Previous Mental Load and Incentives Influence Anticipatory Arousal as Indexed by the Baseline Pupil Diameter in a Speech-in-Noise Task

Listening effort and fatigue are common experiences when conversing in noisy environments. Much research has investigated listening effort in relation to listening demand using the speech-in-noise paradigm. Recent conceptualizations of listening effort postulate that mental fatigue should result in decreased arousal and a reluctance to invest further effort, particularly when the effort is not worthwhile. The aim of the study was to investigate the influence of fatigue on listening effort, in interaction with listening demands and motivation. To induce fatigue 30 adults with normal hearing completed a 40-minute long speech-in-noise task (“load sequence”). Pre- and post-load sequence listening effort was probed in easy and hard listening demands (individually adjusted signal-to-noise ratios); with high and low motivation (manipulated with monetary incentives). Subjective effort, estimated performance, and tendency to quit listening were collected using rating scales. Baseline pupil diameter and mean pupil dilation were recorded as indices of anticipatory arousal and objective effort. Self-reported effort and mean pupil dilation were overall larger during hard SNR as compared to easy SNR. Baseline pupil diameter declined from pre- to post-load sequence, suggesting an overall decrease in arousal. Monetary incentives had no influence on the baseline pupil diameter for the easy SNR condition, but for the hard SNR condition larger incentives led to larger baseline pupil diameter. These results suggest that anticipatory arousal may be influenced by fatigue and motivation effects. Models of listening effort should account for the independent influence of motivation and previous load on anticipatory arousal and effort in distinct parameters

Motivation and fatigue effects in pupillometric measures of listening effort

Listening effort and fatigue are common among individuals with hearing impairment, although within hearing sciences the relationship between effort and fatigue is not fully understood. The objective measurement of listening effort has commonly involved pupillometry in combination with the speech-in-noise paradigm, where the baseline pupil diameter (BPD) is used as a reference point, and the mean and peak pupil dilation (MPD and PPD) as indices of listening effort. Research to quantify listening effort to date has mostly investigated effort as a function of listening demands. Recent research has shown a correlation between PPD and daily-life fatigue. Furthermore, monetary incentives have been shown to increase the PPD, suggesting that listening demands alone are insufficient to explain variation in PPD. How motivation and fatigue influence the pupil metrics remains unclear. Frameworks and models of listening effort and listening-related fatigue postulate that larger previous load should result in larger subsequent fatigue. Fatigue manifests as a reluctance to mobilize further effort, particularly when listening conditions are difficult, and when expected rewards are low. In this study we experimentally investigated the interactive influences of task-induced fatigue, motivation, and listening demands on the BPD, MPD, and PPD in the speech-in-noise task. Participants completed a speech-in-noise task of 30-40 minutes without any breaks (“load sequence”) in 3 experiments. Pre- and post- load sequence listening effort was assessed under varying signal-to-noise ratios (SNRs; listening demands), monetary incentives (motivation level; Experiment 1), and magnitudes of load sequence (fatigue level; Experiment 2) in normal hearing adults. In adults with impaired hearing (Experiment 3), pre- and post-load sequence listening effort was investigated when wearing hearing aids that were described as novel technology (implied reward; high motivation) and conventional technology (no reward; low motivation). In addition to the pupil metrics, need for recovery, self-reported effort, estimated performance, and tendency to quit listening were assessed. In Experiment 1 and 2, there was a consistent decline in BPD from pre- to post- load sequence, independent of listening demands, monetary incentives, and load sequence magnitude. These results indicate declines in arousal with time-on-task. Replicating earlier research, the MPD scaled with listening demand. Crucially, the pre- to post- load sequence change in PPD was larger with smaller monetary incentives, and larger with larger load sequence magnitude. This result is in line with the conceptualization that larger previous effort results in larger mental fatigue. Furthermore, in a state of fatigue, the mobilization of effort depends on the willingness to perform well. In Experiment 3, we have shown that in adults with impaired hearing, need for recovery and load sequence may interactively influence the BPD and PPD. In all experiments, there was no evidence for a change in speech reception performance, self-reported effort, estimated performance, or tendency to quit listening from pre- to post-load sequence, as a function of load sequence magnitude, monetary incentives, or hearing aid descriptions. This is in line with the understanding that the PPD reveals valuable information that is not captured through traditional speech recognition tests or self-report measures. Overall, by demonstrating the direct influence of previous load sequence on the PPD, these studies suggest that listening-related fatigue may influence listening effort. Furthermore, this influence may be modulated by motivational factors. Thus, models that explain listening effort and listening-related fatigue need to consider the interactive influence of motivation and fatigue on listening effort

