The effect of sentence length on question comprehension in children with cochlear implants.

OBJECTIVES: The present study investigated the comprehension of subject and object who and which questions in children with cochlear implants (CI). METHODS: Growth Curve Analysis (GCA) was used to compare eye gaze fixations and gaze patterns to the appropriate subject or object nouns within a four-picture array between 16 children with CI and 31 children with typical hearing (aged 7;0-12;0) on wh-questions with and without added adjectives to increase length. Offline accuracy was also compared. RESULTS: Findings indicated children with typical hearing exhibited more fixations to the target noun across all conditions, supporting higher comprehension accuracy. Both groups of children demonstrated more fixations to the target noun in object questions and questions without added length. Patterns of eye movement were significantly different between groups, suggesting different patterns of eye gaze across the array before fixation on the target noun. Children with CI exhibited fewer fixations, slower speed to fixation, and differences in gaze patterns that may imply the presence of processing limitations. Error analyses also suggested that children with CI frequently fixated on a picture similar to the target noun. CONCLUSIONS: Results indicate children with CI comprehend questions more slowly than their hearing peers, which may be related to limitations in working memory.

Rates and mechanisms of bacterial mutagenesis from maximum-depth sequencing.

In 1943, Luria and Delbrück used a phage-resistance assay to establish spontaneous mutation as a driving force of microbial diversity. Mutation rates are still studied using such assays, but these can only be used to examine the small minority of mutations conferring survival in a particular condition. Newer approaches, such as long-term evolution followed by whole-genome sequencing, may be skewed by mutational 'hot' or 'cold' spots. Both approaches are affected by numerous caveats. Here we devise a method, maximum-depth sequencing (MDS), to detect extremely rare variants in a population of cells through error-corrected, high-throughput sequencing. We directly measure locus-specific mutation rates in Escherichia coli and show that they vary across the genome by at least an order of magnitude. Our data suggest that certain types of nucleotide misincorporation occur 10(4)-fold more frequently than the basal rate of mutations, but are repaired in vivo. Our data also suggest specific mechanisms of antibiotic-induced mutagenesis, including downregulation of mismatch repair via oxidative stress, transcription­replication conflicts, and, in the case of fluoroquinolones, direct damage to DNA.

Language processing in children with cochlear implants: a preliminary report on lexical access for production and comprehension.

In this plenary paper, we present a review of language research in children with cochlear implants along with an outline of a 5-year project designed to examine the lexical access for production and recognition. The project will use auditory priming, picture naming with auditory or visual interfering stimuli (Picture-Word Interference and Picture-Picture Interference, respectively) and eye tracking paradigms to examine the roles of semantic and various phonological factors. Preliminary data are presented from auditory priming, picture-word interference and picture-picture interference tasks. The emergence of group difference is briefly discussed.

Simultaneous event-based and emergent timing: synchronization, continuation, and phase correction.

It has been claimed that rhythmic tapping and circle drawing represent fundamentally different timing processes (event-based and emergent, respectively) and also that circle drawing is difficult to synchronize with a metronome and exhibits little phase correction. In the present study, musically trained participants tapped with their left hands, drew circles with their right (dominant) hands, and also performed both tasks simultaneously. In Experiment 1, they synchronized with a metronome and then continued on their own, whereas in Experiment 2, they synchronized with a metronome containing phase perturbations. Circle drawing generally exhibited reliable synchronization, although with greater variability than tapping, and also showed a clear phase-correction response that evolved gradually during the cycle immediately following a perturbation. When carried out simultaneously in synchrony, with or without a metronome, the two tasks affected each other in some ways but retained their distinctive timing characteristics. This shows that event-based and emergent timing can coexist in a dual-task situation. Furthermore, the authors argue that the two timing modes usually coexist in each individual task, although one mode is often dominant.

The experience of children in a joint-custody arrangement: a report of a study.

The psychological experience of 32 children living in a joint-custody arrangement with their parents is examined. This report is part of a larger study, begun in 1978, of 24 families in which parents have shared childrearing responsibilities and physical custody of their children following marital separation. Findings suggest that joint custody is not a simple solution, and that the reaction of children is highly individual. The need for further study is emphasized.