Human visual perception varies as a function of stimulus location.
Does the adult visual cortex represent space differently than that of a child?
“Comparing retinotopic maps of children and adults reveals a late-stage change in how V1 samples the visual field”
by Marc Himmelberg, Ekin Tünçok, Jesse Gomez, Kalanit Grill-Spector, Marisa Carrasco and Jonathan Winawer
published in Nature Communications
A fascinating discovery from my PhD research revealed how children's brains organize visual space differently than adults. Using brain imaging, we found that while many aspects of visual processing are remarkably mature by early childhood, there's one crucial difference that emerges later in development.
Both adults and children show better visual performance for stimuli along the horizontal than vertical meridian of the visual field. Adults show better visual performance for stimuli at the lower than the upper vertical meridian, but not children. We found that the horizontal-vertical asymmetry that is present in both adults and children is matched by how much brain tissue is dedicated to processing these regions in early visual cortex. Strikingly, adult humans but not children show a cortical asymmetry between the lower and upper vertical meridian locations — in line with behavioral performance observed in these age groups!
This means that even though most of the visual system looks adult-like by childhood, there's a large, late-stage change in how V1 samples the visual field that parallels the emergence of a vertical meridian asymmetry in visual performance by adulthood.
This finding suggests that our brains continue to adapt to the demands of our visual environment well into development—perhaps reflecting how children and adults navigate and interact with the world differently.
Does visual performance vary by location similarly in macaque monkeys and humans?
“Opposite asymmetry in visual perception of humans and macaques”
by Ekin Tünçok, Lynne Kiorpes and Marisa Carrasco
published in Current Biology
One of the most interesting discoveries from my PhD research was finding that humans and our close evolutionary relatives see the world differently. While we both have spatial 'blind spots' and strengths in our vision, they're actually in opposite locations.
When we tested motion perception across the visual field in humans versus macaque monkeys, we discovered that humans show the lowest perceptual sensitivity around the upper vertical meridian from their gaze position, while the macaque performance is the poorest around the lower vertical meridian location from their gaze! This was surprising because for decades, researchers have used macaque monkeys as models for human vision, assuming our visual systems work similarly.
This finding suggests that different evolutionary pressures shaped how humans and macaques process visual information. Perhaps our upright posture and walking behavior led to different environmental statistics in the lower parts of our visual field, while macaques' arboreal lifestyle favored upper visual field processing for detecting threats and navigating climbing.
