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Sökning: FÖRF:(Mats Dahl)

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1.
  • Sikström, Sverker, et al. (författare)
  • How bad is bad? Perceptual differences in the communication of severity in intimate partner violence
  • 2023
  • Ingår i: Humanities and Social Sciences Communications. - 2662-9992. ; 10:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Accurate communication of the severity of violence in intimate relations is essential for the appropriate evaluation of offenders and victims in contexts such as court trials, custody cases, and the continuation of relationships. Using a new paradigm, this study quantifies discrepancies in how the severity of violence is communicated in texts written by offenders, victims, and bystanders who witness violence. The study was conducted in two phases, where participants were randomly sampled from the same population to participate in either Phase 1 or Phase 2. In the first Phase, witnesses (narrators) provided nine narratives about self-experienced intimate partner violence and rated the violence’s severity; then in the second Phase non-witnesses (recipients) read all the narratives and rated the severity of the violence. Four types of perceptual differences (calibration, accuracy, gender, and role perceptual differences) were identified when rating the severity of three types of violence (psychological, physical, and sexual) as communicated by three types of witnesses (victims, offenders, and bystanders) of violence in heterosexual, romantic relationships. Several novel findings were made related to a strong perceptual difference in calibration, i.e., a tendency for the recipient to rate the violence more severely than the narrator, where this effect was mainly found for victims and bystanders, but not for offenders. Also, the calibration effect was largely seen in the sexual and physical, but not psychological, narratives. The recipients’ accuracy was considerably lower for psychological rather than sexual violence. Finally, the validity of the method was confirmed by replicating earlier findings on perceptual differences in roles where witnesses rated violence more severely than victims or offenders and women were rated more severely than men, which was especially true for male raters. These results suggest systematic perceptual differences in severity ratings and may have substantial implications for victims and offenders in real-life settings. These findings may potentially be used to ameliorate the negative effects of perceptual differences.
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2.
  • Sikström, Sverker, et al. (författare)
  • Removing Biases in Communication of Severity Assessments of Intimate Partner Violence : Model Development and Evaluation
  • 2023
  • Ingår i: Journal of Medical Internet Research. - : JMIR Publications Inc.. - 1438-8871. ; 25
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: To support a victim of violence and establish the correct penalty for the perpetrator, it is crucial to correctly evaluate and communicate the severity of the violence. Recent data have shown these communications to be biased. However, computational language models provide opportunities for automated evaluation of the severity to mitigate the biases. Objective: We investigated whether these biases can be removed with computational algorithms trained to measure the severity of violence described. Methods: In phase 1 (P1), participants (N=71) were instructed to write some text and type 5 keywords describing an event where they experienced physical violence and 1 keyword describing an event where they experienced psychological violence in an intimate partner relationship. They were also asked to rate the severity. In phase 2 (P2), another set of participants (N=40) read the texts and rated them for severity of violence on the same scale as in P1. We also quantified the text data to word embeddings. Machine learning was used to train a model to predict the severity ratings. Results: For physical violence, there was a greater accuracy bias for humans (r2=0.22) compared to the computational model (r2=0.31; t38=–2.37, P=.023). For psychological violence, the accuracy bias was greater for humans (r2=0.058) than for the computational model (r2=0.35; t38=–14.58, P<.001). Participants in P1 experienced psychological violence as more severe (mean 6.46, SD 1.69) than participants rating the same events in P2 (mean 5.84, SD 2.80; t86=–2.22, P=.029<.05), whereas no calibration bias was found for the computational model (t134=1.30, P=.195). However, no calibration bias was found for physical violence for humans between P1 (mean 6.59, SD 1.81) and P2 (mean 7.54, SD 2.62; t86=1.32, P=.19) or for the computational model (t134=0.62, P=.534). There was no difference in the severity ratings between psychological and physical violence in P1. However, the bias (ie, the ratings in P2 minus the ratings in P1) was highly negatively correlated with the severity ratings in P1 (r2=0.29) and in P2 (r2=0.37), whereas the ratings in P1 and P2 were somewhat less correlated (r2=0.11) using the psychological and physical data combined. Conclusions: The results show that the computational model mitigates accuracy bias and removes calibration biases. These results suggest that computational models can be used for debiasing the severity evaluations of violence. These findings may have application in a legal context, prioritizing resources in society and how violent events are presented in the media.
