Is vocabulary growth influenced by the relations among words in a language learner's vocabulary?

Several recent studies have explored the applicability of the preferential attachment principle to account for vocabulary growth. According to this principle, network growth can be described by a process in which existing nodes recruit new nodes with a probability that is an increasing function of their connectivity within the existing network. The current study combined subjective estimates of the age of acquisition (AoA) and associations among words in a large corpus to estimate the organization of semantic knowledge at multiple points in vocabulary growth. Consistent with previous studies, the number of connections or relations among words followed a power law distribution in which relatively few words were highly connected with other words and most words were connected to relatively few words. In addition, the growth in the number of connections of a word was a linear function of its initial number of connections, and the ratio of connections to any two words was relatively constant over time. Finally, number of connections to known words was a reliable predictor of a word's AoA. All of these findings can be shown to be consistent with the preferential attachment principle.

Differential impacts of age of acquisition on letter and semantic fluency in Alzheimer's disease patients and healthy older adults.

The degree to which the typical age of acquisition (AoA) of words and word frequency have separable influences on verbal production tasks has been strongly debated. To examine the overlap between these factors in verbal fluency tasks, the performance of Alzheimer's disease (AD) patients (N = 34) and normal elderly controls (N = 36) was compared on semantic (e.g., vegetables) and letter (e.g., words that begin with F) fluency tasks. These comparisons revealed that words generated for the semantic fluency task had an earlier AoA while words generated for the letter fluency task had a higher word frequency. Differences in AoA between AD patients and controls were larger for semantic than letter fluency. These results suggest that AoA has an effect on verbal production that is independent of word frequency and that AoA has a semantic locus.

Is memory for stimulus magnitude Bayesian?

This study was designed to determine whether memory for stimulus values is a Bayesian weighting of the magnitude of a stimulus and the central tendency of an exemplar's category (Huttenlocher, Hedges, & Vevea, 2000). In five experiments, participants reproduced the remembered size of a geometric figure drawn from one of two categories whose means for size differed. Reproductions were biased toward the mean of the combined distribution rather than the mean of either category. Reproductions were also influenced by the size of the stimulus on the preceding trial. Neither of these results is entirely consistent with the view that recollections are partially constructed from a consideration of the long-run probabilities established by category membership.

The nature of memory errors for verbally quantified information.

A variety of theoretical proposals claim that memory is not a faithful reproduction of what was encountered but a blend of what was encountered and knowledge from other sources. We showed participants simple pairings of a person's name and a height or weight or a food name and a calorie count at study. Once veridical responses were removed, there was little evidence that the remaining responses were influenced by the specific value of the studied stimulus. These results suggest that the appearance of memory blends for verbally quantified information may be induced by averaging over different knowledge states.