Although there is a wealth of knowledge on categorization early in life, there are still many unanswered questions about the nature of category representation in infancy. For example, it is unclear whether infants are sensitive to boundaries between complex categories, such as types of animals, or whether young infants exhibit such sensitivity without explicit experience in the lab. Using a morphing technique, we linearly altered the category composition of images and measured 6.5-month-olds’ attention to pairs of animal faces that either did or did not cross the categorical boundary, with the stimuli in each pair being equally dissimilar from one another across the two types of image pairs. Results indicated that infants dichotomize the continua between cats and dogs and between cows and otters, but only when the images are presented in their canonical, upright orientations. These findings demonstrate a propensity to dichotomize early in life that could have implications for social categorizations, such as race and gender.

In clinical research, it is sometimes desirable to dichotomize a continuous variable so that the information expressed using a dichotomous variable is more straightforward for clinicians to interpret and communicate. The distribution of a continuous variable can differ between two populations defined by the case status. Under such a scenario, the dichotomization process can be based on distributions of the continuous variable in two distinct populations. The resulting dichotomous variable can be used as an endpoint in future studies. Even though dichotomization has not been extensively studied, dichotomization has been commonly carried out in clinical trials. We developed a methodology on dichotomization based on maximizing the correlation between the two populations and the dichotomous variable. We have investigated several commonly assumed distributions (e.g., normal, log-normal and gamma distribution) of the continuous variable for the two populations and developed a numerical algorithm for the proposed method to determine the optimal cutoff point. The two populations can differ in form and/or parameters. The proposed method of finding the optimal cutoff was also extended to adjust for covariates. In real world scenarios where the two samples from the two populations are not completely identified, we recommended using the EM method to first estimate the parameters associated with the two populations before applying the proposed method to find the optimal cutoff point. The performance of the proposed method with the numerical algorithm and the EM method has been studied for several theoretical distributions and using simulated data. These methods were also applied to a varicella vaccine example. / Statistics

The aim of this thesis is to describe some central conceptual ideas expressed in the language of six computer interested boys. The starting-point is the philosophy of language of Ludwig Wittgenstein, where language is seen as something deeply integrated in our practices, traditions and culture. The use of our language shows its meaning. The material consists of 18 months of observations in the computer room of a secondary school and a series of three deep-interviews with each one of the boys over a period of three years. The computer has a central function in their identity work. Within our culture, this object - with its structure and its ways of operating - has become a metaphor for human thinking. It offers freedom and control. The discussions involved in this work and its form of representation problemize some of the fundamental assumptions of linguistics and the humanities. The three portraits (chapters 3-5) are to be understood as meaningful examples, while the persons portrayed are to be seen as symbols, inviting the reader to reflect over our culture and our practices. The fostering into the computer world and the ways of looking at the world are shown through the "personal voice", each followed by an interpretation linked to the theories and results of other researchers. In the boys' ways of using language there are differences and similarities. Learning, growing, creating, signifying 'freedom', can be seen as central notions in the identity work of one of them. With another of the boys there is a strong resemblance in his talking of computers and of his personal God; he "fixes" the world through dividing-lines, strong recommendations, further emphasized through the frequent use of the verb ska (shall, should). In the third portrait it is evident that the boy's abundance of words and narrative-making is a strategy of preventing nearness and to be able both to control the interview situation and to intensify the here and now. "Going deep" into computers make certain assumptions about the world more essential than others. Central concepts explicit in their common language game are logic, power and control (chapter 7). There is a common tendency to hierarchize and dichotomize the world; upper/under world, outer/inner world, logic/feeling, we/they, right/wrong. Stability can be seen as a summarizing notion. The deeper significance of their feeling of safety and control in the computer world is a fostering both into male dominance and into a dominant way of thinking about knowledge as something primarily logical, controllable and possible to account for. This masculinist language game is confirmed in different ways: individually, in the group and at a more subtle and symbolic level. / <p>Diss. Umeå : Univ., 1992</p> / digitalisering@umu