The purpose of this paper is to explore six studies on the effect of stress on memory retrieval. The first study discusses how psychosocial stress affects episodic memory updating. The second study discusses acute psychosocial stress and children’s memory. The third study looks at the effects of stress on memory in children and adolescents by testing causal connections. The fourth study examines impeded memory impacts following severe stress in Distinctive Forces applicants through investigating path procedures between production of cortisol and ability to remember. Fifth study finds out how psychosocial stress impairs working memory at high loads and the sixth one researches onsevere stress and memory retrieval in the elderly. This paper ends with summarizing my opinion to what I consider the most enlightening study.
Keywords: stress, memory retrieval, glucocorticoids, cortisol
Effect of Stress on Memory Retrieval
This research paper summarizes the findings from six peer psychology journals that examined the effect of stress on memory retrieval. The purpose of the first study was to investigate how psychosocial stress affects episodic memory updating (Dongaonkar, Hupbach, Gomez, & Nadel, 2013). The hypothesis of the research was that stress prior to reactivation or reconsolidation could weaken memory updating. The participants learned a set of objects (List 1) on the first day. On the second day, some participants were reminded of list 1 before learning a second set of objects (List 2). The memory for list 1 was tested on the third day. Additionally, stress was directed either prior to reactivation of the first list on day 2 (experiment 1) or before reconsolidation of the first list, that is, after reactivation and studying the second list on day 2 (experiment 2).
Memory updating entails incorporating list 2 items into list 1 memory, depending on the reactivation of list 1 memory. In experiment 1, the reminder group had increased intrusions compared to the non-reminder groups. However, contrary to the anticipations, stress did not reduce the reminder effect. Stress effects were evident in experiment 2. Therefore, the reminder category that was strained after reactivation and acquiring new knowledge exhibited less interruptions compared to the control reminder category. The findings show that stress prior to reactivation cannot damage memory updating but stress at the beginning of reconsolidation can. Additionally, programing may reveal the effects of stress on memory processing (Dongaonkar et al., 2013).
Researches in humans that have studied the effects of stress on re-stabilization phase of reconsolidation have indicated the damage of the original memory in some instances and improvement in others. The original memory was changed under the influence of stress. In the researches, the participants clearly recall the original memory, contrary to the more subtle form of reactivation utilized in this study. It is important to note that stress did not affect the list 1 recall, implying that whatever the nature of the memory reactivation initiated by the reminder manipulation, re-stabilization of the memory is not affected by stress. Nevertheless, the subtle reactivation elicited an update of the original memory with new objects from list 2, which is shown in the high intrusions witnessed in the control reminder group. Stress after learning list 2 impaired but did not completely abolish this updating. Therefore, it is concluded that stress impaired the updating of original memory (list 1) with new items from list 2, but it did not impair the ability to recall list 1(Dongaonkar et al., 2013).
When a combined memory is reactivated, it can be adjusted before the next reconsolidation. Reactivation can be regarded the opposite of consolidation since it entails a protein degradation process that makes the reactivated memory labile and permits modifications to be made to the present representation. After activation, protein synthesis is conducted again to combine the reactivated memory depiction. Additionally, based on the conditions, reactivation can function to either reinforce the original memory, make it weak, or even update, therefore, changing it. Several brain parts, such as the prefrontal cortex and hippocampus, are involved in triggering the episodic memory and preserving this lively condition. Actions in these parts react to neuromodulators, particularly glucocorticoids and catecholamines like dopamine and norepinephrine. Normally, neuromodulatory effects in prefrontal cortex and hippocampus follow an inverted U-shaped function whereby modest amounts of glucocorticoids and catecholamines enhance their function whereas amounts that are either too low or too high weaken their activities. Additionally, stress-induced increases in glucocorticoid and catecholamine levels can suppress the operation of memory-related brain regions and result in deficiencies at memory retrieval (Dongaonkar et al., 2013).
