Inferring children's categorizations from sequential touching behaviors: an analytical model

Assessing categorization performance at the individual level: a comparison of Monte Carlo simulation and probability estimate model procedures

Two analytical procedures for identifying young children as categorizers, the Monte Carlo Simulation and the Probability Estimate Model, were compared. Using a sequential touching method, children aged 12, 18, 24, and 30 months were given seven object sets representing different levels of categorical classification. From their touching performance, the probability that children were categorizing was then determined independently using Monte Carlo Simulation and the Probability Estimate Model. The two analytical procedures resulted in different percentages of children being classified as categorizers. Results using the Monte Carlo Simulation were more consistent with group-level analyses than results using the Probability Estimate Model. These findings recommend using the Monte Carlo Simulation for determining individual categorizer classification.

Toddlers can adaptively change how they categorize: same objects, same session, two different categorical distinctions

Two experiments demonstrate that 14- to 18-month-old toddlers can adaptively change how they categorize a set of objects within a single session, and that this ability is related to vocabulary size. In both experiments, toddlers were presented with a sequential touching task with objects that could be categorized either according to some perceptually salient dimension corresponding to a taxonomic distinction (e.g. animals vs. vehicles) or to some less obvious dimension (e.g. rigid vs. deformable). In each experiment, children with larger productive vocabularies responded to both dimensions, showing evidence of sensitivity to each way of categorizing the items. Children with smaller productive vocabularies attended only to the taxonomically related categorical grouping. These experiments confirm that toddlers can adaptively shift the basis of their categorization and highlight the dynamic interaction between the child and the current task in early categorization.

TouchStat v. 3.00: a new and improved Monte Carlo adjunct for the sequential touching task

The sequential-touching procedure is employed by researchers studying nonlinguistic categorization in toddlers. TouchStat 3.00 is introduced in this article as an adjunct to the sequential-touching procedure, allowing researchers to compare children's actual touching behavior to what might be expected by chance. Advantages over the Thomas and Dahlin (2000) framework include ease of use, and fewer assumptive limitations. Improvements over TouchStat 1.00 include calculation of chance probabilities for multiple "special cases" and for immediate intercategory alternations. A new feature for calculating mean run length is also included.

Flexible and Context-Dependent Categorization by Eighteen-Month-Olds

One hundred 18-month-olds were tested using sequential touching and following 4 different priming contexts using sets of toys that could be simultaneously categorized at either the basic or global level. An exact expression of the expected mean sequence length for arbitrary categories was derived as a function of the number of touches made, and a finite mixture model analytic method was also used to explore individual variability in categorization. Toddlers could categorize flexibly and spontaneously selected the level of categorization as a function of the prior prime. Perceptual Variability emerged as a predictor of the level at which infants subsequently categorized. The infants were also able to classify objects as members of both basic- and global-level categories simultaneously.

From infant to child: the dynamics of cognitive change in the second year of life

The authors review several key areas of early cognitive development in which an abrupt shift in ability at the end of the second year of life has been traditionally assumed. These areas include deferred imitation, self-recognition, language, and categorization. Contrary to much conventional theorizing, the evidence shows robust continuities in all domains of early cognitive development. Where there is evidence of a reorganization of behavior that makes a new level of performance possible, dynamic-systems analyses indicate that even these may be driven by underlying processes that are continuous. Although there remain significant definitional and methodological issues to be resolved, the outcome of this review augers well for newer models in which cognitive development is viewed as a continuous, dynamic process.