The role of edges in object recognition by pigeons

In three experiments, we explored how pigeons use edges, corresponding to orientation and depth discontinuities, in visual recognition tasks. In experiment 1, we compared the pigeon's ability to recognize line drawings of four different geons when trained with shaded images. The birds were trained with either a single view or five different views of each object. Because the five training views had markedly different appearances and locations of shaded surfaces, reflectance edges, etc, the pigeons might have been expected to rely more on the orientation and depth discontinuities that were preserved over rotation and in the line drawings. In neither condition, however, was there any transfer from the rendered images to the outline drawings. In experiment 2, some pigeons were trained with line drawings and shaded images of the same objects associated with the same response (consistent condition), whereas other pigeons were trained with a line drawing and a shaded image of two different objects associated with the same response (inconsistent condition). If the pigeons perceived any correspondence between the stimulus types, then birds in the consistent condition should have learned the discrimination more quickly than birds in the inconsistent condition. But, there was no difference in performance between birds in the consistent and inconsistent conditions. In experiment 3, we explored pigeons' processing of edges by comparing their discrimination of shaded images or line drawings of four objects. Once trained, the pigeons were tested with planar rotations of those objects. The pigeons exhibited different patterns of generalization depending on whether they were trained with line drawings or shaded images. The results of these three experiments suggest that pigeons may place greater importance on surface features indicating materials, such as food or water. Such substances do not have definite boundaries cued by edges which are thought to be central to human recognition.     

Suicide compared to other causes of mortality in physicians

Physicians frequently are early adopters of healthy behaviors based on their knowledge and economic resources. The mortality patterns of physicians in the United States, particularly suicide, have not been rigorously described for over a decade. Previous studies have shown lower all-cause mortality among physicians yet reported conflicting results about cause-specific mortality such as suicide. In this study, we compared all-cause and cause-specific mortality in a sample of physicians to the age-gender matched general U.S. population from 1948 through 1998. We also compared the mortality experience across medical specialties. The risk of all-cause mortality was 56% lower than expected in men, and 26% lower in women, compared to the general population. Standardized mortality ratios (SMRs) were markedly lower for diseases strongly linked to smoking, e.g., cardiovascular diseases, respiratory diseases, and lung cancer. Suicide was the only cause of death where risk was greater than the general population. Overall, we found that physicians are at substantially lower risk of dying compared to the general population for all causes of death except suicide. The findings for suicide are strikingly different than other causes of death and should provide impetus for new research on the mental health of physicians.     

Hallucinations in schizophrenia, sensory impairment, and brain disease: a unifying model

Based on recent insight into the thalamocortical system and its role in perception and conscious experience, a unified pathophysiological framework for hallucinations in neurological and psychiatric conditions is proposed, which integrates previously unrelated neurobiological and psychological findings. Gamma-frequency rhythms of discharge activity from thalamic and cortical neurons are facilitated by cholinergic arousal and resonate in networks of thalamocortical circuits, thereby transiently forming assemblies of coherent gamma oscillations under constraints of afferent sensory input and prefrontal attentional mechanisms. If perception is based on synchronisation of intrinsic gamma activity in the thalamocortical system, then sensory input to specific thalamic nuclei may merely play a constraining role. Hallucinations can be regarded as underconstrained perceptions that arise when the impact of sensory input on activation of thalamocortical circuits and synchronisation of thalamocortical gamma activity is reduced. In conditions that are accompanied by hallucinations, factors such as cortical hyperexcitability, cortical attentional mechanisms, hyperarousal, increased noise in specific thalamic nuclei, and random sensory input to specific thalamic nuclei may, to a varying degree, contribute to underconstrained activation of thalamocortical circuits. The reticular thalamic nucleus plays an important role in suppressing random activity of relay cells in specific thalamic nuclei, and its dysfunction may be implicated in the biological vulnerability to hallucinations in schizophrenia. Combined with general activation during cholinergic arousal, this leads to excessive disinhibition in specific thalamic nuclei, which may allow cortical attentional mechanisms to recruit thalamic relay cells into resonant assemblies of gamma oscillations, regardless of their actual sensory input, thereby producing an underconstrained perceptual experience.     

Amplitude scaling in a bimanual circle-drawing task: pattern switching and end-effector variability

The authors manipulated movement amplitude in a bimanual circle-tracing task performed by 11 participants. With pacing frequency fixed, the systematic increase and decrease of circle diameter within a trial induced phase transitions from the asymmetric (33% of trials) to the symmetric bimanual circle-tracing pattern; the transitions resulted from a loss of stability in the asymmetric pattern. Tracing frequency varied inversely with circle diameter so that end-effector variability was minimized in a set of self-paced trials in which the circle diameter in a trial was fixed. In the amplitude-scaling trials, end-effector variability varied directly with circle diameter, a consistent speed-accuracy tradeoff. The results support the conclusion that movement amplitude is a nonspecific control parameter. The findings are discussed with reference to several factors, e.g., tactile feedback, the recruitment and suppression of biomechanical degrees of freedom, and the role those factors may play in stabilizing bimanual coordination patterns     

Bullying and victimization: prevalence and relationship to gender, grade level, ethnicity, self-esteem, and depression

This study investigated the prevalence of bullying and victimization among students in grades 7 and 8. It also explored the relationship of bullying and victimization to gender, grade level, ethnicity, self-esteem, and depression. Three survey instruments were used to obtain data from a convenience sample of 454 public school students. Twenty-four percent reported bullying involvement. Chi-square tests indicated significantly more male than female bullying involvement, seventh graders reported more involvement than did eighth graders, and there were no statistically significant differences in involvement based on ethnicity. Both bullies and victims manifested higher levels of depression than did students who were neither bullies nor victims. There were no significant differences between groups in terms of self-esteem.     

