The suggestion has been made (2, 3, 4, 10) that man's control of precise hand and arm movements is analogous to the operation of a servo system. The response of a continuously-following servo involves the comparison, at all times, between the input and the output with the discrepancy between the two utilized as the basis of control. If man acted as a continuously-following servo motor his responses would be guided continually by the degree to which the intended motion had not yet been made.Such a mode of control would require that continuous information be furnished concerning where the body member is and where it should be. The position of the hand or arm in space might be derived from visual or kinesthetic stimulation (or feedback, as it is called by engineers).

No abstract

"Using a simple test apparatus, Ss were required to make arm-hand corrective movements of five to 80 millimeters in extent." The results show that: "1. The maximum rate and average rate of a movement increase systematically with increasing extent of movement. The relation is approximately linear in most cases . . . . Reaction times are relatively independent of the distance to be moved. 2. In the situations studied, rates are highest for movements from left to right and are successively lower for forward, left, and backward movements. 3 . . . . For movements of comparable distance in each case, rates at the pointer are slightly lower, and rates at the hand are higher at the 3:1 than at the 1:1 ratio [of control sensitivity]. In general, the operator tends to compensate for the change in sensitivity in such a way as to produce nearly the same perceived result with respect to both rate and accuracy. 4. The addition of an appreciable amount of inertia to the control knob causes the rate to be decreased for given distances of movement and the precision to be slightly improved. With additional friction . . . the responses are speeded up and precision is definitely lower than when minimum friction is present . . . ."

Aided Tracking 10 Aiding with Different Types of Controls 10 The AidinG Required to Track Maneuvering Targets 11 Aiding Ratios 12 The Relative Difficulty of MeaW Int~qrtio and Differentiation 13 APPLICATION OF THE PRIDNCM TO THE DZSWN OF SPELIAL CONTROL SYSTEM DPLAYS is Uburdenn and Quickeal 15 *A Quickiened Display is Quickenitr4 a Filtered Display 17 PAXT 2 A STM MUM-RPOM AMALTM OF T7= BMP,"TCATION PRINCW LZ STaMLUS-REWO5? INTGRITYY Incomplete Umburdml' Taidequate Quickenn LEARNING COMPENSATORY AND-PURUTDUPLAYS-7 "OW LE DGMENT .EFFRENCES 27 N4AVAL HZIARCN LABORATO. V T he man is schematized by the boxes shown above the heavy black line, whtie r.Vmpionents of die machine are block~ed in below. In the human, three sets of organs or func-A tions are important to man-machine system operation, these are the receptors, the central nervous system (CN3), and the effectors. The r,eptors consist of tho sense organs of the body; for example, special coils in the retina of the eye, *he organs of Corti in the ear, ard the proprioceptors in the muscles, tendons, and joints. It to through the receptor organs that changes in energy in the external environment take effect upon the human organism. Such energy changes which excite receptor cells are called stimuli (S). But nr* only Is the organism acted upon by the environment-in turn the man mnodifies the external world through responses; (t) of the effector organs. In the human, the effectors consist of muscles andt glands, thcugi' only the former are directly Involved in manmachine system function.

No abstract