Essential independence and likelihood-based ability estimation for polytomous items

A definition ofessential independence is proposed for sequences of polytomous items. For items satisfying the reasonable assumption that the expected amount of credit awarded increases with examinee ability, we develop a theory ofessential unidimensionality which closely parallels that of Stout. Essentially unidimensional item sequences can be shown to have a unique (up to change-of-scale) dominant underlying trait, which can be consistently estimated by a monotone transformation of the sum of the item scores. In more general polytomous-response latent trait models (with or without ordered responses), anM-estimator based upon maximum likelihood may be shown to be consistent for under essentially unidimensional violations of local independence and a variety of monotonicity/identifiability conditions. A rigorous proof of this fact is given, and the standard error of the estimator is explored. These results suggest that ability estimation methods that rely on the summation form of the log likelihood under local independence should generally be robust under essential independence, but standard errors may vary greatly from what is usually expected, depending on the degree of departure from local independence. An index of departure from local independence is also proposed.This work was supported in part by Office of Naval Research Grant N00014-87-K-0277 and National Science Foundation Grant NSF-DMS-88-02556. The author is grateful to William F. Stout for many helpful comments, and to an anonymous reviewer for raising the questions addressed in section 2. A preliminary version of section 6 appeared in the author's Ph.D. thesis.     

Locus of causality and the use of information in the development of causal attributions1

Two studies were conducted to examine whether attributions made about events may be influenced by individual assumptions regarding causation that are age related. In Study 1, 96 subjects at three age levels (four and five years, eight and nine years, and college students) observed a target actor on videotape select an item from an unseen array, and four other actors either agree (high consensus) or disagree (low consensus) with the choice. Subjects were asked to decide why the actor liked the chosen object best—because of something about the actor (person attribution) or because of something about the item (entity attribution). The results showed that perceived locus of causality shifted from entity to person attributions with age. In addition, subjects at all ages were able to utilize the consensus information when they had no opportunity to form their own impressions about the items in the array. In Study 2, 126 subjects at four age levels (five and six years, seven and eight years, nine and ten years, and high school students) chose an item from among an array for themselves and responded to a person (self)/entity attribution question regarding the locus of their own choice. The entity to person shift with age was again found and was supported by additional measures. The results are discussed in terms of children's causal reasoning capacities and social environmental factors affecting developmental change in social judgments.     

Coping as a mediator between personality and stress outcomes: a longitudinal study with cataract surgery patients

Personality and coping were specified as predictors of emotional outcomes of a mildly stressful medical procedure. Situation-specific coping was examined in contrast to dispositional coping, and it was tested whether one or the other would mediate the relationship between higher-order personality factors and stress outcomes. Cataract patients (N=110) participated at four measurement points in time during a six-week period surrounding their scheduled surgery. Dispositional coping did not mediate the personality–outcome relationship. In contrast, situation-specific coping acquired a mediator status between personality and adaptational criteria and accounted for independent outcome variance once personality traits were included as predictors in the models. Thus, the data suggest that whether or not coping mediates between personality factors and affective outcomes may be related to the methodological approaches of its operationalization. Copyright © 2005 John Wiley & Sons, Ltd.     

Defensive reactions of “wild-type” and “Domesticated” wild rats to approach and contact by a threat stimulus

Selective breeding of wild rats over many generations on the basis of low or high defensive threat and attack to human approach and contact has produced highly polarized “domesticated” and “wild-type” animals. Because the selection procedure selectively involves these two defense patterns, and these clearly differ in the two groups, it is of interest to determine if other, nonselected, defensive behaviors to threat stimuli also change. “Domesticated” and “wild-type” rats of the thirty-fifth generation were run in a fear defense test battery (F/DTB) to systematically evaluate defensive behaviors to a variety of present threat stimuli. “Domesticated” rats showed reduced avoidance and slower flight speed to an approaching experimenter, reduced jump/startle response to handelap and dorsal contact, less vocalization and boxing to vibrissae stimulation or to an anesthetized conspecific, and reduced defensiveness to an attempted pickup by the experimenter. These results indicate that selective bi-directional breeding for defensive threat and attack to human approach and contact produces group differences in a variety of defensive behaviors, and in defensiveness to stimuli other than those on which the selection was based. © 1994 Wiley-Liss, Inc.     

