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PubMed2001

Eddies in the stream: the prevalence of uncertain plans for retirement.

OBJECTIVE: This study examined an assumption of retirement theory that typifies older workers as preretirees who are planfully engaged in paths toward retirement. METHODS: Using survey responses among workers in the 1992 and 1994 waves of the Health and Retirement Study, we described the prevalence of nonsubstantive answers to questions about the expected form and timing of retirement (e.g., "don't know," "haven't thought about it"). We tested explanations for this uncertainty as an artifact of the survey process, but also as an outcome of the opportunity structure for retirement planning. RESULTS: Survey procedure did generate some of these noncommittal responses. Depending on question type, approximately 10% to 40% of workers did not state when or how they would retire, and such responses were less prevalent across age and time. In addition, categorical uncertainty about form and timing was theoretically predictable in a framework that supposed that workers less subject to a socially attended life--at work or away--would be more undecided about the future. DISCUSSION: Uncertainty is an authentic, meaningful stance toward retirement that theory and research design should not ignore. Just as actual transitions to retirement can be ambiguous or blurred, the expectation of retirement, as well, can be untidy.

Age Factors↗
PubMed1994

The special nature of psychoanalytic facts.

Psychoanalytic facts are almost always capable of being put into words and they include things the patient tells us, things we tell the patient, and things we tell our colleagues. They include various combinations of observation and theory, evidence and hearsay, dream and reality. In contrast to the more usual facts of the everyday world, a psychoanalytic fact is almost never based on pure observation and it is partly for this reason that a dispute over facts frequently conceals a dispute over theory. It also follows that bare facts are almost never presented by themselves; when they are presented (as in a publication), they are almost never quite the same as when experienced in the session. Some meanings are lost in publication; others are inadvertently added by the reader, as he tries to fill in the gaps of a vague report. 'Clinical' facts (which have just been described) should be distinguished from 'contextual' facts, which colour the way we hear the patient's reports, and from 'latent' facts, which cannot be detected by the analyst in the session but must be measured by other techniques. Because the proportion of theory to observation is probably greater in clinical facts than in latent facts, the latter may provide more reliable measures of a clinical happening. Greater reliance on latent facts may also reduce our dependence on metaphor and smooth the transition from clinical moment to published account.

Adult↗
PubMed1975

The attainment of formal operations: a comparison of probability concepts in deaf and hearing adolescents.

In a series of six experiments deaf and hearing adolescents were compared on attainment of formal operations in Piaget's theory as represented by performance on probability problems. Performance of deaf subjects provided a desirable control comparison, since their knowledge of probability concepts was most likely acquired outside school classrooms. The probability problems were usually binary choice situations that required no verbalizations and were designed to illuminate strategies, as well as to indicate conceptual stage. Two experiments, one a long-term training study of over two years' duration, used supplementary preadolescent subject groups. Most of the hearing adolescents and many of the deaf adolescents attained the formal operatory level for probability concepts according to the criteria described by Piaget and Inheldermtheir criteria can be criticized, however, as insufficiently demanding, although they do point up the difficulty of defining the place of computational abilities in formal operationsmresults from several experiments suggested a second and higher level of formal operatory attainment around the ages of 14 to 15. Further theoretical insights were obtained regarding the implicit rules that frequently appeared to guide subjects' choices; a surprising variety of strategies were reported. Analysis of choice tendendies showed consistent avoidance of calculations and selection of the choice with the greatest absolute rather than relative frequency (or area) even when these strategies produced systematic errors. Subjects were generally unable to combine probability information from two different sources. In the long-term training experiment spontaneous improvement was shown by children at formal operatory ages even without training, but not by younger children. Deaf adolescents performed as well as hearing adolescents on easy problems, but they made more errors on several types of more difficult problems; Deaf adolescents were also less consistent than the hearing in use of rules, and in several experiments they showed a two- to three-year performance lag.

