Motion perception and aging.

The authors used a correlated motion paradigm to investigate the effects of aging and gender on motion sensitivity. In 2 experiments with a total of 50 elderly and 50 young subjects, motion thresholds were significantly higher for elderly women. The correlated motion signal, which was embedded in random motion, may have been coherent to subjects in much the same way a form is in Witkin's Embedded Figures Test (EFT). In Experiment 2, EFT scores were obtained. A significant positive relationship between motion thresholds and EFT performance was found within each age group. Although gender-related perceptual style differences may contribute to motion perception effects, the authors argue that a common neural factor contributes to performance on both the EFT and the correlated motion task.     

Introduction to two-dimensional Fourier analysis

The application of two-dimensional Fourier analysis provides new avenues for research in visual perception. This tutorial serves as an introduction to some of the methods used in two-dimensional Fourier analysis and an introduction to two-dimensional image processing in general.     

Enhanced right hemisphere activation in the mathematically precocious: A preliminary EEG investigation

A preliminary electroencephalographic (EEG) investigation was conducted to determine if the pattern of hemispheric activation in mathematically precocious youth differs from that of average math ability subjects. Alpha activity at four brain sites (frontal, temporal, parietal, and occipital lobes) over the left and right cerebral hemispheres (LH/RH) was monitored while 12- to 14-year-old, right-handed males: (a) looked at a blank slide (baseline condition), (b) judged which of two chimeric faces was "happier," and (c) determined if a word was a noun or a verb. At baseline, the LH of the precocious group was found to be more active at all four brain sites relative to that of the average ability group. During chimeric face processing, the gifted subjects exhibited a significant reduction in alpha power over the RH, primarily at the temporal lobe, while no such alpha suppression was observed in the average ability subjects. For noun/verb determinations, no significant alpha power reductions were obtained for either group. These electrophysiological data generally corroborate the behavioral findings of O'Boyle and Benbow (1990a) and support their contention that enhanced RH involvement during cognitive processing may be a correlate of mathematical precocity. Moreover, the pattern of activation observed across tasks suggests that the ability to effectively coordinate LH and RH processing resources at an early age may be linked to intellectual giftedness.     

Schizophrenia and deliberate self-harm: a systematic review of risk factors

Deliberate self-harm (DSH) is a strong predictor of suicide in schizophrenia. The aim of this review was to identify risk factors for DSH in schizophrenia. This systematic review of the international literature examined cohort and case-control studies of patients with schizophrenia or related diagnoses that reported DSH as an outcome. Studies were identified by searching electronic databases and reference lists, and by consulting international experts. Fourteen studies met the eligibility criteria. Of the 29 variables examined by two or more studies, five (past or recent suicidal ideation, previous DSH, past depressive episode, drug abuse or dependence, and higher mean number of psychiatric admissions) were associated with an increased risk of DSH, and one (unemployment) was associated with a reduced risk. Schizophrenic patients with these risk factors need careful follow-up and monitoring, with treatment of any associated comorbid depression or drug abuse. Large, prospective studies of DSH in schizophrenia are needed to further define risk factors and to build on the findings of this review.     

Perception of place-of-articulation information in natural speech by monkeys versus humans

Four monkeys and 6 humans representing five different native languages were compared in the ability to categorize natural CV tokens of /b/ versus /d/ produced by 4 talkers of American English (2 male, 2 female) in four vowel contexts (/i, e, a, u/). A two-choice "left/right" procedure was used in which both percentage correct and response time data were compared between species. Both measures indicated striking context effects for monkeys, in that they performed better for the back vowels /a/ and /u/ than for the front vowels /i/ and /e/. Humans showed no context effects for the percentage correct measure, but their response times showed an enhancement for the /i/ vowel, in contrast with monkeys. Results suggest that monkey perception of place of articulation is more dependent than human perception on the direction of the F2 onset transitions of syllables, since back-vowel F2s differentiate /b/ and /d/ more distinctively. Although monkeys do not provide an accurate model of the adult human in place perception, they may be able to model the preverbal human infant before it learns a more speech-specific strategy of place information extraction.     

Representation of two geometric features of the environment in the domestic chick (<Emphasis Type="Italic">Gallus gallus</Emphasis>)

We report experiments based on a novel test in domestic chicks (Gallus gallus), designed to examine the encoding of two different geometric features of an enclosed environment: relative lengths of the walls and amplitude of the corners. Chicks were trained to search for a food reward located in one corner of a parallelogram-shaped enclosure. Between trials, chicks were passively disoriented and the enclosure was rotated, making reorientation possible only on the basis of the internal spatial structure of the enclosure. In order to reorient, chicks could rely on two sources of information: the relative lengths of the walls of the enclosure (associated to their left-right sense order) and the angles subtended by walls at corners. Chicks learned the task choosing equally often the reinforced corner and its rotational equivalent. Results of tests carried out in novel enclosures, the shapes of which were chosen ad hoc (1) to induce reorientation based only on the ratio of walls lengths plus sense (rectangular enclosure), or (2) to induce reorientation based only on corner angles (rhombus-shaped enclosure), suggested that chicks encoded both features of the environment. In a third test, in which chicks faced a conflict between these geometric features (mirror parallelogram-shaped enclosure), reorientation seemed to depend on the salience of corner angles. These results shed light on the elements of the environmental geometry which control spatial reorientation, and broaden the knowledge on the geometric representation of space in animals.     

Knowing in advance: the impact of prior event information on memory and event knowledge

We examined the influence of newly acquired information on children's memory and general representation of a personally experienced event. Thirty-five children between the ages of 5 and 7 years participated in the novel event (Visiting the Pirate). The day before participating, children were: (1) provided with new information specific to the up-coming event; (2) engaged in a discussion generally related to the event topic based on existing knowledge; or (3) discussed an unrelated topic. Advance information specific to the event led to better recall and, in particular, to better integration of the experience into a general event representation both soon after the event and at a follow-up interview 4 months later, whereas general discussion of the topic without the event specific information neither enhanced memory reports nor facilitated the integration of event information. Providing information in advance can have significant effects on memory and knowledge acquisition although many variables, including those relating to the specific content of the information, will affect this relation.     

Change in self-stigma among persons with schizophrenia enrolled in rehabilitation: associations with self-esteem and positive and emotional discomfort symptoms

Self-stigma is a barrier to the recovery of persons with schizophrenia. Little is known about whether participation in rehabilitation is naturalistically linked to declines in self-stigma, and if so, what is correlated with changes in self-stigma. The current study examined in a quasi-experimental design the rate of change of self-stigma and whether changes were correlated with self-esteem, positive symptoms, and emotional distress for persons enrolled in rehabilitation. Symptoms were measured using the Positive and Negative Syndrome Scale (Kay, Fizsbein, & Opler, 1987), self-esteem was measured with the Multidimensional Self-Esteem Inventory (Lysaker, Ringer, & Davis, 2008), and self-stigma was assessed using the Internalized Stigma of Mental Illness Scale (Ritsher, Otilingam, & Grajales, 2003). Seventy persons with schizophrenia who worked at least one month in a vocational rehabilitation program were assessed on all measures at baseline and five months later. Results indicated a 25% decrease in self-stigma for 38% of the sample; these individuals tended to have less emotional distress both at baseline and follow-up, and had higher levels of self-esteem at follow-up. No differences in positive symptoms were found for groups whose stigma did or did not decrease. Results suggest that decreases in self-stigma may be correlated with increased self-esteem, while higher levels of emotional distress may be a barrier to stigma reduction.