Poster A91, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
Changes in Item Representations Following Category Learning
Stefania Ashby1, Caitlin Bowman1, Dagmar Zeithamova1; 1University of Oregon
Learning about category membership can alter representations of individual items resulting in increased perceived similarity of items within a category and decreased perceived similarity of items from different categories. The current study aimed to investigate changes in subjective similarity ratings and neural pattern representations before and after category learning. Stimuli were faces constructed as 50/50 blends of never-seen “parent” faces. Two parent faces determined category membership and were each blended with three other parent faces for a total of six unique face stimuli. Thus, pairs of faces could share a parent face relevant for categorization, a parent face irrelevant for categorization, or not share a parent face. Participants first rated the similarity of pairs of faces and then passively viewed the stimuli during functional MRI prior to category learning. The same passive viewing and subjective similarity ratings were repeated after participants were trained to sort the six face blends into two categories. Prior to category learning, subjective similarity ratings were the same for pairs of faces from the same category as for pairs of faces from different categories that had a parent in common. After category learning, similarity ratings for items within a category increased, while rated similarity of faces that shared a parent but belonged to different categories decreased. Tracking the behavioral data, neural patterns in the ventromedial prefrontal cortex differentiated category membership of faces after learning but not before. These findings elucidate the neural mechanisms underlying the changes in item representations resulting from category learning.
Topic Area: LONG-TERM MEMORY: Episodic