Assessing Sequential Knowledge through Performance Measures: The Influence of Short-term Sequential Effects

Studies on implicit sequence learning have employed the methodology oftask dissociations to show that tasks of conscious memory fail to reveal knowledge expressed in performance measures of learning. One critical requirement of this methodology is that the conscious memory tests tap the same type of information that is expressed in performance measures. When a deterministic sequence is being repeated during practice, identification of the exact type of sequential information that is learned can be achieved by a trial-by-trial comparison between the practised sequence and a control sequence. In Experiment 1 we examine whether short-term sequential effects are present in choice response time tasks and may therefore contaminate this trial-by-trial comparison. In Experiment 2 we control for these effects and demonstrate how specification of the exact sub-parts of the sequence that are learned is necessary before testing for task dissociations. Our findings indicate a dissociation between a response time task and a free generation task. This dissociation, however, is obtained for selected sub-parts of the sequence and may be caused by the insensitivity of the free-generation task to low confidence knowledge.     

Comparison of Suicide Attempters and Decedents in the U.S. Army: A Latent Class Analysis

A clearer understanding of risk factors for suicidal behavior among soldiers is of principal importance to military suicide prevention. It is unclear whether soldiers who attempt suicide and those who die by suicide have different patterns of risk factors. As such, preventive efforts aimed toward reducing suicide attempts and suicides, respectively, may require different strategies. We conducted a latent class analysis (LCA) to examine classes of risk factors among suicide attempters (n = 1,433) and decedents (n = 424). Both groups were represented by three classes: (1) External/Antisocial Risk Factors, (2) Mental Health Risk Factors, and (3) No Pattern. These findings support the conceptualization that military suicide attempters and decedents represent a single population.     

Reciprocal overshadowing in flavour-aversion learning

The present experiments were concerned with the overshadowing by a novel flavour which preceded the pairing of a target flavour and toxicosis. This effect was demonstrated in Experiment I as was reciprocal overshadowing by a novel flavour which was interpolated between the target flavour and illness. Experiment 2 indicated that such overshadowing only occurred if the novel flavour was presented immediately prior to the target flavour; an interval of 10 min between the two abolished the effect. Experiment 3 indicated that the failure to observe overshadowing with a delay of 10 min between the two flavours was not due to a lack of association between the interfering flavour and illness. These data were interpreted as demonstrating that the introduction of the interfering flavour on the training day resulted in a perceptual generalisation decrement and a subsequent reduction in the aversion displayed to the target flavour.