Webb, Abigail LM and Hibbard, Paul B and O'Gorman, Rick (2020) Contrast normalisation masks natural expression-related differences and artificially enhances the perceived salience of fear expressions. PLoS One, 15 (6). e0234513-e0234513. DOI https://doi.org/10.1371/journal.pone.0234513
Webb, Abigail LM and Hibbard, Paul B and O'Gorman, Rick (2020) Contrast normalisation masks natural expression-related differences and artificially enhances the perceived salience of fear expressions. PLoS One, 15 (6). e0234513-e0234513. DOI https://doi.org/10.1371/journal.pone.0234513
Webb, Abigail LM and Hibbard, Paul B and O'Gorman, Rick (2020) Contrast normalisation masks natural expression-related differences and artificially enhances the perceived salience of fear expressions. PLoS One, 15 (6). e0234513-e0234513. DOI https://doi.org/10.1371/journal.pone.0234513
Abstract
Fearful facial expressions tend to be more salient than other expressions. This threat bias is to some extent driven by simple low-level image properties, rather than the high-level emotion interpretation of stimuli. It might be expected therefore that different expressions will, on average, have different physical contrasts. However, studies tend to normalise stimuli for RMS contrast, potentially removing a naturally-occurring difference in salience. We assessed whether images of faces differ in both physical and apparent contrast across expressions. We measured physical RMS contrast and the Fourier amplitude spectra of 5 emotional expressions prior to contrast normalisation. We also measured expression-related differences in perceived contrast. Fear expressions have a steeper Fourier amplitude slope compared to neutral and angry expressions, and consistently significantly lower contrast compared to other faces. This effect is more pronounced at higher spatial frequencies. With the exception of stimuli containing only low spatial frequencies, fear expressions appeared higher in contrast than a physically matched reference. These findings suggest that contrast normalisation artificially boosts the perceived salience of fear expressions; an effect that may account for perceptual biases observed for spatially filtered fear expressions.
Item Type: | Article |
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Uncontrolled Keywords: | Humans; Facial Expression; Photic Stimulation; Fear; Pattern Recognition, Visual; Attention; Image Processing, Computer-Assisted; Adolescent; Adult; Female; Male; Young Adult |
Divisions: | Faculty of Science and Health Faculty of Science and Health > Psychology, Department of |
SWORD Depositor: | Unnamed user with email elements@essex.ac.uk |
Depositing User: | Unnamed user with email elements@essex.ac.uk |
Date Deposited: | 19 Jun 2020 21:18 |
Last Modified: | 30 Oct 2024 17:22 |
URI: | http://repository.essex.ac.uk/id/eprint/27936 |
Available files
Filename: journal.pone.0234513.pdf
Licence: Creative Commons: Attribution 3.0