A probabilistic real-time algorithm for detecting blinks, saccades, and fixations from EOG data

We present a computationally light real-time algorithm which automatically detects blinks, saccades, and fixations from electro-oculography (EOG) data and calculates their temporal parameters. The method is probabilistic which allows to consider the uncertainties in the detected events. The method is real-time in the sense that it processes the data sample-by-sample, without a need to process the whole data as a batch. Prior to the actual measurements, a short, unsupervised training period is required. The parameters of the Gaussian likelihoods are learnt using an expectation maximization algorithm. The results show the promise of the method in detecting blinks, saccades, and fixations, with detection rates close to 100 %. The presented method is published as an open source tool

Saccadic eye movements estimate prolonged time awake

Prolonged time awake increases sleep drive and causes sleepiness. Increasing sleep drive induces rapid and uncontrolled sleep initiation leading to unstable cognitive performance which is comparable to alcohol intoxication. Sleepiness causes 10 – 20 % of traffic accidents hence being a major identifiable and preventable cause of accidents. Even though the severeness of sleepiness -related accidents and hazards have been recognized and the state of New Jersey (USA) even has a law that forbids driving after being awake for more than 24 h, there is no reliable on-site test for estimating total time awake of a person. A reliable, objective, and practical metrics for measuring sleepiness outside the laboratory would be valuable. This thesis presents a novel approach and examines whether an eye movement based metric could serve as an on-site test metric for time awake. The rationale for the studying the use of eye movements to estimate overall time awake is as follows: Different cognitive functions, especially attentional ones are vulnerable to sleepiness. The attentional and oculomotor processes share neuroanatomical networks in the brain and saccadic eye movements have been used to study attentional functions. Moreover, saccadic eye movements are sensitive to sleepiness. The thesis consists of two parts: 1) Algorithm development for electro-oculographic (EOG) feature extraction to enable effective and practical analyses of measurements conducted outside the laboratory, and 2) Development of an eye movement based metric to estimate prolonged time awake. Saccadic eye movements were measured from eleven healthy adults every sixth hour with EOG in a 8-minute saccade task during 60 h of prolonged time awake. The saccade task performance, estimated as the number of saccades, decreased as a function of time awake on an individual level. The saccadic performance differed between the participants but was stable within participants (tested with 5 participants). The circadian rhythm affected the saccade task performance. Thus, the three-process model of alertness (TPMA) was fitted to, and the circadian component (C-component) was removed from, the measured data. After removing the C-component, the linear model revealed a significant trend for six out of eleven participants. The results imply that saccades measured with EOG could be used as a time awake metric outside the laboratory. The metric needs individual calibration before the time awake of a person can be estimated. More research is needed to study individual differences, optimize the measurement duration, and stimulus parameters.Pitkittynyt hereilläoloaika lisää unipainetta ja siten väsymystä. Kasvava unen tarve aiheuttaa kontrolloimattomia torkahduksia, jotka heikentävät merkittävästi ihmisen tarkkaavuutta ja siten kognitiivisia toimintoja. Univajeen aiheuttama epävakaa tila on verrattavissa humalatilaan. Liikenneonnettomuuksista 10 – 20 % on väsymyksen aiheuttamia. Väsymys on näin ollen yksi suurimmista tunnetuista, estettävissä olevista onnettomuuksien syistä. Väsymyksestä johtuvien onnettomuuksien ja katastrofien vakavuus on tunnistettu; mm. New Jerseyssä (Yhdysvallat) on säädetty laki, joka kieltää ajamisen yli 24 tunnin hereilläoloajan jälkeen. Mittalaitetta, jolla kenttäolosuhteissa pystytään mittaamaan luotettavasti, objektiivisesti ja käytännöllisesti kuljettajan hereilläolon kokonaisaikaa ei kuitenkaan ole tällä hetkellä saatavilla. Tässä väitöskirjassa on kehitetty silmänliikkeisiin perustuva mittausmenetelmä, jonka avulla voidaan mitata hereilläoloaikaa laboratorion kenttäolosuhteissa, laboratorion ulkopuolella. Univajeessa kognitiiviset toiminnot heikkenevät, erityisesti tarkkaavuus sekä visuaalinen, silmänliikkeiden avulla tapahtuva ympäristön havainnointi. Tarkkaavuutta ja okulomotorisia toimintoja säätelevät osittain samat aivojen otsalohkoalueiden hermoverkot. Tästä syystä sakkadisia silmänliikkeitä voidaan käyttää sekä tarkkaavuuden että univajeen ja väsymyksen tutkimiseen. Väitöskirja koostuu kahdesta osiosta: 1) Algoritmikehitystyöstä silmänliikkeiden tunnistamiseksi luotettavasti kenttäolosuhteissa silmänliikesignaalista, 2) Silmänliikepohjaisen menetelmän kehittäminen hereilläoloajan estimointiin. Sakkadisia silmänliikkeitä mitattiin yhdeltätoista terveeltä aikuiselta kuuden tunnin välein 60 tunnin yhtäjaksoisen univajeen aikana. Silmänliikkeet rekisteröitiin elektro-okulografia (EOG) -menetelmällä 8 minuuttia kestävän sakkaditestin aikana. Tehtävässä suoriutumista arvioitiin sen aikana suoritettujen sakkadien lukumäärällä. Sakkadien lukumäärä laski hereilläoloajan funktiona kaikilla tutkittavilla. Sakkaditehtävässä suoriutuminen vaihteli henkilöiden välillä. Testin toistettavuutta tutkittiin viidellä henkilöllä ja se todettiin toistettavaksi. Vuorokaudenaika vaikutti tehtävässä suoriutumiseen ja tästä syystä vuorokausivaihteluun liittyvä sirkadiaaninen rytmi poistettiin vireystilaa mallintavan mallin avulla (three-process model of alertness, TPMA). Sirkadiaanisen rytmin poistamisen jälkeen sakkadien lukumäärän lasku hereilläoloajan funktiona oli lineaarinen kuudella tutkimushenkilöllä yhdestätoista. Väitöskirjassa esitettyjen tulosten perusteella EOG-menetelmällä mitattujen silmänliikeiden avulla voidaan estimoida hereilläoloaikaa kenttäolosuhteissa. Tällä hetkellä mittaus vaatii henkilökohtaisen kalibrointimittauksen ennen varsinaista testimittausta. Lisää tutkimustyötä tarvitaan henkilöiden yksilöllisten erojen tutkimiseen, sekä mittausasetelman optimointiin kenttäolosuhteisiin laajemmin sopivaksi

