The effects of varied retrieval cues on reminiscence in eyewitness memory

Eyewitnesses sometimes recall things at later interviews that they did not recall at previous interviews (reminiscence). When these cases are argued in the courtroom, attorneys may claim (and judges may warn jurors) that eyewitnesses who provide reminiscences are necessarily inaccurate witnesses. Consequently, their testimony may be prematurely discredited or dismissed. We examined here the role of varying the retrieval cues across interviews to account for reminiscence. Participants watched a videotaped mock crime and were tested for recall on two occasions using the same or different cues. Results supported the hypothesis that varying retrieval cues increases the amount of reminiscence. Furthermore, nearly all participants exhibited some reminiscence. Finally, reminiscence was not significantly correlated with overall accuracy of testimony. These findings suggest that many of the assumptions underlying legal tactics and judges' instructions regarding reminiscent inconsistencies are erroneous. Copyright © 2006 John Wiley & Sons, Ltd.     

Hippocampus function predicts severity of post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) is often accompanied by memory problems and abnormal brain structure, particularly within the hippocampus. We implemented a cross-species, hippocampal-dependent task--the virtual Morris Water task--to assess hippocampal function in people with PTSD and age-matched controls during functional magnetic resonance imaging (fMRI). Performance on the task was equivalent between the groups. However, when correlating fMRI-derived hippocampal activity during this task with PTSD severity, we observe a -0.84 correlation, indicating that those with reduced hippocampal activity show more severe PTSD symptoms. This correlation is not explained by differences in task performance, IQ, duration since trauma, nor time with PTSD. Hence, PTSD severity is predicted by functionally assessing the hippocampus using the virtual Morris water task, suggesting that this task may be used to identify those at risk for developing PTSD following a trauma.     

Contingency is used to prepare for outcomes: Implications for a functional analysis of learning

It is generally assumed that the function of contingency learning is to predict the occurrence of important events in order to prepare for them. This assumption, however, has scarcely been tested. Moreover, the little evidence that is available suggests just the opposite result. People do not use contingency to prepare for outcomes, nor to predict their occurrence, although they do use it to infer the causal and predictive value of cues. By using both judgmental and behavioral data, we designed the present experiments as a further test for this assumption. The results show that—at least under certain conditions—people do use contingency to prepare for outcomes, even though they would still not use it to predict their occurrence. The functional and adaptive aspects of these results are discussed in the present article.     

Effects of reinforcement magnitude and ratio values on behaviour maintained by a cyclic ratio schedule of reinforcement

In Experiments 1 and 2, lever pressing by rats was reinforced on a cyclic ratio schedule of food reinforcement, comprising a repeated sequence of fixed-ratio component schedules. Reinforcement magnitude was varied, on occasional sessions in Experiment 1 and across blocks of sessions in Experiment 2, from one to two or three 45-mg food pellets. In the one-pellet condition, post-reinforcement pauses increased with component schedule value. At higher magnitudes, post-reinforcement pauses increased, and overall response rates declined. Response rate on component schedules was a decreasing linear function of the obtained rate of reinforcement in all conditions. Plotted against component schedule value, response rate increased exponentially to an asymptote that decreased when reinforcement magnitude increased. These findings are consistent with regulatory accounts of food reinforced behaviour. In Experiment 3, rats were trained under a cyclic ratio schedule comprising fixed-ratio components including higher values, and some inverted U-shaped response functions were obtained. Those rats that did not showthis relationship were trained on cyclic ratios with even higher values, and all showed inverted U-shaped response functions. This suggests that behaviour on cyclic ratio schedules can reflect activating of reinforcement as well as the satiating effects seen in Experiments 1 and 2.     

The Ethics of Producing In Vitro Meat

The prospect of consumable meat produced in a laboratory setting without the need to raise and slaughter animals is both realistic and exciting. Not only could such in vitro meat become popular due to potential cost savings, but it also avoids many of the ethical and environmental problems with traditional meat productions. However, as with any new technology, in vitro meat is likely to face some detractors. We examine in detail three potential objections: 1) in vitro meat is disrespectful, either to nature or to animals; 2) it will reduce the number of happy animals in the world; and 3) it will open the door to cannibalism. While each objection has some attraction, we ultimately find that all can be overcome. The upshot is that in vitro meat production is generally permissible and, especially for ethical vegetarians, worth promoting.     

Macrosocial determinants of social integration: Social class and area effect

Theory and research on social support have paid little attention to the existence of important macrosocial variables determining level and content of social relationships. This study examines variations in social integration as a function of social class and residential area characteristics. Results for 234 subjects living in high and low risk neighbourhoods indicated that differences between higher and lower social class groups follow different patterns in different residential areas. Also, same social class position appeared to have different significance as a function of residential area characteristics. The levels of three social integration measures—community integration and satisfaction, community association and participation, and contribution in community organizations—were significantly higher for lower class in low risk neighbourhoods than in high risk ones. However, significant differences were found in only one measure for higher social class groups, with higher levels of community association and participation in high risk neighbourhoods than in low risk ones. The discussion examines a ‘social impoverishment’ hypothesis for high risk environments, and proposes possible protective factors for higher status residents. Relations between formal and informal sources of support, and implications for social intervention strategies are also considered.     

Dimensions of interpersonal orientation: Cross-cultural studies regarding the structure of the ‘DOI Kit’

The DOI Kit is a four-version instrument (Junior Self and Other-Report, and Adult Self-and Other-Report) developed in Spain to measure ‘Dimensions of Interpersonal Orientation’ (Spanish: ‘Dimensiones de Orientación Interpersonal’ or DOI), which are defined as prevalent postures in interpersonal behaviour. The DOI Kit has six first-level scales that collapse into two broad oblique dimensions: Prosocial versus Antisocial Behaviour, and Sociability versus Unsociability.The aim of this article is to find out whether the first- and second-level structure of the Spanish DOI Kit can also be applied to data gathered in Chile and in Germany. A total of eight groups of data were studied. In order to find the best common structure for Spanish, Chilean, and German samples, Simultaneous Component Analysis (SCA) was applied. SCA shows an excellent replication of the original DOI Kit structure. This is also found when separate factor analyses (varimax and oblimin rotations) are performed.