Stimulus Intensity And Probability Of Stimulus Change As Determinants Of Simple Reaction Time

Many reaction time investigators have shown that as stimulus intensities increase response latencies decrease. In addition, Spiess (1971) demonstrated that the presentation of knowledge concerning the nature of the upcoming stimulus prior to its onset (preknowledge) could result in decreased reaction times. Spiess concluded that this preknowledge effect was interpretable within the framework of Grice\u27s variable criterion model. Grice\u27s model assumes that a response would occur when information concerning the onset of a stimulus reached a required level or criterion. The rate at which this information accumulates is determined by the intensity of the stimulus with stronger stimuli resulting in faster accumulation. According to Spiess, preknowledge resulted in a lower criterion, which was reflected by faster responses. The present experiment was designed to further investigate the feasibility of using the criterion model to explain the preknowledge effect. In the present study an attempt was made to manipulate stimulus expectancy by varying the probability that the stimulus would remain unchanged from one trial to the next. When the probability of change was low, the same stimulus that was presented on the previous trial should be expected on the subsequent trial, and when the probability of stimulus change was high, presentation of the same stimulus on the following trial would presumably be unexpected. Each subject received a series of stimuli with the probability of change being equal to .00, .10, .25, .50, .75, .90, or 1.00, resulting in seven groups of subjects, with each group receiving a sequence with one of these probabilities of stimulus change. The findings showed that stimuli following the predominant pattern (either having changed from the intensity presented on the previous trial or not depending on which sequence was being presented), were responded to more quickly than were stimuli that deviated from the overall pattern. These results were not easily interpretable using Grice\u27s variable criterion model. The model could explain these findings, however, if two criteria were assumed to exist rather than the single criterion presently employed by the model, or if the rate of information accumulation was made to depend not only on stimulus intensity but also upon stimulus expectancy

Mishap Trends in Several Air Force Aircraft: Implications for CRM Training

Human factors trends in C-130, F-16, and A-10 mishaps were reviewed for relevance to cockpit/crew resource management (CRM) course content. The current Air Force Safety Center human factors taxonomy includes about 360 detailed human factors elements. About sixty of these taxonomy elements map directly into the six CRM core areas identified in Air Force Flying Operations publications (communication, risk management/decision making, situational awareness, task management, crew coordination/flight integrity, and mission preparation/ debriefing). This small fraction of human factors elements accounted for well over half of the causal and strongly contributing factors cited in each platform. The relative contributions of specific CRM core areas varied across applications. Tactical airlift mishap CRM factors were fairly uniformly distributed across all six traditional CRM areas. In F-16 and A-10 mishaps, task management and situational awareness were particularly frequent causal and major contributing factors. Planning, flight integrity, and communication were rarely cited. We describe the mishap data that are available from the Air Force Safety Center, our analytic approach, trends identified, and implications for CRM training. We anticipate that these analyses will contribute to better focused CRM training objectives and course content that will, in turn, enable CRM training to be a major contributor to the success of recent Department of Defense efforts to reduce preventable mishaps

Depression, Anxiety and Stress in Collegiate Aviators

The purpose of this mixed-method research was to determine if students who are enrolled in a collegiate flight program exhibit significantly higher rates of depression, stress, and anxiety. This study compared collegiate flight students to non-professional flight students to determine whether collegiate flight students have higher rates of depression, anxiety or stress. In addition, this study sought to determine if there were higher depression, anxiety, and stress levels in upperclassmen (juniors and seniors) than in lowerclassmen (freshman and sophomore). These groups were compared to each other by using results from the DASS-21, a survey that measures depression, anxiety, and stress. There were no statistically significant results indicating no singular group is more or less prone to depression, anxiety, or stress

Training Interventions to Reduce Air Force Predator Mishaps

The use of unmanned aerial systems (UASs) is expanding rapidly. In military operations, this increased use has been accompanied by relatively high mishap rates compared with rates across more mature manned aircraft. These higher rates led to multiple high-level reviews of unmanned operations, but surprisingly little consensus emerged across reports regarding root causes. To help close this gap, Air Force Predator Class A mishap reports through FY 2008 were analyzed in detail. Mishap rates, counts, and causal factors appeared to shift systematically over time, with an increase in mishap reports citing shortfalls in several skill and knowledge areas in FY 2004-2006. Individual and team Predator training objectives were revisited at the end of 2006 and the content of crew resource management (CRM) training was refocused on improving these key operator skills. In FY 2007-2008, Predator Class A mishap attributed to operator error decreased despite increasing numbers of mishaps overall

