Editors can lead researchers to confidence intervals, but can't make them think: statistical reform lessons from medicine

Since the mid-1980s, confidence intervals (CIs) have been standard in medical journals. We sought lessons for psychology from medicine's experience with statistical reform by investigating two attempts by Kenneth Rothman to change statistical practices. We examined 594 American Journal of Public Health (AJPH) articles published between 1982 and 2000 and 110 Epidemiology articles published in 1990 and 2000. Rothman's editorial instruction to report CIs and not p values was largely effective: In AJPH, sole reliance on p values dropped from 63% to 5%, and CI reporting rose from 10% to 54%; Epidemiology showed even stronger compliance. However, compliance was superficial: Very few authors referred to CIs when discussing results. The results of our survey support what other research has indicated: Editorial policy alone is not a sufficient mechanism for statistical reform. Achieving substantial, desirable change will require further guidance regarding use and interpretation of CIs and appropriate effect size measures. Necessary steps will include studying researchers' understanding of CIs, improving education, and developing empirically justified recommendations for improved statistical practice.     

The Impact of the Built Environment on Children’s School Conduct Grades: The Role of Diversity of Use in a Hispanic Neighborhood

A population-based study examined the relationship between diversity of use of the built environment and teacher reports of children’s grades. Diversity of use of the built environment (i.e., proportion of a block that is residential, institutional, commercial and vacant) was assessed for all 403 city blocks in East Little Havana, Miami—a Hispanic neighborhood. Cluster analysis identified three block-types, based on diversity of use: Residential, Mixed-Use, and Commercial. Cross-classified hierarchical linear modeling was used to examine the impact of diversity of use, school, gender, and year-in-school on academic and conduct grades for 2857 public school children who lived in these blocks. Contrary to popular belief, mixed-use blocks were associated with optimal outcomes. Specifically, follow-up analyses found that a youth living on a residential block had a 74% greater odds of being in the lowest 10% of conduct grades (conduct GPA <2.17) than a youth living on a mixed-use block. In fact, an analysis of the population attributable fraction suggests that if the risk associated with residential blocks could be reduced to the level of risk associated with mixed-use blocks, a 38% reduction in Conduct GPAs <2.17 could be achieved in the total population. These findings suggest that public policy targeting the built environment may be a mechanism for community-based interventions to enhance children’s classroom conduct, and potentially related sequelae.     

The syllable-based word length effect and stimulus set specificity

The word length effect is the finding that a list of items that take less time to pronounce is better recalled on an immediate serial recall test than an otherwise equivalent list of items that take more time to pronounce. Contrary to the predictions of all major models of the word length effect, Hulme, Suprenant, Bireta, Stuart, and Neath (2004) found that short and long items presented within the same list were recalled equally as well as short items presented in lists of just short items. Different results were reported by Cowan, Baddeley, Elliot, and Norris (2003), who found that mixed lists were recalled worse than pure short lists, but better than pure long lists. The experiments reported here suggest that the different empirical findings are due to properties of the stimulus sets used: one stimulus set produces results that replicate Cowan et al., whereas all other sets tested so far yield results that replicate Hulme et al.     

Distinctiveness models of memory and absolute identification: evidence for local, not global, effects

Many models of memory assume that the probability of remembering an item is related to how distinctive that item is relative to all the other items in the set, with no distinction made between the contributions of near or far items. These “global” distinctiveness models do well in accounting for the ubiquitous serial position effects observed in numerous memory paradigms, including absolute identification. Here, we provide experimental confirmation of Bower's (1971) suggestion that, contrary to a fundamental prediction of global distinctiveness models, midseries items can be more discriminable than their immediate neighbours. We show that such data are consistent with a revised distinctiveness account in which the factor affecting discrimination performance is primarily the distinctiveness of an item relative to its close neighbours.     

