There is remarkable agreement between Ruchkin et al.'s psychophysiological views and my own model, based on developmental-experimental evidence, of working memory as activated long-term memory (LTM). I construe subvocal rehearsal as an operative scheme that maintains order information and demands attentional resources. Encoding and retrieving operations also demand attention. Another share of resources is used for keeping activated specific LTM representations.

I compare the concepts of “activation” and “storage” as foundations of short-term memory, and suggest that an attention-based view of STM does not need to posit specialized short-term stores. In particular, no compelling evidence supports the hypothesis of time-limited stores. Identifying sources of activation, examining the role of activated procedural knowledge, and studying working memory development are central issues in modelling capacity-limited focal attention.

This article describes a study on capacity limitations that affect the construction of spatial mental models. A process model is presented, according to which the construction of a mental model in Ehrlich and Johnson-Laird's (1982) spatial descriptions task places a workload of six information chunks for continuous and semi-continuous descriptions, and seven chunks for discontinuous descriptions. Participants (48 undergraduate students) performed the spatial descriptions task and the figural intersections test (FIT), which yields a capacity score. The pattern of errors and (...) sentence reading times in the spatial descriptions task confirmed that participants were using mental models. The FIT score was positively correlated with accuracy in the spatial descriptions task. Prediction analysis of cross-classification tables showed that, for successful performance in continuous and semi-continuous descriptions, a FIT score of 6 was necessary, and a score of 7 in discontinuous descriptions. These results are in agreement with theoretical predictions. The issue of integrating mental models theory with analyses of capacity limitations in performance is discussed. (shrink)