FIRST IMPRESSIONS ARE LASTING IMPRESSIONS - A PRIMACY EFFECT IN MEMORY FOR REPETITIONS

Two experiments demonstrated that the encoding of a repeated object is biased toward the attributes of its first presentation. In Experiment 1, subjects saw objects five times each, but either the first present ation or the fifth presentation was the mirror reverse of the standard orientation seen on the other four trials. When recognition was teste d with both orientations simultaneously, subjects reported seeing only the single mirror-reverse orientation more often if it was the first presentation than when it was the fifth presentation, and seeing only the standard orientation more often if it was presentations 1-4 than w hen it was presentations 2-5. A second experiment demonstrated that th is primacy effect generalized to size changes. This pattern of results is consistent with the hypothesis that top-down biases affect what su bjects learn: The first representation established for a stimulus is l ikely to influence the encoding of subsequent repetitions.