A challenge to current models of past tense inflection: the impact of phonotactics

Is past tense production better modelled by a Single Mechanism or a Words and Rules model? We present data concerning a phenomenon that has not been considered by either model-regular past tense verbs with contrasting phonotactics. One set of verbs contains clusters at the inflected verb end that also occur in monomorphemic words ('monomorphemically legal clusters', MLC) whereas the other has clusters that can only occur in inflected forms ('monomorphemically illegal clusters', MIC). We argue that if children apply a morphological rule, phonotactics will not affect performance. Conversely, if children store past tense forms, they will perform better on verbs with MLCs because these clusters are more frequent. We investigated three populations--typically developing children, Grammatical-SLI (G-SLI) and Williams Syndrome (WS)--using past tense elicitation tasks. In Experiment 1 we reanalyse data from van der Lely and Ullman [van der Lely, H. K. J. & Ullman, M. (2001). Past tense morphology in specifically language impaired and normally developing children. Language and Cognitive Processes, 16: 177-217] and show that G-SLI children perform better on MLC verbs, whereas for typically developing children phonotactics do not affect performance. In Experiment 2 we replicate these findings in new groups of G-SLI and typically developing children. In Experiment 3 we reanalyse data from Thomas et al. [Thomas, M. S. C., Grant, J., Barham, Z., Gsodl, M., Laing, E., Lakusta, L., Tyler, L.K., Grice, S., Paterson, S. & Karmiloff-Smith, A. (2001) Past tense formation in Williams Syndrome. Language and Cognitive Processes, 16: 143-176] and show that phonotactics do not affect performance in individuals with WS. We argue that the results elucidate the underlying nature of morphology in these populations, and are better accommodated within a Words and Rules model of past tense acquisition.     

Brain activation and the phonological loop: the impact of rehearsal

Brain activation studies offer valuable techniques for exploring human cognition to complement behavioral measures and several studies report a wide range of neuroanatomical networks activated during verbal immediate memory. Behavioral investigations have shown use of multiple cognitive strategies across and within individuals, although aggregate data appear to reflect a common cognitive function. Variation in cognitive strategies could result in aggregate activation patterns that are relatively widespread and difficult to interpret. Imaging data (fMRI) from six participants instructed to use subvocal rehearsal showed significant left hemisphere activation in the inferior parietal gyrus and inferior and middle frontal gyri, a pattern of activation more clearly focused than in previous brain activation studies of immediate verbal serial ordered recall. Our results should be relatively free of the influence of other mental operations, and emphasise the importance of considering which cognitive strategies might give rise to focused or to diverse patterns of brain activation.     

Perinatal substance abuse and human subjects research: are privacy protections adequate?

Privacy incursions in the clinical care of substance abusing pregnant women have gained lay and professional attention recently as the result of a high-profile Supreme Court finding in Ferguson vs City of Charleston et al. In March, 2001 the Supreme Court determined that nonconsensual drug screening of pregnant women by clinicians in a public hospital violated the women's Fourth Amendment rights to be secure against unreasonable search and seizure. Coercive or punitive policy approaches to perinatal substance abuse are often based on mistaken assumptions about the nature of addiction and the outcomes of punitive interventions. Much attention has been given to efforts to criminalize pregnancy for drug using women, and civil laws are also coming under increasing scrutiny. Although no state has passed a law criminalizing pregnancy and drug use, an estimated 250 women in more than 30 states have been prosecuted around the country on theories of "fetal abuse." A growing number of states (eighteen to date) have amended their civil child welfare laws to address specifically the subject of a woman's drug use during pregnancy. No one has examined how these laws and social policies could affect research that includes pregnant and parenting women; women (and their families) who stand to lose a great deal should their drug use be brought to the attention of child welfare or criminal justice authorities. We examine the adequacy of current protective mechanisms, such as federal certificates of confidentiality, in protecting research subjects (and investigators) who may be subject to punitive civil or criminal sanctions. We determine that current protective mechanisms may be insufficient to protect research subjects and that investigators and IRB members are often ignorant of the risks imposed by punitive policy approaches to perinatal substance abuse or fall prey to the same mistaken assumptions that inform punitive policies. We conclude that investigators and IRB members have a moral responsibility to understand local, state and national policies and laws governing perinatal substance abuse. Investigators and IRB members should balance the harms of punitive interventions against the protections that may, or may not be afforded to prospective research subjects as well as the prospective benefits, individual and social, of the research. In situations where criminal or punitive policies are in effect, investigators and IRB members should consider whether adequate protections can be achieved. In the context of inadequate protections, potential risks to prospective research subjects and their families may outweigh the individual or social benefits that accrue from the research. Clinical researchers are professionally obligated to work toward amending laws and policies that are not in the best interests of prospective research subjects.     

