The use of psychophysiology to assess driver status

Twenty subjects completed an on-the-road driving experiment, consisting of two different tests conducted on two separate days. A two-part test was administered while subjects were under the influence of alcohol (BAC<=0·05%); a four-part test was administered without alcohol consisting of a 2·5?h driving test under vigilance conditions on a quiet highway. The order of the tests was balanced across subjects. Changes in relevant physiological parameters, such as ECG and EEG, reflected changes in driver status and predicted driving impairment. Impairment of driving performance was measured in a standard driving test (SD lateral position and SD steering wheel movements) and in a recently developed car-following test (reaction to speed changes of a leading car).     

The effect of speech and speech intelligibility on task performance

The aim of this study was to find out what are the effects of three different sound environments on performance of cognitive tasks of varying complexity. These three sound environments were ‘speech’, ‘masked speech’ and ‘continuous noise’. They corresponded to poor, acceptable and perfect acoustical privacy in an open-plan office, respectively. The speech transmission indices were 0.00, 0.30 and 0.80, respectively. Sounds environments were presented at 48 dBA. The laboratory experiment on 36 subjects lasted for 4 h for each subject. Proofreading performance deteriorated in the ‘speech’ (p < 0.05) compared to the other two sound environments. Reading comprehension and computer-based tasks (simple and complex reaction time, subtraction, proposition, Stroop and vigilance) remained unaffected. Subjects assessed the ‘speech’ as the most disturbing, most disadvantageous and least pleasant environment (p < 0.01). ‘Continuous noise’ annoyed the least. Subjective arousal was highest in ‘masked speech’ and lowest in ‘continuous noise’ (p < 0.05). Performance in real open-plan offices could be improved by reducing speech intelligibility, e.g. by attenuating speech level and using an appropriate masking environment.     

Passenger comfort on high-speed trains: effect of tunnel noise on the subjective assessment of pressure variations

When passing through a tunnel, aerodynamic effects on high-speed trains may impair passenger comfort. These variations in atmospheric pressure are accompanied by transient increases in sound pressure level. To date, it is unclear whether the latter influences the perceived discomfort associated with the variations in atmospheric pressure. In a pressure chamber of the DLR-Institute of Aerospace Medicine, 71 participants (M = 28.3 years ± 8.1 SD) rated randomised pressure changes during two conditions according to a crossover design. The pressure changes were presented together with tunnel noise such that the sound pressure level was transiently elevated by either +6 dB (low noise condition) or +12 dB (high noise condition) above background noise level (65 dB(A)). Data were combined with those of a recent study, in which identical pressure changes were presented without tunnel noise (Schwanitz et al., 2013, ‘Pressure Variations on a Train – Where is the Threshold to Railway Passenger Discomfort?’ Applied Ergonomics 44 (2): 200-209). Exposure-response relationships for the combined data set comprising all three noise conditions show that pressure discomfort increases with the magnitude and speed of the pressure changes but decreases with increasing tunnel noise.

Practitioner Summary: In a pressure chamber, we systematically examined how pressure discomfort, as it may be experienced by railway passengers, is affected by the presence of tunnel noise during pressure changes. It is shown that across three conditions (no noise, low noise (+6 dB), high noise (+12 dB)) pressure discomfort decreases with increasing tunnel noise.     

Sir Frederic Bartlett: 1886—1969 A PERSONAL HOMAGE

Abstract

Fatigue was measured on 68 air traffic controllers using the following methods: critical fusion frequency (CFF), tapping test, grid tapping test, self-rating. The measurements were taken 9 times within 24 hours over 3 weeks. Stress was measured on the basis of a questionnaire and of catecholamine excretion in urine. The four fatigue tests showed significant agreement. There was a marked decrease in the values after the 6th hour of work. During the night hours, the test values were lower, and the subjects stated they were more tired. For the first work hour and for the 9th to 11th work hour Spearman's correlation coefficients between the two sets of data were calculated. A significant correlation was found (a) between CFF and grid tapping (p<0·02); (b) between CFF and self-rating ‘ refreshed-tired ’ (p<0·05); (c) between grid tapping and self-rating ‘ refreshed-tired ’ (p<0·02). This means that subjects with a marked decrease in CFF or in grid tapping performance have a greater tendency to ‘ tired ’ in the self-rating test. On the basis of this finding it might therefore be hypothesized that all measures are indicative of a common state of fatigue.

