Comparing one-step m-estimators of location corresponding to two independent groups

Experience with real data indicates that psychometric measures often have heavy-tailed distributions. This is known to be a serious problem when comparing the means of two independent groups because heavy-tailed distributions can have a serious effect on power. Another problem that is common in some areas is outliers. This paper suggests an approach to these problems based on the one-step M-estimator of location. Simulations indicate that the new procedure provides very good control over the probability of a Type I error even when distributions are skewed, have different shapes, and the variances are unequal. Moreover, the new procedure has considerably more power than Welch's method when distributions have heavy tails, and it compares well to Yuen's method for comparing trimmed means. Wilcox's median procedure has about the same power as the proposed procedure, but Wilcox's method is based on a statistic that has a finite sample breakdown point of only 1/n, wheren is the sample size. Comments on other methods for comparing groups are also included.     

Central auditory processing : II. Effects of anterior temporal lobectomy

Ear dominance for the pitch of dichotically presented tonal stimuli was measured in nine patients before and after a unilateral anterior temporal lobectomy. Four subjects had a left and five had a right lobectomy. Every patient exhibited a change of ear dominance consistent with the hypothesis that a unilateral lobectomy decreases the perceptual salience of the tone presented to the ear contralateral to the lesion. Depending on the direction and magnitude of the subject's preoperative ear dominance and the side of the lobectomy, the postoperative results either increased or decreased the strength of ear dominance in a predictable fashion. The results support the idea that within each temporal lobe lie physiological mechanisms which can enhance the perceptual salience of the acoustic signal emitted by one sound source when other, concurrent, spatially separated sound sources are present. It is also argued that the same mechanism operates on speech, melodic, and tonal signals.     

Apractic agraphia in a patient with normal praxis

Most right-handed crossed aphasics are not apractic. They usually have agraphia characterized by misspellings but retain the ability to write well-formed graphemes. We describe a right-handed patient with a right parietal lesion who was aphasic and not apractic. He was unable to write any formed graphemes despite a relatively preserved ability to spell aloud. We postulate that praxis and writing are dissociated in this patient because the motor engrams for praxis were located in his left hemisphere and the engrams for writing were in his right hemisphere. In addition, he comprehended commands for limb motor activities (praxis) far better than he comprehended other speech. This suggests that in this patient the areas used to comprehend limb motor commands may be anatomically distinct from areas important in comprehending other aspects of speech.     

The relationship between treatment exposure times and changes in stuttering frequency during contingent stimulation

Four adult stutterers were exposed to 60 consecutive minutes of verbal contigent stimulation. In each session subjects spoke until a stuttering frequency stability criterion was met (baserate) followed by 60 min of exposure to the word wrong presented contingently upon each instance of stuttering. The data were analyzed according to changes in stuttering which occured following 20, 40, and 60 min of treatment exposure. The results revealed that stuttering frequency was reduced for all subjects during all three 20-min segments of the treatment condition. The only significant reductions in stuttering frequency, however, occured within the first 20 min of treatment.     

Social problem solving and mother-child interactions of educable mentally retarded children

Mothers of retarded children and nonretarded children were observed and videotaped as they interacted with their own child in a seminaturalistic situation, requiring teaching, cooperation, and free play. The child's social problem-solving abilities were assessed independently. The Vineland scale was employed to provide some convergent evidence of social problem-solving as a component of social competence. Twelve educable mentally retarded and 19 nonretarded 10-year-old children and their mothers comprised the sample. For the mentally retarded group, it was found that the higher maternal directiveness, the lower the child's social problem-solving skills. Mothers who often gave the child opportunity for decision-making and social influence had children with higher problem-solving skills. The retarded children produced significantly fewer different strategies for solving social problems, but gave a wider range of strategies than has been found in previous research. There was some support that social problem-solving skills are related to social maturity.     

Auditory evoked potentials and sex-related differences in brain development

Auditory evoked potentials (AEPs) were obtained to probe tones which were delivered during the presentation of complex verbal and nonverbal auditory stimulation to 3-month-old infants. Significant sex-dependent AEP amplitude asymmetries were found. Females produced higher-amplitude responses from the left hemisphere and males produced higher-amplitude responses from the right hemisphere during both the verbal and nonverbal presentations. No significant AEP asymmetries were obtained in an independent group of infants that received only the probe tones. These findings are consistent with theories and behavioral data suggesting differences between males and females in the development of language and spatial functions.     

Evidence for the external validity of a social simulation measure of social skills

Two studies were conducted in order to obtain evidence regarding the external validity of a social simulation measure of social skills. The first study employed a contrasted group design, with the groups consisting of National Guardsmen and psychiatric patients. As predicted, trained judges rated the performances of the National Guardsmen in the simulations as more skillful and appearing less anxious than the psychiatric patients. In the second study, trained judges' ratings of psychiatric patients' performances in the simulations were found to be significantly related to ratings made by interviewers who had conducted a structured social history interview with the patients, nurses' ratings based on their observations of patients after 3 days on the psychiatric unit, a research assistant's ratings based on contact with the patient during the experiment, and finally, the subject's own self-ratings. In discussing the findings, it is hypothesized that one reason why support was found for the external validity of the simulation strategy in this study, in contrast to some previously reported studies, was the use of molar ratings in this study as opposed to the more molecular rating procedures used in those previous studies.These studies were funded in part by a research grant from the Veterans Administration.     

Where Grammar and Interaction Meet: A Study of Co-Participant Completion in Japanese Conversation

This article examines the practice of "co-participant completion" in Japanese conversation, and explores what kinds of resources are mobilized to provide the opportunity to complete another participant's utterance-in-progress. It suggests the following observations as potential characteristics of Japanese co-participant completion: (i) Syntactically-defined two-part formats (e.g. [If X] + [then Y]) may not play as prominent a role as in English; (ii) The majority of cases of co-participant completion take the form of 'terminal item completion;' (iii) Locally emergent structures like 'contrast' and 'list' as well as 'unprojected' features of turn construction often play an important role in enhancing the opportunity for completing another participant's utterance-in-progress. The article then discusses the implications of these findings for the investigation of the mutual bearing of grammar and social interaction. In particular, the discussion focuses on what we can learn from the practice of co-participant completion about how projection of turn-shapes is accomplished in Japanese conversation.     

对变化/分割模型的检验(Ⅱ)

在前一报告的基础上设计了两个实验,对变化／分割模型做进一步的检验。实验3控制目标时距和该时距内的填充数字系列的分割段数以及段的持续时间,操纵段内的项目数;结果显示,数字系列的分割段数明显影响延迟操作条件下的时距估计,而段内的项目数则不影响对时距的估计。实验4控制目标时距和该时距内填充数字系列的分割段数以及段内的项目数,操纵段的持续时间;结果显示,对时距的估计取决于被试所使用的时间标尺。四个实验结果表明,变化／分割模型只有较高的预测效度,但也有不足之处。为了更好地从认知的观点解释时距估计的影响因素,作者对已提出的分段综合模型做了进一步的论证,并认为分段综合模型是一个能较完整解释影响人类时距估计的各种因素的理论模型。