The same for the cold spots; they fill a continuous area.

He finds, however, as other investigators have found, that the heat areas are generally in large measure separate from the cold areas, only to a certain extent overlapping here and there, and also that there are regions of the skin where we have very little sense of either sort of temperature.
The general results will show, therefore, if they should be confirmed by other investigators, that our temperature sense is located in what might be called somewhat large blotches on the skin, and not in minute spots; while the evidence still remains good, however, to show that we have two senses for temperature, one for cold and the other for hot.
II.

_Reaction-Time Experiments._--Work in so-called "reaction times" constitutes one of the most important and well-developed chapters in experimental psychology.

In brief, the experiment involved is this: To find how long it takes a person to receive a sense impression of any kind--for example, to hear a sound-signal--and to move his hand or other member in response to the impression.

A simple arrangement is as follows: Sit the subject comfortably, tap a bell in such a way that the tapping also makes an electric current and starts a clock, and instruct the subject to press a button with his finger as soon as possible after he hears the bell.