Human Performance in the Cold

1967 ◽  
Vol 9 (3) ◽  
pp. 203-220 ◽  
Author(s):  
William F. Fox
Keyword(s):  
Reaction Time ◽  
Skin Temperature ◽  
Human Performance ◽  
Cold Environment ◽  
Tactile Sensitivity ◽  
Ambient Temperatures ◽  
Manual Performance ◽  
Competing Stimuli

The literature dealing with human performance in the cold is reviewed. Seven major areas are discussed: a) tactile sensitivity, b) manual performance, c) tracking, d) reaction time, e) complex behaviors, f) maintaining hand skin temperature (HST) as a means of maintaining operator effectiveness, and g) adaptation and acclimatization to low ambient temperatures. Performance decrements at low ambient temperatures appear to result principally from lowered HST and competing stimuli provided by the cold environment.

Thermoregulation in Exercising White Rats

1973 ◽  
Vol 51 (11) ◽  
pp. 814-824 ◽  
Author(s):  
K. Myhre ◽  
B. Hellstrøm
Keyword(s):  
Thermal Stress ◽  
Skin Temperature ◽  
Albino Rats ◽  
Cold Environment ◽  
Exercise Time ◽  
Ambient Temperatures ◽  
Warm Environment ◽  
White Rats ◽  
Skin Temperatures ◽  
Trunk Skin

Colonic temperatures (TC), heart rates (HR), back skin and tail skin temperatures (TST) were measured in six warm acclimated (+24 °C) male albino rats running on a treadmill at three different work loads (HR ranging from 400 beats/min to 500 beats/min). Ambient temperatures (TA) ranged from about +8 °C to about +30 °C. TC increased immediately upon onset of work. Exercising in a cold environment ultimately made the rats hypothermic and in a warm environment hyperthermic. Within the limits set by the external thermal stress the rats controlled TC independently of the work intensity.High trunk skin temperatures were recorded in all experiments. Exercise in cold and cool environments produced tail skin vasoconstriction. In the 21 °C environment half of the rats produced tail skin vasodilation. In the 28 °C environment most experiments produced this effect. Cessation of work was accompanied by prompt vasoconstriction. The results indicated that exercise time before tail vasodilation was affected by exercise as well as by the tail skin temperature prior to vasodilation.

An Examination by Forearm EMG on Pain Reaction Time to Radiant Heat

1993 ◽  
Vol 76 (3_suppl) ◽  
pp. 1139-1146 ◽  
Author(s):  
Toshiteru Hatayama ◽  
Kayoko Shimizu
Keyword(s):  
Reaction Time ◽  
Time Delay ◽  
Skin Temperature ◽  
Motor Response ◽  
Pain Threshold ◽  
Radiant Heat ◽  
Repeated Measurements ◽  
Pain Sensation ◽  
Pain Thresholds ◽  
Pain Reaction

The present study was done to estimate rise in skin temperature during a pain reaction time (pain RT) as a means of investigating why a pricking pain threshold, produced by thermal stimulation using time method, often increases during repeated measurements. The pain RT, or the time-delay between occurrence of pain sensation and a subsequent motor response, was measured by making EMG recording on a forearm. The radiant heat stimuli were three, 200, 300, and 350 mcal/sec./cm2, each of which was given through a round radiation window of an algesiometer head. Analysis showed that the pain RTs would be too short to explain higher pain thresholds often found using the time method.

