Symmetric patterns with different luminance polarity (anti‐symmetry) generate an automatic response in extrastriate cortex

Abstract

People can quickly detect bilateral reflection in an image. This is true when elements of the same luminance are matched on either side of the axis (symmetry) and when they have opposite luminance polarity (anti‐symmetry). Using electroencephalography, we measured the well‐established sustained posterior negativity (SPN) response to symmetry and anti‐symmetry. In one task, participants judged the presence or absence of regularity (Regularity Discrimination Task). In another, they judged the presence or absence of rare colored oddball trials (Colored Oddball Task). Previous work has concluded that anti‐symmetry is only detected indirectly, through serial visual search of element locations. This selective attention account predicts that the anti‐symmetry SPN should be abolished in the Colored Oddball Task because there is no need to search for anti‐symmetry. However, this prediction was not confirmed: The symmetry and anti‐symmetry SPN waves were not modulated by task. We conclude that at least some forms of anti‐symmetry can be extracted from the image automatically, in much the same way as symmetry. This is an important consideration for models of symmetry perception, which must be flexible enough to accommodate opposite luminance polarity, while also accounting for the fact anti‐symmetry is often perceptually weaker than symmetry.

Electrophysiological priming effects demonstrate independence and overlap of visual regularity representations in the extrastriate cortex

“…black regions paired with white and white regions paired with black). We know that anti-symmetry generates an SPN, albeit with slightly reduced amplitude [ 39 , 44 ]. However, it is uncertain whether symmetry and anti-symmetry are coded by the same extrastriate networks [ 38 ].…”

Lessons from a catalogue of 6674 brain recordings

“…This approach can be illustrated with 0.5 microvolt SPNs. Although these are at the low end of the distribution ( Figure 4A ), they can be interpreted and published (e.g., Makin et al, 2020a ). The average d z for a 0.5 microvolt SPN is –0.469.…”

The effect of art expertise on visual symmetry and asymmetry preference

“…/ Symmetry preference is considered to be based on an evolutionary aspect. Previous study results show that humans have a natural tendency to prefer symmetrical faces and shapes over asymmetrical ones (Makin et al, 2019). In the case of abstract stimuli, symmetry tends to have a major influence on preference, and besides symmetry, stimulus complexity also has an impact on the aesthetical experience (Gartus & Leder, 2017).…”