An Investigation of Neural Mechanisms for Reversed Inversion Effect in Learning Faces Varying in Pose

Abstract

Our previous studies have shown that multiple exposures coupled with sufficient pose variation can lead to robust recognition and significant generalization (Shyi & Lin, 2014; Cheng & Shyi, 2014). However, only upright faces were tested in those studies. Here we investigated whether it would be possible to train participants to learn about inverted faces with the same set of manipulations that have been used to learn about upright faces. The results revealed both significant learning and generalization of inverted faces comparable to their upright counterparts. Further analyses, revealed that compared to upright faces, the learning of inverted faces was contaminated with an inflated rate of false positives, suggesting that there was actually very little learning of inverted faces. Somewhat surprisingly, we also found evidence implicating a reversed inversion effect where inverted faces during learning yielded significant generalization when they were tested upright during recognition test. To understand the possible neural mechanisms that may account for the reversed inversion effect, we asked participants to perform a one-back task and judged whether the identity of currently viewed face was the same as the immediately preceding one. They made the judgment while viewing sequences of animation portraying rotation in pose. Structural and functional images of brain regions selective for face processing were acquired. The results showed brain activations for both upright and inverted faces underwent pose rotation were greater than that for scrambled controls. Furthermore, while areas underlying the core face system were activated in processing both upright and inverted faces, stronger activations of bilateral OFA and FFA were found processing inverted than processing upright faces. We suspected that the greater involvement of bilateral face-selective regions may reflect more processing and hence better learning of facial features, but not configuration, comprising inverted faces, which in turn may have led to reversed inversion effect.

Meeting abstract presented at VSS 2018