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3.
  • Dahl, Mats, et al. (författare)
  • Quiet Eye and Computerized Precision Tasks in First-Person Shooter Perspective Esport Games
  • 2021
  • Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 12, s. 1-10
  • Tidskriftsartikel (refereegranskat)abstract
    • The gaze behavior in sports and other applied settings has been studied for more than 20 years. A common finding is related to the “quiet eye” (QE), predicting that the duration of the last fixation before a critical event is associated with higher performance. Unlike previous studies conducted in applied settings with mobile eye trackers, we investigate the QE in a context similar to esport, in which participants click the mouse to hit targets presented on a computer screen under different levels of cognitive load. Simultaneously, eye and mouse movements were tracked using a high-end remote eye tracker at 300 Hz. Consistent with previous studies, we found that longer QE fixations were associated with higher performance. Increasing the cognitive load delayed the onset of the QE fixation, but had no significant influence on the QE duration. We discuss the implications of our results in the context of how the QE is defined, the quality of the eye-tracker data, and the type of analysis applied to QE data.
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4.
  • Sikström, Sverker, et al. (författare)
  • What you say and what I hear-Investigating differences in the perception of the severity of psychological and physical violence in intimate partner relationships
  • 2021
  • Ingår i: PLOS ONE. - San Francisco, CA, United States : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 16:8
  • Tidskriftsartikel (refereegranskat)abstract
    • The correct communication of the severity of violence is essential in the context of legal trials, custody cases, support of victims, etc., for providing fair treatment. A narrator that communicates their experiences of interpersonal violence may rate the seriousness of the incident differently than a rater reading the narrators text, suggesting that there exist perceptual differences (PD) in severity ratings between the narrator and the rater. We propose that these perceptual differences may depend on whether the narrative is based on physical or psychological violence, and on gender differences. Physical violence may be evaluated as more serious by the receiver of the narrative than by the narrator (Calibration PD), whereas the seriousness of psychological violence may be difficult to convey, leading to a discrepancy in the seriousness ratings between the narrator and the rater (Accuracy PD). In addition, gender stereotypes may influence the seriousness rating (Gender PD), resulting in violence against women being perceived as more serious than the same violence against men. These perceptual differences were investigated in 3 phases using a new experimental procedure. In Phase 1, 113 narrators provided descriptions and seriousness ratings of self-experienced physical and psychological violence in relationships. In Phase 2, 340 independent raters rated the seriousness of 10 randomly selected narrations from Phase 1. In Phase 3, the genders in the narrations were changed to the opposite gender, and seriousness ratings were collected from 340 different raters. Our results confirmed the hypothesized perceptual differences. Violence to male victims was considerably more likely to be seen as severe when the raters were misled to believe the victim was a woman. We propose that these data provide practical guidelines for how to deal with misinformation in the communication of violence. The data also show that mean values and the confidence of such severity ratings need to be adjusted for several factors, such as whether it is self-experienced or communicated, the type of violence, and the gender of the victims and raters.
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5.
