Caloric vestibular stimulation induces vestibular circular vection even with a conflicting visual display presented in a virtual reality headset.

This study explored visual-vestibular sensory integration when the vestibular system receives self-motion information using caloric irrigation. The objectives of this study were to (1) determine if measurable vestibular circular vection can be induced in healthy participants using caloric vestibular stimulation and (2) determine if a conflicting visual display could impact vestibular vection. In Experiment 1 (E1), participants had their eyes closed. Air caloric vestibular stimulation cooled the endolymph fluid of the horizontal semi-circular canal inducing vestibular circular vection. Participants reported vestibular circular vection with a potentiometer knob that measured circular vection direction, speed, and duration. In Experiment 2 (E2), participants viewed a stationary display in a virtual reality headset that did not signal self-motion while receiving caloric vestibular stimulation. This produced a visual-vestibular conflict. Participants indicated clockwise vection in the left ear and counter-clockwise vection in right ear in a significant proportion of trials in E1 and E2. Vection was significantly slower and shorter in E2 compared to E1. E2 results demonstrated that during visual-vestibular conflict, visual and vestibular cues are used to determine self-motion rather than one system overriding the other. These results are consistent with optimal cue integration hypothesis.

Towards ubiquitous and nonintrusive measurements of brain function in the real world: assessing blink-related oscillations during simulated flight using portable low-cost EEG.

Blink-related oscillations (BRO) are newly discovered neurophysiological phenomena associated with spontaneous blinking and represent cascading neural mechanisms including visual sensory, episodic memory, and information processing responses. These phenomena have been shown to be present at rest and during tasks and are modulated by cognitive load, creating the possibility for brain function assessments that can be integrated seamlessly into real-world settings. Prior works have largely examined the BRO phenomenon within controlled laboratory environments using magnetoencephalography and high-density electroencephalography (EEG) that are ill-suited for real-world deployment. Investigating BROs using low-density EEG within complex environments reflective of the real-world would further our understanding of how BRO responses can be utilized in real-world settings. We evaluated whether the BRO response could be captured in a high-fidelity flight simulation environment using a portable, low-density wireless EEG system. The effects of age and task demands on BRO responses were also examined. EEG data from 30 licensed pilots (age 43.37 +/- 17.86, 2 females) were collected during simulated flights at two cognitive workload levels. Comparisons of signal amplitudes were undertaken to confirm the presence of BRO responses and mixed model ANOVAs quantified the effects of workload and age group on BRO amplitudes. Significant increases in neural activity were observed post-blink compared to the baseline period (p < 0.05), confirming the presence of BRO responses. In line with prior studies, results showed BRO time-domain responses from the delta band (0.5-4 Hz) consisting of an early negative peak followed by a positive peak post-blink in temporal and parietal electrodes. Additionally, task workload and age-related effects were also found, with observations of the enhancement of BRO amplitudes with older age and attenuation of BRO responses in high workloads (p < 0.05). These findings demonstrate that it is possible to capture BRO responses within simulated flight environments using portable, low-cost, easy-to-use EEG systems. Furthermore, biological and task salience were reflected in these BRO responses. The successful detection and demonstration of both task-and age-related modulation of BRO responses in this study open the possibility of assessing human brain function across the lifespan with BRO responses in complex and realistic environments.

Prospective memory failures in aviation: effects of cue salience, workload, and individual differences.

INTRODUCTION: Prospective memory allows people to complete intended tasks in the future. Prospective memory failures, such as pilots forgetting to inform pattern traffic of their locations, can have fatal consequences. The present research examined the impact of system factors (memory cue salience and workload) and individual differences (pilot age, cognitive health, and expertise) on prospective memory for communication tasks in the cockpit. METHODS: Pilots (N = 101) flew a Cessna 172 simulator at a non-towered aerodrome while maintaining communication with traffic and attending to flight parameters. Memory cue salience (the prominence of cues that signal an intended action) and workload were manipulated. Prospective memory was measured as radio call completion rates. RESULTS: Pilots' prospective memory was adversely affected by low-salience cues and high workload. An interaction of cue salience, pilots' age, and cognitive health reflected the effects of system and individual difference factors on prospective memory failures. For example, younger pilots with low levels of cognitive health completed 78% of the radio calls associated with low-salience memory cues, whereas older pilots with low cognitive health scores completed just 61% of similar radio calls. DISCUSSION: Our findings suggest that technologies designed to signal intended future tasks should target those tasks with inherently low-salience memory cues. In addition, increasing the salience of memory cues is most likely to benefit pilots with lower levels of cognitive health in high-workload conditions.

Effects of conversation on situation awareness and working memory in simulated driving.

