Chromatic confocal displacement sensing at oblique incidence angles.

A commercial chromatic confocal displacement sensor, designed for probing a target at normal incidence, is adapted to probe reflective targets at an oblique incidence angle. The sensor is modified by positioning two low-cost optical elements-a collimating lens and a retro-reflector-in the reflection plane.

Involving schoolchildren in radon surveys by means of the "RadonTest" online system.

A 'citizen science' approach was evaluated as an approach to organize an extensive radon survey to be representative of the population of either single regions or a whole country. The "RadonTest" online system allowed schoolchildren to undertake and record short-term radon tests in their homes. Measurements were carried out in Israel using charcoal in miniature flacons and simple detectors with high sensitivity. Among other things, the "RadonTest" online system implements an alternative principle of building a radon map, allowing the display of radon tests more clearly than the traditional approach, while ensuring the confidentiality of test participants. Examples of public radon maps are presented, and the first test results are discussed. A scientifically based approach for the effective identification of buildings with a high radon concentration, based on the principle of radon regulation, is proposed.

Expanding the realm of fiber optic confocal sensing for probing position, displacement, and velocity.

We describe a fiber optic confocal sensor (FOCOS) system that uses an optical fiber and a lens to accurately detect the position of an object at, or close to, the image plane of the fiber tip. The fiber characteristics (diameter and numerical aperture) and optics (lens F/# and magnification) define the span and precision of the sensor and may be chosen to fit a desired application of position and displacement sensing. Multiple measurement points (i.e., fiber-tip images) may be achieved by use of multiple wavelengths in the fiber, so that each wavelength images the fiber at a different plane due to the chromatic dispersion of the optics. Further multiplexing may be achieved by adding fibers on the optical axis. A FOCOS with multiplexed fibers and wavelengths may also be used for velocity measurements.

The beguiling pursuit of more information.

BACKGROUND: The authors tested whether clinicians make different decisions if they pursue information than if they receive the same information from the start. METHODS: Three groups of clinicians participated (N=1206): dialysis nurses (n=171), practicing urologists (n=461), and academic physicians (n=574). Surveys were sent to each group containing medical scenarios formulated in 1 of 2 versions. The simple version of each scenario presented a choice between 2 options. The search version presented the same choice but only after some information had been missing and subsequently obtained. The 2 versions otherwise contained identical data and were randomly assigned. RESULTS: In one scenario involving a personal choice about kidney donation, more dialysis nurses were willing to donate when they first decided to be tested for compatibility and were found suitable than when theyknew they were suitable from the start (65% vs. 44%, P= 0.007). Similar discrepancies were found in decisions made by practicing urologists concerning surgery for a patient with prostate cancer and in decisions of academic physicians considering emergency management for a patient with acute chest pain. CONCLUSIONS: The pursuit of information can increase its salience and cause clinicians to assign more importance to the information than if the same information was immediately available. An awareness of this cognitive bias may lead to improved decision making in difficult medical situations.

Misremembrance of options past: source monitoring and choice.

This study reveals that when remembering past decisions, people engage in choice-supportive memory distortion. When asked to make memory attributions of options' features, participants made source-monitoring errors that supported their decisions. They tended to attribute, both correctly and incorrectly, more positive features to the option they had selected than to its competitor. In addition, they sometimes attributed, both correctly and incorrectly, more negative features to the nonselected option. This pattern of distortion may be beneficial to people's general well-being, reducing regret for options not taken. At the same time, it is problematic for memory accuracy, for accountability, and for learning from past experience.

Why some are perceived as more confident and more insecure, more reckless and more cautious, more trusting and more suspicious, than others: enriched and impoverished options in social judgment.

In line with the principle of compatibility, when making social judgments, people tend to focus on personality attributes compatible with the trait under consideration. Better known, or enriched, personages are more likely to present attributes that are compatible with a particular trait than are personages about whom little is known. As a result, enriched personages are more likely to have various, sometimes even conflicting, traits attributed to them. This hypothesis is supported by a number of studies that compare the frequency with which some people are chosen as being better described by opposite trait adjectives than are others. Celebrities more often have both of a pair of opposing adjectives ascribed to them than do less well known figures. Similarly, subjects judge themselves to be better described by either of a pair of opposite adjectives than is a person who is relatively unknown in their lives. The implications for social judgment and for everyday decisions are discussed.

