Working memory impairments in schizophrenia: a meta-analysis

Working memory (WM) deficit is a cardinal cognitive symptom of schizophrenia, but the differences among the tasks and measures used to assess WM make it difficult to compare across studies. The authors conducted a meta-analytic review to address 3 major questions: (a) Do patients with schizophrenia show WM deficits across diverse methodology; (b) Is WM deficit supramodal; and (c) Does the WM deficit worsen with longer delays? The results indicate that significant WM deficit was present in schizophrenia patients in all modalities examined. Increasing delay beyond 1 s did not influence the performance difference between schizophrenia patients and healthy control participants in WM. These results suggest that WM deficit in schizophrenia is modality independent and that encoding and/or early part of maintenance may be problematic.     

The multiple neural networks of familiarity: A meta-analysis of functional imaging studies

Recent research has demonstrated the critical role of the feeling of familiarity in recognition memory. Various neuroimaging paradigms have been developed to identify the brain regions that sustain the processing of familiarity; however, there is still considerable controversy about the functional significance of each brain region implicated in familiarity-based retrieval. Here, we focused on the differences between paradigms that assess familiarity, with or without the encoding phase. We used the activation likelihood estimation (ALE) algorithm to conduct a whole-brain meta-analysis of neuroimaging studies that involved a familiarity task. Sixty-nine studies, performed in healthy subjects to determine the specific functions of the identified regions in familiarity processing, were finally selected. Distinct subanalyses were performed according to the experimental procedures used in the original studies. The ALE clusters that were highlighted revealed common activations for paradigms with and without encoding in the prefrontal cortex and in the parietal cortex. Additionally, supplementary activations related to specific familiarity (i.e., without the encoding phase) were observed in the limbic system (i.e., the amygdala, hippocampus, cingulate cortex, and insula) and in the associative sensory areas. The differences in the reported findings for different procedures are possibly due to differences in the concept of familiarity. To aid the exploration of the neural correlates of familiarity in future studies, the strengths and weaknesses of these experimental procedures are critically discussed.     

Comorbidity in schizophrenia: A prognostic study of personality disorders in recovered and non-recovered schizophrenia patients

Symptoms and outcome in schizophrenia are heterogeneous. Part of the variation in outcome might be due to the coexistence of other forms of psychopathology. In the present study the prevalence of personality disorders in a group of recovered and non-recovered schizophrenia patients was focused to examine the prognostic implications of comorbidity for the outcome of the disorder. The results showed no significant differences in prevalence of personality disorders in the two groups at first admission to the hospital, but the difference at the time of interview was close to significance. Emotional and conduct difficulties in adolescence were significantly more prevalent in the non-recovered group. Schizoid features and emotional and conduct disorders in childhood were also more often reported among the non-recovered subjects. The results confirm that comorbidity contributes to the variation in outcome for schizophrenia patients, but does not confirm its prognostic significance.     

Social networks and the treatment of schizophrenia

The importance of social network relations to the clinical status of schizophrenic patients is documented. The author notes that recent innovative clinical treatment programs incorporate social network concepts, although not always using such theoretical concepts. The importance of social network concepts in treatment and rehabilitation is noted.     

Dysexecutive syndrome in schizophrenia: A cross-cultural comparison between Japanese and British patients

This study tested the hypothesis that the dysexecutive syndrome of schizophrenia is impervious to cultural differences. 18 Japanese and 22 British patients and 14 Japanese and 19 British control subjects were compared on the BADS (Behavioural Assessment of Dysexecutive Syndrome), a comprehensive neuropsychological assessment battery, designed for 'ecological validity', and other measures of frontal executive functions (EFs). Both cultural groups of schizophrenic patients showed equally severe impairment in most executive tests including the BADS (verbal fluency and intelligence were less impaired). Irrespective of cultural origin, similar neuropsychological deficits were found in patients with minimal intellectual deterioration. Our study suggests that socio-cultural background does not affect the dysexecutive profile of schizophrenia very much, and that neuropsychological assessment may possibly provide added clinical information relevant to the management and rehabilitation of schizophrenic patients across different cultures.     

