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Studies of syllogistic reasoning have shown that the size of the belief bias effect varies with manipulations of logical validity and problem form. This paper presents a mental models-based account, which explains these findings in terms of variations in the working-memory demands of different problem types. We propose that belief bias may reflect the use of a heuristic that is applied when a threshold of uncertainty in one's processing--attributable to working-memory overload--is exceeded during reasoning. Three experiments are reported, which tested predictions deriving from this account. In Experiment 1, conclusions of neutral believability were presented for evaluation, and a predicted dissociation was observed in confidence ratings for responses to valid and invalid arguments, with participants being more confident in the former. In Experiment 2, an attempt to manipulate working-memory loads indirectly by varying syllogistic figure failed to produce predicted effects upon the size of the belief bias effect. It is argued that the employment of a conclusion evaluation methodology minimized the effect of the figural manipulation in this experiment. In Experiment 3, participants' articulatory and spatial recall capacities were calibrated as a direct test of working-memory involvement in belief bias. Predicted differences in the pattern of belief bias observed between high and low spatial recall groups supported the view that limited working memory plays a key role in belief bias.

Bookmarks are a valuable webpage re-visitation technique, but it is often difficult to find desired items in extensive bookmark collections. This experiment used response-time measures and eye-movement tracking to investigate how different information structures within bookmarks influence their salience and recognizability. Participants were presented with a series of news websites. The task following presentation of each site was to find the bookmark indexing the previously-seen page as quickly as possible. The Informational Structure of bookmarks was manipulated (top-down vs. bottom-up verbal organizations), together with the Number of Informational Cues present (one, two or three). Only this latter factor affected gross search times: Two cues were optimal, one cue was highly sub-optimal. However, more detailed eye-movement analyses of fixation behaviour on target items revealed interactive effects of both experimental factors, suggesting that the efficacy of bookmark recognition is crucially dependent on having an optimal combination of information quantity and information organization.

Three experiments are reported that used eye-movement tracking to investigate the inspection-time effect predicted by Evans' (1996) heuristic-analytic account of the Watson selection task. Evans' account proposes that card selections are based on the operation relevance -determining heuristics, whilst analytic processing only rationalizes selections. As such, longer inspection times should be associated with selected cards (which are subjected to rationalization) than with rejected cards. Evidence for this effect has been provided by Evans (1996) using computer-presented selection tasks and instructions for participants to indicate (with a mouse pointer) cards under consideration. Roberts (1996) has argued that mouse pointing gives rise to artefactual support for Evans' predictions because of biases associated with the task format and the use of mouse pointing. We eradicated all sources of artefact by combining careful task constructions with eye-movement tracking to measure directly on-line attentional processing. All three experiments produced good evidence for the robustness of the inspection-time effect, supporting predictions of the heuristic-analytic account.