Attention psychophysical approaches - Oxford Reference

Attention is the mechanism that allows us to selectively process the vast amount of information that we receive and to guide our behaviour. Visual spatial attention can be deployed overtly, accompanied by eye movements to the relevant location, or covertly, without eye movements (Helmholtz 1910/1925, Posner 1980). There are two types of covert attention: sustained attention refers to the voluntary, endogenous directing of attention to a location in the visual field, and transient attention refers to the automatic, exogenous capture of attention to a location, brought about by a sudden change in the environment (Nakayama and Mackeben 1989, Posner 1980).