Laterality and (in)visibility in emotional face perception: Manipulations in spatial frequency content

Area of Science:

• Neuroscience
• Cognitive Psychology
• Visual Perception

Background:

• Hemispheric lateralization in emotional face perception is established.
• The underlying neural mechanisms, particularly the role of spatial frequencies and processing routes (cortical vs. subcortical), remain unclear.

Purpose of the Study:

• To investigate if low spatial frequency content drives hemispheric asymmetries in emotional face perception.
• To determine if these effects differ for clearly visible versus hidden emotional expressions.
• To elucidate the contribution of cortical and subcortical pathways to emotional processing.

Main Methods:

• Utilized broadband and hybrid faces (combining low and high spatial frequencies of different expressions).
• Employed the free-viewing emotional chimeric faces task (ECFT).
• Participants reported perceived emotional intensity between two chimeric faces presented vertically.

Main Results:

• Broadband emotional faces elicited the typical left visual field/right hemisphere (LVF/RH) bias for all basic emotions.
• Hybrid faces showed a significant LVF/RH bias only for happiness.
• Low spatial frequencies alone were insufficient to induce a consistent LVF bias, especially when emotions were not explicitly perceived.

Conclusions:

• The observed LVF/RH bias in emotional face perception is predominantly mediated by cortical pathways.
• Subcortical processing via the magnocellular pathway, activated by low spatial frequencies, is not sufficient to explain this bias under free-viewing conditions.
• Spatial frequency content plays a nuanced role, with higher frequencies potentially being necessary for robust lateralization.