Can blind people tell the difference between night and day?
If we assume a person is totally blind (i.e., without eyes), it remains possible to identify day or night through skill, training, and experience. Environmental sounds change throughout the day. Some sounds occur more frequently at dawn – anyone who keeps birds as pets is well aware of this. Different animals are active at different times of the day – one can listen for these sounds. Insects provide many audible cues (e.g., cicadas usually sing during the heat of the day). Environmental sounds are also created by human activities. Traffic is heavier during daylight hours than at night. Traffic is heaviest in the morning (e.g., between 07:00 and 09:00) and in the afternoon (e.g., between 16:00 and 18:00). Many similar audible cues exist. A person can roughly identify at what point the sun lies above the horizon, if the day is sufficiently clear. This is done by sensing temperature differences on parts of the body. Warmer areas are facing the sun and cooler ones facing away. There are ma