Results of the questionnaire (62 subjects): in difficult situations 60 subjects felt nervous, tense, irritated, 13 were anxious and trembling, 19 had increased perspiration, 14 had increased pulse rate and heart ache, 25 suffered from insomnia and chronic fatigue.

Urine samples front 6 subjects were taken after normal office work, easy ground control work, and radar air traffic control. There was a significant increase in the catecholamines in the last condition.     

Selected physiological and psychobiological responses to physical activity in different configurations of firefighting gear

The aim was to examine selected physiological and psychobiological responses to different configurations of protective firefighting gear. Career firefighters (n = 10) walked on a treadmill (3·5?km · h^?1, 10% grade) for 15?min in three different clothing configurations. On separate days subjects wore: (a) ‘station blues’, (b) a hip boot configuration of firefighting gear, and (c) the current ‘NFPA 1500 standard’ gear. Physiological, psychophysical, and psychological measurements were recorded pre-exercise (5?min), during exercise (15?min), and during post-exercise recovery (10min). Repeated measures ANOVA revealed significant main effects for condition, time, and interaction (p < 0·001) for heart rate (HR), rectal temperature, mean skin temperature, oxygen consumption, breathing distress, thermal sensations, and affect. Furthermore, post hoc analyses revealed that all variables were significantly higher in the NFPA 1500 standard versus the hip boot or the station blues clothing configurations. These data suggest that the current NFPA 1500 standard configuration results in greater physiological and psychobiological stress at a given workload.     

Optimal Duration of Endurance Performance on the Cycle Ergometer in Relation to Maximal Oxygen Intake

The problem was to determine the optimal duration of endurance performance on the bicycle ergometer using max [Vdot]o₂ as the criterion of validity. Max [Vdot]o₂ was measured in 50 male college students using the, step-increment method (the initial resistance was 2·5 at 60 rpm on a bicycle ergometer, and was increased by 0·5 kg each two minutes until the subject would no longer turn.the ergometer, or when the rate fell to 40 to 50 rev/min).,In contrast, the endurance performance test was of the ‘ steady- pace ’ type in which all of the subjects began pedalling at the same initial rate of 69. pedal rpm at a work rate of 1656 kgm/min for 12 minutes. Although the rate of pedalling (and thus the Work rate) declined as fatigue developed, the friction load remained constant at124 kg throughout the test. There were 12 endurance scores for each individual, endurance being measured as the cumulated work done up to a particular minute. The 12 scores ranged from no decrement in the case of a few subjects with complete endurance to 24 percent in the subjeots with least endurance.

The validity correlations (i.e., the min-by-min correlations between, max [Vdot]o₂and the 12 endurance scores), progressively increased to Y = 0·78 at minute 12. An empirical equation of the form, Y =C ? at, was used to fit. a smooth curve to the trend of the correlations so its' changing rate of curvature could be determined quantitatively. The rate of change was found to slow down considerably in the; later stages of performance, especially after minutes 7 or 8, where the change, was less than 0·04 correlation units.

It was concluded that max [Vdot]o₂ does hot predict endurance performance effectively unless the performance is continued for a least 8 minutes under the conditions of the present experiment. With a,12 minute test, the validity is 96 percent of the asymptotic value, suggesting little further gains can be expected beyond 12 minutes.     

The Kinetics of Recovery Oxygen Intake and Blood Lactic Acid Concentration Measured to a Baseline of Mild Steady Work

The relationship between blood lactate, pyruvate and excess lactate removal and the excess oxygen consumed during the recovery from work on a stationary bicycle ergometer was studied intensively on two healthy male subjects. The results showed contrary to the recent work of Huckabee (1958) and the studies of Rowell et al. (1966) that a clear quantitative relationship exists between the area under the second portion of a double exponential Vo², recovery curve and the O² equivalents of LA: the association between the two variables being r = 0·93 which accounted for over 80% of the total variance of the two measurements. The findings fully support the earlier concept of Margaria et al. (1933) of separate ‘ alactic ’ and ‘ lactic ’ portions of the O² debt and suggest that it is these components of the post exercise V?o², which must be used in the analysis and interpretation of the contribution of anaerobic processes during work.     

Industrial Inspection Efficiency and the Probability of a Defect Occurring

Abstract

Following Colquhouu's more general result that in a vigilance task probability rather than frequency of occurrence determines an operator's efficiency, the effect of ‘ probability ’ has been tested on the shop floor for probabilities in the range 0·01 to 0·05 for paced and unpaced inspection.