Predicting Human Performance IV: Choice Reaction Time

1972 ◽  
Author(s):  
Warren H. Teichner ◽  
Marjorie J. Krebs
Keyword(s):  
Reaction Time ◽  
Choice Reaction Time ◽  
Human Performance

Analysis of energy expenditure at different ambient temperatures in mice lacking DGAT1

2003 ◽  
Vol 284 (1) ◽  
pp. E213-E218 ◽  
Author(s):  
Hubert C. Chen ◽  
Zuleika Ladha ◽  
Steven J. Smith ◽  
Robert V. Farese
Keyword(s):  
Food Intake ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Cold Environment ◽  
Normal Surface ◽  
Ambient Temperatures ◽  
Active Mechanism ◽  
Key Enzyme ◽  
Secondary Mechanism ◽  
Obesity Resistance

Mice lacking acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1), a key enzyme in triglyceride synthesis, have increased energy expenditure and therefore are resistant to obesity. Because ambient temperature can significantly affect energy expenditure in mice, we undertook these studies to determine the effects of different ambient temperatures on energy expenditure, food intake, and thermoregulation in DGAT1-deficient [ Dgat1(−/−)] mice. Dgat1(−/−) mice had increased energy expenditure irrespective of changes in the ambient temperature. Although core temperature was normal, surface temperature was increased in Dgat1(−/−) mice, most likely reflecting an active mechanism to dissipate heat from increased thermogenesis. Dgat1(−/−) mice had increased food intake at baseline, and this hyperphagia became more pronounced upon exposure to cold. When fasted in a cold environment, Dgat1(−/−) mice developed hypothermia, which was associated with hypoglycemia. These results suggest that the hyperphagia in Dgat1(−/−) mice is a secondary mechanism that compensates for the increased utilization of fuel substrates. Our findings offer insights into the mechanisms of hyperphagia and increased energy expenditure in a murine model of obesity resistance.

scholarly journals Face Detection: Mapping Human Performance

Perception ◽  
10.1068/p5007 ◽  
2003 ◽  
Vol 32 (8) ◽  
pp. 903-920 ◽  
Author(s):  
Michael B Lewis ◽  
Andrew J Edmonds
Keyword(s):  
Reaction Time ◽  
Face Detection ◽  
Human Performance ◽  
Limited Attention ◽  
Focused Attention ◽  
Deformable Template ◽  
Detection Systems ◽  
Face Experiment ◽  
Extensive Body ◽  
Inversion Effects

The recognition of faces has been the focus of an extensive body of research, whereas the preliminary and prerequisite task of detecting a face has received limited attention from psychologists. Four experiments are reported that address the question how we detect a face. Experiment 1 reveals that we use information from the scene to aid detection. In experiment 2 we investigated which features of a face speed the detection of faces. Experiment 3 revealed inversion effects and an interaction between the effects of blurring and reduction of contrast. In experiment 4 the sizes of effects of reversal of orientation, luminance, and hue were compared. Luminance was found to have the greatest effect on reaction time to detect faces. The results are interpreted as suggesting that face detection proceeds by a pre-attentive stage that identifies possible face regions, which is followed by a focused-attention stage that employs a deformable template. Comparisons are drawn with automatic face-detection systems.

scholarly journals Subtropical mouse-tailed bats use geothermally heated caves for winter hibernation

2015 ◽  
Vol 282 (1804) ◽  
pp. 20142781 ◽  
Author(s):  
Eran Levin ◽  
Brit Plotnik ◽  
Eran Amichai ◽  
Luzie J. Braulke ◽  
Shmulik Landau ◽  
...  
Keyword(s):  
High Temperature ◽  
Skin Temperature ◽  
Metabolic Rates ◽  
Evaporative Water ◽  
Open Flow ◽  
Ambient Temperatures ◽  
Northern Edge ◽  
Average Skin ◽  
World Distribution ◽  
Winter Hibernation

