Measuring category intuitiveness in unconstrained categorization tasks

What makes a category seem natural or intuitive? In this paper, an unsupervised categorization task was employed to examine observer agreement concerning the categorization of nine different stimulus sets. The stimulus sets were designed to capture different intuitions about classification structure. The main empirical index of category intuitiveness was the frequency of the preferred classification, for different stimulus sets. With 169 participants, and a within participants design, with some stimulus sets the most frequent classification was produced over 50 times and with others not more than two or three times. The main empirical finding was that cluster tightness was more important in determining category intuitiveness, than cluster separation. The results were considered in relation to the following models of unsupervised categorization: DIVA, the rational model, the simplicity model, SUSTAIN, an Unsupervised version of the Generalized Context Model (UGCM), and a simple geometric model based on similarity. DIVA, the geometric approach, SUSTAIN, and the UGCM provided good, though not perfect, fits. Overall, the present work highlights several theoretical and practical issues regarding unsupervised categorization and reveals weaknesses in some of the corresponding formal models

The Relationships between the Perception of Physical and Economic Risks Measured within the Road Environment and within the Digital Environment and the Relationships between Risk Perceptions Measured in Separate Environments

Risk perception may be measured in different, separate environments. For example, drivers and pedestrians assess the risks in the road environment and workers assess the risks in the workplace environment. The purpose of this study is to examine the relationships between the risks perceived in several different environments in order to examine whether separate environments – such as the workplace environment and the road environment – are perceived as distinct environments, and whether the knowledge gained by learning to assess risks in one environment can be transferred to a new one. This study found a relationship between measures of risk perception while driving and a while crossing a road. Another finding is that a relationship was observed between the perception of risks related to vaccines and those related to medication, and a relationship was also observed between measures of risk perception while browsing the Internet and while using social media. The relationships between the measures of risk perception while crossing a road and the measures of risk perception while hiking in nature or in the workplace are small, as are the relationships between health-related risks and stock market-related risks. These findings suggest that separate environments, such as the workplace environment and the natural environment, are perceived as distinct environments from the road environment, and that knowledge learned in one environment cannot be transferred and used when in the other environment. The findings are discussed in the context of digital classroom learning

Isoflavones, lignans and stilbenes – origins, metabolism and potential importance to human health

The glucosinolates are a large group of sulphur-containing compounds which occur in all the economically important varieties of Brassica vegetable. Their common structure comprises a -D-thioglucose group, a sulphonated oxime moiety and a variable side-chain derived from methionine, tryptophan or phenylalanine. When the plant tissue is damaged the glucosinolates are hydrolysed by the endogenous enzyme myrosinase (thioglucoside glycohydrolase EC 3:2:3:1), to release a range of breakdown products including the bitter, biologically active isothiocyanates. Although these compounds exert antinutritional effects in animals there is also substantial evidence that they are the principal source of anticarcinogenic activity in Brassica vegetables, and this provides a strong motive for the manipulation of glucosinolate levels in vegetables for human consumption. This review provides an overview of the evidence for a beneficial role for glucosinolates in human health, and describes the current state of knowledge regarding the genetics and biosynthesis of glucosinolates, their chemical analysis, their behaviour during cooking and processing, and their bioavailability to humans. As the genetic basis of glucosinolate biosynthesis becomes more apparent, and tools for marker-assisted plant breeding become more available, the selective breeding of horticultural brassicas with different levels and types of glucosinolates, whether by conventional means or genetic manipulation, is becoming a practical possibility. However before this strategy becomes commercially viable, the health benefits of glucosinolates for human beings must be unequivocally establishe