The utility of the A1 and A2 criteria in the diagnosis of PTSD

In the field of posttraumatic stress disorder (PTSD), the revisions to the DSM-IV definition of a potentially traumatic event are contentious. Proponents praise the subjective emphasis, while others contend that the changes to the criterion broadened the conceptualization of PTSD. This study examined the predictive utility of Criterion A events, examining the stressor (A1) and subjective emotional response (A2) components of the definition of a traumatic event. Rates of Criterion A events and PTSD were calculated for three diverse samples, and predictive power, sensitivity, specificity, and ROC curves were computed to determine the predictive utility of Criterion A requirements for PTSD symptom, duration, and functional impairment diagnostic criteria. Across all samples, the current Criterion A requirements did not predict much better than chance. Specifically, A2 reports added little to the predictive ability of an A1 stressor, though the absence of A2 predicted the absence of PTSD-related symptoms, their duration, and impairment. Notably, the combination of three A1 and A2 criteria showed the best prediction. Confronted events also showed less predictive ability than experienced events, with more variable performance across samples. These results raise fundamental questions about the threshold or "gate" that Criterion A ought to play in our current nosology.     

Bayes factors: Prior sensitivity and model generalizability

Model selection is a central issue in mathematical psychology. One useful criterion for model selection is generalizability; that is, the chosen model should yield the best predictions for future data. Some researchers in psychology have proposed that the Bayes factor can be used for assessing model generalizability. An alternative method, known as the generalization criterion, has also been proposed for the same purpose. We argue that these two methods address different levels of model generalizability (local and global), and will often produce divergent conclusions. We illustrate this divergence by applying the Bayes factor and the generalization criterion to a comparison of retention functions. The application of alternative model selection criteria will also be demonstrated within the framework of model generalizability.     

Forgetting of Foreign‐Language Skills: A Corpus‐Based Analysis of Online Tutoring Software

We explore the nature of forgetting in a corpus of 125,000 students learning Spanish using the Rosetta Stone^® foreign‐language instruction software across 48 lessons. Students are tested on a lesson after its initial study and are then retested after a variable time lag. We observe forgetting consistent with power function decay at a rate that varies across lessons but not across students. We find that lessons which are better learned initially are forgotten more slowly, a correlation which likely reflects a latent cause such as the quality or difficulty of the lesson. We obtain improved predictive accuracy of the forgetting model by augmenting it with features that encode characteristics of a student's initial study of the lesson and the activities the student engaged in between the initial and delayed tests. The augmented model can predict 23.9% of the variance in an individual's score on the delayed test. We analyze which features best explain individual performance.     

The Mid-Career Award

Working memory is an extremely influential concept within experimental psychology, with, at the time of writing, over 90 papers with this term in their title published in this journal alone since 2000. One reason for this interest is that measures of working memory tend to be strong correlates of important indices of real-world function. In addition, at first sight working memory appears to be a relatively simple concept to understand. However, despite this apparent simplicity, explaining working memory performance is not straightforward. In this paper I address this challenge, with a particular focus on the development of working memory performance in children; both children developing typically and those experiencing atypical development. I specifically highlight the multiple constraints on working memory performance, and how these constraints inter-relate. I then consider the broader theoretical implications of each of these constraints for current accounts of working memory and its development.     

The form of the forgetting curve and the fate of memories

Psychologists have debated the form of the forgetting curve for over a century. We focus on resolving three problems that have blocked a clear answer on this issue. First, we analyzed data from a longitudinal experiment measuring cued recall and stem completion from 1 min to 28 days after study, with more observations per interval per participant than in previous studies. Second, we analyzed the data using hierarchical models, avoiding distortions due to averaging over participants. Third, we implemented the models in a Bayesian framework, enabling our analysis to account for the ability of candidate forgetting functions to imitate each other. An exponential function provided the best fit to individual participant data collected under both explicit and implicit retrieval instructions, but Bayesian model selection favored a power function. All analysis supported above chance asymptotic retention, suggesting that, despite quite brief study, storage of some memories was effectively permanent.     

