The real relationship between short-term memory and working memory

Storage-oriented memory span tasks with no explicit concurrent processing are usually referred as short-term memory (STM) tasks, whereas tasks involving storage plus concurrent processing requirements are designated as working memory (WM) tasks. The present study explores a question that remains unsolved: Do STM and WM tasks clearly tap distinguishable theoretical constructs? For that purpose, a large sample of 403 participants was tested through 12 diverse memory span tasks. Half of those tasks are widely accepted as measures of STM, whereas the other half measure WM. The results show that STM and WM share largely overlapping underlying capacity limitations, suggesting that all memory span tasks tap essentially the same construct. Some implications are discussed.     

Complex span tasks, simple span tasks, and cognitive abilities: A reanalysis of key studies

There is great interest in the relationships between memory span tasks and cognitive abilities. However, the causes underlying their correlation remain unknown. In the present article, five key data sets were reanalyzed according to two criteria: They must consider complex span tasks (so-called working memory [WM] tasks) and simple span tasks (so-called short-term memory [STM] tasks), and they must comprise cognitive ability measures. The obtained results offer several points of interest. First, memory span tasks should be conceived from a hierarchical perspective: They comprise both general and specific components. Second, the general component explains about four times the variance explained by the specific components. Third, STM and WM measures are closely related. Fourth, STM and WM measures share the same common variance with cognitive abilities. Finally, the strong relationship usually found between memory span tasks and cognitive abilities could be tentatively interpreted by the component shared by STM and WM--namely, the capacity for temporarily preserving a reliable memory representation of any given information.     

Young adult drivers' sensitivity to changes in speed and driving mode in a simple vehicle simulator

The study was done to check replication of changes in sensitivity with a simple simulator as had been obtained in an experiment using the real road situation. Another purpose was to control simulator sickness which could have confounded data from testing with a simulator or in actual driving. Sensitivity of the drivers (72 healthy young adults, M age = 24 yr., SD = 5) while performing the driving task was measured in terms of subjective ratings of simulator sickness and affect, and physiological measures (i.e., galvanic skin responses and skin temperature) at different driving speeds and in driving mode conditions, using a simple vehicle simulator. Analysis showed measures of drivers' state, including simulator sickness, physiological indices, and subjective reports, increased with driving speed (30 --> 90 -->120 km/hr.) and driving mode change from the regular speed to sudden increasing to sudden decreasing speeds. Particularly, the results suggest that the increased autonomic nervous activation induces increase of rated simulator sickness. Based upon the same tendency in change of the simulator sickness and physiological state with driving speed and driving mode conditions, it was concluded that, if the results obtained from the simulator experiment can be generalized to the real situation, the simulator sickness must be considered a confounding factor. The results also suggest that the changes in human sensitivity are dependent upon aspects related to speed of a vehicle and driving mode.     

Response-specific sources of dual-task interference in human pre-motor cortex

It is difficult to perform two tasks at the same time. Such performance limitations are exemplified by the psychological refractory period (PRP): when participants make distinct motor responses to two stimuli presented in rapid succession, the response to the second stimulus is increasingly slowed as the time interval between the two stimuli is decreased. This impairment is thought to reflect a central limitation in selecting the appropriate response to each stimulus, but not in perceptually encoding the stimuli. In the present study, it was sought to determine which brain regions are specifically involved in response selection under dual-task conditions by contrasting fMRI brain activity measured from a response selection manipulation that increased dual-task costs, with brain activity measured from an equally demanding manipulation that affected perceptual visibility. While a number of parieto-frontal areas involved in response selection were activated by both dual-task manipulations, the dorsal pre-motor cortex, and to a lesser extent the inferior frontal cortex, were specifically engaged by the response selection manipulation. These results suggest that the pre-motor cortex is an important neural locus of response selection limitation under dual-task situations.     

Are false memories more difficult to forget than accurate memories? The effect of retention interval on recall and recognition

What is the effect of retention interval on accurate and false recollection in the Deese, Roediger, and McDermott (DRM) procedure? Previous research has suggested that false recall is more persistent than accurate recall, but the recognition results have been inconsistent. In two parametric studies, we tested recall and recognition for the same DRM lists, over retention intervals that ranged from no delay to a 2-month delay. We found that accurate and false memory were diminished by increases in retention interval, false memory persistence was present for recall and recognition, greater persistence for false memory than for accurate memory was more readily observed for recall than recognition, and the highthreshold (Pr), signal detection (d’), and nonparametric (A’) recognition measures differed in their sensitivity for detecting change. The effect of retention interval on accurate and false memory is consistent with expectations from fuzzy trace theory. In the DRM procedure, truth is not more memorable than fiction.     