A ‘ probability ’ effect was found for the ‘ unpaced condition ’. Raising the probability increased the level of detection of defects significantly

The practical and theoretical implications of the current study are discussed: particularly relating the relevance of laboratory studies to practical situations.     

Predicting battlefield vigilance: a multivariate approach to assessment of attentional resources

Technological innovation increasingly requires operators in various applied settings to maintain vigilance for extended periods. However, standard psychometric tests typically predict less than 10% of performance variance. The present study (N = 462) aimed to apply the resource theory of sustained attention to construct a multivariate test battery for predicting battlefield vigilance. The battery included cognitive ability tests, a high-workload short vigilance task and subjective measures of stress response. Four versions of a 60- min simulated military battlefield monitoring task were constructed to represent different operational requirements. The test battery predicted 24–44% of criterion variance, depending on task version, suggesting that it may identify vigilant operators in military and other applied contexts. A multiple-groups path analysis showed that relationships between ability and vigilance were moderated by working memory demands. Findings are consistent with a diffuse theoretical concept of ‘resources’ in which performance energisation depends on multiple, loosely coupled processes.     

The effects of alcohol on learning as a function of drinking habits

Thirty-six subjects were categorized as light social drinkers (LSD) and 36 as heavy social drinkers (HSD) on the basis of both biological criteria, gamma-glutamyl transferase (GGT) and the mean corpuscular volume (MCV) and by self-reports of drinking habits. This study examined the effects of alcohol (0.7 ml/kg) and of noise (75 dB(A)) on learning and performance, in choice RT and in immediate memory tasks. Each subject was tested in two consecutive sessions (the time factor) under one of the following experimental conditions: (a) silence+placebo; (b) silence-I-alcohol; (c) noise+placebo; and (d) noise+alcohol. On immediate memory, there was a strong effect of time which interacted with 'drinker’ category, suggesting that HSD subjects learn less rapidly than LSD. Time interacted also with state (sober or intoxicated), showing that learning might be impaired even by a moderate dose of alcohol. On the reaction time task no main effects were found but the time × drinker category interaction was significant; in session 1 LSD's RT were shorter than those of HSD. It is suggested that regular heavy drinking might affect the learning abilities of those who are not yet labelled as alcoholics.     

Prediction of strain for intermittent heat exposures

Under intermittent heat exposures, predictions of body sweat loss ()Δm) could be derived either from the ambient conditions or from their time-weighted average. To compare the accuracy of these two procedures, five subjects exercised, semi-nude, for 120min at constant work load (50 W) under six environmental conditions: four conditions with 20 min duration ‘square pulse(rsquo; variations in either air temperature (T _a or ambient vapour pressure (P _a, and two conditions with constant T _a and P _a, levels. Selected ambient conditions involved skin wettedness (w) levels ranging from 0·35 up to 1. The recorded Δm were compared to the values predicted (PΔm) using the ‘Analytical determination of thermal stress’ model (ISO-DP 7933). Results showed that PΔm were lower than observed Δm by 2 to 10% depending on the condition. This trend could mainly be ascribed to the proposed relation between the evaporative efficiency of sweating and wettedness levels. For exposures consisting of T _a variations, the prediction error was not markedly different whether a time-weighted average of the ambient variables was used or not For exposures consisting of P _a, variations, the expected dripping of sweat during the humid exposures was limited by the short duration of these periods and the averaging procedure gave the best prediction of the actual sweat loss. It is concluded that under intermittent heat stress conditions, a time-weighted average of the ambient conditions may be used for thermal strain predictions, provided that the heat exposure periods are of short duration.     

Evaluation of foot swelling and lower-limb temperatures in relation to leg activity during long-term seated office work

Seven healthy females were studied during three experimental days, each comprising 8 hours of seated office work at different well-defined levels of leg activity. The mean foot swelling was 4·8% in the case of no leg activity (‘inactive sitting’), 2·3% when the legs were moved freely (‘ semi-active sitting’) and 0·8% at the highest activity level (‘active sitting’). The activity of the soleus muscle was evaluated by EMG and discussed in relation to the function of the musculovenous pump. The decrease in skin temperature (T_sk ) of the foot and lower leg was completed after half the working day, and on average it was 4·6°C/2·8°C (foot) and 3·3°C/l·6°C (lower leg) during ‘inactive sitting’/‘active sitting’. The mean temperature in the flexor hallucis longus muscle (T_m ) decreased by 3·7°C during the 8 hours of ‘inactive sitting’, but was almost constant during ‘active sitting’. The discomfort of the lower leg and foot was significantly correlated to foot swelling and T_m , but not to T_sk . The mean heart rate was highest during ‘inactive sitting’.

