Positivity Effect and Working Memory Performance Remains Intact in Older Adults After Sleep Deprivation

Background: Older adults perform better in tasks which include positive stimuli, referred to as the positivity effect. However, recent research suggests that the positivity effect could be attenuated when additional challenges such as stress or cognitive demands are introduced. Moreover, it is well established that older adults are relatively resilient to many of the adverse effects of sleep deprivation. Our aim was to investigate if the positivity effect in older adults is affected by one night of total sleep deprivation using an emotional working memory task.Methods: A healthy sample of 48 older adults (60-72 years) was either sleep deprived for one night (n = 24) or had a normal night’s sleep (n = 24). They performed an emotional working memory n-back (n = 1 and 3) task containing positive, negative and neutral pictures.Results: Performance in terms of accuracy and reaction times was best for positive stimuli and worst for negative stimuli. This positivity effect was not altered by sleep deprivation. Results also showed that, despite significantly increased sleepiness, there was no effect of sleep deprivation on working memory performance. A working memory load × valence interaction on the reaction times revealed that the beneficial effect of positive stimuli was only present in the 1-back condition.Conclusion: While the positivity effect and general working memory abilities in older adults are intact after one night of sleep deprivation, increased cognitive demand attenuates the positivity effect on working memory speed

PERSONLIG MUSIKSMAK : sambandet mellan musikpreferenser och personlighetsdrag

Personlighet och dess betydelse för beteende har under lång tid varit ett lika aktuellt som välundersökt forskningsområde. Denna studie syftar undersöka sambandet mellan personlighetsdrag enligt Five Factor Model och musikpreferenser i en svensk population. Resultaten förväntas ligga i linje med tidigare studiers, vilka funnit vissa positiva samband bl. a. mellan Extraversion och konventionell musik samt Öppenhet för erfarenheter och traditionell, komplex musik. Deltagarna (107) svarade på ett webbaserat formulär avsett att mäta musikpreferenser    och    personlighetsdrag.    Musikpreferenstestet utgjordes av 22 genrer varav 20 ingick i en analys resulterandes i sex musikdimensioner. Resultaten visade bl.a. att Öppenhet för erfarenheter    korrelerade    positivt    med    musikdimensionerna Amerikansk traditionell och Europeisk traditionell och Extraversion korrelerade positivt med Konventionell musik. Vidare fanns även könsskillnader vad gällde musikpreferenser. Resultaten följde tidigare forskning trots vissa metodologiska skillnader, vilket ger ytterligare tyngd åt kopplingen mellan musikpreferenser och personlighetsdrag

Processing affective information after sleep loss

It is not fully understood why we need to sleep, although it is evident that sleep loss has consequences for many emotional and cognitive functions. The last couple of decades, sleep researchers have been increasingly devoted to better understand the relationship between sleep and affect. However, it is still poorly understood how sleep deprivation influences the way in which affective information is processed. The aim of this thesis was to investigate if there is a bias towards affective information after sleep deprivation and whether such bias influence information processing. Study I tested reinforcement learning from positive as compared to negative feedback after two nights of sleep restriction. There were no indications of the expected reward-seeking behavior in generalized learning or in the learning strategy. A slowing in learning rate inferred from computational modeling was observed primarily for negative feedback. This could be indicative of a slowing in memory integration. It is unclear if the dopamine alterations proposed to cause reward-seeking behavior after total sleep deprivation are also implicated after sleep restriction. Study II examined the neurophysiological response of the competition of attention between unpleasant and neutral pictures after two nights of sleep restriction. We found no alterations of sleep restriction on attention in relation to picture valence, or on executive control of attention. Despite observations of an increased sleepiness, an impaired sustained attention, and reduced positive affect, the few hours of allowed sleep may have been enough to counteract an affective bias and an executive control impairment. Study III tested if one night of total sleep deprivation altered working memory for positive, negative, or neutral pictures using two levels of working memory load. Results showed that working memory accuracy was generally impaired after sleep deprivation, independent of picture valence. However, in the sleep deprived group we observed faster responses to positive and slower responses to negative pictures. These results could indicate a bias towards both positive and negative pictures, but with opposite consequences on working memory speed. Study IV used the same protocol as Study III to combinedly test two common findings among older adults: That they prioritize positive over negative stimuli (the positivity effect), and that they are less affected by sleep deprivation. Working memory performance was overall better for positive than negative pictures, with no differences between the sleep conditions. This positivity effect was only present in the low working memory load condition. These results show that even after a state-dependent challenge such as sleep deprivation, the positivity effect remains in older adults, at least when working memory load is low. Overall, the Studies in this thesis demonstrate signs of affective bias as well as lack thereof after total and partial sleep deprivation. The use of a diverse set of tasks and methodology may have contributed to the discrepancies in the findings, but it also highlights that we have yet to fully understand how lack of sleep may influence the processing of affectively valuable information

