Analogous disabilities occur in respect to other movements. It may happen, through injury somewhere near the motor area, though not precisely in that area, that one who clearly perceives a seen object is still quite incapable of handling it. He knows the object, and he knows in an abstract way what to do with it, but how to go about it he cannot remember. This type of disturbance is called "motor apraxia", and, like motor aphasia, it proves that there is a preparation that follows perception and still precedes actual movement. Paralysis of the motor area is different; then, the subject both perceives the object, and gets all ready to act upon it; only, the movement does not occur. The truth seems to be that a series of four responses occurs in the brain, in the process of making a skilled movement dealing with a perceived object. First, sensation; second, perception of the object; third, coördinating preparation for the act; and fourth, execution of the act by the motor area arousing the lower motor centers and through them the muscles. The first response is like receiving signals {429} or code messages; the second deciphers the messages and knows the state of affairs; the third plans action; and the fourth sends out orders to the agents that perform the action. The distinction between perception and preparation for action is sometimes rather difficult to draw. The twelve o'clock whistle means time to drop your tools, and it is hard to draw a line between knowing the fact and beginning the act. On the other hand, when my watch tells me the noon hour is almost over, some little time may be required before I get into motion. Where there is no block or inhibition, the chain of responses runs off with such speed as to seem a single response. But a block may occur at any one of several places. It may check the actual movement, as in the "delayed reaction", [Footnote: See p. 76.] and in cases where we itch to do something yet check ourselves. Here the preparation occurs, but the execution is checked. Sometimes the block occurs between perception and preparation, when we know a fact but find nothing to do about it or hesitate between two ways of acting. Sometimes, also, the block occurs between sensation and perception; a sudden loud noise will sometimes throw a person into a momentary state of confusion during which he is unable to recognize the noise.