Signal probability and spatial location as possible bases for increased selectivity in noise

It was previously found that noise increased both performance on a primary tracking task and the detection of centrally located signals in a secondary multi-source monitoring task. The present experiment examines the effect of changing the distribution of signals across the monitoring display. When equal numbers are seen at all locations there is no differential effect of noise for central and peripheral locations. Such an effect only occurs when central signals are seen to have greater probability. This result points to the selectivity effect in noise being a function of task priorities and not of physical location.