Misperceptions of stock and fl ow relationships are pervasive and an important problem to solve in system dynamics. Prior studies have shown that individuals perform poorly on accumulation problems, even when considering relatively simple systems, an effect termed the Stock-Flow (SF) failure. This study examines the effects of domain experience in overcoming the SF failure. We compared performance of medical students and undergraduates with no medical education on accumulation problems in medical and general domains. Medical students performed better than undergraduates only in some of the problems (including the general domain problems), and they performed equally poorly as undergraduates in problems that required medical domain experience. There was no correlation between performance in the stock and fl ow problems and either duration of medical education or age. Thus we conclude that domain experience is not a strong indicator for overcoming the SF failure.

Two experiments were conducted, contrasting a minimally guided discovery condition with a variety of instructional conditions. College students interacted with a computer-based tutor that presented algebralike problems in a novel graphical representation. Although the tutor provided no instruction in a discovery condition, it constrained the possible actions sufficiently that students could always discover the algebraic transformations they needed to learn. In Experiment 1, with ample practice for each new transformation, students performed better in the discovery condition than any instructional condition. In Experiment 2, with only a little practice for each transformation, students performed worst in the discovery condition. The authors suggest that the high levels of practice in the 1st experiment made students more efficient at discovering the algebraic transformations. When the cognitive demands were manageable, the discovery students may have more often encoded the algebraic transformations in mathematically correct ways.

Hypertext research results suggest that building a correct representation of the hypertext structure enables users to navigate effectively within the text. Therefore, text comprehension processes involved in hypertext reading should be investigated. In an experimental study, we differentiated the text structure from the dimensions of a postulated coherent situation model in order to compare them. Three electronic text versions, varying in navigational facility, and text structure visualization were compared with respect to orientation, navigation, eye movements, mental representation of text structure and content (situation model). Results demonstrate that when text structure visualization was unavailable, a reorganization of readers’ representations of the text structure towards their situation model took place. Navigation within the text particularly affected mental representation of text structure and content.

This study investigated the ability to generalize acquired skills from training conditions to novel conditions, in a complex perceptual and cognitive task of luggage screening. We examined category and exemplar diversity during training for preparing learners to detect novel items during transfer. Category diversity was manipulated in terms of heterogeneity of training categories: Participants either trained with targets from one category or with targets from several categories. Exemplar diversity was manipulated between participants by presenting either a few or many exemplars for both category diversity conditions. Seventy-two participants were trained to identify threats in pieces of luggage. Thereafter they were transferred to novel stimuli. Results can be summarized in support for the diversity of training hypothesis for preparing for novelty: To the best training for novel luggage screening situations is achieved using fewer items in a variety of categories.