Neuroscience Across the Curriculum
November 23, 2015
Perception of Space
On November 23, 2015, Carly Leonard, PhD, a post-doctoral researcher at the University of California at Davis’s Center of Mind and Brain, spoke of the perception of space. She spoke of the historical and subjective perception of the external world, the biological mechanisms of perception, and some abstract principles that evolve from discussions of perception. She began with a brief discussion of the idea of extromission, which was a popular philosophical idea that was endorsed by Plato, Aristotle, and Euclid, among others, which believed that the eyes emitted a “visual fire” and that this light interacted with another body of light to produce the perception of space. Modern physiology tells us that this intuition is incorrect. Rods and cones within the fovea work to transduce photons of light to the optic nerve, which leads to the opening and closing of ion channels to allow for the brain activity to occur within the occipital lobe, extrastriate cortex, etc. However, with this knowledge of basic physiology, over 40% of individuals believe that at least some light is emitted from the eyes in order to visually perceive stimuli. Dr. Leonard used this idea to describe the various times when our perception fails us, and we do not see things that we may suspect that we see. In the “Door” study, researchers found that 50% of people did not notice when the person they were giving directions to was swapped out for another individual as a door passed them by. Leonard then spoke of how her research would run, with her using event related potentials from visuospatial attention with EEG.Her research would essentially prime individuals for a visual stimulus to appear on either the right side or the left side, with the patient having the understanding that the primer would be accurate. However, as trials continue, Leonard would vary the likelihood of the stimulus appearing on the primed side. At which point, the time it takes for the individual to push a key would be recorded to determine how quickly an individual can perceive a stimulus.