Spatial frequencies and the cerebral hemispheres: contrast sensitivity, visible persistence, and letter classification

The hypothesis that the two cerebral hemispheres are specialized for processing different visual spatial frequencies was investigated in three experiments. No differences between the left and right visual fields were found for: (1) contrast-sensitivity functions measured binocularly with vertical gratings ranging from 0.5 to 12 cycles per degree (cpd); (2) visible persistence durations for 1- and 10-cpd gratings measured with a stimulus alternation method; and (3) accuracy (d') and reaction times to correctly identify digitally filtered letters as targets (L or H) or nontargets (T or F). One significant difference, however, was found: In Experiment 3, a higher decision criterion (beta) was used when filtered letters were identified in the right visual field than when they were identified in the left. The letters were filtered with annular, 1-octave band-pass filters with center spatial frequencies of 1, 2, 4, 8, and 16 cpd. Combining four center frequencies with three letter sizes (0.5 degrees, 1 degree, and 2 degrees high) made some stimuli equivalent in distal spatial frequency (cycles per object) and some equivalent in proximal spatial frequency (cycles per degree). The effective stimulus in the third experiment seemed to be proximal spatial frequency (cycles per degree) not distal (cycles per object). We conclude that each cerebral hemisphere processes visual spatial frequency information with equal accuracy but that different decision rules are used.     

Perirhinal cortex lesions impair context aversion learning

Rats with perirhinal cortex lesions were compared with sham controls on a conditional discrimination in which saccharin was paired with LiCl in context 1, but paired with saline in context 2. Perirhinal-lesioned rats were slightly slower to acquire the discrimination but reached control levels by the end of acquisition. Both groups showed transfer to familiar tap water, consuming less in context 1 than in context 2. Unlike sham rats, perirhinal rats failed to show an aversion to context 1 on a place choice test. These data provide neuroanatomical support for the postulated difference between Pavlovian conditioning and conditional learning.     

The choice of constraints in correspondence analysis

A discussion of alternative constraint systems has been lacking in the literature on correspondence analysis and related techniques. This paper reiterates earlier results that an explicit choice of constraints has to be made which can have important effects on the resulting scores. The paper also presents new results on dealing with missing data and probabilistic category assignment.I am most grateful to the following for their helpful comments. Arto Demirjian, Michael Greenacre, Michael Healy, Shizuhiko Nishisato, Roderick Mcdonald, and several anonymous referees.     

Optimizing treatment of schizophrenia. Enhancing affective/cognitive and depressive functioning

Recognition and treatment of schizophrenia has largely focused on positive symptoms of the disorder, such as delusions, hallucinations, and disorganization. However, other important symptoms, such as depression, cognition, and social functioning, have not received comparable attention. Fifty percent of schizophrenic patients suffer from comorbid depression, which is a major risk factor for suicide in this population, while 10% to 25% suffer from comorbid obsessive-compulsive disorder. Cognitive deficits commonly observed in patients with schizophrenia include problems with concentration, attention, and memory, as well as problem-solving and verbal skills. These deficits are observed at early stages of the illness and can predict deficits in functional capabilities, such as occupational and social skills, educational attainment, and the ability to live independently. The severity of such impairments affects all patient in this population, including up to 10% of patients working full time and up to one third of those working part time. In light of the debilitating effects of depression, cognitive impairment, and other aspects of affective functioning on the quality of life of patients with schizophrenia, physicians need to partner with their patients to address these concerns and determine an appropriate treatment regimen. This can be done with simple functional-based cognitive questioning, the use of evidence-based psychosocial practices, and psychoeducation on the many pharmacotherapeutic options. It is recommended that depressive or suicidal symptoms of schizophrenia be treated with an antidepressant or mood stabilizer only if the symptoms have not subsided after treatment of the psychosis with an atypical antipsychotic. Additionally, relative to older medications, atypicals have demonstrated benefit in improving some of the cognitive impairments.     

Chaos,danger, and maternal parenting in families: Links with adolescent adjustment in low‐ and middle‐income countries

The current longitudinal study is the first comparative investigation across low‐ and middle‐income countries (LMICs) to test the hypothesis that harsher and less affectionate maternal parenting (child age 14 years, on average) statistically mediates the prediction from prior household chaos and neighborhood danger (at 13 years) to subsequent adolescent maladjustment (externalizing, internalizing, and school performance problems at 15 years). The sample included 511 urban families in six LMICs: China, Colombia, Jordan, Kenya, the Philippines, and Thailand. Multigroup structural equation modeling showed consistent associations between chaos, danger, affectionate and harsh parenting, and adolescent adjustment problems. There was some support for the hypothesis, with nearly all countries showing a modest indirect effect of maternal hostility (but not affection) for adolescent externalizing, internalizing, and scholastic problems. Results provide further evidence that chaotic home and dangerous neighborhood environments increase risk for adolescent maladjustment in LMIC contexts, via harsher maternal parenting.     

Giving and sharing in the computer‐mediated economy

The paper examines how digital technology mediates the behaviour of consumers in three online systems that facilitate offline gift giving and sharing (Freecycle, Couchsurfing, and Landshare). Findings derived from a netnography and depth interviews reveal how technology is used to enact and influence the management of identity, partner selection, ritual normalisation, and negotiation of property rights. The findings have significant implications for the design and management of systems that encourage non‐monetary forms of collaborative consumption. Copyright © 2014 John Wiley & Sons, Ltd.