Inattentional blindness for a noxious multimodal stimulus

Previous research has shown that people can miss salient stimuli outside the focus of their attention. This phenomenon, called inattentional blindness, typically is observed when people are given a task requiring them to focus their attention on one aspect of a complex visual scene. While participants are doing this task, an unexpected stimulus appears, and participants' awareness of it is tested shortly thereafter. In the present experiments, noxious bimodal stimuli were used as a test case to measure the strength of inattentional blindness. We tested whether participants would notice a person enter a scene and scratch her fingernails down a chalkboard (thus making a sound called a "gride"). A large proportion of participants failed to detect this event even when the noxious audio associated with it was strengthened and isolated in time from surrounding noises.     

Anxiety-related differences in affective categorizations of lexical stimuli

Effects of emotional valence on attention have been shown to occur even when stimuli are presented outside awareness. The impact of negative valence on stimulus processing has been demonstrated to be particularly salient in anxiety. Therefore, it has been hypothesized that compared to nonanxious individuals, anxious individuals have an enhanced ability to detect the valence of negative stimuli. However, it remains unclear whether anxious individuals are better at identifying the valence of threatening stimuli or, rather, more likely to label ambiguous stimuli as threatening. To investigate these hypotheses, high and low anxious participants categorized lexical stimuli as "safe" or "dangerous." Stimuli were presented at durations that allowed for both conscious (unmasked) and nonconscious (masked) processing. Results show that on masked trials, anxious individuals evidenced an enhanced ability to correctly classify threatening information, whereas nonanxious participants demonstrated an enhanced ability to correctly classify neutral or positive information. Signal detection analyses indicated results were explained by a response bias, whereby anxious individuals were more likely than nonanxious individuals to categorize masked words as threatening and nonanxious individuals were more likely to categorize masked words as nonthreatening. No group differences for nonword stimuli emerged, suggesting that anxiety-related response bias tendencies are activated only after detection of a weak semantic signal.     

Is light in pictures presumed to come from the left side?

For good ecological reasons humans assume that the illumination in pictures comes from overhead rather than from below. Recent work has also raised the possibility that the preferred angle of illumination is between 20 degrees and 30 degrees to the left of vertical, although the ecological basis for that is obscure. We describe two studies of this question. In study 1, twenty subjects looked in free, unrestricted vision, at a picture of a single 'bubble' which appeared either convex if the illumination was from above, or concave if the illumination was from below. There was no evidence in study 1 that illumination from the left produced a different appearance from illumination from the right, the preferred angle of illumination being 0.5 degrees to the right of vertical. In study 2, on forty subjects, there was fast presentation (200 ms) of an array of 16 bubbles, one of which, the target, was illuminated from the opposite direction to the others, and hence 'popped out' from the display, appearing concave if the others were convex, or vice-versa. The preferred angle of illumination for detection of the target was about 14 degrees to the left of vertical in study 2. The estimates from studies 1 and 2 did not differ significantly, and when combined gave a preferred angle of 9 degrees to the left of vertical. The reasons for the seeming discrepancy between studies 1 and 2, or the smaller overall effect than that found in previous studies are not clear since the methodologies seem equivalent. In both studies 1 and 2 there was a highly significant association between the direction of spontaneous head tilt and preferred direction of illumination, and this factor has not previously been taken into account in studies of the phenomenon. Contrary to the study of Sun and Perona (1998, Nature Neuroscience 1 183-184), there was no association with handedness or other measures of functional lateralisation.     

Extensive lesions of cholinergic basal forebrain neurons do not impair spatial working memory

A recent studysuggests that lesions to all major areas of the cholinergic basal forebrain in the rat (medial septum, horizontal limb of the diagonal band of Broca, and nucleus basalis magnocellularis) impair a spatial working memory task. However, this experiment used a surgical technique that mayhave damaged cerebellar Purkinje cells. The present studytested rats with highlyselective lesions of cholinergic neurons in all major areas of the basal forebrain on a spatial working memorytask in the radial arm maze. In postoperative testing, there were no significant differences between lesion and control groups in working memory, even with a delayperiod of 8 h, with the exception of a transient impairment during the first 2 d of postoperative testing at shorter delays (0 or 2 h). This finding corroborates other results that indicate that the cholinergic basal forebrain does not playa significant role in spatial working memory. Furthermore, it underscores the presence of intact memoryfunctions after cholinergic basal forebrain damage, despite attentional impairments that follow these lesions, demonstrated in other task paradigms.     

Depression After Traumatic Brain Injury: A Review of Evidence for Clinical Heterogeneity

Depression represents a major source of disability among individuals who have suffered a traumatic brain injury (TBI), with estimates of prevalence in this population ranging over 50%. In comparison with other sequelae of TBI, depression is often poorly conceptualized and treated among acute care and rehabilitation professionals. One reason for this is the lack of clear etiological models for the development of depression following TBI. This paper argues that post-TBI depression actually represents a heterogeneous category, with multiple etiologic pathways and clinical implications. The literature in this area is reviewed, with an emphasis on an appreciation of the diversity within this clinical population. Conclusions focus on suggestions for differential diagnosis and treatment options.     

