[Forensic evaluation of manual temperature estimation]

The policemen sometimes feel the bonnet of a car for warmth to check wether it had been used just before. But in court it is difficult to quantify the temperature of the car. Therefore, 541 volunteers were given warmed steel plates to feel at different ambient temperatures between -8 degrees C and 30 degrees C and were asked to estimate their temperature. Highest and lowest temperatures for estimating metal plates as hot, warm, slightly warm or cold were measured. Combined with the known decrease of temperature after using an engine, the time at which the engine stopped can be estimated after this study. The sense of warmth and coldness turned out to be significantly influenced by the ambient temperature, by the time of day and by the volunteers' energy balance. In the morning volunteers estimated temperatures 2.5 degrees C higher and more precisely than in the afternoon and evening. For hungry volunteers the seemed 2.5 degrees C colder than for volunteers with a postprandially elevated energy balance. The lowest necessary temperature to cause a slightly warm sensation was 16 degrees C lower at -8 degrees C ambient temperature than at 30 degrees C ambient temperature. The risk of estimating a plate as warm by mistake was found in only 0.57%. Confirmed by this study, estimated temperatures can be considered reliable enough to cite in court.