This study compared the effects of (+/-)3,4-methylenedioxymethamphetamine, d-amphetamine, and cocaine on performance of rats in a delayed matching-to-sample procedure using a variety of indices of performance to determine the mechanism by which working memory task impairments arise. All 3 drugs produced an overall delay-independent decrease in accuracy rather than a delay-dependent increase in the rate of forgetting. This impairment arose as a result of current-trial choice responses being progressively more affected by responses made in the immediately preceding trial as drug dose increased. Therefore, all 3 drugs produced qualitatively similar disruptions in memory task performance best characterized as an impairment arising from proactive sources of interference.

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Despite the prevalence of problem gamblers and the ethical issues involved in studying gambling behavior with humans, few animal models of gambling have been developed. When designing an animal model it is necessary to determine if behavior in the paradigm is similar to human gambling. In human studies, response latencies following winning trials and near win trials are greater than those following clear losses. Weatherly and Derenne (Anal Gambl Behav 1:79-89, 2007) investigated whether this pattern was found with rats working in an animal analogue of slot machine gambling. They found a similar pattern of response latencies but the subjects' behavior did not come under control of the visual stimuli signalling the different outcomes. The animal model of slot machine gambling we used addressed procedural issues in Weatherly and Derenne's model and examined whether reinforcer magnitude and the presence of near win trials influenced response latency and resistance to extinction. Response latencies of the six female Norway Hooded rats varied as a function of reinforcer magnitude and the presence of near-win trials. These results are consistent with prior research and with the idea that near win trials serve as conditional reinforcers.

Recent evidence suggests that the disruptive effects of acute exposure to (+/-)3,4-methylene dioxymethamphetamine (MDMA) on memory performance may be the result of increased confusion between previous-trial and current-trial events. The current study tested this hypothesis by examining the effects of MDMA on performance of rats in a delayed matching-to-sample procedure when the length of the intertrial interval (ITI) was altered. Consistent with the possibility that limiting the conditions under which responses made on a previous trial would interfere with current-trial choice, a 15-s ITI ameliorated the disruptive effects caused by MDMA on trial performance when the ITI was 5 s. Therefore, the disruptive effects of MDMA on memory can be attenuated by methods that separate current-trial "to-be-remembered" events from previous-trial events.

Delay and uncertainty of receipt both reduce the subjective value of reinforcers. Delay has a greater impact on the subjective value of smaller reinforcers than of larger ones while the reverse is true for uncertainty. We investigated the effect of reinforcer magnitude on discounting of delayed and uncertain reinforcers using a novel approach: embedding relevant choices within a computer game. Participants made repeated choices between smaller, certain, immediate outcomes and larger, but delayed or uncertain outcomes while experiencing the result of each choice. Participants' choices were generally well described by the hyperbolic discounting function. Smaller numbers of points were discounted more steeply than larger numbers as a function of delay but not probability. The novel experiential choice task described is a promising approach to investigating both delay and probability discounting in humans.

In New Zealand, Māori (indigenous New Zealanders) and Pacific students tend not to attain the same levels of educational success as Pākehā (New Zealanders of European descent). Addressing this problem is a particular challenge in the sciences. The kaupapa (values-base) of Te Rōpū Ā whina (Ā whina) is to produce Māori and Pacific professionals to contribute to Māori and Pacific development and leadership through the creation of an inclusive off-and on-campus whānau (extended family) environment where high expectations, aspirations and achievement, collective success, and reciprocity are normalised. This paper reviews theories and practices of recruitment and retention relevant to Māori and Pacific students at tertiary level, presents the rationale for Ā whina in the Faculties of Science and Architecture and Design at Victoria University of Wellington, and assesses the impact of the whānau. Based on analyses of quantitative measures of student achievement, and biennial surveys of student responses from the first 6 years of Ā whina, it is suggested that the results are consistent with improving Māori and Pacific graduate and postgraduate achievement and retention. Potential implications for efforts to reduce disparities in tertiary education in New Zealand and elsewhere are summarised.

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