cultural validity generalization of the Hare Psychopathy Checklist: Screening Version (PCL:SV) in a sample of more than 560 male and female Swedish forensic psychiatric treatment patients, forensic evaluation patients, and criminal offenders. Structural reliability was excellent for most indices. PCL:SV scores were higher for males than females for total and Part 1 scores (interpersonal/affective features) but not for Part 2 (behavioral features). With some exceptions, PCL:SV scores were meaningfully related to aggression to others, a measure of risk for violence, substance use problems, personality disorder (positive), and psychosis (negative). Correlations between PCL:SV and aggression were larger for females than males, although the difference was smaller when personality disorder was held constant. The structural reliability and pattern of validity coefficients were comparable in these Swedish samples to other non-North American samples. Implications for the cross-cultural manifestation and correlates of psychopathy are discussed.     

Change in cognitive capabilities in the oldest old: the effects of proximity to death in genetically related individuals over a 6-year period

Change in cognitive abilities was assessed over a 6-year period in a sample of monozygotic and same-sex dizygotic twin pairs (N = 507 individuals), aged 80 and older (mean age = 83.3 years: SD = 3.1). who remained nondemented over the course of the study. Latent growth models (LGMs) show that chronological age and time to death are consistent predictors of decline in measures of memory, reasoning, speed, and verbal abilities. Multivariate LGM analysis resulted in weak and often negative correlations among rates of change between individuals within twin pairs, indicating greater differential change within twin pairs than occurs on average across twin pairs. These findings highlight several challenges for estimating genetic sources of variance in the context of compromised health and mortality-related change.     

Differential mastication kinematics of the rabbit in response to food and water: Implications for conditioned movement

Analysis of naturalistic chewing patterns may provide insight into mapping the neural substrates of jaw movement control systems, including their adaptive modification during the classically conditioned jaw movement (CJM) paradigm. Here, New Zealand White rabbits were administered food and water stimuli orally to evaluate the influence of stimulus consistency on masticatory pattern. Chewing patterns were recorded via video camera and movements were analyzed by computerized image analysis. The mandibular kinematics, specifically the extent of dorsal/ventral, medial/lateral, and rostral/caudal movement, were significantly larger in food-evoked than water-evoked chewing. Water-evoked chewing frequency, however, was significantly higher than that of food-evoked movements. In light of known cortical mastication modulatory centers, our findings implicate different neural substrates for the responses to food and water stimuli in the rabbit. A detailed delineation of jaw movement patterns and circuitry is essential to characterize the neural substrates of CJM.     

Large-scale ensemble averaging of ambulatory impedance cardiograms

Impedance cardiography has been used increasingly to measure human physiological responses to emotional and mentally engaging stimuli. The validity of large-scale ensemble averaging of ambulatory impedance cardiograms was evaluated for preejection period (PEP), interbeat interval, and dZ/dt_(min) amplitude. We tested whether the average of “classical” 60-sec ensemble averages across periods with fixed activity, posture, physical load, social situation, and location could be accurately estimated from a single large-scale ensemble average spanning these entire periods. Impedance and electrocardiograms were recorded for about 24-h from 21 subjects. Recordings were scored by seven raters, using both methods for each subject. Good agreement (average intraclass correlation coefficient was .91) between both ensemble averaging methods was found for all three cardiac function measures. The results indicate that for unambiguous ambulatory impedance cardiograms, large-scale ensemble averaging is valid, which makes measuring prolonged changes in cardiac sympathetic activity by measuring ambulatory PEP feasible even in large epidemiological samples.     

Effect of masker level on infants' detection of tones in noise

In adult listeners, the signal-to-noise ratio at masked threshold remains constant with increases in masker level over a wide range of stimulus conditions. This relationship was examined in 7-month-old infants by obtaining masked thresholds for .5- and 4-kHz tones presented in four levels of continuous masking noise. Adults were also tested for comparison. Masker spectrum levels ranged from 5 to 35 dB/Hz for .5-kHz tones, and from -5 to 25 dB/Hz for 4-kHz stimuli. Thresholds were determined for stimuli of both 10 and 100 msec in duration. The results indicated that infants' performance was more adult-like for 4-kHz stimuli. Although mean thresholds for both 10- and 100-msec, 4-kHz tones were approximately 7 dB higher in infants than in adults, E/N0 at threshold remained essentially constant over the 30-dB range of maskers employed. By contrast, infants' thresholds for .5-kHz tones were exceptionally high at lower levels of the masker. Threshold E/N0 decreased significantly as masker level increased from 5 to 35 dB/Hz, and this decrease was significantly greater for 10- than for 100-msec stimuli. Temporal summation of .5-kHz tones, measured as the difference between thresholds obtained at the two signal durations, was greater for infants than for adults at low levels of the masker. However, because infants' thresholds improved more rapidly with level for 10- than for 100-msec tones, age differences in temporal summation were no longer significant when masker spectrum level was 35 dB/Hz. These results suggest that the relationship between signal-to-noise ratio at masked threshold and level of the masker is dependent on both signal frequency and duration during infancy.     

Referential Attribution

Philosophical Studies -     

Evaluation of antecedent stimulus parameters for the treatment of escape-maintained aberrant behavior

We evaluated a methodology for identifying the range of stimulus features of antecedent stimuli associated with aberrant behavior in demand contexts in natural settings. For each participant, an experimental analysis of antecedents (Phase 1) was conducted to confirm the hypothesis that task instructions occasioned increases in aberrant behavior. During Phase 2, specific stimulus features associated with the presentation of task instructions were assessed by evaluating the child's behavior across two distinct settings, therapists, and types of tasks in a sequential fashion. Aberrant behavior occurred immediately across settings and therapists, presumably because the presence of a discriminative stimulus for escape-maintained behavior (the delivery of a task instruction) occasioned aberrant behavior. However, aberrant behavior decreased initially across tasks, suggesting that familiarity with the task might be a variable. During Phase 3, an experimental (functional) analysis of consequences was conducted with 2 participants to verify that aberrant behavior was maintained by negative reinforcement. During Phase 4, a treatment package that interspersed play with task instructions was conducted to disrupt the ongoing occurrence of aberrant behavior. Immediate and durable treatment effects occurred for 2 of the 3 participants.