Ultra-Short Window Length and Feature Importance Analysis for Cognitive Load Detection from Wearable Sensors

Human cognitive capabilities are under constant pressure in the modern information society. Cognitive load detection would be beneficial in several applications of human–computer interaction, including attention management and user interface adaptation. However, current research into accurate and real-time biosignal-based cognitive load detection lacks understanding of the optimal and minimal window length in data segmentation which would allow for more timely, continuous state detection. This study presents a comparative analysis of ultra-short (30 s or less) window lengths in cognitive load detection with a wearable device. Heart rate, heart rate variability, galvanic skin response, and skin temperature features are extracted at six different window lengths and used to train an Extreme Gradient Boosting classifier to detect between cognitive load and rest. A 25 s window showed the highest accury (67.6%), which is similar to earlier studies using the same dataset. Overall, model accuracy tended to decrease as the window length decreased, and lowest performance (60.0%) was observed with a 5 s window. The contribution of different physiological features to the classification performance and the most useful features that react in short windows are also discussed. The analysis provides a promising basis for future real-time applications with wearable sensors

Breakfast high in whey protein or carbohydrates improves coping with workload in healthy subjects

Peer reviewe

Algorithm for automatic analysis of electro-oculographic data

Peer reviewe

Eye movement behavior in a real-world virtual reality task reveals ADHD in children

Peer reviewe

Sensory Appeal and Routines Beat Health Messages and Visibility Enhancements : Mixed-Methods Analysis of a Choice-Architecture Intervention in a Workplace Cafeteria

Easier recognition and enhanced visibility of healthy options supposedly increase healthy choices, but real-world evidence remains scarce. Addressing this knowledge gap, we promoted nutritionally favourable foods in a workplace cafeteria with three choice-architectural strategies—priming posters, point-of-choice nutrition labels, and improved product placement—and assessed their effects on visual attention, food choices, and food consumption. Additionally, we developed a method for analysing real-world eye-tracking data. The study followed a pretest–posttest design whereby control and intervention condition lasted five days each. We monitored visual attention (i.e., total number and duration of fixations) and food choices with eye tracking, interviewed customers about perceived influences on food choices, and measured cafeteria-level food consumption (g). Individual-level data represents 22 control and 19 intervention participants recruited at the cafeteria entrance. Cafeteria-level data represents food consumption during the trial (556/589 meals sold). Results indicated that the posters and labels captured participants’ visual attention (~13% of fixations on defined areas of interest before food choices), but the intervention had insignificant effects on visual attention to foods, on food choices, and on food consumption. Interviews revealed 17 perceived influences on food choices, the most common being sensory appeal, healthiness, and familiarity. To conclude, the intervention appeared capable of attracting visual attention, yet ineffective in increasing healthier eating. The developed method enabled a rigorous analysis of visual attention and food choices in a natural choice setting. We discuss ways to boost the impact of the intervention on behaviour, considering target groups’ motives. The work contributes with a unique, mixed-methods approach and a real-world setting that enabled a multi-dimensional effects evaluation with high external validity.publishedVersionPeer reviewe

Tafoxiparin, a novel drug candidate for cervical ripening and labor augmentation : results from 2 randomized, placebo-controlled studies