We report that two species of mouse-tailed bats ( Rhinopoma microphyllum and R. cystops ) hibernate for five months during winter in geothermally heated caves with stable high temperature (20°C). While hibernating, these bats do not feed or drink, even on warm nights when other bat species are active. We used thermo-sensitive transmitters to measure the bats’ skin temperature in the natural hibernacula and open flow respirometry to measure torpid metabolic rate at different ambient temperatures ( T a , 16–35°C) and evaporative water loss (EWL) in the laboratory. Bats average skin temperature at the natural hibernacula was 21.7 ± 0.8°C, and no arousals were recorded. Both species reached the lowest metabolic rates around natural hibernacula temperatures (20°C, average of 0.14 ± 0.01 and 0.16 ± 0.04 ml O 2 g −1 h −1 for R. microphyllum and R. cystops , respectively) and aroused from torpor when T a fell below 16°C. During torpor the bats performed long apnoeas (14 ± 1.6 and 16 ± 1.5 min, respectively) and had a very low EWL. We hypothesize that the particular diet of these bats is an adaptation to hibernation at high temperatures and that caves featuring high temperature and humidity during winter enable these species to survive this season on the northern edge of their world distribution.

Extremity skin temperature in British and Zebu cross cattle

1967 ◽  
Vol 69 (1) ◽  
pp. 1-7 ◽  
Author(s):  
K. G. Johnson ◽  
M. E. D. Webster
Keyword(s):  
Skin Temperature ◽  
Lower Leg ◽  
Zebu Cattle ◽  
Temperature Changes ◽  
Ambient Temperatures ◽  
Thermal Environments ◽  
Air Temperatures ◽  
Environmental Temperatures ◽  
Skin Temperatures ◽  
Trunk Skin

1. Extremity skin temperature changes in British and Zebu cross cattle examined in moderate thermal environments followed a thermoregulatory pattern similar to that describedby Whittow (1962). At low environmental temperatures, ear and lower leg skin temperatures were usually only slightly above air temperature. At a variable time after air temperatures began to rise or the animals were fed, extremity skin temperatures increased suddenly to near trunk skin temperature.2. In eight of the ten pairs of animals studied in rising ambient temperatures and during feeding after fasting for 36–72 hr, increases in ear temperature were measured in the British animal before similar changes occurred in its Zebu counterpart. Changes in lower leg skin temperature followed a similar pattern.Trunk skin temperatures and respiratory frequencies were significant higher in British cross animals than in Zebu cross animals of similar thermal history. The mean rectal temperature of both British and Zebu cattle was 38·5 °C.

Evaluation of Algorithms for Combining Independent Data Sets in a Human Performance Expert System

1987 ◽  
Vol 31 (7) ◽  
pp. 811-814
Author(s):  
Valerie J. Gawron ◽  
David J. Travale ◽  
Colin Drury ◽  
Sara Czaja
Keyword(s):  
Reaction Time ◽  
Expert System ◽  
Human Performance ◽  
Test Procedure ◽  
Reaction Time Task ◽  
Error Rates ◽  
Task Completion ◽  
Data Sets ◽  
Independent Data ◽  
Independent Variables

A major problem facing system designers today is predicting human performance in: 1) systems that have not yet been built, 2) situations that have not yet been experienced, and 3) situations for which there are only anecdotal reports. To address this problem, the Human Performance Expert System (Human) was designed. The system contains a large data base of equations derived from human performance research reported in the open literature. Human accesses these data to predict task performance times, task completion probabilities, and error rates. A problem was encountered when multiple independent data sets were relevant to one task. For example, a designer is interested in the effects of luminance and front size on number of reading errors. Two data sets exist in the literature: one examining the effects of luminance, the other, font size. The data in the two sets were collected at different locations with different subjects and at different times in history. How can the two data sets be combined to address the designer's problem? Four combining algorithms were developed and then tested in two steps. In step one, two reaction-time experiments were conducted: one to evaluate the effect the number of alternatives on reaction time; the second, signals per minute and number of displays being monitored. The four algorithms were used on the data from these two experiments to predict reaction time in the situation where all three independent variables are manipulated simultaneously. In step two of the test procedure, a third experiment was conducted. Subjects who had not participated in either Experiment One or Two performed a reaction-time task under the combined effects of all three independent variables. The predictions made from step one were compared to the actual empirical data collected in step two. The results of these comparisons are presented.

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