The purpose of the second study was to investigate whether children’s performance on working memory (WM) and delayed retrieval (DR) tasks decreased after stress exposure and how physiological stress responses related to performance under stress (de Veld, Riksen-Walraven, & de Weerth, 2014). Approximately, 158 children were used in the study whereby 83 girls executed two WM tasks (MW forward and MW backward) and a DR memory task first during a control condition, and one week later during a stress challenge. Salivary alpha-amylase (sAA) and cortisol were evaluated during the challenge. Only WM backward performance deteriorated over conditions. In addition, correlations between physiological stress responses and performance within the stress challenge were present only for WM forward and DR. For WM forward, higher cortisol responses were associated with better performance. For DR, there was an inverted U-shape relation between cortisol responses and performance including a cortisol x sAA interaction with concurrent high or low responses related to optimal performance. This emphasizes the significance of including curvilinear and interaction effects when associating physiology with memory (de Veld, Riksen-Walraven, & de Weerth, 2014).
Children face different stressors at school, which raise the concern of how stress may affect school performance. Two memory procedures vital to school performance include working memory (WM) and the retrieval of previously learned information. This study sought to increase the comprehension of effects of stress on children’s WM and retrieval. Declarative long-term memory means the explicit storage of facts and events that can later be purposely retrieved. This retrieval is called delayed retrieval (DR). In older people, high glucocorticoid levels during DR impaired memory for stressor-unrelated information.
This study also examined the interactive effects of the HPA axis (concurrent glucocorticoid) and the SNS (noradrenergic activation) on both DR and WM. It hypothesized WM and DR to be worse under stress than in a control condition, and HPA axis activation to result in worse memory performance only if SNS activation is also high. Since there were indications that glucocorticoid effects on memory follow an inverted U-shape, called the Yerkes-Dodson law, the study also hypothesized memory performance to be the best in children with intermediate HPA axis reactivity (de Veld, Riksen-Walraven, & de Weerth, 2014).
The anticipated memory performance decline under stress versus control was discovered only for backward task (WMbw), not for forward task (WMfw) or DR. Nevertheless, within the stress condition, cortisol and sAA responses were associated with MWbw performance, raising the concern on whether this performance decline emanated from high HPA-axis and SNS activation in the stress condition. It is evident that children’s attempts to control their emotional responses to the stress task reduced their task performance. Although children did not exhibit a significant decrease in forward tasks (WMfw) performance across conditions, there was a significant correlation between cortisol stress reactivity and WMfw performance. However, contrary to the hypothesis, the correlation was positive: higher reactivity was associated with better performance.
The study indicated that physiological responses to a stress task were associated with children’s WMfw and DR performance under stress. The decline in backward tasks (WMbw) over conditions, without a relation between physiological stress responses and WMbw under stress, inspires further research into factors like emotional regulation techniques that may lead to adverse effects of stress on cognitive functioning. The findings show that during mild stressor, children’s DR performance is optimal under conditions of concurrent (de)activation of the SNS and HPA-axis (de Veld, Riksen-Walraven, & de Weerth, 2014).
The purpose of the third study was to determine how arousal affected children’s memory and whether the effects of arousal varied across age. The study exposed 7-8 and 12-14-year olds to the Trier Social Stress Test-Modified (TSST-M), a widely utilized laboratory stress task that requires people to give an impromptu speech and conduct arithmetic before spectators. Fourteen days later, surprise memory examination about the TSST-M was administered. The first analysis demonstrated that the TSST-M reliably induced arousal in 9-year-olds through young adults across several markers of arousal (behavioral, observer, physiological). The study was also interested in whether the participants’ physiological arousal during the TSST-M relative to their arousal beforehand predicted their subsequent memory (Quas, Rush, Yim, & Nikolayev, 2014).
