A Multinomial Processing Tree inferred from age-related memory-error probabilities: Possibility of inferring more if response times were available

Abstract

Use of Multinomial Processing Tree (MPT) models is illustrated by fitting one to data of Dhir (2017). Her experiment examined age and association type in a paired-associate recall task. Age and Pair-Type had interactive effects on probability of a correct response. A natural interpretation of the interaction would be that both factors impact the same mental process. However, fitting an MPT leads to the conclusion that Age and Pair-Type selectively influence two separate processes, one following the other. A possible interpretation of these is as attempts at specific (verbatim) retrieval and knowledge supported (gist) processing, selectively influenced by Age and Pair-Type, respectively. The order of these processes is not determined by the response probabilities. In a further section of the paper, we show that if response times or other measures had also been available, they could have resolved the process order, but might have left it undetermined. We give necessary and sufficient conditions for two factors to selectively influence two ordered vertices in an MPT, with either order of the vertices accounting for both response probability and response time. They do so if and only if the MPT is equivalent to a special processing tree, not necessarily an MPT itself.