Separate and combined effects of location cuing and repetition priming on perceptual encoding of words

We describe a methodology for investigating whether two manipulations exert independent effects on perception. This method avoids the strong scaling assumptions inherent to traditional analysis of variance techniques, and we used it to investigate the combined effects of cued visual attention and stimulus repetition. Subjects identified previously studied (primed) and new (unprimed) masked words that were presented to validly and invalidly cued locations for varying durations. Performance improved more rapidly with increasing exposure duration for primed than for unprimed, and for attended than for unattended, stimuli. We interpret this finding as indicating that both variables speed the rate of information acquisition. The speedup provided by priming and attention combined equaled the product of benefits for each alone, providing evidence they are serial, independent effects.