Interest in how stress affects children’s memory has resulted in an impressive body of scientific research examining how well children remember a range of prior experiences, including medical procedures, emergency room visits, arousing video clips, and surprise laboratory tests. Though some studies state that high levels of arousal facilitate memory, others state the opposite that high arousal hinders or is not associated with memory. To find clear information, it is essential to experimentally manipulate arousal during a to-be-remembered event and compare memory for the event between children who endured the more versus less arousing version. Firstly, concerning the effects of stress on memory, some studies indicate that stress assists children’s memory while others state that stress is not related to memory or hurts their memory. In several studies, children’s familiarity with events and their level of involvement differed in a manner that could have influenced their memory despite stress levels (Quas et al., 2014).
The results showed that greater HPA axis activation during the TSST-M was related to enhanced memory. The pattern was especially robust in 9-12-year-olds in one study but across age in the other. Additionally, greater arousal at retrieval hinders memory, which is contrary to arousal at encoding. The study was determined to find out how stress directly and together with the context at retrieval affected memory across development. In both age groups, the participants who experienced the high-stress TSST-M did not evenly recall the experience better than those who experienced the less-arousing version. The children and adolescents in the high-stress TSST-M condition reacted with arousal but they did not show correspondingly better memory. Therefore, exposure to a more stressful event did not enhance the memory of the event. It is important to note that autobiographical memories are influenced by a variety of factors like novelty, interest, and level of personal involvement besides the level of arousal (Quas et al., 2014).
The results do not offer a direct answer concerning how stress affects children and adolescents’ memory. They point out an important issue that requires attention: the effects of stress on episodic memory are likely much more complex than effects of stress on memory for standardized laboratory-based, non-interactive materials.
The aim of the fourth study was to explore delayed effects of high endogenously evoked cortisol concentrations on visuo-spatial declarative memory (Taverniers, Taylor, & Smeets, 2013). It also applied multiple mediation (MM) examination in establishing path procedures between stressful activities and mental functioning. Twenty-four men from the applicants’ group were selected to participate in the study. Stressful activities triggered vigorous rises in amounts of cortisol in addition to substantial failure in instantaneous remembrance ability. The research also utilized a MM design that entailed distribution-independent asymptotic and resampling techniques to prolong customary bivariate examination. Multiple mediation outcomes indicated that ROCF performance was facilitated by high cortisol amounts. Regarding the examined variables, the present analysis was the first one to offer statistical support for the generally acknowledged thesis that cortisol secretion in itself rather than subjective strain or the experimental treatment, affects cognitive performance (Taverniers, Taylor, & Smeets, 2013).
Sufficient studies indicate that high cortisol secretion can have several immediate effects on human cognition. Additionally, externally directed cortisol has both instant adverse outcomes and lead to impeded memory retrieval deficits. Cortisol is the main glucocorticoid in humans and is secreted by the stress-responsive hypothalamic-pituitary-adrenal (HPA) axis, fundamentally a multifaceted technique of response mechanisms. Because of specific features like its lipophilic structure and atomic dimension, cortisol easily flows through a semipermeable blood-brain barrier that operates as a brain-protective interface and has several carrier-mediated transport systems for small molecules. Consequently, and in interaction with other transmitter systems, cortisol can modulate memory in several ways, which are determined by the envisaged memory phase. For example, although higher cortisol concentrations normally facilitate memory when cortisol is produced during the consolidation phase, it may impair memory retrieval any time of the day. The memory impairment seems to be highly evident in cases of serious acute stress, where the operation of the sympathetic nervous system is elevated. This process is consistent with models that emphasize a significant role for noradrenergic activity in the basolateral of the amygdala (Taverniers, Taylor, & Smeets, 2013).
This research studied immediate and prolonged effects of cortisol secretion that was evoked by strong naturalistic stress. Firstly, it proved that the presence of severe air force stressful conditions initiates high cortisol secretion, which significantly impairs immediate visuo-spatial declarative memory recall. The study revealed lasting impacts of increased endogenously induced cortisol absorptions on visuo-spatial declarative memory. The outcomes also showed that the impairing effects of cortisol on memory retrieval emanate from an initial phase of memory development since memory deterioration tend to stay moderately steady alongside same weakening rates for those who were and those who were not exposed to stress. This supports the proposed mechanism of diminished rehearsal due to increased cortisol levels. Throughout the process, non-retrieved memory traces are weakened or lost.