The incremental validity and clinical utility of the MMPI-2 infrequency posttraumatic stress disorder scale

The incremental validity and clinical utility of the recently developed Minnesota Multiphasic Personality Inventory-2 (MMPI-2) Infrequency Posttraumatic Stress Disorder Scale (Fptsd) was examined in relation to the family of MMPI-2 F scales in distinguishing feigned post-traumatic stress disorder (PTSD) from disability claimants with PTSD. Research participants instructed to feign PTSD when completing the MMPI-2 scored significantly higher on the MMPI-2 family of F scales and the Fptsd scale compared with their responses when completing the MMPI-2 under standard instructions and the sample of claimants with PTSD. Although comparable in magnitude, effect sizes derived from mean group differences and hierarchical logistic regressions for the Fptsd scale never exceeded those for F(B), and F(P), F, F(B), and F(P) added incrementally to Fptsd in the prediction of feigned PTSD. These results suggest that the Fptsd scale does not afford any incremental predictive utility for detecting feigned PTSD relative to the complement of the existing family of F scales.     

Culture-fair cognitive ability assessment: information processing and psychophysiological approaches

Valid assessment with diverse populations requires tools that are not influenced by cultural elements. This study investigated the relationships between culture, information processing efficiency, and general cognitive capacities in samples of Caucasian and Mexican American college students. Consistent with the neural efficiency hypothesis, pupillary responses (indexing mental effort) and detection accuracy scores on a visual backward-masking task were both significantly related to the Wechsler Adult Intelligence Scale-Revised (WAIS-R) Full Scale scores. These measures of information processing efficiency were similar in the two groups. However, they were related only to Caucasian American, but not to a comparable sample of Mexican American, students' WAIS-R scores. Therefore, the differential validity in prediction suggests that the WAIS-R test may contain cultural influences that reduce the validity of the WAIS-R as a measure of cognitive ability for Mexican American students. Information processing and psychophysiological approaches may be helpful in developing culture-fair cognitive ability measures.     

Self-regulation and inhibition in comorbid ADHD children: an evaluation of executive functions

The relationship between executive function and comorbid diagnoses in ADHD children is examined. One hundred six children between 7 and 15 years of age are assessed using the Tower of London (TOL), a test of executive function, and the Kiddie Schedule of Affective Disorders and Schizophrenia, Present and Lifetime Version, a diagnostic interview. All children met the diagnostic criteria for ADHD. A majority of the children had comorbid anxiety disorders, mood disorders, or oppositional defiant disorder. Measures on the TOL are total move score, total initiation time, and total rule violations. Age is predictive in all three measures of executive function as assessed by the TOL. Gender is predictive of total initiation time and total rule violations. Comorbid disorders are found to not have significance on executive function as measured by the TOL. This study concludes that comorbid disorders may not affect executive function.     

Development and validation of a modified version of the Peritraumatic Dissociative Experiences Questionnaire

This article reports results from 3 studies conducted to develop and validate a modified version of the self-administered form of the Peritraumatic Dissociative Experiences Questionnaire (PDEQ; C. R. Marmar, D. S. Weiss, & T. J. Metzler, 1997). The objective was to develop an instrument suitable for use with persons from diverse ethnic and socioeconomic backgrounds. In Study 1, the original PDEQ was administered to a small sample (N = 15) recruited from among men admitted to the hospital for physical injuries stemming from exposure to community violence. Results led to modifications aimed at improving the utility of the instrument. In Study 2, the modified PDEQ was subjected to structural equation modeling and item response theory analyses to assess its psychometric properties in a larger, primarily male, sample of community violence survivors (N = 284). In Study 3, the reliability and validity of the modified instrument were further assessed in a sample of female survivors of sexual assault (N = 90). Results attest to the psychometric properties as well as the reliability and validity of the modified 8-item PDEQ.     

Client Perceptions of Couples Therapy: Helpful and Unhelpful Aspects

This article describes a qualitative study that investigated client perceptions of helpful and unhelpful aspects of couples therapy. A thematic analysis of interviews revealed among other themes, that couple participants associated helpful therapy experiences with (a) being given choices regarding ideas and ways of working that fit for them, (b) working with a therapist they trusted, and (c) developing new ideas about the couple relationship. Implications of this study for future research, practice, and training are described.     

Transient photoconductivity in n-type a-Si: H

Abstract

The long-time transient photocurrent decay in annealed and light-exposed P-doped a-Si: H is examined experimentally and by numerical modelling. The decay is a dispersive power law with sublinear index, extending to times longer than 1s, and the decay rate increases with temperature. Light exposure dramatically decreases the decay amplitude but does not affect the rate of decay. The phenomenon is discussed in terms of a comprehensive multiple-trapping model in which transport of thermalized electrons is essentially non-dispersive, and recombination of free carriers via defects is dispersive, owing to continued thermalization of excess holes. The slower recombination step is free-hole capture by D^? states, while the decay of the total excess ensemble is controlled by hole release from valence-band tail traps. The index of the excess photoelectron decay provides information on the valence-band tail states, which are exponentially distributed, with a characteristic energy estimated as 0·06 eV.