Charles C.-F. Or¹, Wei Xuan Ang², Yi Ning Tan², Alan L.F. Lee³; ¹University of Plymouth, ²Nanyang Technological University, ³Lingnan University

The eyebrows have been argued to provide important diagnostic information for identifying faces, especially when the eyes are occluded (e.g., Sadr et al., 2003, Perception). In real-life settings, the unoccluded eyebrows might be useful when sunglasses only occlude the eyes. Here, we tested this hypothesis with multiple face memory tests that involved studying and testing with different combinations of face occlusions, including (1) full, unoccluded faces, (2) faces with small sunglasses occluding the eyes only but not the eyebrows, and (3) faces with big sunglasses occluding both the eyes and eyebrows. In each condition, observers first studied 21 faces in a randomized sequence (each face presented twice; stimulus duration: 2000 ms/presentation). Afterwards, their task was to determine whether each of the 42 test faces (21 studied and 21 unseen; stimulus duration: 350 ms) was seen before or novel. The occlusion type of the test faces (e.g., with small sunglasses) either matched with the studied faces (congruent conditions; e g., study small, test small) or not (incongruent conditions; e.g., study full, test small; study big, test small). Results showed impaired performance (d’) when a memory test involved any type(s) of sunglasses during study and/or test, compared to studying and testing with full faces. This confirms that the eye region is crucial for face identification. Critically, unoccluded eyebrows (small sunglasses) did not lead to any significant increases in d’ compared to occluded eyebrows (big sunglasses). Interestingly, studying faces with eyebrows unoccluded and then testing them occluded (study small, test big) did not significantly lower d’ further, while studying faces with eyebrows occluded and then testing them unoccluded (study big, test small) impaired performance. These results suggest that the eyebrows may not necessarily provide useful information for face identification, especially when the eyes are occluded.

Acknowledgements: Supported by UoP School of Psychology travelling funds to C.O., SG-MOE AcRF Tier 1 Grant (RG59/19) to C.O. & A.L., and NTU-URECA funds to C.O. & Y.N.T.