Word and letter string processing networks in schizophrenia: evidence for anomalies and compensation

Imaging studies show that in normal language correlated activity between anterior and posterior brain regions increases as the linguistic and semantic content (i.e., from false fonts, letter strings, pseudo words, to words) of stimuli increase. In schizophrenia however, disrupted functional connectivity between frontal and posterior brain regions has been frequently reported and these disruptions may change the nature of language organization. We characterized basic linguistic operations in word and letter string processing in a region-of-interest network using structural equation modeling (SEM). Healthy volunteers and volunteers with schizophrenia performed an fMRI one-back matching task with real words and consonant letter strings. We hypothesized that left hemisphere network dysfunction in schizophrenia would be present during processes dealing with linguistic/semantic content. The modeling results suggest aberrant left hemisphere function in schizophrenia, even in tasks requiring minimal access to language. Alternative mechanisms included increases in right hemisphere involvement and increased top-down influence from frontal to posterior regions.     

Impulsivity in schizophrenia: A comprehensive update

Impulsivity has been repeatedly identified as a major problem in schizophrenia. The literature revealed several ways of defining and conceptualizing impulsivity as well as a variety of measures and an analysis of the consequences of impulsivity. Thus, we review the lack of agreement in the conceptualization and measurement of impulsivity. We also review the latest evidence that impulsivity may have an important role in the etiology of substance use, aggression, violence, and suicide in schizophrenia. In addition, we outline the recent findings in neuroimaging research to elucidating the neurobiological deficits underlying pathological impulsivity in schizophrenia.     

Gender differences in burnout: A meta-analysis

The literature on male-female differences in burnout has produced inconsistent results regarding the strength and direction of this relationship. Lack of clarity on gender differences in organizationally relevant phenomena, such as work burnout, frequently generates ungrounded speculations that may (mis)inform organizational decisions. To address this issue, we conducted a meta-analysis of the relationship between gender and burnout using 409 effect sizes from 183 studies. Results challenge the commonly help belief that female employees are more likely to experience burnout than male employees, revealing instead that women are slightly more emotionally exhausted than men (δ = .10), while men are somewhat more depersonalized than women (δ = −.19). Although these effects are small, they are practically noteworthy when translated into a percent overlap statistic. Moderator analyses further revealed some intriguing nuances to the general trends, such as larger gender differences in the USA compared to the EU. In contrast, gender differences did not vary significantly in male-typed vs. female-typed occupations. Our analyses also suggest discontinuation of the use of overall burnout measures because they are highly consistent with the emotional exhaustion dimension of burnout only.     

Gender differences in rumination: A meta-analysis

Starting in adolescence and continuing through adulthood, women are twice as likely as men to experience depression. According to the response styles theory (RST), gender differences in depression result, in part, from women’s tendency to ruminate more than men. A meta-analysis was performed to evaluate gender differences in rumination in adults (k = 59; N = 14,321); additionally, an analysis of subtypes of rumination – brooding and reflection – was conducted (k = 23). Fixed effects analyses indicated that women scored higher than men in rumination (d = .24, p < .01, SEd = .02), brooding (d = .19, p < .01, SEd = .03) and reflection (d = .17, p < .01, SEd = .03); there was no evidence of heterogeneity or publication bias across studies for these effect sizes. Although statistically significant, the effect sizes for gender differences in rumination were small in magnitude. Results are discussed with respect to the RST and gender differences in depression.     

Organizational identification: A meta-analysis

The last two decades have witnessed a surge in interest in research on organizational identification (OI). This paper presents a comprehensive meta-analysis of this research (k = 96). Results indicate that (a) OI is correlated with a wide range of work-related attitudes, behaviors, and context variables, (b) OI is empirically distinct from its closest conceptual neighbor, attitudinal organizational commitment (AOC), and (c) the two most common OI measures (the Mael scale and the Organizational Identification Questionnaire) produce very different results. It is argued that OI scales, especially the Mael scale, may be preferable over AOC scales for studies aimed at explaining, and partly also for studies aimed at predicting, work behavior.     

