The "face race lightness illusion": An effect of the eyes and pupils?

Abstract

In an internet-based, forced-choice, test of the ‘face race lightness illusion’, the majority of respondents, regardless of their ethnicity, reported perceiving the African face as darker in skin tone than the European face, despite the mean luminance, contrast and numbers of pixels of the images were identical. In the laboratory, using eye tracking, it was found that eye fixations were distributed differently on the African face and European face, so that gaze dwelled relatively longer onto the locally brighter regions of the African face and, in turn, mean pupil diameters were smaller than for the European face. There was no relationship between pupils’ size and implicit social attitude (IAT) scores. In another experiment, the faces were presented either tachistoscopically (140 ms) or longer (2500 ms) so that, when gaze was prevented from looking directly at the faces in the former condition, the tendency to report the African face as “dark” disappeared, but it was present when gaze was free to move for just a few seconds. We conclude that the presence of the illusion depends on oculomotor behavior and we also propose a novel account based on a predictive strategy of sensory acquisition. Specifically, by differentially directing gaze towards to facial regions that are locally different in luminance, the resulting changes in retinal illuminance yield respectively darker or brighter percepts while attending to each face, hence minimizing the mismatch between visual input and the learned perceptual prototypes of ethnic categories.

Racial bias in face perception is sensitive to instructions but not introspection

“…Laeng et al, 2018), and the centre is lighter for faces with typically African features, local differences in luminance alone cannot explain the race-lightness effect in our results (it would, in fact, predict an effect in the opposite direction). Laeng et al (2018) also noted that participants showed greater pupil constriction when viewing faces with African features. They suggested that this might provide a paradoxical explanation for the race-lightness effect.…”

“…The important point however here, for the current experiment, rests with the difference (Figure 6c) : since participants tend to foveate the centre of these images (e.g. Laeng et al, 2018), and the centre is lighter for faces with typically African features, local differences in luminance alone cannot explain the race-lightness effect in our results (it would, in fact, predict an effect in the opposite direction). Laeng et al (2018) also noted that participants showed greater pupil constriction when viewing faces with African features.…”

“…However, the pupillary light reflex takes a a few hundred milliseconds to occur, and is slower for weaker changes in luminance (Ellis, 1981). The differences in pupil size found by Laeng et al (2018) were only significant almost two seconds after stimulus onset. In contrast, our mouse tracking analyses revealed significant effects of morphology approximately half a second after the onset of the second face.…”

“…It has been suggested that the race lightness effect may be due to local differences in luminance (e.g. Firestone & Scholl, 2016;Laeng et al, 2018). Real and computer-generated face images are not uniformly bright (Figure 6).…”

Filtered beauty in Oslo and Tokyo: A spatial frequency analysis of facial attractiveness

“…The shapes of faces may differ on average morphology, proportions, and/or variance across ethnicities [64][65][66][67][68]. Although for several types of perceptual decisions, there are seemingly no differences across ethnicities [69], European and Asians may sample facial information differently [70]. Some studies suggested that Asians are more "tuned" relatively to Westerners towards the LSF information in face stimuli (e.g., by attending holistically or utilizing a broader spread of attention [71]).…”