Parameter estimation in latent trait models

Latent trait models for binary responses to a set of test items are considered from the point of view of estimating latent trait parameters=( ₁, , _n ) and item parameters=( ₁, , _k ), where _j may be vector valued. With considered a random sample from a prior distribution with parameter, the estimation of (, ) is studied under the theory of the EM algorithm. An example and computational details are presented for the Rasch model.This work was supported by Contract No. N00014-81-K-0265, Modification No. P00002, from Personnel and Training Research Programs, Psychological Sciences Division, Office of Naval Research. The authors wish to thank an anonymous reviewer for several valuable suggestions.     

Event-related brain potentials to grammatical errors and semantic anomalies

Event-related brain potentials (ERPs) were recorded while subjects silently read several prose passages, presented one word at a time. Semantic anomalies and various grammatical errors had been inserted unpredictably at different serial positions within some of the sentences. The semantically inappropriate words elicited a large N400 component in the ERP, whereas the grammatical errors were associated with smaller and less consistent components that had scalp distributions different from that of the N400. This result adds to the evidence that the N400 wave is more closely related to semantic than to grammatical processing. Additional analyses revealed that different ERP configurations were elicited by open-class (“content”) and closed-class (“function”) words in these prose passages.     

Age and cohort effects on personality factor scores across sexes and racial/ethnic groups

Substantial differences exist across ethnic groups and sexes in generational changes in status among groups residing in Hawaii. Despite these generational differences across groups, age differences in personality are remarkably consistent across sexes and racial/ethnic groups, and the few Sex x Age, Ethnicity x Age or Sex x Ethnicity x Age interactions account for little variance in scores. It is concluded that age/generational differences in personality factor scores in these populations result from age and not, to any major degree, from cohort effects.     

Preparing dichotic tapes using a digital music synthesizer

Digital music synthesizers represent audio signals in the form of binary coded numbers. These binary coded numbers can be manipulated by the operator, thereby altering the audio signal in a variety of ways. The present article describes how these capabilities can be used to produce perfectly aligned dichotic tapes in which the stimulus items are matched on all extraneous (timbre, amplitude, duration) factors.     

Incubated reminiscence effects

Reminiscence, the recall of material that was not successfully recalled on a previous attempt, was examined in three experiments as a function of the interest (incubation) interval. Incubation intervals inserted between successive recall tests resulted in increased reminiscence, but the effect was seen primarily in the first retested minute. Neither the duration of the initial test (1-4 min), nor the incubation activity (maze problems vs. rest) affected this incubated reminiscence effect. The results support models in which recall tests cause output interference, but incubation intervals reduce it.     

Abortion and the death of the fetus

Abortion is conceptualized as encompassing two aspects: ending the physical dependency relationship the fetus has to the mother, and terminating the life of the fetus. Analysis of the unique nature of the mother-fetus and mother-child relationship leads to the conclusion that both the act of abortion and the pregnant woman's decision to seek the death of the fetus can be logically justified.     

Preschool peer perceptions of the behavior of hyperactive and aggressive children

To assess if preschool children can successfully identify externalizing symptomatic behaviors in their male classmates, and if these perceptions are associated with peer-rated popularity and rejection, 154 preschool boys and girls were interviewed using a peer nomination procedure. Behavioral data on the same preschool boys (N=86) were also provided by their respective teachers. Preschool children were capable of providing stable nominations of popularity, rejection, and aggression, boys and girls significantly agreed in their nominations, and these nominations were not a function of the age of the rated child, although they differed somewhat as a function of the age of the rater. Teachers and peers reflected significant convergence in ratings of hyperactivity and aggression and teacher ratings of peer problems significantly agreed with actual peer nominations of popularity and rejection. Boys nominated as aggressive were more rejected by their classmates, whereas boys nominated as hyperactive were either more popular and /or more rejected. Limited evidence for differential patterns of relationships among hyperactivity, aggression, and peer status was obtained for both the peer and teacher data.Portions of this paper were presented as part of a symposium, W. Pelham (Chair),Peer relations in hyperactive children: Diagnostic, symptomatic, and treatment consideration, at the annual meeting of the American Psychological Association, Los Angeles, August 1981. This research was supported, in part, by NIMH grant #32992 to the first author.