Context effects in lexical access: A meta-analysis

The modularity hypothesis was evaluated in this review of 25 studies that investigated context effects in early lexical processing. Selection criteria restricted the review to priming studies and to studies that presented the target word before or at the end of the prime word. Meta-analysis was used to provide summary information about the 17 studies in the review for which effect sizes could be calculated. Overall, the analysis revealed a small effect of context on lexical access. Results provide a disconfirmation of the modularity hypothesis; although multiple interpretations of a word were sometimes accessed, the contextually appropriate interpretation was consistently more strongly activated. The lack of significant heterogeneity of variance suggests that the variability observed across studies was due to sampling error; however, task, timing of target presentation, meaning frequency, type of target, and type of context were identified as potential moderator variables.     

Schizotypy in relatives of patients with schizophrenia

Previous studies indicate that relatives of patients with schizophrenia are more likely to present characteristics of schizotypal personality than the general population. Few transcultural studies of schizotypy have been carried out. Most instruments constructed to measure schizotypy have been applied in specific cultures; conceivably, in other populations its components may be distributed in different ways. These cultural differences may affect the relations between schizotypy and schizophrenia. The objective of this study is to obtain data on schizotypy in relatives of patients with schizophrenia and relatives of patients with other disorders in a Latin American rural population. The results suggest that cultural factors must be taken into account in order to establish the relationship between schizotypy and schizophrenia.     

Mind wandering in schizophrenia: A thought-sampling study

Mind wandering has consistently been associated with impairments in cognition, emotion and daily performance. However, few experimental studies on mind wandering have been conducted in individuals with schizophrenia. The present study aimed to examine mind wandering in schizophrenia patients with a thought-sampling experiment embedded in a rapid go/no-go task and the relationship between the frequency of mind wandering and psychotic symptoms. Fifty-eight schizophrenia patients and 56 matched healthy controls were recruited and engaged in a task that assessed mind wandering. The results showed that schizophrenia patients (1.4%) reported less frequent mind wandering than healthy controls (5.8%). Moreover, there was no significant correlation between the frequency of mind wandering and psychotic symptoms in schizophrenia patients. Further studies in different stages of schizophrenia and in patients with more severe psychotic symptoms are needed to demonstrate a more comprehensive picture of mind wandering in schizophrenia.     

Eye movement dysfunction in first-degree relatives of patients with schizophrenia: A meta-analytic evaluation of candidate endophenotypes

Several forms of eye movement dysfunction (EMD) are regarded as promising candidate endophenotypes of schizophrenia. Discrepancies in individual study results have led to inconsistent conclusions regarding particular aspects of EMD in relatives of schizophrenia patients. To quantitatively evaluate and compare the candidacy of smooth pursuit, saccade and fixation deficits in first-degree biological relatives, we conducted a set of meta-analytic investigations. Among 18 measures of EMD, memory-guided saccade accuracy and error rate, global smooth pursuit dysfunction, intrusive saccades during fixation, antisaccade error rate and smooth pursuit closed-loop gain emerged as best differentiating relatives from controls (standardized mean differences ranged from .46 to .66), with no significant differences among these measures. Anticipatory saccades, but no other smooth pursuit component measures were also increased in relatives. Visually-guided reflexive saccades were largely normal. Moderator analyses examining design characteristics revealed few variables affecting the magnitude of the meta-analytically observed effects. Moderate effect sizes of relatives v. controls in selective aspects of EMD supports their endophenotype potential. Future work should focus on facilitating endophenotype utility through attention to heterogeneity of EMD performance, relationships among forms of EMD, and application in molecular genetics studies.     

多媒体学习中线索效应的元分析

作为多媒体学习中一种重要的指导性教学设计形式, 线索能否引导学习者的注意并促进学习效果, 目前结论尚不一致。研究运用元分析技术, 分别以保持测验、迁移测验的成绩作为学习效果的结果变量, 以线索区的注视时间、注视次数作为注意引导的结果变量, 探讨多媒体环境中的线索对学习效果和注意引导的影响, 并通过调节效应检验考察线索效应的边界条件。采用严格标准进行文献检索和筛选后, 共获取43篇符合元分析的文献。在保持测验成绩和迁移测验成绩上, 分别生成了44个(3910人)和41个(3906人)独立效应量; 在对线索区的注视时间和注视次数上, 分别生成了14个(938人)和11个(816人)独立效应量。结果发现, 线索的加入显著提高了保持测验成绩(g = 0.53)和迁移测验成绩(g = 0.36), 同时也增加了学习者对线索区的注视时间(g = 0.50)和注视次数(g = 0.70)。调节效应分析发现：在保持测验成绩上, 静态学习材料、陈述性知识、理工科条件下的线索效应分别高于动态学习材料、程序性知识和文科; 在迁移测验成绩上, 时空线索、静态学习材料、陈述性知识条件下的线索效应分别高于物理线索、动态学习材料和程序性知识; 而在眼动指标上, 线索对注意的引导主要受线索类型的调节, 物理线索条件下学习者对线索区的注视时间和注视次数均高于时空线索。结论认为, 线索的加入确实促进了学习者对学习材料的识记和理解效果, 同时也引导了学习者的注意分配; 但线索效应一定程度上受线索类型、学习材料动态性、知识类型、学科属性等因素的调节。未来研究需进一步考察线索效应的其他边界条件。     

