Primacy in the Effects of Face Exposure: Perception is Influenced More By Faces That Are Seen First

Exposure to faces biases perceptions of subsequently viewed faces. In literature on memory, there are prominent effects of primacy, whereby people remember things better if they are at the beginning of a list. Here we tested for primacy in face exposure by exposing people to faces that had been transformed in opposite directions twice. In one condition, for example, we exposed people to "plus" faces and measured how much they thought "plus" faces appeared normal and then exposed them to "anti" faces and again measured how much they thought "plus" faces appeared normal. A primacy effect would be seen if after the second measurement, judgments of "plus" faces were unchanged from the first measurement whereas a recency effect would be seen if after the second measurement, judgments of "plus" faces were lower than from the first measurement. We found no change in normality judgement between first and second judgments supporting a primacy effect. Our results indicated a primacy effect in adaptation whereby faces seen first affected perception more than faces seen later. This primacy effect could lead to long lasting effects of exposure to faces.