Modeling age and retest processes in longitudinal studies of cognitive abilities

Mixed effects models were used to examine the separate effects associated with age and retest on changes in various cognitive abilities. Individuals (N > 800) ranging in age from 40 to 70 years at the 1st measurement occasion were assessed with measures of memory, spatial abilities, and speed on 4 occasions. All cognitive abilities showed decline associated with increased age and improvement across the 4 measurement occasions. The age-related effects were similar across variables, but the practice effects were largest for memory and smallest for speed. When retest effects were not included in the models, the age-related effects were underestimated, with the magnitude of bias depending on the size of the ignored retest effects. It is suggested that both age and retest should be modeled simultaneously when analyzing longitudinal data because part of the change across occasions may be attributable to practice or reactive effects.     

Bilateral facilitation of motor control in chronic hemiplegia

The present study addressed the efficacy of concurrently moving both arms, with and without a load added to the uninvolved arm, in facilitating the quality of movement of the involved side in individuals with moderate, chronic hemiplegia. Six hemiplegic cerebrovascular accident (CVA) subjects with left-hemisphere lesions participated in the study. The four males and two females ranged from 46 to 77 years of age and 30–96 months post-CVA. All subjects scored at least 70% on the Fugl-Meyer test of motor function. The task was to perform discrete unilateral and bilateral elbow extensions in the horizontal plane. The movements were 45° in amplitude and were to terminate in a 10° target zone that was indicated by an illustration of a coffee mug. The instructions were to move toward the mug as smoothly as possible in a movement time (MT) determined to be 20% longer than their minimal MT for that distance. The primary dependent variable was the percentage of continuous vs. discontinuous trajectories observed in each condition, based on whether or not a transient hesitation or reversal was observed. Phase of peak velocity was also quantified as a general indication of the symmetry of the velocity profile. Three of the six subjects exhibited a greater percentage of continuous movements of the involved arm in the nonloaded bilateral condition than the unimanual condition. Five subjects benefited when the uninvolved arm was inertially loaded in the bilateral condition when compared with unimanual performance. Only the oldest subject failed to exhibit facilitation. Peak velocity phase tended to normalize toward symmetry in the bilateral conditions. These findings are consistent with prior evidence that the control of the involved arm improves during bimanual performance for some hemiplegic subjects. It further suggests loading the uninvolved arm may benefit some subjects with respect to unimanual performance, with age perhaps playing a role in determining efficacy.     

General and specific traits of personality and their relation to sleep and academic performance

Few studies have examined the links between personality variables and sleep and their combined effect on specific real-world outcomes. Participants in this study completed numerous personality, sleep, and performance measures; we examined the associations among these measures. Personality was assessed using the Five-Factor Model. The personality trait of Conscientiousness (especially its facet of Achievement Striving) was a substantial predictor of academic performance. Analyses of the sleep variables revealed three distinct constructs: quantity, quality, and schedule. Sleep quantity showed few interesting correlates. In contrast, sleep quality was associated with greater well-being and improved psychological functioning, whereas sleep schedule (i.e., average rising and retiring times) was significantly related to Conscientiousness, such that conscientious individuals maintain earlier schedules.     

Confirmatory factor analyses of posttraumatic stress symptoms in deployed and nondeployed veterans of the Gulf War

Confirmatory factor analysis was used to compare 6 models of posttraumatic stress disorder (PTSD) symptoms, ranging from 1 to 4 factors, in a sample of 3,695 deployed Gulf War veterans (N = 1,896) and nondeployed controls (N = 1,799). The 4 correlated factors-intrusions, avoidance, hyperarousal, and dysphoria-provided the best fit. The dysphoria factor combined traditional markers of numbing and hyperarousal. Model superiority was cross-validated in multiple subsamples, including a subset of deployed participants who were exposed to traumatic combat stressors. Moreover, convergent and discriminant validity correlations suggested that intrusions may be relatively specific to PTSD, whereas dysphoria may represent a nonspecific component of many disorders. Results are discussed in the context of hierarchical models of anxiety and depression.     

A three-factor model of trait anger: dimensions of affect, behavior, and cognition

The structure of trait anger was tested in a study of 24 self-report scales. Exploratory factor analyses in an undergraduate sample (N = 457) yielded a two-factor model (comprising cynicism and aggression) and a three-factor model (representing angry emotions, aggressive behaviors, and cynicism). Subsequent evaluations, including confirmatory factor analyses, indicated that the three-factor model provided the best characterization of the trait anger domain. The three-factor solution was consistent with an "ABC" conceptualization of trait anger, consisting of the dimensions of affect, behavior, and cognition. The three factors showed strikingly different associations with the Big Five personality traits. Angry Affect was most strongly related to Neuroticism, whereas Behavioral Aggression was associated with low Agreeableness. Cynical Cognition represented a blend of neurotic and disagreeable characteristics. Modest mean-level differences were observed between the genders for each factor.     

布洛贝尔的诺贝尔奖:想象变成了现实

1980年,克丽丝·纽丝兰—沃哈德和埃里克·韦乔斯开始研究果蝇中的胚胎致死突变,这项研究后来获得了诺贝尔奖,在某种意义上,它标志着生物学一个富有魅力的理论时代的终结和缺乏想象力的事实时代的到来(这个短语出自于Ｔ.Ｈ.赫胥黎,他认为悲剧就是“富有魅力的理论被缺乏想象力的事实所扼杀”)。如果沃森和克里克的ＤＮＡ双链结构模型显示了想象力(只具有不多的事实)可以超越自然,那么,纽丝兰—沃哈德和韦乔斯的饱和筛选法则表明进化能够产生如此难以想象的复杂的生物学机制,以致如果以直觉的方法来研究它们,既使不是可笑的,也是毫无用处的。…     

Reviews of current books

Pastoral Psychology -     

Investigating the construct validity of the dissociative taxon: stability analyses of normal and pathological dissociation

Research has suggested the existence of a pathological dissociative taxon. However, relatively little is known about this taxon. This study examined the 2-month retest stability of this taxon--together with other measures of dissociation and the Big Five--in a sample of 465 undergraduates. Contrary to expectation, taxon scores were only modestly stable and were substantially less stable than the other measures, including continuous indicators of dissociation. Furthermore, most individuals who were identified as taxon members at one assessment were classified as nonmembers at the other. These results challenge the existence of a pathological dissociative taxon. More generally, these data demonstrate that statistically identified taxa need to be explicated through the normal process of construct validation.