Mishap Reduction Training for C-130J Crews

The C-130J is an advanced automation aircraft flown with a smaller crew than its tactical airlift predecessors. It is seeing increased action in theater. The Air Mobility Command sponsored a multi-prong project to improve C-130J aircrew training for operations in high threat environments: (1) analyze C-130J and related platform (C-130 E/H, C-17) mishap reports, (2) survey C-130J crew real world experiences regarding threats to safety, and (3) observe C-130J crews as they plan and execute a challenging, tactically relevant simulator scenario. The Air Force C-130J safety record is enviable—no crew-caused Class A mishaps and low rates across all mishap categories relative to other airlift platforms. Human factors frequently cited in Class B and C reports included checklist errors, distraction, task prioritization, and decision making. Incident and mishap reports both frequently mention problems arising from events external to the crew. In the real-world experience survey, several crews described events that closely paralleled events in the simulator scenario. During the challenging simulator scenario, crews generally accomplished the mission but quality of performance varied considerably. Lower performing crews often struggled with risk management during planning and mission evaluation during execution. They also tended to underutilize their loadmasters and had difficulty choosing the most appropriate levels of automation during mission execution. Recommendations included an increased emphasis on threat and error management during training and addressing specific skills at particular points in the syllabus

Companion Trainer Aircraft: Concept Definition and Evaluation

Faced with increasing budget constraints and a need to conserve the B-52 weapon system, the Strategic Air Command has pursued several avenues to make continuation training programs more efficient. Because actual flight training is considered to be critical, one proposed solution involved the use of a low cost business jet to supplement reduced B-52 flying schedules. This jet would be augmented to provide training for the radar navigator, navigator, and electronic warfare officer in addition to the pilot and copilot. Some training missions would be flown in this Companion Trainer Aircraft (CTA) to reduce the need to fly the B-52. This paper describes two efforts concerning training effectiveness of a possible CTA. First, a theoretical approach based on transfer of training considerations was used to predict the training potential of the CTA. Second, because the transfer expectations for the pilot and copilot were particularly difficult to specify, a study was designed involving operational SAC crews. This study employed a modified T-39B to supplement B-52 training for eight aircrews from the 2nd Bombardment Wing, Barksdale Air Force Base, LA. Although the CTA program was cancelled and the test was terminated early, crew responses to the program and problems encountered provide valuable lessons for any future CTA program. </jats:p

Begrepet funksjonshemming – en studie av ulike forståelser på funksjonshemmingssfeltet

Sammendrag Kategoriseringen av mennesker med nedsatt funksjonsevne har siden utviklingen av velferdsstaten utviklet seg fra å være en avgrensing av hvem som hadde krav på visse rettigheter til å bli brukt om en gruppe mennesker. I Norge ble begrepet funksjonshemming først begynt brukt etter Trontalen i 1966. Da dukket begrepet opp som en erstatning for handikapet. Begrepet har gjennom de siste 50 årene blitt forstått, og brukt, på mange ulike måter og med ulike perspektiver. Perspektivene er kontekstavhengig og forståelsen og bruken av begrepet har variert både over tid og samfunn. Målet med oppgaven er å se nærmere på hvordan aktører på feltet benytter seg av begrepet funksjonshemming for å posisjonere seg på funksjonshemmingsfeltet. Problemstillingen er som følger: Hvordan bruker aktører på funksjonshemmingsfeltet nøkkelbegreper for å posisjonere seg? Problemstillingen svarer jeg på ved å først gjennomføre en systematisk dokumentgjennomgang av offentlige dokumenter. Dokumentene er et utvalg av stortingsmeldinger og NOU-er i perioden fra 1964 til nåtid. Denne gjennomgangen av dokumenter bruker jeg som bakgrunn når jeg analyserer data fra intervjuer med seks aktører på feltet. Dokumentene fungerer som nyttig bakgrunnsstoff for å forstå kompleksiteten på feltet og for å ha et bredere og dypere utgangspunkt inn i analysekapittelet. Innen samfunnsvitenskapelig forskning har det vært vanlig å se på funksjonshemning innen en medisinsk modell fram til 1970-tallet. Etter 70-tallet endret forståelsen seg til en sosial- og en relasjonell-modell. På 1960- tallet begynte aktivister i både Nord-Amerika, Skandinavia og Vest-Europa å arbeide og argumentere mot det rådende synet på funksjonshemning. Målet var å skifte fokus vekk fra individet og den medisinske forståelsen av funksjonshemning til et mer samfunnsmessig fokus. Fokuset skulle nå være på funksjonshemmende barrierer av både sosial, politisk, kulturell og økonomisk karakter. Det var på tide at funksjonshemmede fikk de samme rettighetene og mulighetene til deltagelse som andre grupper i samfunnet. Denne bevegelsen har av mange blitt beskrevet som tilsvarende de bevegelsene vi har sett hos andre grupper som har opplevd å stå på siden av samfunnet, som kvinner, mørke og homofile (Barnes og Mercer 2010:1). Sakte men sikkert fulgte det akademiske samfunnet etter med forskning på funksjonshemmede og funksjonshemmende barrierer. Det var likevel ikke før på 1990- tallet at det som har blitt kjent som disability studies virkelig fikk rotfestet seg. Disability studies er et tverrfaglig felt som henter kunnskap fra både samfunnsfag, historie, juss og humaniora. løpet av de siste 20-25 årene har funksjonshemningsforskning rotfestet seg i Norge og i stor grad tatt over et felt som frem til 60-tallet var totalt dominert av en medisinsk forståelse. Framveksten må ses i lys av et behov for mer kunnskap om funksjonshemmetes livssituasjon, og hvordan ulike velferdsordninger virker. En kan nærmest si at samfunnsvitenskapelig forskning om funksjonshemming er et barn av velferdsstaten (Tøssebro 2009:11). Hovedtendensene i data har jeg delt inn i to deler; posisjonering utad og posisjonering innad. Med dette viser jeg at de ulike aktørene på feltet bruker begrepet funksjonshemmet og forståelsen av begrepet til å posisjonere seg på feltet. Ved å benytte seg av og forhandle frem en gitt forståelse posisjonerer aktørene seg ovenfor det politiske systemet, media, hverandre, og innad i organisasjonene. Hovedfunnet mitt er at: a) begrepet brukes av aktørene for å plassere seg i forhold til andre aktører, b) feltets ulike forståelser er kontinuerlig påvirket av hverandre, og c) alle aktørene har store problemer fordi de representerer en uensartet gruppe med ulike behov og interesser