  • Bertilsson, Johan, et al. (författare)
  • Towards systematic and objective evaluation of police officer performance in stressful situations
  • 2020
  • Ingår i: Police Practice and Research. - : Informa UK Limited. - 1561-4263 .- 1477-271X. ; 21:6, s. 655-669
  • Tidskriftsartikel (refereegranskat)abstract
    • To ensure a continuous high standard of police units, it is critical to recruit people who perform well in stressful situations. Today, this selection process includes performing a large series of tests, which still may not objectively reveal a person’s capacity to handle a life-threatening situation when subjected to high levels of stress. To obtain more systematic and objective data, 12 police officers were exposed to six scenarios with varying levels of threat while their heart rate and pupil size were monitored. The scenarios were filmed and six expert evaluators assessed the performance of the police officers according to seven predefined criteria. Four of the scenarios included addressing a moderate threat level task and the scenarios were executed in a rapid sequence. Two further scenarios included a familiar firearm drill performed during high and low threat situations. The results showed that there was a large agreement between the experts in how they judged the performance of the police officers (p < 0.001). Performance increased significantly over tasks in four of the seven evaluation criteria (p ≤ 0.037). There was also a significant effect of pupil size (p = 0.004), but not heart rate, when comparing the different sequential scenarios. Moreover, a high level of threat considerably impaired the motor performance of the police officers during the firearms drill (p = 0.002). Finally, the pupil seemed to systematically dilate more when a threat appeared immediately than with a delay in the scenarios (p = 0.007). We conclude that systematic and quantitative judgments from experts provide valuable and reliable information about the performance of participants in realistic and stressful policing scenarios. Furthermore, objective physiological measures of heart rate and pupil size may help to explain and understand why performance sometimes deteriorates.
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6.
  • Bertilsson, Johan, et al. (författare)
  • Stress Levels Escalate When Repeatedly Performing Tasks Involving Threats
  • 2019
  • Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 10, s. 1562-1562
  • Tidskriftsartikel (refereegranskat)abstract
    • Police work may include performing repeated tasks under the influence of psychological stress, which can affect perceptual, cognitive and motor performance. However, it is largely unknown how repeatedly performing stressful tasks physically affect police officers in terms of heart rate and pupil diameter properties. Psychological stress is commonly assessed by monitoring the changes in these biomarkers. Heart rate and pupil diameter was measured in 12 male police officers when performing a sequence of four stressful tasks, each lasting between 20 and 130 s. The participants were first placed in a dimly illuminated anteroom before allowed to enter a brightly lit room where a scenario was played out. After each task was performed, the participants returned to the anteroom for about 30 s before performing the next sequential task. Performing a repeated sequence of stressful tasks caused a significant increase in heart rate (p = 0.005). The heart rate started to increase already before entering the scenario room and was significantly larger just after starting the task than just before starting the task (p < 0.001). This pattern was more marked during the first tasks (p < 0.001). Issuance of a verbal "abort" command which terminated the tasks led to a significant increase of heart rate (p = 0.002), especially when performing the first tasks (p = 0.002). The pupil diameter changed significantly during the repeated tasks during all phases but in a complex pattern where the pupil diameter reached a minimum during task 2 followed by an increase during tasks 3 and 4 (p ≤ 0.020). During the initial tasks, the pupil size (p = 0.014) increased significantly. The results suggest that being repeatedly exposed to stressful tasks can produce in itself an escalation of psychological stress, this even prior to being exposed to the task. However, the characteristics of both the heart rate and pupil diameter were complex, thus, the findings highlight the importance of studying the effects and dynamics of different stress-generating factors. Monitoring heart rate was found useful to screen for stress responses, and thus, to be a vehicle for indication if and when rotation of deployed personnel is necessary to avoid sustained high stress exposures.
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7.
  • Dahl, Mats, et al. (författare)
  • Analysis of eyewitness testimony in a police shooting with fatal outcome - Manifestations of spatial and temporal distortions
  • 2018
  • Ingår i: Cogent Psychology. - : Taylor & Francis. - 2331-1908. ; 5:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Eyewitness statements are commonly used in the criminal justice system and viewed as having a high-probative value, especially when the witness has no motive to lie, other witness recollection corroborates the account, orthe witness is highly confident. A fatal police shooting incident in Sweden had 13 witnesses (nine civilians and four police officers) and was also filmed with two mobile phones. All interviews were conducted before witnesses viewed the films, allowing for the analysis of discrepancies between their statements and the videos. In this incident, a police patrol was sent to find out a man who was reported to have attacked two persons with a knife. When found, the perpetrator refused to obey the officer's commands, and the police eventually shot at him. The analysis showed clear differences between the witness testimonies and the film. Elements associated with perceived threat, for example, the assailant's armament and movement direction and number of shots fired, were remembered fairly accurately. However, most witnesses poorly recollected when, that is, after which shot, the assailant fell to the ground. Moreover, memory of the actual order of events was altered and important aspects omitted that were crucial from a legal point of view.
