Priming by the mean representation of a set.

Recent evidence suggests that sets of similar objects can be represented in terms of their statistical parameters, such as mean size. Observers are more likely to indicate that a probe item was part of a previously presented set of items when the probe has the same size as the mean size of the set than when it has the same size as one of the set members (e.g., Ariely, 2001). Here we provide further evidence for set representation by statistical properties, by showing priming by the mean size of a set of circles. Observers were presented with a set of circles followed by a degraded outline of a single target circle and were asked to judge the contrast of the target. Target contrast was reported to be significantly higher when the target circle had the same size as the mean size of the preceding set of circles than when it had the same size as one of the members of the preceding set. These findings show that conceptual priming by a summary description can be stronger than exact repetition priming.