The Effect of Stress Management Programs on Physiological and Psychological Components of Stress: The Influence of Baseline Physiological State.

Military personnel are particularly exposed to stressful events, and overexposure to stress is both physically and mentally unhealthy. While stress management programs, such as the Tactics of Optimized Potential (TOP) and Heart Coherence (HC) have been implemented, their efficiency remains to be evaluated. The objective of this randomized control trial was to evaluate the effectiveness of the two programs among a young male population of 180 military fire fighter recruits. Based on two psychological, and one physiological measurement, namely heart rate variability (HRV), we found that both TOP and HC programs significantly increased HRV. This is promising as we know that higher HRV is consistent with better health, in most cases. Moreover, the TOP program significantly reduced perceived stress and negative mood, unlike the HC program. Combining these results, we conclude that while both TOP and HC programs influence physiological measurements, only the TOP modifies psychological evaluations. Finally, we distinguished the effects of the programs on two samples characterized by their HRV level. For the low HRV group, both programs tended to increase their HRV level, while for the high HRV group neither program had a significant effect.

What makes working memory traces stable over time?

Understanding the factors that make working memory (WM) traces stable over time is important because WM is the keystone of general cognitive achievement. Two views of attentional WM maintenance have been suggested to account for the long-term retention of WM information. First, the distractors in a WM task are thought to foster the creation of episodic memory cues through covert retrieval. Second, the cognitive load (CL) of the distractors is thought to vary long-term memory instantiation. In this study, we propose an additional parsimonious perspective: the total time during which each trace is under the control of attention in WM is the key to long-term retention. Participants performed a complex span task in which the CL and number of distractors were orthogonally manipulated, and thereafter the participants performed a delayed recall test. Similar to previous findings, the results showed effects of the number of distractors and of CL on delayed recall. Our results went further, however, by showing a non-linear relationship between delayed recall performance and the free time accumulated between encoding and immediate recall. The role of time in episodic memory performance and the underlying WM maintenance mechanism are discussed.

Reconciling Two Computational Models of Working Memory in Aging.

It is well known that working memory performance changes with age. Two recent computational models of working memory, TBRS* and SOB-CS, developed from young adults WM performances are opposed regarding the postulated causes of forgetting, namely time-based decay and interference for TBRS* and SOB-CS, respectively. In the present study, these models are applied on a set of complex span data produced by young and older adults. As expected, these models are unable to account for the older adult data. An investigation on the effect of the main parameters of these models showed that the poorer performance of older adults does not come from a weaker encoding of item but rather from difficulties during the free time that immediately follows each distractor, as well as from a higher level of confusion between items. These results are discussed with respect to the current theories of working memory and aging.

Working memory still needs verbal rehearsal.

The causal role of verbal rehearsal in working memory has recently been called into question. For example, the SOB-CS (Serial Order in a Box-Complex Span) model assumes that there is no maintenance process for the strengthening of items in working memory, but instead a process of removal of distractors that are involuntarily encoded and create interference with memory items. In the present study, we tested the idea that verbal working memory performance can be accounted for without assuming a causal role of the verbal rehearsal process. We demonstrate in two experiments using a complex span task and a Brown-Peterson paradigm that increasing the number of repetitions of the same distractor (the syllable ba that was read aloud at each of its occurrences on screen) has a detrimental effect on the concurrent maintenance of consonants whereas the maintenance of spatial locations remains unaffected. A detailed analysis of the tasks demonstrates that accounting for this effect within the SOB-CS model requires a series of unwarranted assumptions leading to undesirable further predictions contradicted by available experimental evidence. We argue that the hypothesis of a maintenance mechanism based on verbal rehearsal that is impeded by concurrent articulation still provides the simplest and most compelling account of our results.