Data and scripts

https://doi.org/10.17045/sthlmuni.11955939.v

Ab initio studie av nanotrådars stabilitet

Monoatomic chain formation for Ag, Au, Pd and Pt has been investigated using a model for the tip structure. First-principles calculations, mostly spin polarized, were performed within the framework of the Density Functional theory. Results are presented and discussed on the basis of the electronic structure. Tendencies for chain formation were noted for Ag, Au and Pt

Ab initio studie av nanotrådars stabilitet

Monoatomic chain formation for Ag, Au, Pd and Pt has been investigated using a model for the tip structure. First-principles calculations, mostly spin polarized, were performed within the framework of the Density Functional theory. Results are presented and discussed on the basis of the electronic structure. Tendencies for chain formation were noted for Ag, Au and Pt

Processing affective information after sleep loss

It is not fully understood why we need to sleep, although it is evident that sleep loss has consequences for many emotional and cognitive functions. The last couple of decades, sleep researchers have been increasingly devoted to better understand the relationship between sleep and affect. However, it is still poorly understood how sleep deprivation influences the way in which affective information is processed. The aim of this thesis was to investigate if there is a bias towards affective information after sleep deprivation and whether such bias influence information processing. Study I tested reinforcement learning from positive as compared to negative feedback after two nights of sleep restriction. There were no indications of the expected reward-seeking behavior in generalized learning or in the learning strategy. A slowing in learning rate inferred from computational modeling was observed primarily for negative feedback. This could be indicative of a slowing in memory integration. It is unclear if the dopamine alterations proposed to cause reward-seeking behavior after total sleep deprivation are also implicated after sleep restriction. Study II examined the neurophysiological response of the competition of attention between unpleasant and neutral pictures after two nights of sleep restriction. We found no alterations of sleep restriction on attention in relation to picture valence, or on executive control of attention. Despite observations of an increased sleepiness, an impaired sustained attention, and reduced positive affect, the few hours of allowed sleep may have been enough to counteract an affective bias and an executive control impairment. Study III tested if one night of total sleep deprivation altered working memory for positive, negative, or neutral pictures using two levels of working memory load. Results showed that working memory accuracy was generally impaired after sleep deprivation, independent of picture valence. However, in the sleep deprived group we observed faster responses to positive and slower responses to negative pictures. These results could indicate a bias towards both positive and negative pictures, but with opposite consequences on working memory speed. Study IV used the same protocol as Study III to combinedly test two common findings among older adults: That they prioritize positive over negative stimuli (the positivity effect), and that they are less affected by sleep deprivation. Working memory performance was overall better for positive than negative pictures, with no differences between the sleep conditions. This positivity effect was only present in the low working memory load condition. These results show that even after a state-dependent challenge such as sleep deprivation, the positivity effect remains in older adults, at least when working memory load is low. Overall, the Studies in this thesis demonstrate signs of affective bias as well as lack thereof after total and partial sleep deprivation. The use of a diverse set of tasks and methodology may have contributed to the discrepancies in the findings, but it also highlights that we have yet to fully understand how lack of sleep may influence the processing of affectively valuable information

Viewing distance matter to perceived intensity of facial expressions

In our daily perception of facial expressions, we depend on an ability to generalize across the varied distances at which they may appear. This is important to how we interpret the quality and the intensity of the expression. Previous research has not investigated whether this so called perceptual constancy also applies to the experienced intensity of facial expressions. Using a psychophysical measure (Borg CR100 scale) the present study aimed to further investigate perceptual constancy of happy and angry facial expressions at varied sizes, which is a proxy for varying viewing distances. Seventy-one (42 females) participants rated the intensity and valence of facial expressions varying in distance and intensity. The results demonstrated that the perceived intensity (PI) of the emotional facial expression was dependent on the distance of the face and the person perceiving it. An interaction effect was noted, indicating that close-up faces are perceived as more intense than faces at a distance and that this effect is stronger the more intense the facial expression truly is. The present study raises considerations regarding constancy of the PI of happy and angry facial expressions at varied distances