The objective of the fifth study was to determine whether high cortisol levels harm both working memory and declarative memory retrieval in young healthy men, and to evaluate the relation between the two measures (Oei et al., 2006). Additionally, the study examined whether cortisol differentially affects retrieval of information with diverse arousal properties. Twenty strong male, first-year psychology students were involved in this research. The conditions for inclusion were a body mass index between 19 and 25, and a healthy medical and psychiatric record. The exclusion criterion was use of medication or psychotropic drugs within three months prior to the test sessions, blood pressure over 140/90 mmHg, diabetes mellitus, current and past psychiatric problems and the utilization of remedies that have corticosteroids.
Severe high-levels of glucocorticoid in human beings affect memory and cognition, and stress affects several kinds of memory in different ways. Additionally, higher cortisol amounts after acquiring information improve declarative memory association, particularly of information with emotionally stimulating content. On the contrary, the relation between pre-retrieval stress or high cortisol levels and impaired memory retrieval has been noted consistently. Moreover, emotionally stimulating and negatively valence information seems to be much influenced by elevated cortisol amounts during the period of retrieval experimenting compared to neutral, non-provoking stimuli. The effects of cortisol on declarative memory retrieval have mostly been associated with actions on glucocorticoid (GC) receptors in the hippocampus and the prefrontal cortex (PFC). Furthermore, some researchers discovered that severe increases of exogenous glucocorticosteroids weakened the WM but did not affect the declarative memory. Though declarative memory encoding and consolidation depend on the hippocampus, the retrieval of declarative memory is facilitated by the PFC. Although WM tasks depend on prefrontal brain regions, proof from investigations using magnetic encephalograms (MEG) and functional magnetic resonance imaging (fMRI) indicate that the medial temporal lobe (MTL) is triggered during WM activities. Additionally, activity in the dorsolateral PFC has also been identified during memory retrieval and WM, probably indicating monitoring or selection of task-appropriate data (Oei et al., 2006).
The research indicated that psychosocial stress weakened WM operation at high but not low operating memory loads. Increased amounts of cortisol were linked to slower WM operation at high loads. Moreover, a negative relation between cortisol levels and delayed recall of moderately emotional information was discovered. Recall performance of the moderately emotional paragraphs was also linked to WM performance. On the contrary, such relation was not noted for highly emotional paragraphs.
Expectedly, impaired WM performance at high loads was linked to low retrieval performance. Because the study did not evaluate intelligence, it is likely that the relation between WM and retrieval impairment implied an underlying variance in intelligence levels between the groups. However, there is proof from imaging studies that indicate common activity of the MTL and the PFC during retrieval and MW and cortisol-induced decreases in those regions. Thus, it could be possible that besides direct influence on speciﬁc parts, cortisol damages memory indirectly through general effects on a front temporal network. Low loads from the Sternberg paradigm have been related to instigations in the left ventrolateral PFC but at high loads with right dorsolateral PFC activation. The latter part is related to episodic memory retrieval. This indicates that of the two sub processes of WM, “manipulation” could be more sensitive to the effects of cortisol and stress, as opposed to “maintenance” processes (Oei et al., 2006).
The purpose of the sixth study was to research the impacts of severe stress and cortisol on working memory (WM) (Pulopulos et al., 2015). Two independent studies were conducted with elderly males and females. In study 1, after the TSST, the performance of women (but not men) improved on Digit Span Forward but not Digit Span Backward (Pulopulos et al., 2015). In addition, in women, the amount of cortisol during the time of memory testing indicated a positive relation with the recalling ability element of the operating memory prior and following the test, and with exclusive elements of the operating memory only prior to the stressful activity. With regards to the second experiment, despite participants showing a salivary alpha-amylase and cortisol reaction towards the test, stress had no impact on the functioning of arrangement of numbers and letters in a certain order, which emphasizes highly on the exclusive element of the WM. Cortisol and sAA had no connection with WM. Therefore, the outcomes indicate that flowing cortisol levels during the time of retrieval examination but not stress reaction influences the elderly women’s ability to remember. Additionally, stress and high amounts of cortisol after strenuous activities has no impact on the exclusive element of the operating memory in the elderly.
