Evaluating Risk Communications: Completing and Correcting Mental Models of Hazardous Processes, Part II

We propose a decision-analytic framework, called the mental models approach , for evaluating the impact of risk communications. It employs multiple evaluation methods, including think-aloud protocol analysis, problem solving, and a true-false test that allows respondents to express uncertainty about their answers. The approach is illustrated in empirical comparisons of three brochures about indoor radon.     

Modelling Variability in the Branching Structure of Strawberry Inflorescences

The branching structure of inflorescences of the cultivated strawberry ( Fragaria × ananassa Duch.) is very variable. This paper demonstrates that some aspects of this variability are well described by a simple stochastic model of branching that has two adjustable parameters. The model is shown to provide a good fit to data from a set of almost 700 inflorescences of the cultivar Elsanta, collected over two successive years. For one parameter the maximum likelihood estimator is a moment estimator which is fully efficient even if the detailed branching structure of the inflorescences is not recorded. This parameter provides a convenient summary of branching vigour. The maximum likelihood estimator of the second parameter must be determined iteratively and can be quite inefficient unless the full branching structure is recorded. The model demonstrates that branching structure is affected by the order in which inflorescences emerge on the plant.     

Choice of reinforcement rates and work rates with concurrent schedules

A constrained optimisation theory or choice in concurrent schedules of reinforcement is presented. The theory posits that subjects evaluate both reinforcement rates and the work rates required to produce them and select the most highly valued combination. The chosen reinforcement rate is obtained by efficiently allocating work rate across schedules. The theory provides a unified explanation for maximisation of the overall reinforcement rate, the law of least effort, choice under Conc FR FR, Conc VR VR. Conc VI VI and Conc VI VR schedules, and choice of work rate.     

Television as a diagnostic indicator in child therapy: An exploratory study

This paper explores the relation between television viewing and clinical indicators for the mental health profession. Television viewing is seen from a systemic process perspective, based on data about children in therapy from therapists and parents. Family viewing patterns appear to be related to certain types of clinical indicators, especially attention deficit disorder and acting out. Of particular interest is the finding of a strong association between parental viewing habits and ADD on the part of children. The results suggest that television may be a useful indicator of family health for mental health practitioners and researchers.