A necessary consideration in the development or expansion of courses incorporating techniques such as geographic information systems (GIS) is the establishment of the infrastructure to support such instruction. Planning for the practical application of knowledge involves the determination of hardware, software, data and personnel needs.
Continuity: the tendency to perceive things as simply as possible with a continuous pattern rather than with a complex, broken-up pattern o Contiguity: the tendency to perceive 2 things that happen close together in time as being related Rods and cones, which one is less or more light/color sensitive?
The ability and tendency of certain systems to maintain a relatively constant internal state in spite of changes in external conditions; this ability is achieved by the presence of feedback mechanisms which can adjust the state of the system to compensate for changes in the state caused by the external environment.