Developmental visual perception deficits with no indications of prosopagnosia in a child with abnormal eye movements

Positive and negative facial valence perception are modulated differently by eccentricity in the parafovea: Replication from KDEF to NimStim

While perceiving the emotional state of others may be crucial for our behavior even when this information is present outside of central vision, emotion perception studies typically focus on central visual field. We have recently investigated emotional valence (pleasantness) perception across the parafovea (≤ 4°) and found that for briefly presented (200 ms) emotional face images (from the established KDEF image-set), positive (happy) valence was the least affected by eccentricity (distance from the central visual field) and negative (fearful) valence the most. Furthermore, we found that performance at 2° predicted performance at 4°. Here we tested (n = 37) whether these effects replicate with face stimuli of different identities from a different well-established image-set (NimStim). All our prior findings replicated and eccentricity-based modulation magnitude was smaller with NimStim (~ 16.6% accuracy reduction at 4°) than with KDEF stimuli (~ 27.3% reduction). Our current investigations support our earlier findings that for briefly presented parafoveal stimuli, positive and negative valence perception are differently affected by eccentricity and may be dissociated. Furthermore, our results highlight the importance of investigating emotions beyond central vision and demonstrate commonalities and differences across different image sets in the parafovea, emphasizing the contribution of replication studies to substantiate our knowledge about perceptual mechanisms.

Differentiation of Types of Visual Agnosia Using EEG

Visual recognition deficits are the hallmark symptom of visual agnosia, a neuropsychological disorder typically associated with damage to the visual system. Most research into visual agnosia focuses on characterizing the deficits through detailed behavioral testing, and structural and functional brain scans are used to determine the spatial extent of any cortical damage. Although the hierarchical nature of the visual system leads to clear predictions about the temporal dynamics of cortical deficits, there has been little research on the use of neuroimaging methods with high temporal resolution to characterize the temporal profile of agnosia deficits. Here, we employed high-density electroencephalography (EEG) to investigate alterations in the temporal dynamics of the visual system in two individuals with visual agnosia. In the context of a steady state visual evoked potential paradigm (SSVEP), individuals viewed pattern-reversing checkerboards of differing spatial frequency, and we assessed the responses of the visual system in the frequency and temporal domain. JW, a patient with early visual cortex damage, showed impaired SSVEP response relative to a control group and to the second patient (SM) who had right temporal lobe damage. JW also showed lower decoding accuracy for early visual responses (around 100 ms). SM, whose lesion is more anterior in the visual system, showed good decoding accuracy initially but low decoding after 500 ms. Overall, EEG and multivariate decoding methods can yield important insights into the temporal dynamics of visual responses in individuals with visual agnosia.