Nivel Municipal

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memory studied is working memory, which is operationalized using tests for memory span. This form of memory has been defined as the ability to recall a number of distinct elements for

immediate reproduction (Ekstrom, French, Harman, & Dermen, 1976b, p. 101). Several studies have investigated working memory in IIR. MacFarlane, et al., (2012) designed a study to

understand the impact of impaired memory on information search behaviors by comparing participants with normal memory abilities to participants with dyslexia, a reading disorder caused in part by impairment in phonological processing and working memory. They found that participants with reduced working memory abilities judged fewer documents non-relevant than participants with higher working memory abilities. Participants conducted searches using the TIPSTER collection from TREC 7 and 8. The researchers identified phonological processing working memory as the ability that enables the person to retain words in memory for the several seconds it takes to process and map the meanings of the words to the printed text. Difficulties created by a deficiency in this ability hinder the person’s reading, spelling, and comprehension skills. The researchers tested the eight dyslexic and eight non-dyslexic participants for their reading, comprehension, and spelling abilities; working memory using the Wechsler Adult Intelligence “Digit Span” Scale; as well as for dyslexia using several established assessment instruments. Logged measures included total documents read, judged relevant, judged non- relevant, and examined. They also measured changes of judgments from relevant to non- relevant, level of agreement with TREC relevance judgments, session length, number of searches, hit-lists examined and pool views per iteration.

Both groups judged the same number of documents as relevant, but non-dyslexic users judged an average of 14 more documents non-relevant than did the dyslexic users. In bivariate correlations between the number of documents judged non-relevant and the cognitive measures,

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the researchers found that number of documents judged non-relevant was positively correlated with scores on the digit span test (i.e., the measure of phonological working memory).

Participants with higher digit span scores (i.e., the non-dyslexic participants) judged more documents non-relevant. They suggested that deciding a document is relevant requires less cognitive effort than determining that a document is not relevant. They based this on the notion that in order to determine a document non-relevant, one would have to read and maintain in working memory the contents of the entire document in order to determine if the document matched or did not match the topic, whereas in order to determine that a document is relevant, all one has to do is identify the satisfaction of the first instance of relevance without having to necessarily read the entire document. Thus, the demands on short-term working memory storage would be greater in the case of determining non-relevant documents.

Other studies focused on individual differences in memory ability outside of those with impairments. Gwizdka (2013) explored the effects of task complexity and memory span ability on participants searching a collection of social bookmarks related to travel, sightseeing, and shopping, under two different interface conditions. Tasks required participants to find information about travel and sightseeing topics to recommend to a friend. The simple task required finding a simple fact, such as the location of an airport, whereas the complex tasks required participants to gather information about multiple topics and sites, such as gathering information about three kinds of art collections that could only be found by searching three different museum websites. The search mechanism was a tag set that automatically re-generated with each results set, as the user added (clicked) and deleted tags to form queries for information. The number of tags that were added and deleted was a proxy for number of query refinements. Tag deletions were considered ‘cognitive moves’, or query reformulations, about half the time

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and ‘physical moves’ or navigation actions to go back to a previous results list the other half. The interfaces were either a textual list of results with just tags and URLs or a list of results that also included a tag cloud overview. Once participants found their answers, they were instructed to write them in a message area on the screen, as if they were making a recommendation to their friend.

Participants were tested for working memory and were divided into high and low groups. The high memory span group interacted more with the search system by performing more

actions to find more information, while the low memory span group was the opposite – they looked at fewer websites and engaged less with the system. Thus, cognitive ability of working memory span interacted with task complexity by affecting the search interaction behaviors of the participants. Gwizdka suspected this to be a type of satisficing behavior on the part of the low working memory span participants. Similar to his earlier work in (Gwizdka, 2009), he found that the extra actions of the high ability working memory span users did not result in necessarily immediate better search task outcomes.