Peripheral vision: The effects of developmental,perceptual, and cognitive factors

The effects of perceptual and cognitive factors on information processing in the visual periphery were studied in 5- and 8-year-old children and in adults. Subjects judged either the similarity (Study 1) or the identity (Study 2) of geometric forms. In both studies, two forms were simultaneously presented for 20 msec at 2, 4, or 6°, with one form on either side of the fovea. Type of form and Axis of presentation were varied. Both studies demonstrated declining performance with increasing distance, poorer performance with open than closed forms, poorest performance along the vertical axis, and no major interaction of these factors with age. Greater “flattening” of the visual field was found in Study 2 than in Study 1 for all age groups. The results indicate that the parafoveal visual field is elliptical and that more difficult tasks accentuate this asymmetry. This effect of task demands on the relative flatness of the effective visual field cannot be interpreted on the basis of anatomical factors. The findings indicated striking developmental similarity in the effect of several variables on parafoveal processing and challenge the idea of greater tunnel vision in preschoolers than in adults. Further, the data suggest that perceptual and cognitive factors influence the size and shape of the effective visual field across the full age range studied.     

The Impact of Gender and Setting on Perceptions of Others' Ethics

In this article we explore how differences in gender and setting affect individuals' perceptions of others' ethics. We examine 4 hypotheses: first, that men would be perceived as more utilitarian in their ethics and women would be perceived as more formalist; second, individuals would be perceived to be more utilitarian in work settings than in nonwork settings; third, women would be more accurate in their perceptions of others' ethics; fourth, both men and women would be more accurate in their perceptions of women's ethics. Results strongly support the first, refute the second, modestly support the third, and support the fourth. Overall, the data suggest that men and women share very similar perceptions of own-gender and other-gender ethics. However, these shared perceptions are often quite inaccurate.     

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.     

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.     

Position reversal training in the virginia opossum: Evidence for the acquisition of a learning set

To obtain an estimate of the learning ability of opossums, five tame ones were trained on a series of position reversals to a criterion. With 4 trials per day there was no consistent improvement over a series of 15 reversals. When each daily session was increased to as many trials as needed to reach criterion, errors dropped sharply, indicating the formation of a position learning set. Upon return to 4 trials per day, 3 of 4 animals continued to perform with few errors, showing transfer of learning set. Opossums do more poorly than rats on this task, which is in agreement with the relative phyletic level of the two species.     

A developmental study of the effect of familiarity on short-term visual memory

An attempt was made to specify whether previously reported limitations on young children's full-report capacity lay in a smaller amount of available information, in a shorter trace duration of information in visual information storage (VIS), or in poorer coding of information into permanent storage. Five- and 8-year-olds and adults were shown an eight-item array of figures. followed at varying intervals by an indicator signaling the subject to report the figure to which the indicator had pointed. The effects of three levels of familiarity or “labelability” were examined. While no age differences were revealed in amount of information available nor in the trace duration of information in VIS, strong age differences emerged in coding of information into permanent storage. Data on latency to verbal labeling and familiarity suggested that verbal labeling could not account for the age trends. Rather, the differences seemed to lie in the use of organized visual coding and rehearsal strategies by adults and their relative lack of use by children.     

Visuospatial Neglect: The Ultimate Deconstruction?

Unilateral visuospatial neglect is now widely acknowledged to be a highly heterogeneous condition: The overt manifestations of visual neglect can vary as a function of task, spatial domain, and mode of response (at least). Double dissociations (sometimes of the strong form) have already been reported between most of the components of what was originally thought to be a relatively stable construct within the visual modality. Nonetheless, throughout successive fractionations of neglect, reported cases of bidirectional task-specific neglect after unilateral brain damage are rare. We now report two such cases. After right hemisphere stroke, the first patient reliably showed severe left neglect on cancellation but right neglect on line bisection. After left hemisphere stroke, the second case showed right neglect on cancellation but left neglect on line bisection. Extensive investigation of case 1 confirmed our previous conjecture that the crucial distinction between these tasks lies in the presence or the absence of an overt target. In contrast to cancellation, line bisection demands the internal computation of the location of the “target” (the midpoint), followed by executing a motor response toward the precise location of that “imaginary” midpoint. The relative attentional and premotor contributions of the intact and damaged hemispheres to these forms of bidirectional neglect are also assessed.