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.

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.

Studies of syllogistic reasoning have demonstrated a nonlogical tendency for people to endorse more believable conclusions than unbelievable ones. This belief bias effect is more dominant on invalid syllogisms than valid ones, giving rise to a logic by belief interaction. We report an experiment in which participants' eye movements were recorded in order to provide insights into the nature and time course of the reasoning processes associated with manipulations of conclusion validity and believability. Our main dependent measure was people's inspection times for syllogistic premises, and we tested predictions deriving from three contemporary mental-models accounts of the logic by belief interaction. Results supported recent "selective processing" theories of belief bias (e.g., Evans, 2000; Klauer, Musch, & Naumer, 2000), which assume that the believability of a conclusion biases model construction processes, rather than biasing the search for falsifying models (e.g., Oakhill & Johnson-Laird, 1985) or a response stage of reasoning arising from subjective uncertainty (e.g., Quayle & Ball, 2000). We conclude by suggesting that the eye-movement analyses in reasoning research may provide a useful adjunct to other process-tracing techniques such as verbal protocol analysis.

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Psychopathy is a personality disorder characterised by affective, interpersonal, antisocial, and lifestyle elements. Studies of the association between psychopathy (e.g. as operationalised in the Psychopathy Checklist-Revised) and criminal behaviour suggest that police interviewers and interview advisors would benefi t from an understanding of how psychopathic suspects are likely to behave during investigative interviews. Approaches to the identifi cation of psychopathic characteristics in suspects are considered with reference to the P-Scan screening tool and possible indicators of psychopathic characteristics in serious offences. Psychopathic characteristics that are likely to impact upon interview behaviour are outlined in order to suggest how the effects of these may be anticipated, and how strategies may be employed to maximise an interviewee's productive participation in the interview and to minimise the interviewee's tendency to disrupt, distort, or control the interview process. The manner in which psychopathic individuals attempt to deceive others and how a psychopathic suspect's lies might be identifi ed are discussed.In his highly infl uential clinical profi le, Cleckley (1976) described the prototypical psychopathic individual as superfi cially charming and intelligent, yet unreliable, dishonest, insincere, manipulative, and egocentric. The psychopathic individual is sexually promiscuous, does not experience love or empathy, and does not form lasting attachments to other people or principles. The psychopathic individual exhibits 'inadequately motivated antisocial behaviour' (i.e. antisocial behaviour that has no obvious motivation, such as material gain or infl uence), shows a blatant lack of shame or remorse for harm done to others, and fails to learn from experiences. Studies have shown that psychopathic individuals are responsible for a disproportionate amount of serious, repetitive crime and violence. For example, whilst Neumann and Hare (2008) estimate that the base rate of psychopathy in the general population to be around 1%, between 12.1% and 40% of rapists (depending upon the level of risk of the sample) would satisfy the criteria for a diagnosis of psychopathy (