Errors in the quantification of uncertainty: A product of heuristics or minimal probability knowledge base?

The use of intuitive heuristics (e. g. representativeness and availability) has been put forward as an explanation for peoples' assignment of probabilities (Tversky and Kahneman, 1971). This phenomenon is seen as robust since experts as defined by education (professional psychologisis), despite advanced training in statistics and methodology, rely on the same heuristics as novices (lay people). Both experts and novices, as defined by education, were studied in a series of experiments and further classified as experts and novices according to their probability knowledge base, prior to receiving (or not) a brief (15-minute) training session. Immediately following training, subjects completed a probability test which consisted of ten Tversky and Kahneman (e. g. 1974) problems. The training significantly increased the number of problems correctly solved on the probability test and eliminated the expert/novice education classification. The results of a follow-up test 5 weeks after the experiment indicated that the training group maintained its superior performance. It is proposed that failure to use proper methods of probability assignment may not be due to intrinsic human inference biases or heuristics, but is a result of a minimal probability knowledge base.     

Origins of the misplaced confidence effect in collaborative recall

Studies have shown that dyads and groups place significantly more confidence in wrong answers to questions about a jointly witnessed event than do individuals. This experiment was designed to discover whether this misplaced confidence is influenced by prior free collaborative recall of the events in question. The results clearly indicated that prior group remembering lessens the effect, and improves the testimonial validity of both individual and group answers to questions about a jointly witnessed event. Taken in conjunction with other studies, the results imply that two or more witnesses of an event may profitably discuss what happened, but that they may best be interrogated separately in order to maximize the information available to the interrogator and to minimize misplaced confidence.     

Age and scholarly impact

The claim that older scientists generate research of lower quality than do younger scientists was tested through two analyses in which the age distribution of authors of frequently cited articles in psychology journals was compared with the age distribution of authors of low-impact articles published in the same journals. Most high-impact articles were published by relatively young psychologists, but so were most low-impact articles. When allowance was made for relative numerical representation, there was no evidence that publications from older scientists have less impact. Results are discussed in the context of methodological issues in evaluation of relations between age and scientific achievement.     

TIMEX2: A modified C-language timer for PC AT class machines

Emerson (1988) provided a simple C-language timing routine for use with PC AT class machines. Unfortunately, this version of the timing routine makes use of nonstandard functions that are not available in all C-language packages. A modified version of this timing routine that does not make use of one of these nonstandard functions is provided. This version of TIMEX runs under the widely available Microsoft C 5.1. The need and availability of the remaining four nonstandard C functions is discussed. Constants needed to convert the timing routine units into seconds and milliseconds are also provided.     

Automation of learning-set testing: The video-task paradigm

Researchers interested in studying discrimination learning in primates have typically utilized variations in the Wisconsin General Test Apparatus (WGTA). In the present experiment, a new testing apparatus for the study of primate learning is proposed. In the video-task paradigm, rhesus monkeys (Macaca mulatta) respond to computer-generated stimuli by manipulating a joystick. Using this apparatus, discrimination learning-set data for 2 monkeys were obtained. Performance on Trial 2 exceeded 80% within 200 discrimination learning problems. These data illustrate the utility of the video-task paradigm in comparative research. Additionally, the efficient learning and rich data that were characteristic of this study suggest several advantages of the present testing paradigm over traditional WGTA testing.     

Automated data collection using bar code

Using bar code technology to automate data collection provides a rapid and reliable alternative to paper-and-pencil tracking or keyboard entry into pocket or laptop computer. An array of bar code symbols is printed on a data menu, with a unique symbol corresponding to each possible observation. Bar code symbols are scanned using hand-held readers, which record the event, log the observation time, and store data for transfer to a personal computer. Advantages of the bar code monitoring system include: (1) ease of use by staff with minimal technical training, (2) reduced data entry errors and increased entry speed, (3) reliable portable operation, and (4) low-cost hardware. While the bar code system described here is used for behavioral monitoring in a residential treatment setting for the developmentally disabled, with minimal modification this system can be adapted for use in a wide variety of research and clinical applications.     

Angular homeostasis: IV. Polygonal orbits

Some properties are discussed of regular polygons that may result from angular homeostatic processes in stable orbit. To characterize these homeostatic polygons we need to discuss the winding number, the sidedness (integer, fractional and irrational), multiplicity, envelopes, and density. A regular (i.e., equilateral, equiangular) polygon may be closed in one revolution about its unique center, in multiple revolutions, or not at all. A homeostatic polygon can be generated only if all vertices are included in a single polygon, which occurs if and only if the number of vertices and the number of revolutions required to complete the polygon are relatively prime. For the homeostatic polygon to have a finite number of sides (without repeating itself) the angle subtended by any two successive vertices at the center must be a rational multiple of 2. Biological implications of these properties are illustrated.     

Just health care (II): Is equality too much?

In a previous essay I criticized Engelhardt's libertarian conception of justice, which grounds the view that society's obligation to assure access to adequate health care for all is a matter of beneficence [1]. Beneficence fails to capture the moral stringency associated with many claims for access to health care. In the present paper I argue that these claims are really matters of justice proper, where justice is conceived along moderate egalitarian lines, such as those suggested by Rawls and Daniels, rather than strong egalitarian lines. Further, given the empirical complexity associated with the distribution of contemporary health care, I argue that what we really need to address the relevant policy issues adequately is a theory of health care justice, as opposed to an all-purpose conception of justice. Daniels has made an important start toward that goal, though there are some large policy areas which I discuss that his account of health care justice does not really speak to. Finally, practical matters of health care justice really need to be addressed in a ‘non-ideal’ mode, a framework in which philosophers have done little.     

A program for constructing SVT tests: An alternative way of assessing text comprehension

The sentence verification technique (SVT), developed by Royer, Hastings, and Hook (1979), provides developmental and educational researchers with an alternative way of assessing text comprehension based on all of the information contained in a passage. Students must decide if test sentences have the same meaning as sentences that appeared in an original passage. The program described here automates the more laborious aspects of constructing SVT tests. The user must create a passage using a word processor. The program will prompt the user for information as needed. Finally, printable text files (SVT test and answer key) are generated. The program is written in BASIC for IBM and IBM-compatible computers.