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8.
  • Lundgren-Kownacki, Karin, et al. (författare)
  • Exploring how a traditional diluted yoghurt drink may mitigate heat strain during medium-intensity intermittent work: a multidisciplinary study of occupational heat strain
  • 2018
  • Ingår i: Industrial Health. - : National Institute of Industrial Health. - 0019-8366 .- 1880-8026. ; 56:2, s. 106-121
  • Tidskriftsartikel (refereegranskat)abstract
    • It is common practice in India to consume the dairy drink buttermilk as a way of mitigating occupational heat strain. This paper explores the thermoregulatory and hydration benefits of drinking buttermilk but also the impacts of work in a hot environment on the gut microbiota, renal and cognitive function. Twelve healthy participants were subjected to a 3-h period of medium load physical intermittent work in a climatic chamber (34 degrees C, 60% RH). The subjects were given water, buttermilk (700 ml) or no rehydration at random. Mean body temperatures when no rehydration was given were significantly higher (p <= 0.001). When subjects drank water or buttermilk they had a lower sweat rate than with no rehydration (p <= 0.05) and the perception of feeling hot, uncomfortable, thirsty and physically exerted was significantly reduced (p <= 0.05). A hormonal stress response at the end of the exposure was seen when not drinking (p <= 0.05). No differences in cognitive abilities and gut microbiota were found. The exposure lowered the renal blood flow suggesting an acute impact of short term heat exposure. It was also found that buttermilk has a protective effect on this impact. Our results demonstrated that keeping hydrated by water/buttermilk consumption mitigates heat strain in well-nourished subjects.
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9.
  • Sikström, Sverker, et al. (författare)
  • The Role of Sparsely Distributed Representations in Familiarity Recognition of Verbal and Olfactory Materials
  • 2018
  • Ingår i: Cognitive Processing. - : Springer Science and Business Media LLC. - 1612-4782 .- 1612-4790. ; 19:4, s. 481-494
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the generalized signal detection theory (GSDT), where familiarity is described by a sparse binomial distribution of binary node activity rather than by normal distribution of familiarity. Items are presented in a distributed representation, where each node receives either noise only, or signal and noise. An old response (i.e., a ‘yes’ response) is made if at least one node receives signal plus noise that is larger than the activation threshold, and item variability is determined by the distribution of activated nodes as the threshold is varied. A distinct representation leads to better performance and a lower ratio of new to old item variability, than a more distributed and less distinct representations. Here we apply the GSDT to empirical data on verbal and olfactory memory and suggest that verbal memory relies on a distinct neural item representation whereas olfactory memory has a fuzzy neural representation leading to poorer memory and inducing a larger ratio of new to old item variability.
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10.
  • Dahl, Mats, et al. (författare)
  • Old and very old adults as witnesses: event memory and metamemory
  • 2015
  • Ingår i: Psychology, Crime and Law. - 1477-2744 .- 1068-316X. ; 21:8, s. 764-775
  • Tidskriftsartikel (refereegranskat)abstract
    • Older people constitute an important category of eyewitnesses. Episodic memory performance in older persons is poorer than in younger adults, but little research has been made on older persons' metacognitive judgments. Since more persons of advanced age will likely be called upon as witnesses in coming years, it is critical to characterize this population's metacognitive abilities. We compared event memory metacognition in old adults (66-year-old, n = 74) to very old adults (87 or 90 years old, n = 55). Participants were tested on their memory of a film, using questions with two answer alternatives and the confidence in their answer. As expected, the very old group had a lower accuracy rate than the old group (d = 0.59). The very old group, however, monitored this impairment, since their over-/underconfidence and calibration did not differ from the old group but they displayed a poorer ability to separate correct from incorrect answers (discrimination ability). Possibly, the very old group was able to monitor the level of their over-/underconfidence because they applied general self-knowledge about their memory skills. In contrast, the discrimination of correct from incorrect answers may be more dependent on ability to attend to the features of each retrieved memory.
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