Four studies extending the utility of the Schwartz Outcome Scale (SOS-10)

The Schwartz Outcome Scale (SOS-10; Blais et al., 1999) is a brief, cost free, and easy to administer assessment device designed to measure a broad domain of psychological health. The 4 studies using the SOS-10 reported here extend the initial reliability and validity studies beyond psychiatric patients in a hospital setting to examine (a) test-retest reliability in a college student population, (b) concurrent validity with college students using an indirect technique assessing maladjustment, (c) concurrent validity with college counseling center clients using a self-report measure of client distress, and (d) sensitivity to treatment changes with outpatient clients. These studies lend further support for using the SOS-10 as a measure of psychological well-being and as an outcome measure in varied settings.     

Decursin from Angelica gigas mitigates amnesia induced by scopolamine in mice

We previously reported that a total methanolic extract of the underground part of Angelica gigas Nakai (Umbelliferae) (here-in-after abbreviated AG) significantly inhibited acetylcholinesterase (AChE) activity. We characterized 12 coumarin derivatives including both decursin and decursinol from extracts of AG. In this study, we evaluated the anti-amnestic activity of decursin, a major coumarin constituent isolated from AG, in vivo using ICR mice with amnesia induced by scopolamine (1 mg/kg body weight, s.c.). Decursin, when administered to mice at 1 and 5 mg/kg body weight i.p., significantly ameliorated scopolamine-induced amnesia as measured in both the passive avoidance test and the Morris water maze test. Moreover, decursin significantly inhibited AChE activity by 34% in the hippocampus of treated mice. These results indicate that decursin may exert anti-amnestic activity in vivo through inhibition of AChE activity in the hippocampus.     

Evidence for a conceptual account of same-different discrimination learning in the pigeon

We trained pigeons to peck two different buttons in response to 16-iconsame arrays versus 16-icondifferent arrays. In thesame arrays, the icons were all the same as one another, whereas in thedifferent arrays, the icons were all different from one another. In Experiment 1, we upset the spatial regularities of the displays by disarranging the icons—randomly displacing each icon to reduce the degree of perceptual order. The pigeons’ discriminative performance was unaffected by disarranging. In Experiment 2, spatial regularities were disturbed by varying the rotation of the icons within a display. Again, no disruption in discriminative performance was observed. These and other findings suggest that pigeons treat the 16 icons as either the same or different despite changes in the spatial organization or orientation of the icons, thus implicating a conceptual rather than a perceptual process in same—different discrimination.     

The relations between temperament and empathy in 2-year-olds.

The role of infant and toddler temperament in the prediction of empathy in 2-year-old children was examined. Assessments of temperament included reactivity and affect observed at 4 months of age, as well as inhibition at Age 2. Empathy was measured in 2-year-old children's responses to simulations of distress performed by their mothers and by an unfamiliar person. Children showed relatively more concern for the mother's distress, but they were also responsive to unfamiliar victims. Infants who were unreactive and showed little affect also showed less empathy toward the unfamiliar adult almost 2 years later. Inhibition toward an unfamiliar adult (but not toward the mother) at 2 years of age was negatively related to empathy. Inhibited temperament may thus have a major impact on young children's empathy in unfamiliar contexts. Findings also highlight the need to consider early underarousal as another dimension of temperament that may dampen expressions of empathic concern.     

Adolescent substance use disorders: findings from a 14-year follow-up of speech/language-impaired and control children.

Intervening on the development of adolescent addiction requires an understanding of the role of precursors. In a community sample of youth with and without early childhood speech/language (S/L) impairments, 12.7% of participants had a substance use disorder (SUD). Among these participants, 42.0% met criteria for more than 1 SUD. Interestingly, rates of SUDs did not differ by S/L status. However, S/L-impaired participants did show greater psychiatric comorbidity and poorer functioning. A total of 80% of S/L participants with SUDs had a concurrent diagnosis of antisocial personality disorder, compared with 43.8% of SUDs controls. In a logistic regression analysis, we found age 5 mother-rated problem behavior scores and an interaction between S/L status and teacher-rated conduct problem scores were predictive of SUDs. High conduct scores were predictive of SUDs development among control participants but not among S/L-impaired participants. First substance use and initial SUDs symptoms suggest that a window of opportunity exists to reach these troubled young people before they spiral into addiction.