Motivation and fatigue effects in pupillometric measures of listening effort

Listening effort and fatigue are common among individuals with hearing impairment, although within hearing sciences the relationship between effort and fatigue is not fully understood. The objective measurement of listening effort has commonly involved pupillometry in combination with the speech-in-noise paradigm, where the baseline pupil diameter (BPD) is used as a reference point, and the mean and peak pupil dilation (MPD and PPD) as indices of listening effort. Research to quantify listening effort to date has mostly investigated effort as a function of listening demands. Recent research has shown a correlation between PPD and daily-life fatigue. Furthermore, monetary incentives have been shown to increase the PPD, suggesting that listening demands alone are insufficient to explain variation in PPD. How motivation and fatigue influence the pupil metrics remains unclear. Frameworks and models of listening effort and listening-related fatigue postulate that larger previous load should result in larger subsequent fatigue. Fatigue manifests as a reluctance to mobilize further effort, particularly when listening conditions are difficult, and when expected rewards are low. In this study we experimentally investigated the interactive influences of task-induced fatigue, motivation, and listening demands on the BPD, MPD, and PPD in the speech-in-noise task. Participants completed a speech-in-noise task of 30-40 minutes without any breaks (“load sequence”) in 3 experiments. Pre- and post- load sequence listening effort was assessed under varying signal-to-noise ratios (SNRs; listening demands), monetary incentives (motivation level; Experiment 1), and magnitudes of load sequence (fatigue level; Experiment 2) in normal hearing adults. In adults with impaired hearing (Experiment 3), pre- and post-load sequence listening effort was investigated when wearing hearing aids that were described as novel technology (implied reward; high motivation) and conventional technology (no reward; low motivation). In addition to the pupil metrics, need for recovery, self-reported effort, estimated performance, and tendency to quit listening were assessed. In Experiment 1 and 2, there was a consistent decline in BPD from pre- to post- load sequence, independent of listening demands, monetary incentives, and load sequence magnitude. These results indicate declines in arousal with time-on-task. Replicating earlier research, the MPD scaled with listening demand. Crucially, the pre- to post- load sequence change in PPD was larger with smaller monetary incentives, and larger with larger load sequence magnitude. This result is in line with the conceptualization that larger previous effort results in larger mental fatigue. Furthermore, in a state of fatigue, the mobilization of effort depends on the willingness to perform well. In Experiment 3, we have shown that in adults with impaired hearing, need for recovery and load sequence may interactively influence the BPD and PPD. In all experiments, there was no evidence for a change in speech reception performance, self-reported effort, estimated performance, or tendency to quit listening from pre- to post-load sequence, as a function of load sequence magnitude, monetary incentives, or hearing aid descriptions. This is in line with the understanding that the PPD reveals valuable information that is not captured through traditional speech recognition tests or self-report measures. Overall, by demonstrating the direct influence of previous load sequence on the PPD, these studies suggest that listening-related fatigue may influence listening effort. Furthermore, this influence may be modulated by motivational factors. Thus, models that explain listening effort and listening-related fatigue need to consider the interactive influence of motivation and fatigue on listening effort

Eye movements reveal learning and information-seeking in attentional template acquisition

Visual attention serves to select relevant visual information. However, observers often first need to find out what is relevant. Little is known about this information-seeking process and how it affects attention. We employed a cued visual search task in combination with eye tracking to investigate which oculomotor measures reflect the acquisition of information for a subsequent task. A cue indicated as to which target to look for in a following search display. Cue-target combinations were repeated several times, enabling learning of the target. We found that reductions in cue fixation times and saccade size provided stable indices of learning. Despite the learning, participants continued to attend to repeated cues. Several factors contribute to people attending to information they already know: First, the information value provided by the cue continues to drive attention. Second, even in the absence of information value, attention continues to be directed to cue features that previously signalled relevant information. Third, the decision to attend to a known cue depends on cognitive effort. We propose that this combination of information value, previous relevance, and effort is best captured within an information-seeking framework, and that oculomotor parameters provide a useful proxy for uncovering these factors and their interactions

Brain Volume Differences Associated With Hearing Impairment in Adults

Speech comprehension depends on the successful operation of a network of brain regions. Processing of degraded speech is associated with different patterns of brain activity in comparison with that of high-quality speech. In this exploratory study, we studied whether processing degraded auditory input in daily life because of hearing impairment is associated with differences in brain volume. We compared TI-weighted structural magnetic resonance images of 17 hearing-impaired (HI) adults with those of 17 normal-hearing (NH) controls using a voxel-based morphometry analysis. HI adults were individually matched with NH adults based on age and educational level. Gray and white matter brain volumes were compared between the groups by region-of-interest analyses in structures associated with speech processing, and by whole-brain analyses. The results suggest increased gray matter volume in the right angular gyrus and decreased white matter volume in the left fusiform gyrus in HI listeners as compared with NH ones. In the HI group, there was a significant correlation between hearing acuity and cluster volume of the gray matter cluster in the right angular gyrus. This correlation supports the link between partial hearing loss and altered brain volume. The alterations in volume may reflect the operation of compensatory mechanisms that are related to decoding meaning from degraded auditory input.Funding Agencies|Netherlands Organization for Scientific Research (Veni grant) [45110031]</p

Epidemiology and outcomes of hospital-acquired bloodstream infections in intensive care unit patients: the EUROBACT-2 international cohort study