Mentally walking through doorways causes forgetting: The location updating effect and imagination

Researchers have documented an intriguing phenomenon whereby simply walking through a doorway causes forgetting (the location updating effect). The Event Horizon Model is the most commonly cited theory to explain these data. Importantly, this model explains the effect without invoking the importance or reliance upon perceptual information (i.e., seeing oneself pass through the doorway). This generates the intriguing hypothesis that the effect may be demonstrated in participants who simply imagine walking through a doorway. Across two experiments, we explicitly test this hypothesis. Participants familiarised themselves with both real (Experiment 1) and virtual (Experiment 2) environments which served as the setting for their mental walk. They were then provided with an image to remember and were instructed to imagine themselves walking through the previously presented space. In both experiments, when the mental walk required participants to pass through a doorway, more forgetting occurred, consistent with the predictions laid out in the Event Horizon Model.     

Fit to last: Exploring the longevity of the survival processing effect

Mounting evidence indicates that processing items for their survival value produces superior recall compared to a number of other well-known memory-enhancing techniques, and that this mnemonic advantage remains up to 48 hours after encoding (Raymaekers et al., 2014 Raymaekers, L. H. C., Otgaar, H., &; Smeets, T. (2014). The longevity of adaptive memory: Evidence for the mnemonic advantages of survival processing 24 and 48 hours later. Memory, 22, 19–25. doi: 10.1080/09658211.2013.791321[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). However, little attention has been dedicated to the survival processing effect in location memory, which may represent a better test of adaptive memory than retrieval of verbal information. The current study aims to fill this gap by exploring the longevity of the survival processing effect with both word list (Experiment 1) and location-based (Experiment 2) stimuli. Participants rated target items using a single incidental encoding scenario, either Survival versus Pleasantness (word stimuli) or Survival versus Scavenger Hunt (location stimuli). They were then asked to complete a surprise recall task immediately after the ratings and a second recall task 96 hours later. The results demonstrated that, despite a general reduction in memory performance across time, the survival processing advantage was detected at both test times for both stimuli types. These findings provide further support for the survival processing effect and extend the observed effect duration for both word lists and location to 96 hours.     

Decay theory of immediate memory: From Brown (1958) to today (2014)

This work takes a historical approach to discussing Brown's (1958) paper, “Some Tests of the Decay Theory of Immediate Memory”. This work was and continues to be extremely influential in the field of forgetting over the short term. Its primary importance is in establishing a theoretical basis to consider a process of fundamental importance: memory decay. Brown (1958) established that time-based explanations of forgetting can account for both memory capacity and forgetting of information over short periods of time. We discuss this view both in the context of the intellectual climate at the time of the paper's publication and in the context of the modern intellectual climate. The overarching theme we observe is that decay is as controversial now as it was in the 1950s and 1960s.     

Effects of stimulus duration and choice delay on visual categorization in pigeons

We [Lazareva, O. F., Freiburger, K. L., & Wasserman, E. A. (2004). Pigeons concurrently categorize photographs at both basic and superordinate levels. Psychonomic Bulletin and Review, 11, 1111-1117] previously trained four pigeons to classify color photographs into their basic-level categories (cars, chairs, flowers, or people) or into their superordinate-level categories (natural or artificial). Here, we found that brief stimulus durations had the most detrimental effect on the basic-level discrimination of natural stimuli by the same pigeons. Increasing the delay between stimulus presentation and choice responding had greater detrimental effect on the basic-level discrimination than the superordinate-level discrimination. These results suggest that basic-level discriminations required longer stimulus durations and were more subject to forgetting than were superordinate-level discriminations. Additionally, categorization of natural stimuli required longer stimulus durations than categorization of artificial stimuli, but only at the basic level. Together, these findings suggest that basic-level categorization may not always be superior to superordinate-level categorization and provide additional evidence of a dissociation between natural and artificial stimuli in pigeons’ categorization.     

On growth curves and mixture models

The multilevel model of change and the latent growth model are flexible means to describe all sorts of population heterogeneity with respect to growth and development, including the presence of sub‐populations. The growth mixture model is a natural extension of these models. It comes at hand when information about sub‐populations is missing and researchers nevertheless want to retrieve developmental trajectories from sub‐populations. We argue that researchers have to make rather strong assumptions about the sub‐populations or latent trajectory classes in order to retrieve existing population differences. A simulated example is discussed, showing that a sample of repeated measures drawn from two sub‐populations easily leads to the mistaken inference of three sub‐populations, when assumptions are not met. The merits of methodological advises on this issue are discussed. It is concluded that growth mixture models should be used with understanding, and offer no free way to growth patterns in unknown sub‐populations. Copyright © 2006 John Wiley & Sons, Ltd.