Abstract
Selective attention has been studied extensively using the negative priming (NP) paradigm. An important issue regards the representational level at which NP occurs. We investigated this issue by using numbers as stimuli. Because numbers have a well-defined semantic organization, which can be clearly measured by means of the distance effect, they are very suitable for testing the assumption that NP is situated at a central semantic level. Four experiments are presented in which the numerical distance between prime distractor and probe target was manipulated. The task was magnitude comparison. Target and distractor were defined on the basis of colour. In Experiment 1, all numbers were presented in Arabic format; NP was observed only with identical prime distractor and probe target, and no distance-related NP was observed. This could not be explained by a decay of inhibition since in Experiment 2 similar results were obtained with a shortened response-to-stimulus interval. Experiment 3 showed that these observations also hold for numbers presented verbally. Nevertheless, a cross-notational experiment with Arabic prime and verbal probe (Experiment 4) revealed no NP whatsoever and excluded the possibility that the absence of distance-related negative priming was the result of a fine-tuned inhibitory mechanism operating at the semantic level. The results are considered in the light of current theories of negative priming.
Acknowledgments
The authors are grateful to Annelies Verhaeghe for helping to collect data of Experiment 2. We also want to thank Markus Damian, Bruce Milliken, and an anonymous reviewer for their helpful comments on an earlier version. All participants gave informed consent. This work is supported by Belgian Science Policy (IUAP P5/04) and GOA grant of Ghent University Research Council.
Notes
We report the results of statistical analyses with absolute distances (aggregating positive and negative distances) because these have the strongest statistical power, but the results with relative distances were essentially the same. For the reader’s convenience the results as a function of relative distance are provided in the figures.
We want to thank Bruce Milliken for having pointed us to this possible alternative interpretation.
At the same time this shows that those trials of the Distance 0 condition where the numbers displayed in the prime display reappear in the probe trial (e.g., 1 6 6 1) did not cause the overall slower response on Distance 0 trials. This is important, because design restrictions did not allow this kind of repetition to occur for the distance-larger-than-zero conditions. Similarly, we imposed restrictions to the repetition of distractors in the attended condition to avoid possible side effects of full repetitions. More specifically this means that the Distance 0 condition did not contain any distractor repetition trials, as opposed to the three other distance conditions. However, the argument that this dissimilarity in the design contributes to the pattern of results can be refuted since the removal of distractor repetition trials did not alter the results. This was also the case for all subsequent experiments.