Purpose In the critically ill, hospital-acquired bloodstream infections (HA-BSI) are associated with significant mortality. Granular data are required for optimizing management, and developing guidelines and clinical trials. Methods We carried out a prospective international cohort study of adult patients (≥ 18 years of age) with HA-BSI treated in intensive care units (ICUs) between June 2019 and February 2021. Results 2600 patients from 333 ICUs in 52 countries were included. 78% HA-BSI were ICU-acquired. Median Sequential Organ Failure Assessment (SOFA) score was 8 [IQR 5; 11] at HA-BSI diagnosis. Most frequent sources of infection included pneumonia (26.7%) and intravascular catheters (26.4%). Most frequent pathogens were Gram-negative bacteria (59.0%), predominantly Klebsiella spp. (27.9%), Acinetobacter spp. (20.3%), Escherichia coli (15.8%), and Pseudomonas spp. (14.3%). Carbapenem resistance was present in 37.8%, 84.6%, 7.4%, and 33.2%, respectively. Difficult-to-treat resistance (DTR) was present in 23.5% and pan-drug resistance in 1.5%. Antimicrobial therapy was deemed adequate within 24 h for 51.5%. Antimicrobial resistance was associated with longer delays to adequate antimicrobial therapy. Source control was needed in 52.5% but not achieved in 18.2%. Mortality was 37.1%, and only 16.1% had been discharged alive from hospital by day-28. Conclusions HA-BSI was frequently caused by Gram-negative, carbapenem-resistant and DTR pathogens. Antimicrobial resistance led to delays in adequate antimicrobial therapy. Mortality was high, and at day-28 only a minority of the patients were discharged alive from the hospital. Prevention of antimicrobial resistance and focusing on adequate antimicrobial therapy and source control are important to optimize patient management and outcomes

Presentation, management, and outcomes of older compared to younger adults with hospital-acquired bloodstream infections in the intensive care unit: a multicenter cohort study

Purpose: Older adults admitted to the intensive care unit (ICU) usually have fair baseline functional capacity, yet their age and frailty may compromise their management. We compared the characteristics and management of older (≥ 75&nbsp;years) versus younger adults hospitalized in ICU with hospital-acquired bloodstream infection (HA-BSI). Methods: Nested cohort study within the EUROBACT-2 database, a multinational prospective cohort study including adults (≥ 18&nbsp;years) hospitalized in the ICU during 2019-2021. We compared older versus younger adults in terms of infection characteristics (clinical signs and symptoms, source, and microbiological data), management (imaging, source control, antimicrobial therapy), and outcomes (28-day mortality and hospital discharge). Results: Among 2111 individuals hospitalized in 219 ICUs with HA-BSI, 563 (27%) were ≥ 75&nbsp;years old. Compared to younger patients, these individuals had higher comorbidity score and lower functional capacity; presented more often with a pulmonary, urinary, or unknown HA-BSI source; and had lower heart rate, blood pressure and temperature at presentation. Pathogens and resistance rates were similar in both groups. Differences in management included mainly lower rates of effective source control achievement among aged individuals. Older adults also had significantly higher day-28 mortality (50% versus 34%, p &lt; 0.001), and lower rates of discharge from hospital (12% versus 20%, p &lt; 0.001) by this time. Conclusions: Older adults with HA-BSI hospitalized in ICU have different baseline characteristics and source of infection compared to younger patients. Management of older adults differs mainly by lower probability to achieve source control. This should be targeted to improve outcomes among older ICU patients

The role of centre and country factors on process and outcome indicators in critically ill patients with hospital-acquired bloodstream infections

Purpose: The primary objective of this study was to evaluate the associations between centre/country-based factors and two important process and outcome indicators in patients with hospital-acquired bloodstream infections (HABSI). Methods: We used data on HABSI from the prospective EUROBACT-2 study to evaluate the associations between centre/country factors on a process or an outcome indicator: adequacy of antimicrobial therapy within the first 24&nbsp;h or 28-day mortality, respectively. Mixed logistical models with clustering by centre identified factors associated with both indicators. Results: Two thousand two hundred nine patients from two hundred one intensive care units (ICUs) were included in forty-seven countries. Overall, 51% (n = 1128) of patients received an adequate antimicrobial therapy and the 28-day mortality was 38% (n = 839). The availability of therapeutic drug monitoring (TDM) for aminoglycosides everyday [odds ratio (OR) 1.48, 95% confidence interval (CI) 1.03-2.14] or within a few hours (OR 1.79, 95% CI 1.34-2.38), surveillance cultures for multidrug-resistant organism carriage performed weekly (OR 1.45, 95% CI 1.09-1.93), and increasing Human Development Index (HDI) values were associated with adequate antimicrobial therapy. The presence of intermediate care beds (OR 0.63, 95% CI 0.47-0.84), TDM for aminoglycoside available everyday (OR 0.66, 95% CI 0.44-1.00) or within a few hours (OR 0.51, 95% CI 0.37-0.70), 24/7 consultation of clinical pharmacists (OR 0.67, 95% CI 0.47-0.95), percentage of vancomycin-resistant enterococci (VRE) between 10% and 25% in the ICU (OR 1.67, 95% CI 1.00-2.80), and decreasing HDI values were associated with 28-day mortality. Conclusion: Centre/country factors should be targeted for future interventions to improve management strategies and outcome of HABSI in ICU patients