Acute stress can moderate memory performance through the action of cortisol on glucocorticoid and mineralocorticoid receptors (GR and MR respectively), particularly those placed in the prefrontal cortex (PFC), hippocampus and amygdala. Several inquiries in young adults have indicated that acute stress impairs working memory, but there is also evidence to the contrary (Memory-enhancing effects have only been reported in men). WM is a PFC-dependent ability that comprises both a memory span component (maintenance of a limited amount of information) and an executive component (manipulation of this information). In addition, the executive component seems more prone to being affected by acute stress than the memory limit component (Pulopulos et al., 2015).
The outcomes on this study indicate that older individuals are less sensitive than young ones to the acute effects of stress and cortisol on memory processes. Contrary to the effects detected in young adults, past researches in older animals and humans did not indicate any acute effects on spatial memory, learning, short-term declarative or non-declarative memory, or long-term memory retrieval of pictures, words and stories. Nevertheless, a specific effect of stress-induced cortisol response has been observed on retroactive interference (that is impairment in memory because of the interference of previously learned material) in middle-aged people, but not in young adults. There is evidence of a damaging effect of cortisol increase on short-term word list recall. The wordlist recall was measured after other memory activities were conducted. Therefore, the weakening of word-list recall might have resulted from improvement of retroactive interference. Consequently, most of the memory processes might be unaffected by stress in older people. The results indicated that older women, but not men, increased their memory span after stress. This effect was associated with acute circulating cortisol levels, but not to the magnitude of the stress-induced cortisol increase. Moreover, in both older males and females, cortisol and stress reactions had no effect on the executive component of the WM. The study offers experiential backup for the knowledge that healthy older individuals may be less sensitive compared to younger individuals to the acute effects of stress-induced cortisol increases on various forms of memory processes (Pulopulos et al., 2015).
The study that I found most convincing was the one on impeded memory impacts following severe stress in Distinctive Forces applicants through investigating path procedures between production of cortisol and ability to remember. This study presented MM analyses and offered mathematical support for the generally acknowledged concept in psychoneuroendocrinology that cortisol reactivity in itself, instead of the direct extreme stress treatment and secondary personal stressful events, influences brain performance. I agree with the findings of the studies that stress in most cases impairs memory retrieval, as exposure to stringent stressors triggers cortisol secretion, which signiﬁcantly impairs immediate visuo-spatial declarative memory recall.
de Veld, D. M., Riksen-Walraven, J. M., & de Weerth, C. (2014). Acute psychosocial stress and children’s memory. Stress, 17(4), 305-313.
Dongaonkar, B., Hupbach, A., Gomez, R., & Nadel, L. (2013). Effects of psychosocial stress on episodic memory updating. Psychopharmacology, 226(4), 769-779.
Oei, N. Y. L., Everaerd, W. T. A. M., Elzinga, B. M., Van Well, S., & Bermond, B. (2006). Psychosocial stress impairs working memory at high loads: an association with cortisol levels and memory retrieval. Stress, 9(3), 133-141.
Pulopulos, M. M., Hidalgo, V., Almela, M., Puig-Perez, S., Villada, C., & Salvador, A. (2015). Acute stress and working memory in older people. Stress, 18(2), 178-187.
Quas, J. A., Rush, E. B., Yim, I. S., & Nikolayev, M. (2014). Effects of stress on memory in children and adolescents: Testing causal connections. Memory, 22(6), 616-632.
Taverniers, J., Taylor, M. K., & Smeets, T. (2013). Delayed memory effects after intense stress in Special Forces candidates: Exploring path processes between cortisol secretion and memory recall. Stress, 16(3), 311-320.