[Probcogsci] Friday lab meeting: external speaker Angela Nelson

[Angela J. Yu]

Dear all,

Angela Nelson from Indiana University will be giving the following  
talk during this Friday's natcomp lab meeting at 11:15 AM.  Please let  
me know if you are interested in meeting with her.

Title: Modeling the co-evolution of knowledge and event memory
Almost every study since the 1890s has shown that the way episodic (or  
event) memories are encoded depends on the knowledge (or semantic  
memory) of the individual who is encoding them.  The research  
discussed aims to examine these co-evolving processes by training  
novel items (Chinese characters) in a visual search task to have  
differential experience. The induced frequency differences were shown  
to produce marked effects on episodic and implicit memory transfer  
tasks (Nelson & Shiffrin, 2006). Because each novel item is randomly  
assigned for each participant to a frequency category, these results  
are inconsistent with the REM model account of frequency effects  
(Shiffrin & Steyvers, 1997). This account posited higher frequency  
items to have higher frequency features. We present a new variant of  
the REM model incorporating contextual diversity in an item’s  
representation; particularly the diversity imposed by different item  
sets simultaneously in short term memory during training: Features of  
such nearby items join a target item’s representation. This model is a  
simplification of the REM-II model proposed by Mueller and Shiffrin  
(e.g. 2006), and is related to the ideas found in the TCM model of  
Howard and Kahana (e.g. 2002). Because the higher frequency items are  
seen in a larger variety of contexts than lower frequency items, the  
higher frequency items develop a more diverse representation in the  
lexicon, leading to changes in the similarity structure between items  
of differing frequencies. The model is shown to account for frequency  
effects found by Nelson and Shiffrin (2006).

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Angela J. Yu
Assistant Professor
Department of Cognitive Science
UCSD, Mail Code 0515
9500 Gilman Drive
La Jolla, CA 92093-0515

Email: ajyu at cogsci.ucsd.edu
Phone: 858-822-3317
Fax: 858-534-1128
Website: www.cogsci.ucsd.edu/~ajyu
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