The Latent Structure of Substance Use Among American Indian Adolescents: An Example Using Categorical Variables

Researchers frequently have only categorical data to analyze and cannot, for theoretical or methodological reasons, assume that the observed variables are discrete representations of an underlying continuous variable. We present latent class analysis as an alternative method of measuring latent variables in these circumstances. Latent class analysis does not require the assumptions of factor analyses about the nature of manifest and latent variables, but does allow the use of more precise model selection than techniques such as cluster analysis. We modeled the lifetime substance use of American Indian youth. The latent class model of American Indian teenagers' substance use had four classes: Abstaining, Predominantly Alcohol, Predominantly Alcohol and Marijuana, and Plural Substance. We then demonstrated the usefulness of this latent variable by using it to differentiate levels of several variables in a manner consistent with Social Cognitive Theory.     

Colour perception changes with basic colour word comprehension

Recent work has investigated the origin of infant colour categories, showing pre-linguistic infants categorise colour even in the absence of colour words. These infant categories are similar but not identical to adult categories, giving rise to an important question about how infant colour perception changes with the learning of colour words. Here we present two novel paradigms in which 12- and 19-month-old participants learning English as their first language were assessed on their perception of colour, while data on their colour word comprehension were also collected. Results indicate that participants' perception of colours close to the colour category boundaries dramatically change after colour word learning. The results highlight the shift made from infant colour categories to adult-like linguistically mediated colour categories that accompanies colour word learning.

Research Highlights

• We aimed to test whether colour perception is linguistically mediated in infants.
• We used novel eye-tracking and pupillometry paradigms to test infant colour perception either side of learning colour words.
• Infants' discrimination of colour changes after learning colour words, suggesting a shift due to colour word learning.
• A shift from pre-linguistic colour representation to linguistically mediated colour representation is discussed.

     

Normative roles,conceptual variance,and ardent realism about normativity

ABSTRACT

In Choosing Normative Concepts, Eklund considers a “variance thesis” about our most fundamental (and seemingly most “authoritative”) normative concepts. This thesis raises the threat of an alarming symmetry between different sets of normative concepts. If this symmetry holds, it would be incompatible with “ardent realism” about normativity. Eklund argues that the ardent realist should appeal to the idea of “referential normativity” in response to this challenge. I argue that, even if Eklund is right in his core arguments on this front, many other important challenges for ardent realism remain that also stem from the issues about possible variance in normative concepts that he considers. Following this, I introduce further issues about conceptual variance. These are issues that arise within the context of the framework that Eklund proposes the ardent realist use to confront the variance theses he considers. In particular, the issues concern what normative role as such is, as well as, relatedly, which roles associated with a concept (or predicate) get to count as part of its normative role. The upshot is that issues about conceptual variance in normative domains might be even more challenging for the ardent realist to deal with than Eklund argues.