On the pursuit and misuse of useless information.

Decision makers often pursue noninstrumental information--information that appears relevant but, if simply available, would have no impact on choice. Once they pursue such information, people then use it to make their decision. Consequently, the pursuit of information that would have had no impact on choice leads people to make choices they would not otherwise have made. The pursuit of noninstrumental information is documented and its effects on ensuing decisions are explored in a variety of social, consumer, and strategic situations. The causes and implications of this pattern are discussed.

Medical decision making in situations that offer multiple alternatives.

OBJECTIVE: To determine whether situations involving multiple options can paradoxically influence people to choose an option that would have been declined if fewer options were available. DESIGN: Mailed survey containing medical scenarios formulated in one of two versions. PARTICIPANTS: Two groups of physicians: members of the Ontario College of Family Physicians (response rate = 77%; n = 287) and neurologists and neurosurgeons affiliated with the North American Symptomatic Carotid Endarterectomy Trial (response rate = 84%; n = 352). One group of legislators belonging to the Ontario Provincial Parliament (response rate = 32%; n = 41). INTERVENTION: The basic version of each scenario presented a choice between two options. The expanded version presented three options: the original two plus a third. The two versions otherwise contained identical information and were randomly assigned. OUTCOME MEASURES: Participants treatment recommendations. RESULTS: In one scenario involving a patient with osteoarthritis, family physicians were less likely to prescribe a medication when deciding between two medications than when deciding about only one medication (53% vs 72%; P < .005). Apparently, the difficulty in deciding between the two medications led some physicians to recommend not starting either. Similar discrepancies were found in decisions made by neurologists and neurosurgeons concerning carotid artery surgery and by legislators concerning hospital closures. CONCLUSIONS: The introduction of additional options can increase decision difficulty and, hence, the tendency to choose a distinctive option or maintain the status quo. Awareness of this cognitive bias may lead to improved decision making in complex medical situations.

Extracting the coherent core of human probability judgement: a research program for cognitive psychology.

Human intuition is a rich and useful guide to uncertain events in the environment but suffers from probabilistic incoherence in the technical sense. Developing methods for extracting a coherent body of judgement that is maximally consistent with a person's intuition is a challenging task for cognitive psychology, and also relevant to the construction of artificial expert systems. The present article motivates this problem, and outlines one approach to it.

Uncertainty and the difficulty of thinking through disjunctions.

This paper considers the relationship between decision under uncertainty and thinking through disjunctions. Decision situations that lead to violations of Savage's sure-thing principle are examined, and a variety of simple reasoning problems that often generate confusion and error are reviewed. The common difficulty is attributed to people's reluctance to think through disjunctions. Instead of hypothetically traveling through the branches of a decision tree, it is suggested, people suspend judgement and remain at the node. This interpretation is applied to instances of decision making, information search, deductive and inductive reasoning, probabilistic judgement, games, puzzles and paradoxes. Some implications of the reluctance to think through disjunctions, as well as potential corrective procedures, are discussed.

Ampliative inference: on choosing a probability distribution.

Ampliative inference is the choice of a probability distribution on the basis of incomplete information. We consider some psychological and normative questions that arise about this kind of reasoning. The discussion is largely tutorial although a substantive hypothesis is also advanced.

Reason-based choice.

This paper considers the role of reasons and arguments in the making of decisions. It is proposed that, when faced with the need to choose, decision makers often seek and construct reasons in order to resolve the conflict and justify their choice, to themselves and to others. Experiments that explore and manipulate the role of reasons are reviewed, and other decision studies are interpreted from this perspective. The role of reasons in decision making is considered as it relates to uncertainty, conflict, context effects, and normative decision rules.

Similarity, plausibility, and judgments of probability.

