Comparing Locomotion With Lever-press Travel In An Operant Simulation Of Foraging

An operant model of foraging was studied. Rats searched for food by pressing on the left lever, the patch, which provided one, two, or eight reinforcers before extinction (i.e., zero reinforcers). Obtaining each reinforcer lowered the probability of receiving another reinforcer, simulating patch depletion. Rats traveled to another patch by pressing the right lever, which restored reinforcer availability to the left lever. Travel requirement changed by varying the probability of reset for presses on the right lever; in one condition, additional locomotion was required. That is, rats ran 260 cm from the left to the right lever, made one response on the right lever, and ran back to a fresh patch on the left lever. Another condition added three hurdles to the 260-cm path. The lever-pressing and simple locomotion conditions generated equivalent travel times. Adding the hurdles produced longer times in patches than did the lever-pressing and simple locomotion requirements. The results contradict some models of optimal foraging but are in keeping with McNair's (1982) optimal giving-up time model and add to the growing body of evidence that different environments may produce different foraging strategies.     

The Patient Self-Determination Act and Advance Directives: Snapshots of Activities in a Tertiary Health Care Center

This study describes the results of a retrospective review of patients' charts who had an advanced directive (AD) and who were hospitalized in a tertiary, acute care teaching hospital. The purpose of the review was to understand from clinical, sociological, ethical and legal perspectives the nature and utility of ADs. Findings and implications of the review are discussed in terms of: patient demographics; diagnoses; quality of ADs; influence of ADs on clinical decisions; and legal aspects of ADs.     

Behavior analysis and farm animal welfare

This article demonstrates that there is a role for behavior-analytic techniques in the area of farm animal welfare and provides examples of the kinds of work that can be done. Behavior-analytic procedures, specifically those used in the study of psychophysics, preference, and demand, can provide answers to three questions people concerned with the welfare of farm animals are likely to ask: What can the animals detect? What do they like and dislike? What will they work to attain or preserve? Such information certainly is necessary for making reasonable decisions about animal welfare, although it is not sufficient in and of itself.     

Sexuality education and young people's sexual behavior: a review of studies

Sexuality education for children and young adults is one of the most heavily debated issues facing policy-makers, national AIDS program planners, and educators, provoking arguments over how explicit education materials should be, how much of it there should be, how often it should be given, and at what age instruction should commence. In this context, the World Health Organization's Global Program on AIDS' Office of Intervention Development and Support commissioned a comprehensive literature review to assess the effects of HIV/AIDS and sexuality education upon young people's sexual behavior. 52 reports culled from a search of 12 literature databases were reviewed. The main purpose of the review is to inform policy-makers, program planners, and educators about the impact of HIV and/or sexuality education upon the sexual behavior of youth as described in the published literature. Of 47 studies which evaluated interventions, 25 reported that HIV/AIDS and sexuality education neither increased nor decreased sexual activity and attendant rates of pregnancy and sexually transmitted diseases (STDs). 17 reported that HIV and/or sexuality education delayed the onset of sexual activity, reduced the number of sex partners, or reduced unplanned pregnancy and STD rates Only 3 studies found increases in sexual behavior associated with sexuality education. Inadequacies in study design, analytic techniques, outcome indicators, and the reporting of statistics are discussed.     

Predicting and scaling hens' preferences for topographically different responses

Six hens were exposed to several concurrent (second-order) variable-interval schedules in which the response requirements on the alternatives were varied. The response requirements were one key peck versus five key pecks, one key peck versus one door push, and five key pecks versus one door push. Response- and time-allocation ratios undermatched the obtained reinforcement ratios but were well described by the generalized matching law. Time and response bias estimates from two pairs of response requirements were used to predict bias in the third pairing. The predicted values were close to those obtained; this result supports the notion that both numerically and topographically different responses act as constant sources of bias within the generalized matching law. The differences between the response and time biases could be accounted for by the different times needed to complete each response requirement. The results also suggest that the door push is a useful operant for research with domestic hens.     

