Ophthalmological,cognitive, electrophysiological and MRI assessment of visual processing in preterm children without major neuromotor impairment

Many studies report chronic deficits in visual processing in children born preterm. We investigated whether functional abnormalities in visual processing exist in children born preterm but without major neuromotor impairment (i.e. cerebral palsy). Twelve such children (< 33 weeks gestation or birthweight < 1000 g) without major neuromotor impairment and 12 born full‐term controls were assessed at 8–12 years of age by means of ophthalmological assessment (visual acuity, colour vision, stereopsis, stereoacuity, visual fields, ocular motility, motor fusion), cognitive tests of visual‐motor, visual‐perceptual and visual‐spatial skills and pattern‐reversal visual evoked potentials (PR‐VEPs). All participants also underwent magnetic resonance imaging (MRI) of the brain and neuromotor assessments. No significant differences were found between the groups on the ophthalmological, visual cognitive, neurological, neuromotor or MRI measures. The P100 component of the PR‐VEP showed a significantly shorter latency in the preterm compared with the full‐term participants. Whilst this P100 finding suggests that subtle abnormalities may exist at the neurophysiological level, we conclude that visual dysfunction is not systematically associated with preterm birth in the context of normal neurological status.     

Spatial Segregation and the Impact of Linguistic Multicultural Policies Within the USA

In this article, we examine the impact of multicultural linguistic policy on the residential outcomes of Hispanic and Asian groups in the USA. Arguments linking multiculturalism to residential segregation outcomes are a hotly contested political issue. While spatial segregation is one form of social integration for immigrants, scholars are particularly concerned with residential outcomes because it is theorized to strongly facilitate a wide variety of other forms of integration including language acquisition, the convergence of socio-cultural gender and sexual norms, employment, friendship ties, and intermarriage. From data drawn from the 2010 U.S. Census, we calculate the dissimilarity index for these two groups. We find multicultural linguistic policies increase segregation levels between Asians and non-Hispanic whites, but not between Hispanics and non-Hispanic whites. The results are robust to a host of alternative explanations and model specifications. However, the estimated positive effect of linguistic policy is modest at best and run contrary to fears that multiculturalist policies drastically alter residential outcomes. We close by questioning normative accounts that problematize rising levels of segregation within ethnic communities, which are a far cry from the minority ghettos that are politically portrayed.     

Task-irrelevant sounds influence both temporal order and apparent-motion judgments about tactile stimuli applied to crossed and uncrossed hands

It has been suggested that judgments about the temporal–spatial order of successive tactile stimuli depend on the perceived direction of apparent motion between them. Here we manipulated tactile apparent-motion percepts by presenting a brief, task-irrelevant auditory stimulus temporally in-between pairs of tactile stimuli. The tactile stimuli were applied one to each hand, with varying stimulus onset asynchronies (SOAs). Participants reported the location of the first stimulus (temporal order judgments: TOJs) while adopting both crossed and uncrossed hand postures, so we could scrutinize skin-based, anatomical, and external reference frames. With crossed hands, the sound improved TOJ performance at short (≤300 ms) and at long (>300 ms) SOAs. When the hands were uncrossed, the sound induced a decrease in TOJ performance, but only at short SOAs. A second experiment confirmed that the auditory stimulus indeed modulated tactile apparent motion perception under these conditions. Perceived apparent motion directions were more ambiguous with crossed than with uncrossed hands, probably indicating competing spatial codes in the crossed posture. However, irrespective of posture, the additional sound tended to impair potentially anatomically coded motion direction discrimination at a short SOA of 80 ms, but it significantly enhanced externally coded apparent motion perception at a long SOA of 500 ms. Anatomically coded motion signals imply incorrect TOJ responses with crossed hands, but correct responses when the hands are uncrossed; externally coded motion signals always point toward the correct TOJ response. Thus, taken together, these results suggest that apparent-motion signals are likely taken into account when tactile temporal–spatial information is reconstructed.