Direct Manipulation Interfaces

In this paper we seek a cognitive account of both the advantages and disadvantages of direct manipulation interfaces. We identify two underlying phenomena that give rise to the sensation of directness. One has to do with the information processing distance between the user's intentions and the facilities provided by the machine. Reduction of this distance makes the interface feel direct by reducing the effort required of the user to accomplish goals. The second phenomenon concerns the relation between the input and output vocabularies of the interface language. In particular, direct manipulation requires that the system provide representations of the objects of interest that behave as if they are the objects themselves. This provides the sensation of directness of manipulation. Keywords: Human-machine interface; Cognition; Direct manipulation; Interface language.