Achievement↗
PubMed2000

Cavity formation and the drying transition in the lennard-jones fluid

By simulation and theory, we study the probability of observing N molecular centers within molecular sized volumes for a Lennard-Jones fluid near liquid-vapor coexistence. For large volumes and small N, the probability distribution differs markedly from Gaussian. The free energy per unit surface area to form empty volumes (i.e., cavities) is a rapidly varying function of the radius for small cavities. It becomes constant for large volumes. The source of these behaviors is the occurrence of drying (i.e., solvent depletion) at the cavity surface. The crossover to drying occurs on microscopic length scales, with significant density depletion found for cavities with radii of the order of two or more Lennard-Jones diameters. Reasonable agreement is found between the simulation results and the theory developed by Lum, Chandler, and Weeks [J. Phys. Chem. B 103, 4570 (1999)].

Journal Article↗
PubMed1990

Schedules of presentation and temporal distinctiveness in human memory.

Recency, in remembering a series of events, reflects the simple fact that memory is vivid for what has just happened but deteriorates over time. Theories based on distinctiveness, an alternative to the multistore model, assert that the last few events in a series are well remembered because their times of occurrence are more highly distinctive than those of earlier items. Three experiments examined the role of temporal and ordinal factors in auditorily and visually presented lists that were temporally organized by distractor materials interpolated between memory items. With uniform distractor periods, the results were consistent with Glenberg's (1987) temporal distinctiveness theory. When the procedure was altered so that distractor periods became progressively shorter from the beginning to the end of the list, the results were consistent for only the visual modality; the auditory modality produced a different and unpredicted (by the theory) pattern of results, thus falsifying the claim that the auditory modality derives more benefit from temporal information than the visual modality. We distinguish serial order information from specifically temporal information, arguing that the former may be enhanced by auditory presentation but that the two modalities are more nearly equal with respect to the latter.

Auditory Perception↗
PubMed2003

Risk perception of traffic participants.

This article analyzes the risk perception of traffic participants by making use of Prospect Theory. This methodology makes a conceptual distinction between the perception of risk and the perception of the outcome of an uncertain event. In the field of transport safety such a distinction is desirable, because risks are typically very low and thus sensitive to misperception by traffic participants. Taking into account such misperception will significantly improve estimates of the valuation of transport safety. The first empirical results show that the valuation of losses is well represented by a utility function that is concave in shape. Secondly, our preliminary results show that individuals base their choice mainly on the possible outcomes and not so much on probabilities whenever there are very small probabilities (say <or=1/100) and "bad outcomes" involved.

Accidents, Traffic↗
PubMed2004

Functional systems theory and the probabilistic prediction of behavior.

This article addresses the role of probabilistic prediction in the systems organization of behavioral acts. The systems mechanisms predicting the required results of the behavioral acts of living beings in stable and changing conditions are discussed. It is suggested that in all these types of behavior, the parameters of results satisfying the leading needs, which constitute the aims of behavior, are strictly predicted. The author believes that probabilistic prediction is related only to the means, actions, and accompanying emotional states, as well as that possible ways of achieving results, i.e., not to the parameters but to the means of achieving the required results.

Behavior↗
PubMed1990

An analysis of memory-based theories of automaticity.

Memory-based theories of automaticity predict that performance in a memory search task which is automatic will not require a representation of the memory set in working memory. The information contained in working memory was manipulated by inserting an interference task between the presentation of a memory set and a probe stimulus in a memory search task. The interference task prevented rehearsal, necessitating the retrieval of the memory set from long-term memory in variably mapped (VM) conditions. Performance in consistently mapped (CM) conditions provided strong support for memory-based theories of automaticity. With CM practice, both the effects of memory load and the effect of the interference task were eliminated. Furthermore, there was a temporal coupling in the reduction of these two effects with consistent practice. Monte Carlo simulations of memory-based automaticity predict such a temporal coupling. Automaticity is viewed as a continuum reflecting the relative contribution of the direct memory access of past solutions from long-term memory on performance.

Adolescent↗
PubMed2005

Victimization of the elderly homeless.