Getting older and living up to implicit followership theories: Implications for employee psychological health and job attitudes

Age discrimination at work is a widespread destructive phenomenon that often takes subtle forms. Based on negative stereotypes about older employees, we argue that older employees often experience that they are perceived as less ideal followers than younger employees. We propose that older and younger employees do not differ in what they assume their supervisors expect of an ideal follower (implicit followership theories, IFTs). Thus, we hypothesize that older employees perceive that they compare less favorably to their supervisors' IFTs than younger employees (i.e., worse IFT-fit). This should entail lower quality of the relationship between leader and follower (leader-member-exchange, LMX), which, in turn, should have detrimental effects on employees' health (i.e., burnout) and job attitudes (i.e., job satisfaction, turnover intentions, and identification). We tested our model in a field study with 379 employees. Results differed for ideal and counter-ideal follower attributes. Concerning counter-ideal follower attributes (e.g., being incompetent), age had the proposed negative effect on psychological health and job attitudes that mediated through IFT-fit and LMX. Concerning ideal follower attributes (e.g., thinking ahead), older employees expected their supervisors not only to think less of them than of their younger colleagues, but also expected them to have less demanding IFTs—contrary to our expectations. Employee age was negatively related to psychological health and job attitudes, mediated through lower perceived IFTs, worse perceived appraisal of the actual employee and their joint effects on LMX.     

The effects of gendered information in stories on preschool children’s development of gender stereotypes

Social-cognitive theory posits that children learn gender stereotypes through gendered information. The present study examined whether children learn new gender stereotypes from stories when unknown words are linked to a gendered protagonist or context information. In Experiment 1, 40 3- to 6-year-old preschoolers were read stories with either a gendered protagonist embedded within a non-gendered context, or a non-gendered protagonist embedded within a gendered context. In Experiment 2, the same sample of children were read stories with the protagonist and the context displaying congruent or incongruent gender information. Each story featured an unknown activity linked with the stereotypical content. Both experiments indicate that the children rated the activity according to both the gender of the context and of the protagonist; however, the effect of the latter was stronger. In addition, children showed higher interest in the unknown activity if the protagonist’s gender matched their own sex. Thus, gender information in stories influences how children perceive unknown words.     

The utility of ground rule instructions with younger and older adult witnesses

This study examined the effectiveness of ground rules—simple instructions outlining the communication expectations of an investigative interview—with 73 younger (age 18–40) and 57 older (age 60+) adults. Participants watched a film depicting an implied sexual assault and were interviewed after a brief delay. One third received no ground rules, one third received ground rules as statements, and one third received the statements along with practice examples. The interview contained questions that required participants to apply one of the rules. Those who received ground rules were asked their perceptions of the rules. Results demonstrated that practicing ground rules improved response quality to problematic recognition questions, younger adults showed more variability in responses to different ground rules than older adults, and most participants found ground rule instructions useful in investigative interviews. Results provide support for the use of ground rules in interviews with adult witnesses.     

高低水平汉英二语者阅读难易英语句子的知觉广度

通过考察高、低水平汉英二语者阅读难易英语句子的知觉广度,本研究发现二语水平和句子难度调节汉英二语者的英语阅读速度,但不影响其阅读知觉广度,均表现为注视词左侧1个词至右侧1个词。该结果表明汉英二语者采用相对固定的注意分配策略来阅读英语,与中央凹加工负荷假说不一致。     

Predatory aggression in the mink (Mustela vison): Roles of serotonin and food satiation

5-Hydroxytrypotophan at a dose of 50 mg/kg intraperitoneally (i.p.) sharply increased neural serotonin (5-HT) levels in mink and considerably inhibited that animal's predatory attack on rats. Intraperitoneal injection of 5-HT (10 and 20 mg/kg) did not influence such rat-killing. Neural levels of 5-HT or 5-hydroxyindoleacetic acid (5-HIAA) and subsequent aggression by the predator did not change to any great degree after ingestion of a single meal. Abundance of natural mink food for 3 days was associated with an increased level of 5-HIAA in the lateral hypothalamus and the amygdala as well as with an increased latency to attack and to kill rats. 5-HT seems to represent an endogenous factor that inhibits predatory attack by the mink; this effect appears to function through increased metabolism of 5-HT in some brain regions, which is evident after abundant intake of tryptophan with the natural diet.