Implicit,long-term spatial contextual memory

Learning and memory of novel spatial configurations aids behaviors such as visual search through an implicit process called contextual cuing (M. M. Chun & Y. Jiang, 1998). The present study provides rigorous tests of the implicit nature ofcontextual cuing. Experiment 1 used a recognition test that closely matched the learning task, confirming that memory traces of predictive spatial context were not accessible to conscious retrieval. Experiment 2 gave explicit instructions to encode visual context during learning, but learning was not improved and conscious memory remained undetectable. Experiment 3 illustrates that memory traces for spatial context may persist for at least 1 week, suggesting along-term component of contextual cuing. These experiments indicate that the learning and memory of spatial context in the contextual cuing task are indeed implicit. The results have implications for understanding the neural substrate of spatial contextual learning, which may depend on an intact medial temporal lobe system that includes the hippocampus (Mi. M. Chun & E. A. Phelps, 1999).     

Neighborhood frequency does affect performance in the Reicher task: encoding or decision?

Three experiments using the Reicher task show that performance on low-frequency words is disrupted if the incorrect alternative forms a higher frequency word. This neighborhood frequency effect occurs for both energy and pattern masks and for different sets of items. When the upcoming word is primed and its accessibility is enhanced, the neighborhood frequency effect is eliminated. Experiments 4a and 4b tested the neighborhood frequency effect using a same-different task and a signal-detection analysis. Neighborhood frequency affected the decision criterion but not the sensitivity of the perceptual system. Experiment 5 showed that many words with a frequency in the range from 1 to 5 per million are not recognized out of context. These results are consistent with the hypothesis that frequency effects in the Reicher task are caused by a bias in the decision system and can be simulated with the stochastic activation-verification model.     

When self-help materials help: Examining the effects of self-discrepancy and modes of delivery of positive self-statements

Self-help materials inculcating individuals with positive self-statements are popular in recent years, although the effectiveness of such self-statements on improving individuals’ psychological well-being has not yet been confirmed. Using a control-group pre-test/post-test design, we examined how positive self-statements may or may not benefit individuals’ mood. Individual characteristics and modes of delivery were found to moderate mood changes resulting from positive self-statements. Specifically, we found that participants experienced negative mood change after reading positive self-statements, if they have low level of need satisfaction. However, we also found that participants experienced a mood boost after listening to positive self-statements, and this effect was unrelated to self-esteem or need satisfaction. These findings suggest that self-help materials with a focus on positive self-statements should be used with caution.     

Hope and General Self-efficacy: Two Measures of the Same Construct?

The aim of this study was to test the extent to which hope measure is equivalent to general self-efficacy measure. Questionnaire data on these two constructs and other external variables were collected from 199 Chinese college students. The factor analytic results suggested that hope and self-efficacy items measured the same construct. The unidimensional model combining hope items and GSE items fit the data as well as the bidimensional model, indicating that their corresponding items measured the same underlying construct. Further analyses showed that hope and GSE did not correlate with external variables differently in a systematic manner. Most of these correlational differences were non-significant and negligible. These findings suggested that the literatures studying GSE and hope could be considered to be integrated and that researchers need to recognize and acknowledge the conceptual and operational similarities among these constructs in the literature.     

The Expression of Posttraumatic Stress Symptoms in Daily Life: A Review of Experience Sampling Methodology and Daily Diary Studies

This review examined the assessment of posttraumatic stress symptoms (PTSS) in daily life using experience sampling methodology (ESM)/ecological momentary assessment (EMA) and daily diary studies in adult samples. Fifteen peer-reviewed studies were identified and categorized into areas of total PTSD/multiple PTSS (studies including three or more symptom clusters), intrusive memories, and mood and anxiety symptoms. Overall, ESM and the daily diary method proved feasible for assessing the real-world expression of PTSS, resulted in minimal reactivity, and offered a number of advantages over classical assessment. Even within the two measurement types of ESM and daily diary, there was great variability in study design and analysis. The benefits and limitations of the different approaches are discussed. Different themes in content emerged as well, such as coping strategies and affective instability throughout the course of a day. Gaps in our current understanding are highlighted and suggestions for methodology and future areas of research are proposed.