Estimation of psychometric functions from adaptive tracking procedures

Because adaptive tracking procedures are designed to avoid stimulus levels far from a target threshold value, the psychometric function constructed from the trial-by-trial data in the track may be accurate near the target level but a poor reflection of performance at levels far removed from the target. A series of computer simulations was undertaken to assess the reliability and accuracy of psychometric functions generated from data collected in up-down adaptive tracking procedures. Estimates of psychometric function slopes were obtained from-trial-by-trial data in simulated adaptive tracks and compared with the true characteristics of the functions used to generate the tracks. Simulations were carried out for three psychophysical procedures and two target performance levels, with tracks generated by psychometric functions with three different slopes. The functions reconstructed from the tracking data were, for the most part, accurate reflections of the true generating functions when at least 200 trials were included in the tracks. However, for 50- and 100-trial tracks, slope estimates were biased high for all simulated experimental conditions. Correction factors for slope estimates from these tracks are presented. There was no difference in the accuracy and reliability of slope estimation due to -target-level-for the adaptive track, and only minor differences due to psychophysical procedure. It is recommended that, if both threshold and slope of psychometric functions are to be estimated-from the trial-by-trial tracking data, at least 100 trials should be included in the tracks, and a three- or four-alternative forced-choice procedure should be used. However, good estimates can also be obtained using the two-alternative forced-choice procedure or less than 100 trials if appropriate corrections for bias are applied.     

Systematic bias in successive movement repetitions

In three separate studies, independent groups of subjects made either 10 subjectively defined steps of the same length, 10 subjectively defined linear arm movements of the same extent, or 10 successive movements of a single experimenter defined linear arm movement. In each case, the repetitions of these movements became increasingly longer. This is an initial report of what may be a ubiquitous phenomenon.     

The effects of masturbatory reconditioning with nonfamilial child molesters.

Abel and Annon's (Reducing deviant sexual arousal through satisfaction, Denver, Colo., 1982) suggested combination of 'directed masturbation' and 'satiation' to alter deviant sexual preferences, was applied to 10 nonfamilial child molesters. Post-treatment assessments revealed significant reductions in deviant arousal as was expected, but unfortunately there were also reductions in appropriate arousal although these changes did not achieve statistical significance. The results are discussed in terms of their meaning but it is concluded that empirical support for these clinically popular procedures remains weak.     

Men's job and partner roles: Spillover effects and psychological distress

What is the relationship between the quality of men's job and partnership roles on the one hand and men's mental health on the other? This question was addressed in a random sample of 300 men, ages 25–40, in dual-earner couples. Predictions were made from both main-effects and two interaction-effects models of this relationship. More specifically, negative-spillover effects, as predicted by the role-stress model, were estimated both from work to home and home to work. Positive-spillover effects, as predicted by the role-enhancement model, were estimated from home to work and from work to home. The general finding was that the effects are additive not interactive, thus supporting the main-effects model. With respect to spillover effects, there was some support for the role-stress model, but no support for the role-enhancement model. More specifically, the relationship between job stress and psychological distress was exacerbated among men who had troubled relationships with their partners.     

Do developmental changes in digit span result from acquisition strategies?

This study tested the theoretical proposition that the developmental increase in memory span results from a corresponding increase in the use of grouping strategies. With slow presentation, experimenter-provided grouping eliminated the span differences between sixth graders and adults but, while grouping helped first graders more than adults, a sizable difference in digit span remained. With fast presentation, grouping increased the adults' performance more than the childrens'. Another finding was that both groups of children had greater digit spans with fast presentation than with slow. For adults, the reverse was true.     

Identification of cues and control of sexual arousal by rapists

The experiments in this article pertain to factors relevant to rape. The first experiment examined the ability of four groups to discriminate between appropriate and inappropriate sexual cues. Rapists detected such cues as well as did either Normals or Non-rapist Inmates, in all but the most assaultive rape tape. Normal subjects who had consumed alcohol prior to testing, detected inappropriate cues earlier in the tapes than did all other subjects. The second experiment addressed the ability of subjects to inhibit sexual arousal when instructed to do so. Rapists and Non-rapists were shown to be equally capable of inhibiting arousal in response to both mutually-consenting and rape cues. These findings negate theories suggesting that rapists differ from other men in that they are unable to exert control over their arousal, and that they have difficulty in identifying inappropriate cues to arousal.     

Family timing in late adolescence and early adulthood: The case of southern males

Social science research and theory about familial orientations and reproductive ideals have largely neglected males' attitudes. Drawing on demographic and status attainment perspectives, this study applies a model of processes underlying marriage and family timing to longitudinal data on 288 young adult males from the Southern Youth Study. Several posited influences of family of origin factors, significant others, and adolescent status and familial aspirations on marital timing and early family growth are assessed.Development of this report was sponsored in part by the Texas Agricultural Experiment Station and contributes both to TAES Project H-2811 and to USDA (CSRS) Regional Research Project S-81, and in part by the Maxwell Policy Center on Aging and the All-University Gerontology Center, Syracuse University through Title IV-C Grant #90-A-1054101 from the Administration on Aging, Department of Health, Education, and Welfare. Information for analysis was obtained by pooling data collected under grants provided by the Agricultural Experiment Stations of Alabama, Georgia, South Carolina, and Texas. Appreciation is expressed to John Womack, Paul D. Mader, and G. David Curry for their advice at various stages of this research.     

TGF-β1 in Aplysia: Role in Long-Term Changes in the Excitability of Sensory Neurons and Distribution of TβR-II-Like Immunoreactivity

Exogenous recombinant human transforming growth factor β-1 (TGF-β1) induced long-term facilitation of Aplysia sensory-motor synapses. In addition, 5-HT-induced facilitation was blocked by application of a soluble fragment of the extracellular portion of the TGF-β1 type II receptor (TβR-II), which presumably acted by scavenging an endogenous TGF-β1-like molecule. Because TβR-II is essential for transmembrane signaling by TGF-β, we sought to determine whether Aplysia tissues contained TβR-II and specifically, whether neurons expressed the receptor. Western blot analysis of Aplysia tissue extracts demonstrated the presence of a TβR-II-immunoreactive protein in several tissue types. The expression and distribution of TβR-II-immunoreactive proteins in the central nervous system was examined by immunohistochemistry to elucidate sites that may be responsive to TGF-β1 and thus may play a role in synaptic plasticity. Sensory neurons in the ventral–caudal cluster of the pleural ganglion were immunoreactive for TβR-II, as well as many neurons in the pedal, abdominal, buccal, and cerebral ganglia. Sensory neurons cultured in isolation and cocultured sensory and motor neurons were also immunoreactive. TGF-β1 affected the biophysical properties of cultured sensory neurons, inducing an increase of excitability that persisted for at least 48 hr. Furthermore, exposure to TGF-β1 resulted in a reduction in the firing threshold of sensory neurons. These results provide further support for the hypothesis that TGF-β1 plays a role in long-term synaptic plasticity in Aplysia.     

The apparent length of rotating arcs under conditions of dark adaptation

The apparent contraction of a rotating light arc occurred during the first 20 rain, but not after 25 min, of dark adaptation. Estimates of length obtained after 25 min were affected by the level of luminance of the arc but not by its speed of rotation, by dark gaps in the arc, or by instructions to estimate its length in terms of a brighter region. There was no tendency for a rotating dark arc to appear shorter at any stage of adaptation.