The research misconception

Recently, several researchers and philosophers argued that clinical research trials are not therapy. Their position is based on foundational research ethics documents, such as the Belmont Report, on conceptual analysis, and on the general way clinical trials are conducted. After examining and rejecting these arguments, we claim that good research is consistent with good therapy; that often trials are good therapy; and that a blanket attack on clinical trials as non-therapeutic creates a research misconception. This misconception is potentially harmful because it could weaken trial recruitment, could adversely affect funding for trials, and could overturn needed moral safeguards on therapeutic trials. Our more careful and accurate analysis of the nature of clinical trials can avoid such problems.     

Family predictors of disease management over one year in Latino and European American patients with type 2 diabetes

Family context is thought to influence chronic disease management but few studies have longitudinally examined these relationships. Research on families and chronic illness has focused almost exclusively on European American families. In this prospective study we tested a multidimensional model of family influence on disease management in type 2 diabetes in a bi-ethnic sample of European Americans and Latinos. Specifically, we tested how baseline family characteristics (structure, world view, and emotion management) predicted change in disease management over one year in 104 European American and 57 Latino patients with type 2 diabetes. We found that emotion management predicted change in disease management in both groups of patients as hypothesized, while family world view predicted change in both ethnic groups but in the predicted direction only for European Americans. Examining family context within ethnic groups is required to elucidate unique cultural patterns. Attending to culturally unique interpretations of constructs and measures is warranted. The import of family emotion management, specifically conflict resolution, in disease management deserves further study to support clinical intervention development. Examining multiple domains of family life and multidimensional health outcomes strengthens our capacity to develop theory about family contexts and individual health.     

Histidine-decarboxylase knockout mice show deficient nonreinforced episodic object memory, improved negatively reinforced water-maze performance, and increased neo- and ventro-striatal dopamine turnover

The brain's histaminergic system has been implicated in hippocampal synaptic plasticity, learning, and memory, as well as brain reward and reinforcement. Our past pharmacological and lesion studies indicated that the brain's histamine system exerts inhibitory effects on the brain's reinforcement respective reward system reciprocal to mesolimbic dopamine systems, thereby modulating learning and memory performance. Given the close functional relationship between brain reinforcement and memory processes, the total disruption of brain histamine synthesis via genetic disruption of its synthesizing enzyme, histidine decarboxylase (HDC), in the mouse might have differential effects on learning dependent on the task-inherent reinforcement contingencies. Here, we investigated the effects of an HDC gene disruption in the mouse in a nonreinforced object exploration task and a negatively reinforced water-maze task as well as on neo- and ventro-striatal dopamine systems known to be involved in brain reward and reinforcement. Histidine decarboxylase knockout (HDC-KO) mice had higher dihydrophenylacetic acid concentrations and a higher dihydrophenylacetic acid/dopamine ratio in the neostriatum. In the ventral striatum, dihydrophenylacetic acid/dopamine and 3-methoxytyramine/dopamine ratios were higher in HDC-KO mice. Furthermore, the HDC-KO mice showed improved water-maze performance during both hidden and cued platform tasks, but deficient object discrimination based on temporal relationships. Our data imply that disruption of brain histamine synthesis can have both memory promoting and suppressive effects via distinct and independent mechanisms and further indicate that these opposed effects are related to the task-inherent reinforcement contingencies.     

Judging confidence influences decision processing in comparative judgments

Current theories of confidence in human judgment assume that confidence and the decision it is based on are inextricably tied to the same process (decisional locus theories) or that confidence processing begins only once the primary decision has been completed (postdecisional locus theories). In the absence of auxiliary assumptions, however, neither class of theory permits the judgment of confidence to affect primary decision processing. In the present study, we examined the effect of rendering confidence judgments on the properties of the decision process in a sensory discrimination task. An examination of the properties of the time taken to determine confidence (i.e., the time taken to render the judgment of confidence) revealed clear evidence of postdecisional confidence processing. Concomitantly, the requirement of confidence judgments was found to substantially increase decisional response times, suggesting that some confidence processing occurs during the primary decision process. We discuss the implications of these findings for contemporary models of confidence in human judgment.     

People with Williams syndrome process faces holistically

This study compared the performance of 47 adolescents and adults with Williams syndrome to 39 age-matched controls on a face recognition task. Using the whole-part paradigm developed by Tanaka and his colleagues, we found that although performance overall was lower in the participants with Williams syndrome, both groups showed similar patterns of performance across the different conditions. Both groups performed significantly better in the whole-face than in the isolated-part test condition for upright faces, but not for inverted faces. The whole-face advantage only in the upright condition provides strong evidence that people with Williams syndrome encode and recognize faces holistically in the same way as normal controls, suggesting the use of similar underlying neurocognitive mechanisms. These findings contradict earlier reports in the literature that people with Williams syndrome process faces abnormally.