Evaluation of the Computerized Assessment System for Psychotherapy Evaluation and Research (CASPER) as a measure of treatment effectiveness with psychiatric inpatients

Assessment procedures to evaluate inpatient treatment effectiveness can provide information to inform clinical practice. The Computerized Assessment System for Psychotherapy Evaluation and Research (CASPER) represents a standardized approach to assess patients' target problems that combines elements of individualized and nomothetic approaches. Although previous evaluations of CASPER with other patient populations have been encouraging, its use as a measure of change with an inpatient population has not been examined. In this study, 75 psychiatric inpatients completed CASPER and the Behavior and Symptom Identification Scale-32 (BASIS-32) at hospital admission and discharge. Results supported the concurrent validity of CASPER as a measure of pre- and posttreatment functioning and suggested that CASPER may provide a sensitive measure of change during inpatient treatment. Findings also supported the notion that patients' ratings of the extent to which their treatment focused on the problems they identified as a high priority were related to their overall treatment satisfaction.     

Duration processing in children as determined by time reproduction: implications for a few seconds temporal window

From research carried out over recent years using different experimental paradigms, it has become apparent that central information processing is temporally segmented into sequential units of a few seconds. This segmentation presumably reflects a neuronal process of temporal integration (TI) which automatically binds successive events into temporal units. Support for such TI comes, for example, from studies on temporal reproduction where standards up to approximately 2-3 s are reproduced veridically. Using this paradigm of temporal reproduction, we investigated the effect of normal cognitive development of sensory modality and of the range of presented standards on TI. Sixty children aged 6-7, 9-10 and 13-14 years reproduced visual or auditory standard durations ranged from 1 to 5.5 s or from 1 to 3 s. The results showed that durations of approximately 2 s were reproduced correctly, whereas those longer than 2.5 s were under-reproduced in the three age groups. For standards shorter than 2 s substantial age-related differences were revealed: the youngest group displayed significant over-reproduction comparing to older subjects. These observations indicate that the upper limit for TI is a stable feature across the different age groups. Furthermore an age-related modulation within the temporal window of the operating TI seems to be linked to cognitive development.     

Is the interference between memory processing and timing specific to the use of verbal material?

Increasing load in a memory task performed simultaneously with a timing task shortens perceived time, an effect that has been observed previously with memory tasks using verbal material. The present experiments examine whether two similar memory tasks, one in which verbal material is used and another one in which nonverbal material is used, would produce similar interference effects on concurrent time reproduction. In Experiment 1, the number of nonverbal stimuli (pseudo-random dot patterns) was manipulated in a memory task performed while a temporal interval to be reproduced was encoded. Reproductions shortened proportionally to the duration of memory processing executed during time estimation. Verbal stimuli (consonants) were used in Experiment 2 in otherwise identical experimental conditions. Effects observed in Experiment 2 were comparable to those obtained in Experiment 1. Taken together, these results support the notion that interference from memory tasks on concurrent time estimation is not determined by the specific type of material processed in memory, but instead by the duration of memory processing.     

Fill-in and infill errors in order memory

Many current models of memory are specified with enough detail to make predictions about patterns of errors in memory tasks. However, there are often not enough empirical data available to test these predictions. We report two experiments that examine the relative frequency of fill-in and infill errors. In immediate serial recall tasks, subjects sometimes incorrectly recall item N too soon, placing it in position N-1. The error of interest is which item is recalled after this initial mistake. A fill-in error is the tendency to recall item N-1 next, whereas an infill error is the tendency to recall item N+1 next. Both experiments reveal more fill-in than infill errors, not only overall but at each possible error location throughout the list. The overall ratio is approximately 2:1. We conclude that none of the currently existing models adequately accounts for fill-in and infill errors.     

Nonconscious temporal cognition: Learning rhythms implicitly

Two experiments demonstrate that people can implicitly learn rhythms. Participants responded to a series of fast-paced beeps by pressing a key as soon as possible after each beep. They were not told that the duration (180, 450, or 1,125 msec) between each keypress and the next beep was specified by a repeating sequence. In both experiments, participants responded significantly faster to predictable, sequenced timing than to random timing but did not show more knowledge of the sequence than did control participants on explicit memory measures. This dissociation was obtained even with an explicit memory test in Experiment 2 that maintained the same context and response metric as the implicit task to maximize the transfer of relevant knowledge. Implications for temporal cognition are discussed.