ERP Lab for Developmental Studies

One of the classic findings in the literature of visual orienting of attention is that performance is facilitated by a valid cue even when it is non-informative. This facilitation is then followed by a period of inhibition of the cued area, known as "inhibition of return". Researchers have suggested that the early facilitation is the result of orienting of attention. However, because cues are commonly presented for 100-200 msec, the facilitation usually overlaps cue presentation. Thus, it is possible that facilitation could be attributed to sensory summation rather than to attention. Hence, facilitation may not occur when cue and target do not overlap. Three experiments were designed to clarify this issue. We found early facilitation followed by inhibition. The facilitation was the same whether the cue was present or not. Moreover, facilitation was not affected by cue duration or by target duration. These results reaffirm the idea that a non-informative peripheral cue can activate the exogenous orienting system, to produce both facilitation and inhibition of detection.