The results indicate that it is possible to reduce physiological and discomfort problems in the lower legs and feet during prolonged sedentary work by introducing modest leg activity as a natural part of the seated work.     

Light stress and the cardiovascular system: the glare pressor test

The effects of an impulsive glare of 4100 lx intensity upon the cardiovascular system are investigated in 22 normal males aged 25–40 years. This was part of a battery of reactive tests which included exposure to 90 dB noise and the cold pressor test.

The blood pressure responses to glare were normally distributed. Values in terms of mean ± S.D. were as follows: maximum during glare 119±13·6/90·5 ± 13·7mmHg, mean during glare 114·2±12·2/86·0±12·4, maximum rise 9·5±7·8/13[mddot]7± 10·65 and mean change 4·2±6·0/8·7± 10·2. The maximum rise and mean change in both systolic and diastolic blood pressure differed very significantly from the immediately preceding baseline values.

The maximal blood pressure response during glare did not differ significantly from that during exposure to noise or cold. Glare, however, elicited a significantly greater mean change in both systolic and diastolic blood pressure compared with noise.

We conclude that exposure to an impulsive glare of car headlight intensity is stressful and capable of evoking a hypertensive response in normal subjects. The prognostic significance of this glare pressor test should be prospectively studied. This test may be particularly useful as a screening procedure for identifying cardiovascular hypersensitivity to light stress among exposed groups, notably drivers, who are reported to be overrepresented among victims of cardiovascular disorders.     

A CMOS low noise amplifier based on common source technique for ISM band application

In this paper a 2.45 GHz narrowband low noise amplifier (LNA) for wireless communication system is enunciated. The proposed CMOS Low Noise amplifier has been verified through cadence spectre RF simulation in standard UMC 90 nm CMOS process. The proposed LNA is designed by cascoding of two transistors; that is the common source transistor drives a common gate transistor. To achieve better power gain along with low noise figure, cascoding of two transistor and source degeneration technique is used and for low power consumption, the MOS transistors are biased in subthreshold region. At 2.45 GHz frequency, it exhibits power gain 31.53 dB. The S11, S22 and S12 of the circuit is ?9.14, ?9.22 and ?38.03 dB respectively. The 1 dB compression point of the circuit is ?16.89 dBm and IIP3 is ?5.70 dBm. The noise figure is 2.34 dB, input/output match of ?9.14 dB/?9.22 dB and power consumption 8.5 mW at 1.2 V.     

Comment on ‘ Some Recent Experiments on Learning and their Training Implications’

This study describes the relation between types and frequency of exercises and cardiopulmonary fitness. Of the 255 subjects studied, 69 (27·1%) were non-exercisers, 66 (25·9%) exercised 1 to 2 times/week, 82 (32·1%) exercised 3 to 4 times/week and 38 (14·9%) exercised 5 to 7 times/week. Of the exercisers, 131 (51·3%) subjects were engaged in aerobic exercises and 55 (21·7%) in non-aerobic activities for at least 6 months prior to this study. The 2·4–km run test and the maximum oxygen consumption (V˙O₂ max) determination were used as indicators of aerobic performance or cardiopulmonary fitness. The V˙O₂ max was measured by direct analyses of the expired gases of subjects using a Beckman Metabolic Cart during an all-out run on a treadmill. Regular exercisers who exercised three or more times/week were aerobically fitter than non-exercisers (p< 0·001) and those who exercised less frequently than three times/week (p<0·001). Subjects involved in aerobic exercises had significantly shorter mean 2·4-km run times (p< 0·001) and higher mean V˙O₂ max values (p< 0·001) when compared with non-exercisers or those engaged in non-aerobic activities.     

The intensity of auditory warning tones in the automobile environment: detection and preference evaluations

A variety of auditory warning tones was evaluated to determine generally appropriate intensity levels for presentation in the automobile environment. Twenty-four subjects listened to tones presented at several intensity levels under three background noise conditions recorded in actual vehicles: relatively quiet (35 mile/h (56 km/h), smooth road), relatively loud (55 mile/h (89 km/h), rough road), and radio (35 mile/h (56 km/h), smooth road, and radio broadcast). Data were gathered on the minimum intensity level (in decibels (dB) above the masked threshold (MT) required to achieve a consistent criterion detection rate, as well as the preferred tone intensity level (in dB above the MT) in each background noise condition. The preferred levels were louder than those required to achieve the detection criterion in both the relatively loud and quiet background noise conditions; thus, the preferred levels are the recommended levels under those conditions. This was not the case in the radio condition; therefore, it is recommended that future research efforts evaluate the effects of automatically muting the radio/stereo system when important auditory warning tones are being presented.     