Mood state-dependent memory: A meta-analysis

Abstract

Published research (from 1975 to 1985) on mood state-dependent memory is examined with meta-analytical techniques. Research on mood-congruent memory is also examined when relevant to a mood state-dependent hypothesis. Effect sizes are shown to vary systematically as a function of several variables. Mood state-dependent memory is more often observed with positive rather then negative moods. Also, the strongest effects were found in studies that: (a) used real-life events as the material to be retrieved; (b) selected contrasting moods, i.e. positive vs. negative rather than simply positive or negative vs. neutral moods; (c) used mood states that were specific to the items; (d) lasted longer; (e) had smaller sample size; (f) selected subjects according to direct mood criteria; (g) paid subjects for their participation in the experiment; and (h) used adults rather than students or children. Present findings are consistent with other reviews and with common theories of mood state-dependent memory. However, the findings also highlight the importance of methodological variables, more particularly variables related to the degree of commitment of subjects to the experiment, and variables related to the nature and complexity of the experimental environment. Two dimensions, realism of the experiment and demand sensitivity, compete to account for the methodological results and for some of the theoretical results.     

Functional neuroanatomy of emotions: A meta-analysis

The application of functional neuroimaging to the study of human emotion has yielded valuable data; however, the conclusions that may be drawn from any one study are limited. We applied novel statistical techniques to the meta-analysis of 106 PET and fMRI studies of human emotion and tested predictions made by key neuroscientific models. The results demonstrated partial support for asymmetry accounts. Greater left-sided activity was observed for approach emotions, whereas neural activity associated with negative/withdrawal emotions was symmetrical. Support was also found for affect program emotion accounts. The activation distributions associated with fear, disgust, and anger differed significantly. These emotions were most consistently associated in activity in regions associated with selective processing deficits when damaged: the amygdala, the insula and globus pallidus, and the lateral orbitofrontal cortex, respectively. In contrast, the distributions for happiness and sadness did not differ. These findings are considered in the context of conceptualizations of the neural correlates of human emotion.     

The overjustification effect: A meta-analysis

This article reports the results of a meta-analysis using 50 experimental studies (256 effect sizes) of the overjustification effect. In general, we found support for the effect across age, dependent measure, and design type in specific situations where it is predicted to occur. Findings are less supportive of the theory for situations where there should be no difference between experimental and control groups (e. g. non-contingent or unexpected reward). Suggestions for future research are made.     

Emotion and culture: A meta-analysis

A meta-analysis of 190 cross-cultural emotion studies, published between 1967 and 2000, was performed to examine (1) to what extent reported cross-cultural differences in emotion variables could be regarded as valid (substantive factors) or as method-related (statistical artefacts, cultural bias), and (2) which country characteristics could explain valid cross-cultural differences in emotion. The relative contribution of substantive and method-related factors at sample, study, and country level was investigated and country-level explanations for differences in emotions were tested. Results indicate that a correction for statistical artefacts and method-related factors reduced the observed cross-cultural effect sizes considerably. After controlling for valence (positive vs. negative emotions) and kind of study (self-report vs. recognition studies), the remaining cross-cultural variance was associated with subsistence mode, political system, values, and religiosity. Values explained more variance than did ecological or sociopolitical variables. It was concluded that both method-related factors (13.8% of variance explained) and culture-level factors (27.9% of variance explained) underlie observed cross-cultural differences.