Alternative materials for radiovoltaics

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] This work explores alternative materials for the improvement of radiovoltaic devices. First, lithium fluoride is explored as an effective material for generating and retaining tritium radionuclides for use in radiovoltaics. This development aims to solve a decades-old problem of inadequate tritium hosts, which have been consistently limited in their ability to retain the radioisotope and effectively deliver energy to transducing semiconductors. This new method of tritium production and retention offers new possibilities for use of what has been deemed the safest radioisotope, and offers a simple, rapid production process, which can greatly reduce cumbersome isotope loading processes associated with existing methods of fabrication for devices reliant on tritium or other radioisotopes. The primary focus of this work is the exploration of molten selenium-sulfur as a radiation-resistant semiconductor for radiovoltaic devices. Radiovoltaics have thus far been unable to utilize high energy alpha and beta radiation due to rapid performance degradation imposed by radiation damage. This work includes the exhibition of long-term power output from an alphavoltaic device fueled by 210Po. The 57+ day lifetime of this device is in great contrast to reports of conventional semiconductors, which have consistently exhibited short lifetimes. Moreover, this report details a neutron diffraction study of irradiated Se-S material, which indicates strong radiation-resistance in the liquid phase. With liquid selenium established as a promising material for radiovoltaics, this work also presents a neutron diffraction study on the material's atomic structure, which has been the subject of dispute in published literature. The neutron diffraction study is accompanied by Reverse Monte Carlo analysis, resulting in reliable conclusions regarding the overall structure near the melting point. The analysis of Reverse Monte Carlo models in comparison to experimental data identifies in the pair correlation function a key indicator of 3-fold coordinated defects which disrupt the liquid selenium structure under extreme conditions.Includes biblographical reference

A Joint Service Description of Crew Resource Management for Accident Analysis and Prevention

A Department of Defense (DoD) Cockpit/Crew Resource Management (CRM) working group was established to develop a common definition of CRM and create a method for capturing CRM factors in mishap investigations to be used by the Army, Navy, Air Force and Coast Guard investigators and analysts. The goal of the CRM working group was to build on the substantial commonalities among the services regarding CRM concepts, while also accommodating service-unique requirements. This CRM project was part of a larger DoD initiative to promote a common Human Factors taxonomy, investigation, and analysis system for DoD-wide implementation. Shappell and Weigmann’s Human Factors Analysis and Classification System (HFACS) formed the structure for both the CRM working group and the larger initiative to standardize human factors and human performance terminology across the DoD. A common CRM definition was developed and specific codes were created that can be translated into Army, Navy, Coast Guard, or Air Force CRM skill sets. The resulting specific codes are located in several areas of the HFACS taxonomy. Given the success of the HFACS project, the CRM working group is now exploring ways to further standardize CRM concepts and improve CRM training across services