Fast algorithms for decoding the (23, 12) binary Golay code with four-error-correcting capability

Two new algorithms for decoding the (23, 12) binary Golay code are developed with channel measurement information. For a white gaussian noise channel, each of the two algorithms achieves about 0·8?dB of decoding performance over a conventional hard-decision decoding. Furthermore, one of the algorithms requires a very small amount of computation for decoding a received block, and the other is very suitable for hardware implementation owing to its simple and regular operation. The hardware decoder, based on the latter algorithm, is designed with a pipeline such that it decodes one bit of a received block in a single system clock cycle     

The Relationship Between the Size of Spatial Subsets of GER 63 Channel Scanner Data and the Quality of the Internal Average Relative Reflectance (IARR) Atmospheric Correction Technique

This study examined spatial subsets derived from one flightline of Geophysical Environmental Research (GER) 63 channel scanner data from Makhtesh Ramon, Israel, to determine the relationship between the size of spatial subsets and the quality of the Internal Average Relative Reflectance (IARR) atmospheric correction technique. The IARR procedure was run separately on spatial subsets containing 100, 53, 24, 9, 3, 0·16 and 0·02 per cent of the original data set. The correction quality was determined by comparing the reflectance spectra derived from each subset for a site containing the mineral kaolinite. Signal-to-noise ratio (SNR) calculations illustrate that the raw data quality does not vary significantly from one subset to another. The quality of the correction was affected only by changes in the ‘average reference spectrum’ (ARS) associated with the selected subsets. The short-wave infrared (SWIR) region (1·440?2·443 μm) was found to be less sensitive to ARS changes than the visible (VIS) region (0·477?0·848 μm). It was concluded that the IARR correction technique should be applied to the whole (100 per cent) data set prior to any data subsetting. Three parameters, the ‘target area ratio’ (TAR), the subset size relative to the original data set (SSR), and the correction quality ratio (CQR) are proposed as indicators of IARR correction quality.     

Sleep deprivation,chronic exercise and muscular performance

Muscular performance was tested during 64 hours of sleep deprivation with and without intermittent excercise (treadmill walking at 28% of maximum oxygen intake). The subjects (12 males aged 22·7 ± 2·2 years) carried out a cross-over trial with an 8 week interval separating the two periods of sleep deprivation. The sleep deprivation did not change the time for a 40 m dash, isometric handgrip force or balance (stabilometer test). Vertical jump height decreased, the change being significant for simple sleep deprivation, but not for the combination of deprivation and intermittent exercise. Sleep deprivation decreased isokinetic extension force at 60° s?1, while intermittent walking decreased isokinetic extension force at both 60 and 180° ?1; however, there was no significant difference between exercise plus sleep deprivation and sleep deprivation alone at either angular velocity. We conclude that the moderate intensity of physical activity likely in industrial work has little influence upon human performance under conditions of sleep deprivation.     

Gender, women's work and ergonomics

A submaximal test for estimating the physical work capacity has been developed and compared with a more complicated bicycle test. The testing procedure is a modified Harvard step test which in its original form is a maximal test The pulse rate was counted during work.

The step height was 40 cm for young males and 27 cm for the older ones and for the females 33 cm; the stepping rate was 22·5 steps per min.

The average values for ‘ step test 40 cm ’, and ‘ bicycle test 900 kgm/min ’ for male subjects were: oxygen intake 2·11 ±0·04 and 2·15±0·02 l./min ; pulse rate during work 130±1·5 and 132± 1·9 beats/mm respectively. The average values for ‘ step test 33 cm ’ and ‘ bicycle test 600 kgm/min ’ for female subjects were : oxygen intake 1·56±0·03 and 1·48±0·02 l./min ; pulse rate during work 140±1·6 and 138 ±2·2 beats/min respectively. The mechanical efficiency did not vary with the body height or weight.

As the aerobic capacity for trained individuals without excessive fat is closely correlated to the body weight the light ones will be tested at a relatively higher intensity than the heavy ones, when the bicycle test is used with a fixed load. In the step test the load varies with the body weight but the oxygen intake per kilogram body weight is constant.