Using data from the National Survey of Homeless Assistance Providers and Clients (NSHAPC), this article examines the applicability of Felson's Routine Activities Theory to a national probability sample of older homeless individuals. Results indicate that the relative protection that women often have from most crimes is not transferred to the older homeless woman who is more likely than her male counterparts to be the victim of sexual assault but equally as likely to be the victim of theft and physical assault. Likewise, the protection often noted afforded by age against victimization is also not seen among the homeless. The research demonstrates that being male and having mental and physical health problems as well as substance abuse problems increases the likelihood of victimizations among the homeless population, in general When predictors of victimization were considered for the 50 and older sample, these predictors remained the same except that the gender remained significant only for sexual assault. These findings are consistent with and supportive of utilizing Felson's Routine Activities Theory to understand and explain victimization among the older homeless population.

Adult↗
PubMed2006

Relationships among trait, situational, and comparative optimism: clarifying concepts for a theoretically consistent and evidence-based intervention to maximize resilience.

Research evidence identifies trait optimism as the strongest individual predictor of adolescent resilience when framed within Lazarus's theory of stress and coping. As a precursor to the development of an intervention to maximize resilience, this study clarifies the concept of optimism. Relationships among trait, situational, and comparative optimism were explored. The sample (N = 132) consisted of rural adolescents between 14 and 18 years old who were attending public school. The results demonstrate weak correlations, suggesting that adolescents' perceptions of situations may be amenable to an intervention to maximize resilience but that adolescents also do not expect to experience health or environmental problems. Implications for developing an intervention are discussed.

Adaptation, Psychological↗
PubMed1994

Multi-step rhodopsin inactivation schemes can account for the size variability of single photon responses in Limulus ventral photoreceptors.

Limulus ventral photoreceptors generate highly variable responses to the absorption of single photons. We have obtained data on the size distribution of these responses, derived the distribution predicted from simple transduction cascade models and compared the theory and data. In the simplest of models, the active state of the visual pigment (defined by its ability to activate G protein) is turned off in a single reaction. The output of such a cascade is predicted to be highly variable, largely because of stochastic variation in the number of G proteins activated. The exact distribution predicted is exponential, but we find that an exponential does not adequately account for the data. The data agree much better with the predictions of a cascade model in which the active state of the visual pigment is turned off by a multi-step process.

Animals↗
PubMed1996

Empirical error-confidence curves for neural network and Gaussian classifiers.

"Error-Confidence" measures the probability that the proportion of errors made by a classifier will be within epsilon of EB, the optimal (Bayes) error. Probably Almost Bayes (PAB) theory attempts to quantify how this confidence increases with the number of training samples. We investigate the relationship empirically by comparing average error versus number of training patterns (m) for linear and neural network classifiers. On Gaussian problems, the resulting EC curves demonstrate that the PAB bounds are extremely conservative. Asymptotic statistics predicts a linear relationship between the logarithms of the average error and the number of training patterns. For low Bayes error rates we found excellent agreement between the prediction and the linear discriminant performance. At higher Bayes error rates we still found a linear relationship, but with a shallower slope than the predicted-1. When the underlying true model is a three-layer network, the EC curves show a greater dependence on classifier capacity, and the linear predictions no longer seem to hold.

Bayes Theorem↗
PubMed2001

Independent contribution of myocardial perfusion defects to exercise capacity and heart rate recovery for prediction of all-cause mortality in patients with known or suspected coronary heart disease.