Judging the strength of an argument may underlie many reasoning and decision-making tasks. In this article, we focus on "category-based" arguments, in which the premises and conclusion are of the form All members of C have property P, where C is a natural category. An example is "Dobermans have sesamoid bones. Therefore, German shepherds have sesamoid bones." The strength of such an argument is reflected in the judged probability that the conclusion is true given that the premises are true. The processes that mediate such probability judgments depend on whether the predicate is "blank"--an unfamiliar property that does not enter the reasoning process (e.g., "have sesamoid bones")--or "non-blank"--a relatively familiar property that is easier to reason from (e.g., "can bite through wire"). With blank predicates, probability judgments are based on similarity relations between the premise and conclusion categories. With non-blank predicates, probability judgements are based on both similarity relations and the plausibility of premises and conclusion.

Choosing versus rejecting: why some options are both better and worse than others.

A previously unobserved pattern of choice behavior is predicted and corroborated. In line with the principle of compatibility, according to which the weighting of inputs is enhanced by their compatibility with output, the positive and negative dimensions of options (their pros and cons) are expected to loom larger when one is choosing and when one is rejecting, respectively. Subjects are presented with pairs of options, one of which--the enriched option--has more positive as well as more negative dimensions than does the other, impoverished, option. Because positive dimensions are weighted more heavily in choosing than in rejecting, and negative dimensions are weighted more heavily in rejecting than in choosing, the enriched option tends to be chosen and rejected relatively more often than the impoverished option. These findings are extended to nonbinary decision problems, and their implications for the rational theory of choice and for everyday decisions are discussed.

Thinking through uncertainty: nonconsequential reasoning and choice.

When thinking under uncertainty, people often do not consider appropriately each of the relevant branches of a decision tree, as required by consequentialism. As a result they sometimes violate Savage's sure-thing principle. In the Prisoner's Dilemma game, for example, many subjects compete when they know that the opponent has competed and when they know that the opponent has cooperated, but cooperate when they do not know the opponent's response. Newcomb's Problem and Wason's selection task are also interpreted as manifestations of nonconsequential decision making and reasoning. The causes and implications of such behavior, and the notion of quasi-magical thinking, are discussed.

Geometrical separation between the birefringence components in Faraday-rotation fiber-optic current sensors.

A novel optical fiber current sensor for low-current measurements is proposed and tested. By winding a commonly used low-birefringence single-mode optical fiber in a special geometry, one can circumvent the bend-induced birefringence problem. Smaller sensors can now be built with a sensitivity that linearly increases with the number of fiber windings.

Typicality and reasoning fallacies.

The work of Tversky and Kahneman on intuitive probability judgment leads to the following prediction: The judged probability that an instance belongs to a category is an increasing function of the typicality of the instance in the category. To test this prediction, subjects in Experiment 1 read a description of a person (e.g., "Linda is 31, bright, ... outspoken") followed by a category. Some subjects rated how typical the person was of the category, while others rated the probability that the person belonged to that category. For categories like bank teller and feminist bank teller: (1) subjects rated the person as more typical of the conjunctive category (a conjunction effect); (2) subjects rated it more probable that the person belonged to the conjunctive category (a conjunction fallacy); and (3) the magnitudes of the conjunction effect and fallacy were highly correlated. Experiment 2 documents an inclusion fallacy, wherein subjects judge, for example, "All bank tellers are conservative" to be more probable than "All feminist bank tellers are conservative." In Experiment 3, results parallel to those of Experiment 1 were obtained with respect to the inclusion fallacy.

Asymmetric behavior of polished polarization-maintaining couplers.

Basic asymmetric behavior is experimentally observed in a polished polarization-maintaining fiber coupler. As the two half-couplers are made to slide on top of each other, the output extinction ratio exhibits relatively large variations whose forms depend on the fiber that is selected for the input. We propose that a local distortion of the fiber birefringent axes, which could be caused by the half-coupler polishing process, can generate such features even when the launched light is perfectly polarized along a principal axis of the input fiber.