OBJECTIVE: In the present research, we investigated the hypothesis that working memory mediates conversation-induced impairment of situation awareness (SA) while driving. BACKGROUND: Although there is empirical evidence that conversation impairs driving performance, the cognitive mechanisms that mediate this relationship remain underspecified. Researchers have reported that a phonological working memory task decreased drivers' SA for vehicles located behind them whereas a visuospatial working memory task impaired SA for vehicles ahead. Conversation, therefore, might impair SA for vehicles behind the driver by preferentially taxing the phonological loop. METHOD: A 20-questions task was used as a proxy for natural conversation. In Experiment I, driving performance was measured across three within-subjects conversation conditions (i.e., no conversation, driver asks questions, driver answers questions) with the use of a driving simulator. In Experiment 2, participants drove in the same simulator while either conversing (20-questions task) or not Participants estimated the positions of other vehicles after the screens were blanked at the end of each trial. RESULTS: Speed monitoring and responses to visual probes were impaired by the 20-questions conversation task (Experiment 1). As predicted, conversation impaired SA for the location of other vehicles more for vehicles located behind the driver than for those in front (Experiment 2). CONCLUSION: Conversation impairs drivers' SA of vehicles behind them by taxing working memory's phonological loop and impairs SA generally by taxing working memory's central executive. APPLICATION: Provides a theoretical framework that links driver SA to working memory and a mechanism for understanding why conversation impairs driving performance.

Disruptive camouflage impairs object recognition.

Whether hiding from predators, or avoiding battlefield casualties, camouflage is widely employed to prevent detection. Disruptive coloration is a seemingly well-known camouflage mechanism proposed to function by breaking up an object's salient features (for example their characteristic outline), rendering objects more difficult to recognize. However, while a wide range of animals are thought to evade detection using disruptive patterns, there is no direct experimental evidence that disruptive coloration impairs recognition. Using humans searching for computer-generated moth targets, we demonstrate that the number of edge-intersecting patches on a target reduces the likelihood of it being detected, even at the expense of reduced background matching. Crucially, eye-tracking data show that targets with more edge-intersecting patches were looked at for longer periods prior to attack, and passed-over more frequently during search tasks. We therefore show directly that edge patches enhance survivorship by impairing recognition, confirming that disruptive coloration is a distinct camouflage strategy, not simply an artefact of background matching.

The role of working memory in supporting drivers' situation awareness for surrounding traffic.

OBJECTIVE: To link working memory to driver situational awareness (SA) for surrounding traffic. BACKGROUND: Operating a motor vehicle is a complex activity that requires drivers to maintain a high level of SA. Working memory has been conceptually linked to SA; however, the roles of working memory subsystems in supporting driver SA is unclear. METHOD: Participants drove a simulated vehicle and monitored surrounding traffic while concurrently performing either visuospatial- or phonological-load tasks. Drivers' SA was indexed as the ability to recall the positions of the surrounding traffic relative to their own vehicle at the end of each trial. RESULTS: In Experiment I, a visuospatial task interfered with drivers' ability to recall the positions of traffic located in front of their vehicle. In contrast, a phonological task interfered with drivers' ability to recall the positions of traffic located behind their vehicle. Experiment 2 confirmed and extended the findings of Experiment I with the use of different visuospatial- and phonological-load tasks. CONCLUSION: Visuospatial and phonological codes play a role in supporting driver SA for traffic located in the forward view and the rear view, respectively. APPLICATION: Drivers' SA for surrounding vehicles is disrupted by concurrent performance on secondary tasks. The development and implementation of new in-cabin communication, navigation, and informational technologies needs to be done with the knowledge that components of drivers' working memory capacity may be exceeded, thereby compromising driving safety.

Object-based attention and cognitive tunneling.

Simulator-based research has shown that pilots cognitively tunnel their attention on head-up displays (HUDs). Cognitive tunneling has been linked to object-based visual attention on the assumption that HUD symbology is perceptually grouped into an object that is perceived and attended separately from the external scene. The present research strengthens the link between cognitive tunneling and object-based attention by showing that (a) elements of a visual display that share a common fate are grouped into a perceptual object and that this grouping is sufficient to sustain object-based attention, (b) object-based attention and thereby cognitive tunneling is affected by strategic focusing of attention, and (c) object-based attention is primarily inhibitory in nature.

Stabilization of mRNA expression in whole blood samples.

BACKGROUND: Accurate quantification of mRNA in whole blood is made difficult by the simultaneous degradation of gene transcripts and unintended gene induction caused by sample handling or uncontrolled activation of coagulation. This study was designed to compare a new blood collection tube (PAXgene Blood RNA System) and a companion sample preparation reagent set with a traditional sample collection and preparation method for the purpose of gene expression analysis. METHODS: We collected parallel blood samples from healthy donors into the new sample collection tubes and control EDTA tubes and performed serial RNA extractions on samples stored for 5 days at room temperature and for up to 90 days at 4 and 20 degrees C. Samples were analyzed by Northern blot analysis or reverse transcription-PCR (RT-PCR). RESULTS: Specific mRNA concentrations in blood stored in EDTA tubes at any temperature changed substantially, as determined by high-precision RT-PCR. These changes were eliminated or markedly reduced when whole blood was stored in PAXgene tubes. Loss of specific mRNAs, as measured by RT-PCR, reflected total RNA depletion as well as specific mRNA destruction demonstrated by Northern blot analysis. The salutary effects of PAXgene on mRNA stabilization extended to blood samples from eight unrelated donors. CONCLUSIONS: Compared with whole blood collected in EDTA tubes and extracted by an organic method, the PAXgene Blood RNA System reduced RNA degradation and inhibited or eliminated gene induction in phlebotomy whole blood samples. Storage of whole blood samples in PAXgene tubes can be recommended for clinically related blood samples that will be analyzed for total or specific RNA content.