OBJECTIVES: The goal of this study was to determine the value of thallium201 single photon emission computed tomography (SPECT) imaging for prediction of all-cause mortality when considered along with functional capacity and heart rate recovery. BACKGROUND: Myocardial perfusion defects identified by thallium201 SPECT imaging are predictive of cardiac events. Functional capacity and heart rate recovery are exercise measures that also have prognostic implications. METHODS: We followed 7,163 consecutive adults referred for symptom-limited exercise thallium SPECT (mean age 60 +/- 10, 25% women) for 6.7 years. Using information theory, we identified a probable best model relating nuclear findings to outcome to calculate a prognostic nuclear score. RESULTS: There were 855 deaths. Intermediate- and high-risk prognostic nuclear scores were noted in 28% and 10% of patients. Compared with those with low-risk scans, patients with an intermediate-risk score were at increased risk for death (14% vs. 9%, hazard ratio: 1.67, 95% confidence interval [CI]: 1.44 to 1.95, p < 0.0001), while those with high-risk scores were at greater risk (24%, hazard ratio: 2.98, 95% CI: 2.49 to 3.56, p < 0.0001). In multivariable analyses that adjusted for clinical characteristics, functional capacity and heart rate recovery, an intermediate-risk nuclear score remained predictive of death (adjusted hazard ratio: 1.50, 95% CI: 1.28 to 1.76, p < 0.0001), as did a high-risk score (adjusted hazard ratio: 2.76, 95% CI: 2.13 to 2.56, p < 0.0001). Impaired functional capacity and decreased heart rate recovery provided additional prognostic information. CONCLUSIONS: Myocardial perfusion defects detected by thallium SPECT imaging are independently predictive of long-term all-cause death, even after accounting for exercise capacity, heart rate recovery and other potential confounders.

Activities of Daily Living↗
PubMed1995

Recruitment to a university alcohol program: evaluation of social marketing theory and stepped approach model.

BACKGROUND: This study was a first initiative to evaluate the application of social marketing theory (SMT) to increase attendance at an alcohol abuse education program for university residence hall students and to ascertain whether aggressive recruitment strategies are necessary as part of the stepped approach model (SAM) of service delivery. METHOD: SMT and public health strategies that include focus groups, in-depth interviews, and intercept interviews were used to develop recruitment materials in a Test Hall. These new recruitment materials were introduced to the residents in the Treatment Hall (N = 727) and were compared to the Usual Care, Control Hall (N = 706) which received the recruitment materials normally provided to residents as well as to three Historical Halls separately and combined which had used the Usual Care recruitment materials in the past. RESULTS: The Treatment Hall percentage attendance was significantly superior (0.001 < p < 0.05) in all comparisons. The percentage attendance did not differ significantly from marketing literature expectations. The projections for campus-wide attendance for residence hall students were between 207 and 243 participants and for nationwide attendance, 36,900 +/- 8,185. CONCLUSIONS: The results suggest that the SMT and public health methods used are helpful in developing recruitment strategies and are an important initial step of the SAM and that a "minimal intervention" recruitment strategy is a cost-effective approach that can have a dramatic impact.

Adolescent↗
PubMed2004

Probability density functions of decaying passive scalars in periodic domains: an application of Sinai-Yakhot theory.

Employing the formalism introduced by Phys. Rev. Lett. 63, 1962 (1989)], we study the probability density functions (pdf's) of decaying passive scalars in periodic domains under the influence of smooth large scale velocity fields. The particular regime we focus on is one where the normalized scalar pdf's attain a self-similar profile in finite time, i.e., the so-called strange or statistical eigenmode regime. In accordance with the work of Sinai and Yakhot, the central regions of the pdf's are power laws. However, the details of the pdf profiles are dependent on the physical parameters in the problem. Interestingly, for small Peclet numbers the pdf's resemble stretched or pure exponential functions, whereas in the limit of large Peclet numbers, there emerges a universal Gaussian form for the pdf. Numerical simulations are used to verify these predictions.

Journal Article↗
PubMed2003

An evidential support accumulation model of subjective probability.

A model of cue-based probability judgment is developed within the framework of support theory. Cue diagnosticity is evaluated from experience as represented by error-free frequency counts. When presented with a pattern of cues, the diagnostic implications of each cue are assessed independently and then summed to arrive at an assessment of the support for a hypothesis, with greater weight placed on present than on absent cues. The model can also accommodate adjustment of support in light of the baserate or prior probability of a hypothesis. Support for alternatives packed together in a "residual" hypothesis is discounted; fewer cues are consulted in assessing support for alternatives as support for the focal hypothesis increases. Results of fitting this and several alternative models to data from four new multiple-cue probability learning experiments are reported.

Cues↗