ABSTRACT
This paper is concerned with the process by which one selects information from a sensory channel. Two possibilities are considered. In one the person sets a filter which then passively delivers information from the selected source to consciousness (passive filter). In the second view the person maintains an active set or orientation toward the selected channel. Two sets of experiments are presented. The first shows that any visual signal that occurs at a position eccentric to the line of sight produces a relative slowing on the response times for processing subsequent signals at that spatial position. This effect lasts approximately 1–2 seconds. 50Thus a consequence of a visual stimulus at a spatial position is to reduce the efficiency of attending to subsequent information at that location.
The second set of experiments shows that each visual stimulus causes an active orienting of attention toward its spatial position. This orienting is said to be active because it is reduced or delayed by requiring the subject to perform a secondary task (counting backwards).
Our studies indicated that the basic passive effect of a visual stimulus is to retard processing of subsequent events at that position. This spatially selective sensory inhibition must be overcome by an active process if efficient concentration is to be maintained.
