The role of trial tracking in rats’ working memory

The experiments reported in the present study tested whether decreasing intertrial intervals (ITIs) intensifies the disruptive effects of increasing retention intervals (RIs) in a delayed conditional discrimination by decreasing the animal’s trial tracking accuracy (Cohen & Armstrong, 1996; Cohen & Roberts, 1996). Rats responded on a fixed ratio (FR) 1 or fixed interval (FI) 10-sec reinforcement schedule at a second light or tone stimulus, S2, when the first light or tone stimulus, S1, had signaled an FI 10-sec or FR 1 schedule, respectively. RIs between S1 and S2 were increased from 3 to 24 sec and never exceeded ITIs that were reduced from 24 to 6 sec. For some rats, the trials were separated from each other by extending the lever at S1 and retracting it at the end of S2 (ITI lever-retracted group). For other, control rats, the lever remained extended throughout the session (lever-extended group, Experiment 1) or was extended and retracted with the onset and offset of each stimulus (RI/ITI lever-retracted group, Experiment 2). The rats under all trial conditions learned to delay leverpressing on the FI 10-sec schedule. Latency to begin leverpressing on the FI 10-sec schedule declined as RIs were increased, but this effect was attenuated in the ITI lever-retracted groups in both experiments, as would be predicted by thetrial tracking hypothesis. Decreasing ITIs from 24 to 6 sec intensified the disruptive effects of increasing RIs from 3 to 6 sec in the RI/ITI lever-retracted group (Experiment 2), as would be predicted by the trial tracking hypothesis.     

The Role of Extended Time and Item Content on a High‐Stakes Mathematics Test

The premise of a great deal of current research guiding policy development has been that accommodations are the catalyst for student performance differences. Rather than accepting this premise, two studies were conducted to investigate the influence of extended time and content knowledge on the performance of ninth‐grade students who took a statewide mathematics test with and without accommodations. Each study involved 1,250 accommodated students (extended time only) with learning disabilities and 1,250 nonaccommodated students demonstrating no disabilities. In Study One, a standard differential item functioning (DIF) analysis illustrated that the usual approach to studying the effects of accommodations contributes little to our understanding of the reason for performance differences across students. Next, a mixture item response theory DIF model was used to explore the most likely cause(s) for performance differences across the population. The results from both studies suggest that students for whom items were functioning differently were not accurately characterized by their accommodation status but rather by their content knowledge. That is, knowing students' accommodation status (i.e., accommodated or nonaccommodated) contributed little to understanding why accommodated and nonaccommodated students differed in their test performance. Rather, the data would suggest that a more likely explanation is that mathematics competency differentiated the groups of student learners regardless of their accommodation and/or reading levels.     

An overhead reduction technique for mega-state compression schemes

Many of the most effective compression methods involve complicated models. Unfortunately, as model complexity increases, so does the cost of storing the model itself. This paper examines a method to reduce the amount of storage needed to represent a Markov model with an extended alphabet, by applying a clustering scheme that brings together similar states. Experiments run on a variety of large natural language texts show that much of the overhead of storing the model can be saved at the cost of a very small loss of compression efficiency.     

Spurious Latent Classes in the Mixture Rasch Model

Mixture Rasch models have been used to study a number of psychometric issues such as goodness of fit, response strategy differences, strategy shifts, and multidimensionality. Although these models offer the potential for improving understanding of the latent variables being measured, under some conditions overextraction of latent classes may occur, potentially leading to misinterpretation of results. In this study, a mixture Rasch model was applied to data from a statewide test that was initially calibrated to conform to a 3‐parameter logistic (3PL) model. Results suggested how latent classes could be explained and also suggested that these latent classes might be due to applying a mixture Rasch model to 3PL data. To support this latter conjecture, a simulation study was presented to demonstrate how data generated to fit a one‐class 2‐parameter logistic (2PL) model required more than one class when fit with a mixture Rasch model.     

The influence of game location and outcome on behaviour and mood states among professional rugby league players

In this study, we examined the relationship between home and away matches on mood. In addition, the relationships between game location, game outcome, behavioural factors, and mood were investigated among 12 professional English rugby league players competing in the Super League. Participants completed daily diaries for 27 days. The diary consisted of six analogue scales measuring mood (relaxed-tense, energetic-weary, depressed-elated, tired-alert, anxious-calm, cheerful-miserable) as well as behavioural factors and self-rated performance. There were no significant differences in self-reported mood states leading up to home or away matches except for players feeling more tired when playing away. Significant relationships between mood and behaviours (e.g. sleep and eating) and subjective performance were observed. The outcome of the match was found to influence mood, with a defeat resulting in decreased mood. Our results show that game location did not influence mood and therefore does not provide an explanation for the home advantage.     

Science Teachers’ Professional Development and Changes in Science Practical Assessment Practices: What are the Issues?

This paper considers the circumstances under which science teachers can respond positively and productively to educational policy reforms in the area of science practical assessment. To understand what might be involved in linking science teachers’ assessment capacities and their professional development, we present illustrative data from recent research studies conducted in Singapore and Hong Kong showing contrasting approaches taken in the implementation of reforms in science practical assessment. In Singapore, teachers worked together to select, discuss, clarify and refine their practices as they made decisions about what to teach and assess. In Hong Kong, teachers took a critical stance towards the new policy and learnt from their own experiences in order to build their confidence. With the same policy initiative, one group of teachers focused more on the technicalities of complying with requirements imposed on them while in the other group had their professional consciousness of what they thought was best for their students provoked so that their practices would be transformed. In an attempt to draw lessons for other contexts in supporting the implementation of assessment policy reforms through professional development work, we identify and discuss a range of factors in science teachers’ professional development that arise once in situ professional development work has started. Overall, our intent in this article is to recast assessment reform as a driver or pivot in teachers’ professional development and learning. To do this it is necessary, we argue, to afford teachers’ experiences and the processes involved in learning from them greater emphasis in order to ensure the continuance of innovation in the assessment of laboratory-based work.