TEMPORAL PROPERTIES OF COLOR AND SHAPE PRIMING - EVIDENCE OF MULTIPLECOMPONENTS OF ATTENTION

It has been shown in several studies that the selection of letters or numerals from an array can occur efficiently if criteria such as locat ion, colour, shape, or size are used. It is also known that there are at least two components of spatial attention, the transient exogenous and the sustained endogenous. An interesting question is whether it is possible to elicit similar components when colour or shape informatio n is used as a selection criterion. Experiments are reported the aim o f which was to try to produce colour or shape precue effects on locati on and colour/shape discrimination accuracy, and to determine the mini mum latency of these effects by sampling numerous cue lead times from 0 ms to 1000 ms. The results showed that, although accuracy did not in crease monotonically with increased cue lead time, there were two tran sient peaks of performance at cue lead times of 0-200 ms, culminating at 30-50 ms and at 160-200 ms. It is suggested that the first componen t reflects nonspecific exogenous activation, triggered by the onset of a cue; the second component, in turn, may reflect feature-specific en dogenous activation related to selection by colour or shape.