Dichotic sequence discrimination: The effect of continued practice

Summary Dichotic sequence discrimination was studied by means of a three-alternative forced-choice method. Two of the alternatives (same) consisted of a single pair of dichotic clicks with the stimulus at one ear preceding the stimulus at the other ear by a given temporal separation (e.g., R-t-L). One of the alternatives consisted of a single pair of clicks with the opposite sequence (e.g., L-t-R). The subjects' task was to discriminate between the different and the same dichotic pairs. The results indicate that discrimination is a nonmonotonic function of t, i.e., V- or U-shaped, with high levels at both short and long temporal separations (t=2 and 4 ms and t=64 and 96 ms) and with lower levels of discrimination for intermediate ts. A second experiment was performed to study the effect of continued practice by subjects trained in dichotic sequence discrimination for ts 4 and 64 ms (high discrimination levels) and for t=16 ms (low discrimination level). There was no systematic trend towards improvement over 8 blocks of 50 trials for each t. Discrimination levels of these ts did not differ between Experiments 1 and 2.Dr. Babkoff is spending the 1979–1981 academic year at the Walter Reed Army Institute of Research, Department of Military Medical Psychophysiology, Forest Glen Annex, Building 189, Washington, D.C. 20012, USAThe experiments were conducted at the Bar-Ilan University, Ramat-Gan, Israel. The authors would like to thank the Bar-Ilan Research Committee for making funds available to conduct the experimentsThis material has been reviewed by the Walter Reed Army Institute of Research, and there is no objection to its presentation and/or publication. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense     

The morphological asymmetry of the hemispheres and cerebral dominance for speech: A possible relationship

The asymmetry of the posterior Sylvian branches of the middle cerebral artery was examined on the carotid angiograms of 59 patients in whom the lateralization of speech representation was known from sodium amobarbital (Amytal) studies. The usual asymmetry of these vessels was found to be present in the group of patients with left-hemisphere speech representation but significantly reduced in patients with atypical cerebral dominance for speech. A model of the inheritance of handedness and cerebral dominance is extended to take account of these results.     

A reexamination of sex differences in job preferences

Previous research has found conflicting answers to the question of whether males and females share similar preferences for various job characteristics. It is difficult to determine if the different findings are due to the different populations sampled, the various methodologies employed, or to a real change in the phenomenon itself. This study essentially replicates earlier work by having 130 male and 84 female college students rate the importance of 10 job characteristics for both themselves and members of the opposite sex. Both sexes rated motivators as important, but females also placed importance on the hygienes. Males tended to underestimate the importance of the motivators for females, while females overestimated the importance of hygienes for males. The subject's sex could be predicted by both the importance for self and importance for opposite sex ratings, contrary to the earlier study. The difference in results and interpretation was shown to be due to the type of analyses used. Additionally, it was found that females' job preferences were related to their mothers' educational achievement.     

Apple II/FIRST system control of electrical brain stimulation in the rabbit

An Apple II/FIRST system has been developed to control classical conditioning experiments, collect analog data, and extract dependent variable measures of conditioning from uniphasic (Scandrett & Gormezano, 1980) and multiphasic (Johnson, 1981) response signals. The present paper details the development of an electrical brain stimulation system as a peripheral device to the Apple II/FIRST system. In addition, data are presented that document the capabilities of the EBS system to concurrently stimulate up to eight animals while values along the dimension of each of four stimulation parameters are manipulated by a program written in FIRST. In our judgment, the EBS system has a number of advantages over currently available commercial stimulators, including cost, number of sites that can be independently stimulated, and availability of complete software control.     

Homelessness as psychological trauma. Broadening perspectives.

Most mental health literature on homelessness has focused on characteristics that may be risk factors for homelessness. The authors of this article argue that homelessness itself is a risk factor for emotional disorder and use the construct of psychological trauma--focusing on social disaffiliation and learned helplessness--to understand the potential effects of homelessness. Psychological trauma is likely among homeless individuals and families for three reasons. (a) The sudden or gradual loss of one's home can be a stressor of sufficient severity to produce symptoms of psychological trauma. (b) The conditions of shelter life may produce trauma symptoms. (c) Many homeless people--particularly women--become homeless after experiencing physical and sexual abuse and consequent psychological trauma. Research suggests that negative psychological responses to traumatic events can be prevented or mitigated by a supportive and empowering posttrauma environment. The implications of trauma theory for improving the psychosocial conditions of homeless people are discussed.     

Social influence processes affecting adolescent substance use

Social influence is central to models of adolescent substance use. Nonetheless, researchers fail to delineate the various forms of social influence. A framework that distinguishes between active (explicit drug offers) and passive (social modeling and overestimation of friends' use) social pressure was tested. The effect of these processes on alcohol and cigarette use was examined with 526 seventh graders taking part in an alcohol prevention program. Hierarchical regression analyses demonstrated that pretest measures of alcohol use, offers, modeling, and overestimation each accounted for unique variance in posttest alcohol use. Similar results were obtained for cigarette smoking. The general model was not significantly different for boys and girls, or for prior users and prior nonusers, supporting the generalizability of the framework. Implications for intervention programs are discussed.     

Three methods of developing MMPI taxonomies of sexual offenders

In a sample of 261 state hospital sexual offenders, Minnesota Multiphasic Personality Inventory (MMPI) profiles did not differ for offenders with adult victims versus offenders with child victims when offender age was controlled. MMPI 2-point analyses for the whole sample revealed five common codes that were independent of victim maturity. The sample was randomly divided in half and subjected to a cluster-analytic procedure which revealed two MMPI clusters. The first cluster was unelevated, with Scale 4 as its high point. The second cluster had multiple elevations, with Scales 8, 4, 2, and 7 as the highest scales. These clusters were replicated in a cluster analysis of the second half of the sample. However, when the sample was recombined, the two clusters were not externally validated basis on demographic and criminological variables. The results suggest that common psychological variables among sexual offenders may have more discriminative value than victim maturity in developing sexual offender taxonomies.     

Detecting fake-good and fake-bad MMPI-2 profiles

This study examined the extent to which the validity scales of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) could identify subjects who were faking bad or faking good and differentiate between psychiatric patients and normal subjects who were faking bad. Subjects were 106 undergraduate college students and 50 psychiatric patients. Results indicate that the mean profiles and optimal cutoff scores resembled those previously reported for the original MMPI. Accurate identification of persons who were faking bad or faking good was achieved. It was possible to differentiate between the psychiatric patients and normal persons who were faking bad, but different cutoff scores were needed to differentiate between normals taking the test under standard instructions and those instructed to fake bad. Optimal cutoff scores were suggested.