Maximizing internal and external validity in MMPI malingering research: a study of a military population

The authors investigated the effectiveness of various commonly used Minnesota Multiphasic Personality Inventory (MMPI; Hathaway & McKinley, 1943) indices of exaggeration and malingering in detecting suspected malingering in a military sample of 121 enlisted men. To maximize external validity, only men undergoing psychological evaluation were used as participants. Forty-one participants were identified as suspected malingerers through multiple criteria and were contrasted with schizophrenic-spectrum and clinic outpatient groups. To improve internal validity, the 41 suspected malingering participants were asked to retake the test without exaggerating. Results revealed that there were many false positives and fewer, but nonetheless many, false negatives with standard malingering indices. It appeared that the Gough Dissimulation scale (Gough, 1947) might hold the most promise as a measure of malingering, but other scales are also useful. Individual comparisons between different samples and implications for MMPI-2 (Butcher et al., 1989) are presented.     

Sex-selective abortion: a relational approach

A critical application of Ruddick's model of maternal thinking is the best way to grapple with the ethical dilemmas posed by sex-selective abortion which I view as a "moral mistake." Chief among these is the need to be sensitive to local cultural practices in countries where sex-selective abortion is prevalent, while simultaneously developing consistent international standards to deal with the dangers posed by the use of sex-selective abortion to eliminate female fetuses.     

2001年的科学哲学

一种民主制度的最重要也是讨论最少的任务之一就是要保护它的成员免遭这种制度中的意识形态的伤害.必须正确地看待所有的意识形态.人们必须把它们当作神话故事来看待,它们能告诉人很多有趣的事,但也包含了很多谬误和令人生厌的谎言.当人们按照某一观点行动时,他们的态度也应该像密探一样,为了在一个陌生的国家里获得成功而采纳它的信仰并在细枝末节上按照这些信仰去做,但并不全盘接受.这一点适用于所有的信仰,适用于基督教上帝的存在这一信仰,适用于所有的人生来平等的信仰,也适用于科学.那么,这是否是一种陌生和荒谬的态度呢?科学当然总是处在与权威主义和迷信战斗的前沿.相对于宗教信仰而言,我们有了越来越大的思想自由,这应当归功于科学;人类从古代的僵硬思维方式中解放出来,也应当归功于科学.今天,这些思维方式仅仅是一些糟糕的     

Changes in spinal reflex excitability in a countermanded timed response task

Subjects (N = 8) performed a timed response task in which they attempted to synchronize an impulsive foot-press response with the last in a series of four regularly spaced tones. In Experiment 1, the response was countermanded on one third of the trials (stop trials) by a stop signal that appeared at a predetermined delay after the third tone. No stop signal appeared on the remaining trials (go trials). All subjects showed a systematic transition from withholding the response on stop trials in which the stop signal appeared shortly after the third tone to executing the response on trials in which a single stop signal delay had been chosen so that a response would be made on about 50% of the stop trials. We elicited Hoffmann (H) reflexes from the soleus muscle on all trials to determine whether the reflexes were augmented on occasions on which a response was prepared but withheld. Mean H-reflex amplitudes on go trials and on stop trials on which the response was executed were similar and showed a marked augmentation beginning about 250 ms before response onset; mean H-reflex amplitudes on stop trials on which the response was withheld showed less pronounced augmentation. Inspection of individual H-reflex amplitudes revealed that on stop trials on which the response was withheld the reflexes could be augmented to the same extent as on trials on which the response was executed. This dissociation of H-reflex augmentation and response execution shows that H-reflex augmentation reflects a controlled response process. Ballistic response processes therefore must be limited to a brief duration.     

Crossing without vision of path gaps

Two experiments considered the behavior of subjects who cross gaps in a pathway without benefit of vision. The first experiment contrasted visually and nonvisually guided locomotion, finding a significantly greater number of refusals under nonvisual guidance but no loss of appropriate modulation of step components to the salient dimensions of the actor and layout. Different components of crossing were modified under guidance of different sensory systems; the lengths of the crossing and support spans were primarily altered under nonvisual guidance, and the distance of the support foot to the near edge of the gap was the component of preference under visual guidance. In the second experiment, subjects crossed nonvisually, using probes that varied in length and moment of inertia. The adaptability of the step components to actor and layout dimensions was unchanged, but there was no effect of these mechanical manipulations on the components of crossing identified in Experiment 1.