Background: Slow progression of labor is a common obstetrical problem with multiple associated complications. Tafoxiparin is a depolymerized form of heparin with a molecular structure that eliminates the anticoagulant effects of heparin. We report on 2 phase II clinical studies of tafoxiparin in primiparas. Study 1 was an exploratory, first-in-pregnant-women study and study 2 was a dose-finding study. Objective: Study 1 was performed to explore the effects on labor time of subcutaneous administration of tafoxiparin before onset of labor. Study 2 was performed to test the hypothesis that intravenous treatment with tafoxiparin reduces the risk for prolonged labor after spontaneous labor onset in situations requiring oxytocin stimulation because of dystocia. Study Design: Both studies were randomized, double-blind, and placebo-controlled. Participants were healthy, nulliparous females aged 18 to 45 years with a normal singleton pregnancy and gestational age confirmed by ultrasound. The primary endpoints were time from onset of established labor (cervical dilation of 4 cm) until delivery (study 1) and time from start of study treatment infusion until delivery (study 2). In study 1, patients at 38 to 40 weeks of gestation received 60 mg tafoxiparin or placebo daily as 0.4 mL subcutaneous injections until labor onset (maximum 28 days). In study 2, patients experiencing slow progression of labor, a prolonged latent phase, or labor arrest received a placebo or 1 of 3 short-term tafoxiparin regimens (initial bolus 7, 21, or 35 mg followed by continuous infusion at 5, 15, or 25 mg/hour until delivery; maximum duration, 36 hours) in conjunction with oxytocin. Results: The number of participants randomized in study 1 was 263, and 361 were randomized in study 2. There were no statistically significant differences in the primary endpoints between those receiving tafoxiparin and those receiving the placebo in both studies. However, in study 1, the risk for having a labor time exceeding 12 hours was significantly reduced by tafoxiparin (tafoxiparin 6/114 [5%] vs placebo 18/101 [18%]; P=.0045). Post hoc analyses showed that women who underwent labor induction had a median (range) labor time of 4.44 (1.2–8.5) hours with tafoxiparin and 7.03 (1.5–14.3) hours with the placebo (P=.0041) and that co-administration of tafoxiparin potentiates the effect of oxytocin and facilitates a shorter labor time among women with a labor time exceeding 6 to 8 hours (P=.016). Among women induced into labor, tafoxiparin had a positive effect on cervical ripening in 11 of 13 cases (85%) compared with 3 of 13 participants (23%) who received the placebo (P=.004). For women requiring oxytocin because of slow progression of labor, the corresponding results were 34 of 51 participants (66%) vs 16 of 40 participants (40%) (P=.004). In study 2, tafoxiparin had no positive effects on the secondary endpoints when compared with the placebo. Except for injection-site reactions in study 1, adverse events were no more common for tafoxiparin than for the placebo among either mothers or infants. There were few serious or treatment-related adverse events. Conclusion: Subcutaneous treatment with tafoxiparin before labor onset (study 1) may be effective in reducing the labor time among women undergoing labor induction and among those requiring oxytocin for slow progression of labor. Moreover, tafoxiparin may have a positive effect on cervical ripening. Short-term, intravenous treatment with tafoxiparin as an adjunct to oxytocin in patients with labor arrest (study 2) did not affect labor time or other endpoints. Both studies suggest that tafoxiparin has a favorable safety profile in mothers and their infants.Peer reviewe

Meta-analysis of Genome-Wide Association Studies for Extraversion: Findings from the Genetics of Personality Consortium

Extraversion is a relatively stable and heritable personality trait associated with numerous psychosocial, lifestyle and health outcomes. Despite its substantial heritability, no genetic variants have been detected in previous genome-wide association (GWA) studies, which may be due to relatively small sample sizes of those studies. Here, we report on a large meta-analysis of GWA studies for extraversion in 63,030 subjects in 29 cohorts. Extraversion item data from multiple personality inventories were harmonized across inventories and cohorts. No genome-wide significant associations were found at the single nucleotide polymorphism (SNP) level but there was one significant hit at the gene level for a long non-coding RNA site (LOC101928162). Genome-wide complex trait analysis in two large cohorts showed that the additive variance explained by common SNPs was not significantly different from zero, but polygenic risk scores, weighted using linkage information, significantly predicted extraversion scores in an independent cohort. These results show that extraversion is a highly polygenic personality trait, with an architecture possibly different from other complex human traits, including other personality traits. Future studies are required to further determine which genetic variants, by what modes of gene action, constitute the heritable nature of extraversion

Meta-analysis of genome-wide association studies for extraversion:Findings from the Genetics of Personality Consortium

Extraversion is a relatively stable and heritable personality trait associated with numerous psychosocial, lifestyle and health outcomes. Despite its substantial heritability, no genetic variants have been detected in previous genome-wide association (GWA) studies, which may be due to relatively small sample sizes of those studies. Here, we report on a large meta-analysis of GWA studies for extraversion in 63,030 subjects in 29 cohorts. Extraversion item data from multiple personality inventories were harmonized across inventories and cohorts. No genome-wide significant associations were found at the single nucleotide polymorphism (SNP) level but there was one significant hit at the gene level for a long non-coding RNA site (LOC101928162). Genome-wide complex trait analysis in two large cohorts showed that the additive variance explained by common SNPs was not significantly different from zero, but polygenic risk scores, weighted using linkage information, significantly predicted extraversion scores in an independent cohort. These results show that extraversion is a highly polygenic personality trait, with an architecture possibly different from other complex human traits, including other personality traits. Future studies are required to further determine which genetic variants, by what modes of gene action, constitute the heritable nature of extraversion